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|
||
<h1>Asynchronous Programming<a class="headerlink" href="#asynchronous-programming" title="Permalink to this headline">#</a></h1>
|
||
<section id="summary">
|
||
<h2>Summary<a class="headerlink" href="#summary" title="Permalink to this headline">#</a></h2>
|
||
<ul class="simple">
|
||
<li><p>Use asynchronous calls in preference to synchronous calls or explicit use of
|
||
threads</p></li>
|
||
<li><p>Learn and follow the GLib pattern for declaring asynchronous APIs</p></li>
|
||
<li><p>Place callbacks from asynchronous functions in order down the file, so control
|
||
flow is easy to follow</p></li>
|
||
<li><p>Use the presence of a <code class="docutils literal notranslate"><span class="pre">GTask</span></code> or <code class="docutils literal notranslate"><span class="pre">GCancellable</span></code> to indicate whether an
|
||
operation is ongoing</p></li>
|
||
<li><p>If running operations in parallel, track how many operations are yet to start,
|
||
and how many are yet to finish — the overall operation is complete once both
|
||
counts are zero</p></li>
|
||
<li><p>Separate state for operations into ‘task data’ structures for <code class="docutils literal notranslate"><span class="pre">GTask</span></code>,
|
||
allowing operations to be reused more easily without needing changes to
|
||
global state handling</p></li>
|
||
<li><p>Consider how asynchronous methods on an object instance interact with
|
||
finalization of that instance</p></li>
|
||
</ul>
|
||
</section>
|
||
<section id="concepts">
|
||
<h2>Concepts<a class="headerlink" href="#concepts" title="Permalink to this headline">#</a></h2>
|
||
<p>GLib supports <em>asynchronous programming</em>, where long-running operations can be
|
||
started, run ‘in the background’, and a callback invoked when they are finished
|
||
and their results are available. This is in direct contrast to synchronous
|
||
long-running operations, which are a single function call which blocks program
|
||
control flow until complete.</p>
|
||
<p>As discussed in the <a class="reference internal" href="main-contexts.html"><span class="doc">Main Contexts</span></a> and in the
|
||
<a class="reference internal" href="threading.html"><span class="doc">Threading</span></a> tutorials, asynchronous operations
|
||
should be favoured over synchronous ones and over explicit use of threading.
|
||
They do not block the main context like sychronous operations do; and are
|
||
easier to use correctly than threads. They often also have a lower performance
|
||
penalty than spawning a thread and sending work to it.</p>
|
||
</section>
|
||
<section id="api-patterns">
|
||
<h2>API patterns<a class="headerlink" href="#api-patterns" title="Permalink to this headline">#</a></h2>
|
||
<p>Asynchronous calls follow a standard pattern in GLib code. For an operation
|
||
named <code class="docutils literal notranslate"><span class="pre">load_data</span></code> on the <code class="docutils literal notranslate"><span class="pre">File</span></code> class in the <code class="docutils literal notranslate"><span class="pre">Foo</span></code> namespace, there will
|
||
be:</p>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">foo_file_load_data_async</span><span class="w"> </span><span class="p">(</span><span class="n">FooFile</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="c1">// ...,</span>
|
||
<span class="w"> </span><span class="n">GCancellable</span><span class="w"> </span><span class="o">*</span><span class="n">cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncReadyCallback</span><span class="w"> </span><span class="n">callback</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="n">gboolean</span><span class="w"></span>
|
||
<span class="nf">foo_file_load_data_finish</span><span class="w"> </span><span class="p">(</span><span class="n">FooFile</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="c1">// ...,</span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">**</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The <code class="docutils literal notranslate"><span class="pre">…</span></code> parameters to <code class="docutils literal notranslate"><span class="pre">foo_file_load_data_async()</span></code> are those specific to the
|
||
operation—in this case, perhaps the size of a buffer to load into. Similarly for
|
||
<code class="docutils literal notranslate"><span class="pre">foo_file_load_data_finish()</span></code> they are the operation-specific return
|
||
values—perhaps a location to return a content type string in this case.</p>
|
||
<p>When <code class="docutils literal notranslate"><span class="pre">foo_file_load_data_async()</span></code> is called, it schedules the load operation
|
||
in the background (as a new file descriptor on the <code class="docutils literal notranslate"><span class="pre">GMainContext</span></code> or as a
|
||
worker thread, for example), then returns without blocking.</p>
|
||
<p>When the operation is complete, the callback is executed in the same
|
||
<code class="docutils literal notranslate"><span class="pre">GMainContext</span></code> as the original asynchronous call. The callback is invoked
|
||
exactly once, whether the operation succeeded or failed.</p>
|
||
<p>From the callback, <code class="docutils literal notranslate"><span class="pre">foo_file_load_data_finish()</span></code> may be called by the user’s
|
||
code to retrieve return values and error details, passing the <code class="docutils literal notranslate"><span class="pre">GAsyncResult</span></code>
|
||
instance which was passed to the callback.</p>
|
||
</section>
|
||
<section id="operation-lifetimes">
|
||
<h2>Operation Lifetimes<a class="headerlink" href="#operation-lifetimes" title="Permalink to this headline">#</a></h2>
|
||
<p>When writing asynchronous operations, it is common to write them as methods of a
|
||
class. In this case, it is important to define how ongoing operations on a class
|
||
instance interact with finalization of that instance. There are two approaches:</p>
|
||
<dl class="simple">
|
||
<dt><strong>Strong</strong></dt><dd><p>The ongoing operation keeps a reference to the class instance, forcing it to
|
||
remain alive for the duration of the operation. The class should provide some
|
||
kind of ‘close’ or ‘cancel’ method which can be used by other classes to force
|
||
cancellation of the operation and allow that instance to be finalized.</p>
|
||
</dd>
|
||
<dt><strong>Weak</strong></dt><dd><p>The ongoing operation does <em>not</em> keep a reference to the class instance, and
|
||
the class cancels the operation (using <code class="docutils literal notranslate"><span class="pre">g_cancellable_cancel()</span></code>) in its
|
||
dispose function.</p>
|
||
</dd>
|
||
</dl>
|
||
<p>Which approach is used depends on the class’ design. A class which wraps a
|
||
particular operation (perhaps a <code class="docutils literal notranslate"><span class="pre">MyFileTransfer</span></code> class, for example) might
|
||
want to use the <em>weak</em> approach. A class which manages multiple network
|
||
connections and asynchronous operations on them may use the <em>strong</em> approach
|
||
instead. Due to incoming network connections, for example, it might not be in
|
||
complete control of the scheduling of its asynchronous calls, so the weak
|
||
approach would not be appropriate—any code dropping a reference to the object
|
||
could not be sure it was not accidentally killing a new network connection.</p>
|
||
</section>
|
||
<section id="using-asynchronous-functions">
|
||
<h2>Using asynchronous functions<a class="headerlink" href="#using-asynchronous-functions" title="Permalink to this headline">#</a></h2>
|
||
<p>It is often the case that multiple asynchronous calls need to be used to
|
||
complete an operation. For example, opening a file for reading, then performing
|
||
a couple of reads, and then closing the file. Or opening several network sockets
|
||
in parallel and waiting until they are all open before continuing with other
|
||
work. Some examples of these situations are given below.</p>
|
||
<section id="single-operation">
|
||
<h3>Single operation<a class="headerlink" href="#single-operation" title="Permalink to this headline">#</a></h3>
|
||
<p>A single asynchronous call requires two functions: one to start the operation,
|
||
and one to complete it. In C, the demanding part of performing an asynchronous
|
||
call is correctly storing state between these two functions, and handling
|
||
changes to that state in the time between those two functions being called. For
|
||
example, cancellation of an ongoing asynchronous call is a state change, and if
|
||
not implemented carefully, any UI updates (for example) made when cancelling an
|
||
operation will be undone by updates in the operation’s callback.</p>
|
||
<p>The example below demonstrates copying a file from one location in the file
|
||
system to another. The key principles demonstrated here are:</p>
|
||
<ul class="simple">
|
||
<li><p>Placing the <code class="docutils literal notranslate"><span class="pre">copy_button_clicked_cb()</span></code> (start) and <code class="docutils literal notranslate"><span class="pre">copy_finish_cb()</span></code>
|
||
(finish) functions in order by using a forward declaration for
|
||
<code class="docutils literal notranslate"><span class="pre">copy_finish_cb()</span></code>. This means the control flow continues linearly down the
|
||
file, rather than getting to the bottom of <code class="docutils literal notranslate"><span class="pre">copy_button_clicked_cb()</span></code> and
|
||
resuming in <code class="docutils literal notranslate"><span class="pre">copy_finish_cb()</span></code> somewhere else in the file.</p></li>
|
||
<li><p>Using a <code class="docutils literal notranslate"><span class="pre">GCancellable</span></code> to allow cancelling the operation after it has
|
||
started. The code in <code class="docutils literal notranslate"><span class="pre">cancel_button_clicked_cb()</span></code> is very simple: as the
|
||
<code class="docutils literal notranslate"><span class="pre">copy_finish_cb()</span></code> callback is guaranteed to be invoked when the operation
|
||
completes (even when completing early due to cancellation), all the UI and
|
||
state updates for cancellation can be handled there, rather than in
|
||
<code class="docutils literal notranslate"><span class="pre">cancel_button_clicked_cb()</span></code>.</p></li>
|
||
<li><p>An operation is ongoing exactly while <code class="docutils literal notranslate"><span class="pre">MyObjectPrivate.copy_cancellable</span></code> is
|
||
not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, making it easy to track running operations. Note that this
|
||
means only one file copy operation can be started via
|
||
<code class="docutils literal notranslate"><span class="pre">copy_button_clicked_cb()</span></code> at a time. One <code class="docutils literal notranslate"><span class="pre">GCancellable</span></code> cannot easily be
|
||
used for multiple operations like this.</p></li>
|
||
</ul>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">copy_finish_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">copy_button_clicked_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GtkButton</span><span class="w"> </span><span class="o">*</span><span class="n">button</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="o">*</span><span class="n">destination</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Operation already in progress? */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_debug</span><span class="w"> </span><span class="p">(</span><span class="s">"Copy already in progress."</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">return</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Build source and destination file paths. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_file_new_for_path</span><span class="w"> </span><span class="p">(</span><span class="cm">/* some path generated from UI */</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">destination</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_file_new_for_path</span><span class="w"> </span><span class="p">(</span><span class="cm">/* some other path generated from UI */</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Set up a cancellable. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_cancellable_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_file_copy_async</span><span class="w"> </span><span class="p">(</span><span class="n">source</span><span class="p">,</span><span class="w"> </span><span class="n">destination</span><span class="p">,</span><span class="w"> </span><span class="n">G_FILE_COPY_NONE</span><span class="p">,</span><span class="w"> </span><span class="n">G_PRIORITY_DEFAULT</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">copy_finish_cb</span><span class="p">,</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">destination</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">source</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update UI to show copy is in progress. */</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">copy_finish_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">source</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_FILE</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Handle completion of the operation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_copy_finish</span><span class="w"> </span><span class="p">(</span><span class="n">source</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="w"> </span><span class="o">&&</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">!</span><span class="n">g_error_matches</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_CANCELLED</span><span class="p">))</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Should update the UI to signal failure.</span>
|
||
<span class="cm"> * Ignore failure due to cancellation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Failed to copy file: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_error</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Clear the cancellable to signify the operation has finished. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update UI to show copy as complete. */</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">cancel_button_clicked_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GtkButton</span><span class="w"> </span><span class="o">*</span><span class="n">button</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="o">*</span><span class="n">destination</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Operation in progress? No-op if @copy_cancellable is %NULL. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_cancellable_cancel</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_dispose</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">obj</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Cancel any ongoing copy operation.</span>
|
||
<span class="cm"> *</span>
|
||
<span class="cm"> * This ensures that if #MyObject is disposed part-way through a copy, the</span>
|
||
<span class="cm"> * callback doesn’t get invoked with an invalid #MyObject pointer. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_cancellable_cancel</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">copy_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Do other dispose calls here. */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Chain up. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_OBJECT_CLASS</span><span class="w"> </span><span class="p">(</span><span class="n">my_object_parent_class</span><span class="p">)</span><span class="o">-></span><span class="n">dispose</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
<p>For comparison, here is the same code implemented using the synchronous version
|
||
of <code class="docutils literal notranslate"><span class="pre">g_file_copy()</span></code>. Note how the order of statements is almost identical. The
|
||
UI is blocked from updating and receiving user input, which also means that
|
||
cancellation cannot be supported. This is the main reason why this code should
|
||
not be used in practice:</p>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">copy_button_clicked_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GtkButton</span><span class="w"> </span><span class="o">*</span><span class="n">button</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="o">*</span><span class="n">destination</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Build source and destination file paths. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">source</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_file_new_for_path</span><span class="w"> </span><span class="p">(</span><span class="cm">/* some path generated from UI */</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">destination</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_file_new_for_path</span><span class="w"> </span><span class="p">(</span><span class="cm">/* some other path generated from UI */</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_file_copy</span><span class="w"> </span><span class="p">(</span><span class="n">source</span><span class="p">,</span><span class="w"> </span><span class="n">destination</span><span class="p">,</span><span class="w"> </span><span class="n">G_FILE_COPY_NONE</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="nb">NULL</span><span class="w"> </span><span class="cm">/* cancellable */</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">destination</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">source</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Handle completion of the operation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Should update the UI to signal failure.</span>
|
||
<span class="cm"> * Ignore failure due to cancellation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Failed to copy file: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_error</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update UI to show copy as complete. */</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</section>
|
||
<section id="operations-in-series">
|
||
<h3>Operations in series<a class="headerlink" href="#operations-in-series" title="Permalink to this headline">#</a></h3>
|
||
<p>A common situation is to run multiple asynchronous operations in series, when
|
||
each operation depends on the previous one completing.</p>
|
||
<p>In this example, the application reads a socket address from a file, opens a
|
||
connection to that address, reads a message, and then finishes.</p>
|
||
<p>Key points in this example are:</p>
|
||
<ul class="simple">
|
||
<li><p>Each callback is numbered consistently, and they are all placed in order in
|
||
the file so the code follows sequentially.</p></li>
|
||
<li><p>As in the single-call example, a single <code class="docutils literal notranslate"><span class="pre">GCancellable</span></code> indicates that the
|
||
series of operations is ongoing. Cancelling it aborts the entire sequence.</p></li>
|
||
<li><p>As in the single-call example, the pending operation is cancelled if the
|
||
owning <code class="docutils literal notranslate"><span class="pre">MyObject</span></code> instance is disposed, to prevent callbacks being called
|
||
later with an invalid MyObject pointer.</p></li>
|
||
</ul>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb1</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb2</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb3</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server</span><span class="w"> </span><span class="p">(</span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Already connecting. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">return</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Set up a cancellable. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_cancellable_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Read the socket address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">build_address_file</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_load_contents_async</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">,</span><span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb1</span><span class="p">,</span><span class="w"> </span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb1</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">address_file</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gchar</span><span class="w"> </span><span class="o">*</span><span class="n">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gsize</span><span class="w"> </span><span class="n">address_size</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInetAddress</span><span class="w"> </span><span class="o">*</span><span class="n">inet_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInetSocketAddress</span><span class="w"> </span><span class="o">*</span><span class="n">inet_socket_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">guint16</span><span class="w"> </span><span class="n">port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">123</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketClient</span><span class="w"> </span><span class="o">*</span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_FILE</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish loading the address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_load_contents_finish</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">address</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">&</span><span class="n">address_size</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Parse the address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">inet_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_inet_address_new_from_string</span><span class="w"> </span><span class="p">(</span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">inet_address</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_set_error</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_INVALID_ARGUMENT</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="s">"Invalid address ‘%s’."</span><span class="p">,</span><span class="w"> </span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">inet_socket_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_inet_socket_address_new</span><span class="w"> </span><span class="p">(</span><span class="n">inet_address</span><span class="p">,</span><span class="w"> </span><span class="n">port</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Connect to the given address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_socket_client_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_socket_client_connect_async</span><span class="w"> </span><span class="p">(</span><span class="n">socket_client</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_SOCKET_CONNECTABLE</span><span class="w"> </span><span class="p">(</span><span class="n">inet_socket_address</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb2</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Stop the operation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">g_error_matches</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_CANCELLED</span><span class="p">))</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Failed to load server address: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_error_free</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_free</span><span class="w"> </span><span class="p">(</span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">inet_address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">inet_socket_address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">socket_client</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb2</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketClient</span><span class="w"> </span><span class="o">*</span><span class="n">socket_client</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketConnection</span><span class="w"> </span><span class="o">*</span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInputStream</span><span class="w"> </span><span class="o">*</span><span class="n">input_stream</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_SOCKET_CLIENT</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish connecting to the socket. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_socket_client_connect_finish</span><span class="w"> </span><span class="p">(</span><span class="n">socket_client</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Store a reference to the connection so it is kept open while we read from</span>
|
||
<span class="cm"> * it: #GInputStream does not keep a reference to a #GIOStream which contains</span>
|
||
<span class="cm"> * it. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Read a message from the connection. This uses a single buffer stored in</span>
|
||
<span class="cm"> * #MyObject, meaning that only one connect_to_server() operation can run at</span>
|
||
<span class="cm"> * any time. The buffer could instead be allocated dynamically if this is a</span>
|
||
<span class="cm"> * problem. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">input_stream</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_io_stream_get_input_stream</span><span class="w"> </span><span class="p">(</span><span class="n">G_IO_STREAM</span><span class="w"> </span><span class="p">(</span><span class="n">connection</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_input_stream_read_async</span><span class="w"> </span><span class="p">(</span><span class="n">input_stream</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">sizeof</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_PRIORITY_DEFAULT</span><span class="p">,</span><span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb3</span><span class="p">,</span><span class="w"> </span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Stop the operation. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">g_error_matches</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_CANCELLED</span><span class="p">))</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Failed to connect to server: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_error_free</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb3</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInputStream</span><span class="w"> </span><span class="o">*</span><span class="n">input_stream</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gssize</span><span class="w"> </span><span class="n">len</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">input_stream</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_INPUT_STREAM</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish reading from the socket. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">len</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_input_stream_read_finish</span><span class="w"> </span><span class="p">(</span><span class="n">input_stream</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Handle the message. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_assert_cmpint</span><span class="w"> </span><span class="p">(</span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o">>=</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_assert_cmpuint</span><span class="w"> </span><span class="p">((</span><span class="n">gsize</span><span class="p">)</span><span class="w"> </span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o"><=</span><span class="p">,</span><span class="w"> </span><span class="k">sizeof</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">handle_received_message</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">,</span><span class="w"> </span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Unconditionally mark the operation as finished.</span>
|
||
<span class="cm"> *</span>
|
||
<span class="cm"> * The streams should automatically close as this</span>
|
||
<span class="cm"> * last reference is dropped. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Warn about the error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="o">!</span><span class="n">g_error_matches</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_CANCELLED</span><span class="p">))</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Failed to read from the server: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_error_free</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_dispose</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">obj</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Cancel any ongoing connection operations.</span>
|
||
<span class="cm"> *</span>
|
||
<span class="cm"> * This ensures that if #MyObject is disposed part-way through the</span>
|
||
<span class="cm"> * connect_to_server() sequence of operations, the sequence gets cancelled and</span>
|
||
<span class="cm"> * doesn’t continue with an invalid #MyObject pointer. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_cancellable_cancel</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Do other dispose calls here. */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Chain up. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_OBJECT_CLASS</span><span class="w"> </span><span class="p">(</span><span class="n">my_object_parent_class</span><span class="p">)</span><span class="o">-></span><span class="n">dispose</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</section>
|
||
<section id="operations-in-parallel">
|
||
<h3>Operations in parallel<a class="headerlink" href="#operations-in-parallel" title="Permalink to this headline">#</a></h3>
|
||
<p>Another common situation is to run multiple asynchronous operations in parallel,
|
||
considering the overall operation complete when all its constituents are
|
||
complete.</p>
|
||
<p>In this example, the application deletes multiple files in parallel.</p>
|
||
<p>Key points in this example are:</p>
|
||
<ul class="simple">
|
||
<li><p>The number of pending asynchronous operations (ones which have started but not
|
||
yet finished) is tracked as <code class="docutils literal notranslate"><span class="pre">n_deletions_pending</span></code>. The <code class="docutils literal notranslate"><span class="pre">delete_files_cb()</span></code>
|
||
callback only considers the entire operation complete once this reaches zero.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">n_deletions_to_start</span></code> tracks deletion operations being started, in case
|
||
<code class="docutils literal notranslate"><span class="pre">g_file_delete_async()</span></code> manages to use a fast path and complete
|
||
synchronously (without blocking).</p></li>
|
||
<li><p>As in the single-call example, all pending deletions are cancelled if the
|
||
owning <code class="docutils literal notranslate"><span class="pre">MyObject</span></code> instance is disposed, to prevent callbacks being called
|
||
later with an invalid <code class="docutils literal notranslate"><span class="pre">MyObject</span></code> pointer.</p></li>
|
||
</ul>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">delete_files_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">delete_files</span><span class="w"> </span><span class="p">(</span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GPtrArray</span><span class="cm">/*<owned GFile*>>*/</span><span class="w"> </span><span class="o">*</span><span class="n">files</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Set up a cancellable if no operation is ongoing already. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">delete_cancellable</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">delete_cancellable</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_cancellable_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_total</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update internal state, and temporarily set @n_deletions_to_start. This is</span>
|
||
<span class="cm"> * used in delete_files_cb() to avoid indicating the overall operation has</span>
|
||
<span class="cm"> * completed while deletions are still being started. This can happen if</span>
|
||
<span class="cm"> * g_file_delete_async() completes synchronously, for example if there’s a</span>
|
||
<span class="cm"> * non-blocking fast path for the given file system. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="n">files</span><span class="o">-></span><span class="n">len</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_total</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="n">files</span><span class="o">-></span><span class="n">len</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_to_start</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">files</span><span class="o">-></span><span class="n">len</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update the UI to indicate the files are being deleted. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">update_ui_to_show_progress</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_total</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Start all the deletion operations in parallel. They share the same</span>
|
||
<span class="cm"> * #GCancellable. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="p">(</span><span class="n">i</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="w"> </span><span class="o"><</span><span class="w"> </span><span class="n">files</span><span class="o">-></span><span class="n">len</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">files</span><span class="o">-></span><span class="n">pdata</span><span class="p">[</span><span class="n">i</span><span class="p">];</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_to_start</span><span class="o">--</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_delete_async</span><span class="w"> </span><span class="p">(</span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="n">G_PRIORITY_DEFAULT</span><span class="p">,</span><span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">delete_cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">delete_files_cb</span><span class="p">,</span><span class="w"> </span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">delete_files_cb</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">file</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_FILE</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish deleting the file. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_delete_finish</span><span class="w"> </span><span class="p">(</span><span class="n">file</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="w"> </span><span class="o">&&</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">!</span><span class="n">g_error_matches</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_CANCELLED</span><span class="p">))</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_warning</span><span class="w"> </span><span class="p">(</span><span class="s">"Error deleting file: %s"</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="o">-></span><span class="n">message</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_error</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update the internal state. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_assert_cmpuint</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="p">,</span><span class="w"> </span><span class="o">></span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="o">--</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Update the UI to show progress. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">update_ui_to_show_progress</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_total</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* If all deletions have completed, and no more are being started,</span>
|
||
<span class="cm"> * update the UI to show completion. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_pending</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">&&</span><span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_to_start</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">update_ui_to_show_completion</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Clear the operation state. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">delete_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">n_deletions_total</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_dispose</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">obj</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">MY_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Cancel any ongoing deletion operations.</span>
|
||
<span class="cm"> *</span>
|
||
<span class="cm"> * This ensures that if #MyObject is disposed part-way through the</span>
|
||
<span class="cm"> * delete_files() set of operations, the set gets cancelled and</span>
|
||
<span class="cm"> * doesn’t continue with an invalid #MyObject pointer. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_cancellable_cancel</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">delete_cancellable</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Do other dispose calls here. */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Chain up. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_OBJECT_CLASS</span><span class="w"> </span><span class="p">(</span><span class="n">my_object_parent_class</span><span class="p">)</span><span class="o">-></span><span class="n">dispose</span><span class="w"> </span><span class="p">(</span><span class="n">obj</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</section>
|
||
<section id="wrapping-with-gtask">
|
||
<h3>Wrapping with GTask<a class="headerlink" href="#wrapping-with-gtask" title="Permalink to this headline">#</a></h3>
|
||
<p>Often when an asynchronous operation (or set of operations) becomes more
|
||
complex, it needs associated state. This is typically stored in a custom
|
||
structure — but defining a new structure to store the standard callback, user
|
||
data and cancellable tuple is laborious. <code class="docutils literal notranslate"><span class="pre">GTask</span></code> eases this by providing a
|
||
standardized way to wrap all three, plus extra custom ‘task data’.</p>
|
||
<p>The use of a <code class="docutils literal notranslate"><span class="pre">GTask</span></code> can replace the use of a <code class="docutils literal notranslate"><span class="pre">GCancellable</span></code> for
|
||
indicating whether an operation is ongoing.</p>
|
||
<p>This example is functionally the same as the operations in series example,
|
||
but refactored to use a <code class="docutils literal notranslate"><span class="pre">GTask</span></code> to wrap the sequence of operations.</p>
|
||
<p>Key points in this example are:</p>
|
||
<ul class="simple">
|
||
<li><p>State which was in <code class="docutils literal notranslate"><span class="pre">MyObjectPrivate</span></code> in the series example is now in the
|
||
<code class="docutils literal notranslate"><span class="pre">ConnectToServerData</span></code> closure, which is set as the ‘task data’ of the
|
||
<code class="docutils literal notranslate"><span class="pre">GTask</span></code> representing the overall operation. This means it’s automatically
|
||
freed after the operation returns.</p></li>
|
||
<li><p>Furthermore, this means that manipulations of <code class="docutils literal notranslate"><span class="pre">MyObjectPrivate</span></code> state are
|
||
limited to the start and end of the sequence of operations, so reusing the
|
||
task in different situations becomes possible—for example, it is now a lot
|
||
easier to support running multiple such tasks in parallel.</p></li>
|
||
<li><p>As the <code class="docutils literal notranslate"><span class="pre">GTask</span></code> holds a reference to <code class="docutils literal notranslate"><span class="pre">MyObject</span></code>, it is impossible for the
|
||
object to be disposed while the sequence of operations is ongoing, so the
|
||
<code class="docutils literal notranslate"><span class="pre">my_object_dispose()</span></code> code has been removed. Instead, a
|
||
<code class="docutils literal notranslate"><span class="pre">my_object_close()</span></code> method exists to allow any pending operations can be
|
||
cancelled so <code class="docutils literal notranslate"><span class="pre">MyObject</span></code> can be disposed when desired.</p></li>
|
||
</ul>
|
||
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb1</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb2</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb3</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="k">typedef</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketConnection</span><span class="w"> </span><span class="o">*</span><span class="n">connection</span><span class="p">;</span><span class="w"> </span><span class="cm">/* nullable; owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">guint8</span><span class="w"> </span><span class="n">message_buffer</span><span class="p">[</span><span class="mi">128</span><span class="p">];</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"> </span><span class="n">ConnectToServerData</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_data_free</span><span class="w"> </span><span class="p">(</span><span class="n">ConnectToServerData</span><span class="w"> </span><span class="o">*</span><span class="n">data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">data</span><span class="o">-></span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_connect_to_server_async</span><span class="w"> </span><span class="p">(</span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GCancellable</span><span class="w"> </span><span class="o">*</span><span class="n">cancellable</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncReadyCallback</span><span class="w"> </span><span class="n">callback</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GTask</span><span class="w"> </span><span class="o">*</span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">ConnectToServerData</span><span class="w"> </span><span class="o">*</span><span class="n">data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">MY_IS_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">));</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">G_IS_CANCELLABLE</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_report_new_error</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"> </span><span class="n">callback</span><span class="p">,</span><span class="w"> </span><span class="n">user_data</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_PENDING</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="s">"Already connecting to the server."</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">return</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Set up a cancellable. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">else</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">cancellable</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_cancellable_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Set up the task. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_new</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"> </span><span class="n">cancellable</span><span class="p">,</span><span class="w"> </span><span class="n">callback</span><span class="p">,</span><span class="w"> </span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_set_check_cancellable</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">FALSE</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_malloc0</span><span class="w"> </span><span class="p">(</span><span class="k">sizeof</span><span class="w"> </span><span class="p">(</span><span class="n">ConnectToServerData</span><span class="p">));</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_set_task_data</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">data</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">(</span><span class="n">GDestroyNotify</span><span class="p">)</span><span class="w"> </span><span class="n">connect_to_server_data_free</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Read the socket address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">build_address_file</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_load_contents_async</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">,</span><span class="w"> </span><span class="n">g_task_get_cancellable</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb1</span><span class="p">,</span><span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">));</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_unref</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb1</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GTask</span><span class="w"> </span><span class="o">*</span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GFile</span><span class="w"> </span><span class="o">*</span><span class="n">address_file</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gchar</span><span class="w"> </span><span class="o">*</span><span class="n">address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gsize</span><span class="w"> </span><span class="n">address_size</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInetAddress</span><span class="w"> </span><span class="o">*</span><span class="n">inet_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInetSocketAddress</span><span class="w"> </span><span class="o">*</span><span class="n">inet_socket_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">guint16</span><span class="w"> </span><span class="n">port</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">123</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketClient</span><span class="w"> </span><span class="o">*</span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">address_file</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_FILE</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_TASK</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_source_object</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish loading the address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_file_load_contents_finish</span><span class="w"> </span><span class="p">(</span><span class="n">address_file</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">address</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">&</span><span class="n">address_size</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Parse the address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">inet_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_inet_address_new_from_string</span><span class="w"> </span><span class="p">(</span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">inet_address</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_set_error</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">error</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR</span><span class="p">,</span><span class="w"> </span><span class="n">G_IO_ERROR_INVALID_ARGUMENT</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="s">"Invalid address ‘%s’."</span><span class="p">,</span><span class="w"> </span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">inet_socket_address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_inet_socket_address_new</span><span class="w"> </span><span class="p">(</span><span class="n">inet_address</span><span class="p">,</span><span class="w"> </span><span class="n">port</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Connect to the given address. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_socket_client_new</span><span class="w"> </span><span class="p">();</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_socket_client_connect_async</span><span class="w"> </span><span class="p">(</span><span class="n">socket_client</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_SOCKET_CONNECTABLE</span><span class="w"> </span><span class="p">(</span><span class="n">inet_socket_address</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_get_cancellable</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb2</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Stop the operation and propagate the error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_return_error</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_free</span><span class="w"> </span><span class="p">(</span><span class="n">address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">inet_address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">inet_socket_address</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">socket_client</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb2</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GTask</span><span class="w"> </span><span class="o">*</span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">ConnectToServerData</span><span class="w"> </span><span class="o">*</span><span class="n">data</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketClient</span><span class="w"> </span><span class="o">*</span><span class="n">socket_client</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GSocketConnection</span><span class="w"> </span><span class="o">*</span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInputStream</span><span class="w"> </span><span class="o">*</span><span class="n">input_stream</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">socket_client</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_SOCKET_CLIENT</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_TASK</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_task_data</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_source_object</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish connecting to the socket. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_socket_client_connect_finish</span><span class="w"> </span><span class="p">(</span><span class="n">socket_client</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Store a reference to the connection so it is kept open while we read from</span>
|
||
<span class="cm"> * it: #GInputStream does not keep a reference to a #GIOStream which contains</span>
|
||
<span class="cm"> * it. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">data</span><span class="o">-></span><span class="n">connection</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Read a message from the connection. As the buffer is allocated as part of</span>
|
||
<span class="cm"> * the per-task @data, multiple tasks can run concurrently. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">input_stream</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_io_stream_get_input_stream</span><span class="w"> </span><span class="p">(</span><span class="n">G_IO_STREAM</span><span class="w"> </span><span class="p">(</span><span class="n">connection</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_input_stream_read_async</span><span class="w"> </span><span class="p">(</span><span class="n">input_stream</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">data</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">sizeof</span><span class="w"> </span><span class="p">(</span><span class="n">data</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">G_PRIORITY_DEFAULT</span><span class="p">,</span><span class="w"> </span><span class="n">g_task_get_cancellable</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">),</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">connect_to_server_cb3</span><span class="p">,</span><span class="w"> </span><span class="n">g_object_ref</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Stop the operation and propagate the error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_return_error</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">connection</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="k">static</span><span class="w"> </span><span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">connect_to_server_cb3</span><span class="w"> </span><span class="p">(</span><span class="n">GObject</span><span class="w"> </span><span class="o">*</span><span class="n">source_object</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gpointer</span><span class="w"> </span><span class="n">user_data</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GTask</span><span class="w"> </span><span class="o">*</span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"> </span><span class="cm">/* owned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">ConnectToServerData</span><span class="w"> </span><span class="o">*</span><span class="n">data</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GInputStream</span><span class="w"> </span><span class="o">*</span><span class="n">input_stream</span><span class="p">;</span><span class="w"> </span><span class="cm">/* unowned */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">gssize</span><span class="w"> </span><span class="n">len</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">input_stream</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_INPUT_STREAM</span><span class="w"> </span><span class="p">(</span><span class="n">source_object</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">task</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">G_TASK</span><span class="w"> </span><span class="p">(</span><span class="n">user_data</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">data</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_task_data</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">self</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_source_object</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Finish reading from the socket. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">len</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_input_stream_read_finish</span><span class="w"> </span><span class="p">(</span><span class="n">input_stream</span><span class="p">,</span><span class="w"> </span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Handle the message. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_assert_cmpint</span><span class="w"> </span><span class="p">(</span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o">>=</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_assert_cmpuint</span><span class="w"> </span><span class="p">((</span><span class="n">gsize</span><span class="p">)</span><span class="w"> </span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o"><=</span><span class="p">,</span><span class="w"> </span><span class="k">sizeof</span><span class="w"> </span><span class="p">(</span><span class="n">data</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">handle_received_message</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">,</span><span class="w"> </span><span class="n">data</span><span class="o">-></span><span class="n">message_buffer</span><span class="p">,</span><span class="w"> </span><span class="n">len</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">done</span><span class="p">;</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="cm">/* Success! */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_return_boolean</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">TRUE</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="nl">done</span><span class="p">:</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Unconditionally mark the operation as finished.</span>
|
||
<span class="cm"> *</span>
|
||
<span class="cm"> * The streams should automatically close as this</span>
|
||
<span class="cm"> * last reference is dropped. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="cm">/* Stop the operation and propagate the error. */</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_task_return_error</span><span class="w"> </span><span class="p">(</span><span class="n">task</span><span class="p">,</span><span class="w"> </span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_clear_object</span><span class="w"> </span><span class="p">(</span><span class="o">&</span><span class="n">task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_connect_to_server_finish</span><span class="w"> </span><span class="p">(</span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GAsyncResult</span><span class="w"> </span><span class="o">*</span><span class="n">result</span><span class="p">,</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GError</span><span class="w"> </span><span class="o">**</span><span class="n">error</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">MY_IS_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">));</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">g_task_is_valid</span><span class="w"> </span><span class="p">(</span><span class="n">result</span><span class="p">,</span><span class="w"> </span><span class="n">self</span><span class="p">));</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">error</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="o">*</span><span class="n">error</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_task_propagate_boolean</span><span class="w"> </span><span class="p">(</span><span class="n">G_TASK</span><span class="w"> </span><span class="p">(</span><span class="n">result</span><span class="p">),</span><span class="w"> </span><span class="n">error</span><span class="p">);</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
|
||
<span class="kt">void</span><span class="w"></span>
|
||
<span class="nf">my_object_close</span><span class="w"> </span><span class="p">(</span><span class="n">MyObject</span><span class="w"> </span><span class="o">*</span><span class="n">self</span><span class="p">)</span><span class="w"></span>
|
||
<span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">MyObjectPrivate</span><span class="w"> </span><span class="o">*</span><span class="n">priv</span><span class="p">;</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">g_return_if_fail</span><span class="w"> </span><span class="p">(</span><span class="n">MY_IS_OBJECT</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">));</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="n">priv</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">my_object_get_instance_private</span><span class="w"> </span><span class="p">(</span><span class="n">self</span><span class="p">);</span><span class="w"></span>
|
||
|
||
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">GCancellable</span><span class="w"> </span><span class="o">*</span><span class="n">cancellable</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">g_task_get_cancellable</span><span class="w"> </span><span class="p">(</span><span class="n">priv</span><span class="o">-></span><span class="n">connect_task</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="n">g_cancellable_cancel</span><span class="w"> </span><span class="p">(</span><span class="n">cancellable</span><span class="p">);</span><span class="w"></span>
|
||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||
<span class="p">}</span><span class="w"></span>
|
||
</pre></div>
|
||
</div>
|
||
</section>
|
||
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||
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Contents
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<div class="toc-tree-container">
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<div class="toc-tree">
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<ul>
|
||
<li><a class="reference internal" href="#">Asynchronous Programming</a><ul>
|
||
<li><a class="reference internal" href="#summary">Summary</a></li>
|
||
<li><a class="reference internal" href="#concepts">Concepts</a></li>
|
||
<li><a class="reference internal" href="#api-patterns">API patterns</a></li>
|
||
<li><a class="reference internal" href="#operation-lifetimes">Operation Lifetimes</a></li>
|
||
<li><a class="reference internal" href="#using-asynchronous-functions">Using asynchronous functions</a><ul>
|
||
<li><a class="reference internal" href="#single-operation">Single operation</a></li>
|
||
<li><a class="reference internal" href="#operations-in-series">Operations in series</a></li>
|
||
<li><a class="reference internal" href="#operations-in-parallel">Operations in parallel</a></li>
|
||
<li><a class="reference internal" href="#wrapping-with-gtask">Wrapping with GTask</a></li>
|
||
</ul>
|
||
</li>
|
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|
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|
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