67 lines
3.0 KiB
Python
67 lines
3.0 KiB
Python
|
# Copyright 2018 The Chromium OS Authors. All rights reserved.
|
||
|
|
# Use of this source code is governed by a BSD-style license that can be
|
||
|
|
# found in the LICENSE file.
|
||
|
|
|
||
|
|
"""This is a shim library for the ec3po transition from subprocesses to threads.
|
||
|
|
|
||
|
|
This is necessary because ec3po is split between the platform/ec/ and
|
||
|
|
third_party/hdctools/ repositories, so the transition cannot happen atomically
|
||
|
|
in one change. See http://b/79684405 #39.
|
||
|
|
|
||
|
|
This contains only the multiprocessing objects or threading-oriented equivalents
|
||
|
|
that are actually in use by ec3po. There is no need for further functionality,
|
||
|
|
because this shim will be deleted after the migration is complete.
|
||
|
|
|
||
|
|
TODO(b/79684405): Stop using multiprocessing.Pipe. The
|
||
|
|
multiprocessing.Connection objects it returns serialize and deserialize objects
|
||
|
|
(via Python pickling), which is necessary for sending them between processes,
|
||
|
|
but is unnecessary overhead between threads. This will not be a simple change,
|
||
|
|
because the ec3po Console and Interpreter classes use the underlying pipe/socket
|
||
|
|
pairs with select/poll/epoll alongside other file descriptors. A drop-in
|
||
|
|
replacement would be non-trivial and add undesirable complexity. The correct
|
||
|
|
solution will be to split off the polling of the pipes/queues from this module
|
||
|
|
into separate threads, so that they can be transitioned to another form of
|
||
|
|
cross-thread synchronization, e.g. directly waiting on Queue.Queue.get() or a
|
||
|
|
lower-level thread synchronization primitive.
|
||
|
|
|
||
|
|
TODO(b/79684405): After this library has been updated to contain
|
||
|
|
threading-oriented equivalents to its original multiprocessing implementations,
|
||
|
|
and some reasonable amount of time has elapsed for thread-based ec3po problems
|
||
|
|
to be discovered, migrate both the platform/ec/ and third_party/hdctools/ sides
|
||
|
|
of ec3po off of this shim and then delete this file. IMPORTANT: This should
|
||
|
|
wait until after completing the TODO above to stop using multiprocessing.Pipe!
|
||
|
|
"""
|
||
|
|
|
||
|
|
# Imports to bring objects into this namespace for users of this module.
|
||
|
|
from Queue import Queue
|
||
|
|
from multiprocessing import Pipe
|
||
|
|
from threading import Thread as ThreadOrProcess
|
||
|
|
|
||
|
|
# True if this module has ec3po using subprocesses, False if using threads.
|
||
|
|
USING_SUBPROCS = False
|
||
|
|
|
||
|
|
|
||
|
|
def _DoNothing():
|
||
|
|
"""Do-nothing function for use as a callback with DoIf()."""
|
||
|
|
|
||
|
|
|
||
|
|
def DoIf(subprocs=_DoNothing, threads=_DoNothing):
|
||
|
|
"""Return a callback or not based on ec3po use of subprocesses or threads.
|
||
|
|
|
||
|
|
Args:
|
||
|
|
subprocs: callback that does not require any args - This will be returned
|
||
|
|
(not called!) if and only if ec3po is using subprocesses. This is
|
||
|
|
OPTIONAL, the default value is a do-nothing callback that returns None.
|
||
|
|
threads: callback that does not require any args - This will be returned
|
||
|
|
(not called!) if and only if ec3po is using threads. This is OPTIONAL,
|
||
|
|
the default value is a do-nothing callback that returns None.
|
||
|
|
|
||
|
|
Returns:
|
||
|
|
Either the subprocs or threads argument will be returned.
|
||
|
|
"""
|
||
|
|
return subprocs if USING_SUBPROCS else threads
|
||
|
|
|
||
|
|
|
||
|
|
def Value(ctype, *args):
|
||
|
|
return ctype(*args)
|