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3d401c263f
Since fetches involve multiple subprocess calls, any of which can be slow, the per-subprocess caffeination strategy does not seem suitable -- the Mac might sleep as soon as the wake lock is dropped, before it starts a new one. This instead implements a context manager to allow caffeinating a scope. To allow flag control, caffeinate.scope takes an argument that decides whether or not it should actually do anything useful; it looks silly, but the alternative is to interfere with flag parsing more or to require users to write separate codepaths to decide whether to enter the context manager scope or not; the "use the context manager in a mode where it does not do anything" prevents this. Bug: 462507017 Change-Id: Icc5bb9cadda30b5a120f112b10bf96ffd3b6550f Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/7183647 Reviewed-by: Gavin Mak <gavinmak@google.com> Commit-Queue: Adam Norberg <norberg@google.com>
60 lines
1.9 KiB
Python
60 lines
1.9 KiB
Python
# Copyright 2025 The Chromium Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import contextlib
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import os
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import subprocess
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import sys
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_NO_CAFFEINATE_FLAG = '--no-caffeinate'
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_HELP_MESSAGE = f"""\
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caffeinate:
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{_NO_CAFFEINATE_FLAG} do not prepend `caffeinate` to ninja command
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"""
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def call(args, **call_kwargs):
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"""Runs a command (via subprocess.call) with `caffeinate` if it's on macOS."""
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if sys.platform == 'darwin':
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if isinstance(args, (str, bytes, os.PathLike)):
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args = [args]
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if '-h' in args or '--help' in args:
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print(_HELP_MESSAGE, file=sys.stderr)
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if _NO_CAFFEINATE_FLAG in args:
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args.remove(_NO_CAFFEINATE_FLAG)
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else:
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args = ['caffeinate'] + args
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return subprocess.call(args, **call_kwargs)
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@contextlib.contextmanager
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def scope(actually_caffeinate=True):
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"""Acts as a context manager keeping a Mac awake, unless flagged off.
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If the process is not running on a Mac, or `actually_caffeinate` is falsey,
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this acts as a context manager that does nothing. The `actually_caffeinate`
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flag is provided so command line flags can control the caffeinate behavior
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without requiring weird plumbing to use or not use the context manager.
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If running on a Mac while actually_caffeinate is True (the default), this
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runs `caffeinate` in a separate process, which is terminated when the
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context manager exits.
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"""
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if sys.platform != 'darwin' or not actually_caffeinate:
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# Behave like a no-op context manager.
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yield False
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return
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cmd = ['caffeinate', '-i', '-w', str(os.getpid())]
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proc = subprocess.Popen(cmd,
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stdin=subprocess.DEVNULL,
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stdout=subprocess.DEVNULL,
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stderr=subprocess.DEVNULL)
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try:
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yield True
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finally:
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proc.terminate()
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