764 lines
29 KiB
Python
764 lines
29 KiB
Python
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# MIT License
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#
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# Copyright The SCons Foundation
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be included
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# in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
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# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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"""Serial and Parallel classes to execute build tasks.
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The Jobs class provides a higher level interface to start,
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stop, and wait on jobs.
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"""
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import SCons.compat
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import logging
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import os
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import queue
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import signal
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import sys
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import threading
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from enum import Enum
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import SCons.Errors
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import SCons.Warnings
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# The default stack size (in kilobytes) of the threads used to execute
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# jobs in parallel.
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#
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# We use a stack size of 256 kilobytes. The default on some platforms
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# is too large and prevents us from creating enough threads to fully
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# parallelized the build. For example, the default stack size on linux
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# is 8 MBytes.
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explicit_stack_size = None
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default_stack_size = 256
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interrupt_msg = 'Build interrupted.'
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class InterruptState:
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def __init__(self) -> None:
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self.interrupted = False
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def set(self) -> None:
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self.interrupted = True
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def __call__(self):
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return self.interrupted
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class Jobs:
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"""An instance of this class initializes N jobs, and provides
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methods for starting, stopping, and waiting on all N jobs.
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"""
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def __init__(self, num, taskmaster) -> None:
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"""
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Create 'num' jobs using the given taskmaster. The exact implementation
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used varies with the number of jobs requested and the state of the `legacy_sched` flag
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to `--experimental`.
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"""
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# Importing GetOption here instead of at top of file to avoid
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# circular imports
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# pylint: disable=import-outside-toplevel
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from SCons.Script import GetOption
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stack_size = explicit_stack_size
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if stack_size is None:
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stack_size = default_stack_size
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experimental_option = GetOption('experimental') or []
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if 'legacy_sched' in experimental_option:
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if num > 1:
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self.job = LegacyParallel(taskmaster, num, stack_size)
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else:
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self.job = Serial(taskmaster)
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else:
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self.job = NewParallel(taskmaster, num, stack_size)
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self.num_jobs = num
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def run(self, postfunc=lambda: None) -> None:
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"""Run the jobs.
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postfunc() will be invoked after the jobs has run. It will be
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invoked even if the jobs are interrupted by a keyboard
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interrupt (well, in fact by a signal such as either SIGINT,
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SIGTERM or SIGHUP). The execution of postfunc() is protected
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against keyboard interrupts and is guaranteed to run to
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completion."""
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self._setup_sig_handler()
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try:
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self.job.start()
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finally:
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postfunc()
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self._reset_sig_handler()
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def were_interrupted(self):
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"""Returns whether the jobs were interrupted by a signal."""
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return self.job.interrupted()
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def _setup_sig_handler(self) -> None:
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"""Setup an interrupt handler so that SCons can shutdown cleanly in
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various conditions:
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a) SIGINT: Keyboard interrupt
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b) SIGTERM: kill or system shutdown
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c) SIGHUP: Controlling shell exiting
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We handle all of these cases by stopping the taskmaster. It
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turns out that it's very difficult to stop the build process
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by throwing asynchronously an exception such as
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KeyboardInterrupt. For example, the python Condition
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variables (threading.Condition) and queues do not seem to be
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asynchronous-exception-safe. It would require adding a whole
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bunch of try/finally block and except KeyboardInterrupt all
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over the place.
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Note also that we have to be careful to handle the case when
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SCons forks before executing another process. In that case, we
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want the child to exit immediately.
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"""
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def handler(signum, stack, self=self, parentpid=os.getpid()) -> None:
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if os.getpid() == parentpid:
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self.job.taskmaster.stop()
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self.job.interrupted.set()
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else:
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os._exit(2) # pylint: disable=protected-access
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self.old_sigint = signal.signal(signal.SIGINT, handler)
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self.old_sigterm = signal.signal(signal.SIGTERM, handler)
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try:
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self.old_sighup = signal.signal(signal.SIGHUP, handler)
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except AttributeError:
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pass
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if (self.old_sigint is None) or (self.old_sigterm is None) or \
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(hasattr(self, "old_sighup") and self.old_sighup is None):
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msg = "Overwritting previous signal handler which was not installed from Python. " + \
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"Will not be able to reinstate and so will return to default handler."
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SCons.Warnings.warn(SCons.Warnings.SConsWarning, msg)
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def _reset_sig_handler(self) -> None:
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"""Restore the signal handlers to their previous state (before the
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call to _setup_sig_handler()."""
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sigint_to_use = self.old_sigint if self.old_sigint is not None else signal.SIG_DFL
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sigterm_to_use = self.old_sigterm if self.old_sigterm is not None else signal.SIG_DFL
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signal.signal(signal.SIGINT, sigint_to_use)
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signal.signal(signal.SIGTERM, sigterm_to_use)
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try:
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sigterm_to_use = self.old_sighup if self.old_sighup is not None else signal.SIG_DFL
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signal.signal(signal.SIGHUP, sigterm_to_use)
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except AttributeError:
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pass
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class Serial:
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"""This class is used to execute tasks in series, and is more efficient
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than Parallel, but is only appropriate for non-parallel builds. Only
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one instance of this class should be in existence at a time.
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This class is not thread safe.
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"""
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def __init__(self, taskmaster) -> None:
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"""Create a new serial job given a taskmaster.
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The taskmaster's next_task() method should return the next task
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that needs to be executed, or None if there are no more tasks. The
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taskmaster's executed() method will be called for each task when it
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is successfully executed, or failed() will be called if it failed to
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execute (e.g. execute() raised an exception)."""
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self.taskmaster = taskmaster
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self.interrupted = InterruptState()
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def start(self):
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"""Start the job. This will begin pulling tasks from the taskmaster
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and executing them, and return when there are no more tasks. If a task
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fails to execute (i.e. execute() raises an exception), then the job will
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stop."""
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while True:
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task = self.taskmaster.next_task()
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if task is None:
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break
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try:
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task.prepare()
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if task.needs_execute():
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task.execute()
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except Exception:
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if self.interrupted():
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try:
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raise SCons.Errors.BuildError(
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task.targets[0], errstr=interrupt_msg)
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except Exception:
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task.exception_set()
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else:
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task.exception_set()
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# Let the failed() callback function arrange for the
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# build to stop if that's appropriate.
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task.failed()
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else:
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task.executed()
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task.postprocess()
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self.taskmaster.cleanup()
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class Worker(threading.Thread):
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"""A worker thread waits on a task to be posted to its request queue,
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dequeues the task, executes it, and posts a tuple including the task
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and a boolean indicating whether the task executed successfully. """
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def __init__(self, requestQueue, resultsQueue, interrupted) -> None:
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super().__init__()
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self.daemon = True
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self.requestQueue = requestQueue
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self.resultsQueue = resultsQueue
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self.interrupted = interrupted
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self.start()
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def run(self):
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while True:
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task = self.requestQueue.get()
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if task is None:
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# The "None" value is used as a sentinel by
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# ThreadPool.cleanup(). This indicates that there
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# are no more tasks, so we should quit.
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break
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try:
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if self.interrupted():
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raise SCons.Errors.BuildError(
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task.targets[0], errstr=interrupt_msg)
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task.execute()
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except Exception:
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task.exception_set()
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ok = False
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else:
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ok = True
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self.resultsQueue.put((task, ok))
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class ThreadPool:
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"""This class is responsible for spawning and managing worker threads."""
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def __init__(self, num, stack_size, interrupted) -> None:
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"""Create the request and reply queues, and 'num' worker threads.
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One must specify the stack size of the worker threads. The
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stack size is specified in kilobytes.
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"""
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self.requestQueue = queue.Queue(0)
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self.resultsQueue = queue.Queue(0)
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try:
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prev_size = threading.stack_size(stack_size * 1024)
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except AttributeError as e:
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# Only print a warning if the stack size has been
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# explicitly set.
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if explicit_stack_size is not None:
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msg = "Setting stack size is unsupported by this version of Python:\n " + \
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e.args[0]
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SCons.Warnings.warn(SCons.Warnings.StackSizeWarning, msg)
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except ValueError as e:
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msg = "Setting stack size failed:\n " + str(e)
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SCons.Warnings.warn(SCons.Warnings.StackSizeWarning, msg)
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# Create worker threads
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self.workers = []
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for _ in range(num):
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worker = Worker(self.requestQueue, self.resultsQueue, interrupted)
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self.workers.append(worker)
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if 'prev_size' in locals():
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threading.stack_size(prev_size)
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def put(self, task) -> None:
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"""Put task into request queue."""
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self.requestQueue.put(task)
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def get(self):
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"""Remove and return a result tuple from the results queue."""
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return self.resultsQueue.get()
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def preparation_failed(self, task) -> None:
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self.resultsQueue.put((task, False))
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def cleanup(self) -> None:
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"""
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Shuts down the thread pool, giving each worker thread a
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chance to shut down gracefully.
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"""
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# For each worker thread, put a sentinel "None" value
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# on the requestQueue (indicating that there's no work
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# to be done) so that each worker thread will get one and
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# terminate gracefully.
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for _ in self.workers:
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self.requestQueue.put(None)
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# Wait for all of the workers to terminate.
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#
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# If we don't do this, later Python versions (2.4, 2.5) often
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# seem to raise exceptions during shutdown. This happens
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# in requestQueue.get(), as an assertion failure that
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# requestQueue.not_full is notified while not acquired,
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# seemingly because the main thread has shut down (or is
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# in the process of doing so) while the workers are still
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# trying to pull sentinels off the requestQueue.
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#
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# Normally these terminations should happen fairly quickly,
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# but we'll stick a one-second timeout on here just in case
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# someone gets hung.
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for worker in self.workers:
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worker.join(1.0)
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self.workers = []
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class LegacyParallel:
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"""This class is used to execute tasks in parallel, and is somewhat
|
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less efficient than Serial, but is appropriate for parallel builds.
|
||
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This class is thread safe.
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||
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"""
|
||
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def __init__(self, taskmaster, num, stack_size) -> None:
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"""Create a new parallel job given a taskmaster.
|
||
|
|
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The taskmaster's next_task() method should return the next
|
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task that needs to be executed, or None if there are no more
|
||
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tasks. The taskmaster's executed() method will be called
|
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for each task when it is successfully executed, or failed()
|
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will be called if the task failed to execute (i.e. execute()
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raised an exception).
|
||
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Note: calls to taskmaster are serialized, but calls to
|
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execute() on distinct tasks are not serialized, because
|
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that is the whole point of parallel jobs: they can execute
|
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multiple tasks simultaneously. """
|
||
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self.taskmaster = taskmaster
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self.interrupted = InterruptState()
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self.tp = ThreadPool(num, stack_size, self.interrupted)
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self.maxjobs = num
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def start(self):
|
||
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"""Start the job. This will begin pulling tasks from the
|
||
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taskmaster and executing them, and return when there are no
|
||
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more tasks. If a task fails to execute (i.e. execute() raises
|
||
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an exception), then the job will stop."""
|
||
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jobs = 0
|
||
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||
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while True:
|
||
|
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# Start up as many available tasks as we're
|
||
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# allowed to.
|
||
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while jobs < self.maxjobs:
|
||
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task = self.taskmaster.next_task()
|
||
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if task is None:
|
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break
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try:
|
||
|
|
# prepare task for execution
|
||
|
|
task.prepare()
|
||
|
|
except Exception:
|
||
|
|
task.exception_set()
|
||
|
|
task.failed()
|
||
|
|
task.postprocess()
|
||
|
|
else:
|
||
|
|
if task.needs_execute():
|
||
|
|
# dispatch task
|
||
|
|
self.tp.put(task)
|
||
|
|
jobs += 1
|
||
|
|
else:
|
||
|
|
task.executed()
|
||
|
|
task.postprocess()
|
||
|
|
|
||
|
|
if not task and not jobs:
|
||
|
|
break
|
||
|
|
|
||
|
|
# Let any/all completed tasks finish up before we go
|
||
|
|
# back and put the next batch of tasks on the queue.
|
||
|
|
while True:
|
||
|
|
task, ok = self.tp.get()
|
||
|
|
jobs -= 1
|
||
|
|
|
||
|
|
if ok:
|
||
|
|
task.executed()
|
||
|
|
else:
|
||
|
|
if self.interrupted():
|
||
|
|
try:
|
||
|
|
raise SCons.Errors.BuildError(
|
||
|
|
task.targets[0], errstr=interrupt_msg)
|
||
|
|
except Exception:
|
||
|
|
task.exception_set()
|
||
|
|
|
||
|
|
# Let the failed() callback function arrange
|
||
|
|
# for the build to stop if that's appropriate.
|
||
|
|
task.failed()
|
||
|
|
|
||
|
|
task.postprocess()
|
||
|
|
|
||
|
|
if self.tp.resultsQueue.empty():
|
||
|
|
break
|
||
|
|
|
||
|
|
self.tp.cleanup()
|
||
|
|
self.taskmaster.cleanup()
|
||
|
|
|
||
|
|
# An experimental new parallel scheduler that uses a leaders/followers pattern.
|
||
|
|
class NewParallel:
|
||
|
|
|
||
|
|
class State(Enum):
|
||
|
|
READY = 0
|
||
|
|
SEARCHING = 1
|
||
|
|
STALLED = 2
|
||
|
|
COMPLETED = 3
|
||
|
|
|
||
|
|
class Worker(threading.Thread):
|
||
|
|
def __init__(self, owner) -> None:
|
||
|
|
super().__init__()
|
||
|
|
self.daemon = True
|
||
|
|
self.owner = owner
|
||
|
|
self.start()
|
||
|
|
|
||
|
|
def run(self) -> None:
|
||
|
|
self.owner._work()
|
||
|
|
|
||
|
|
class FakeLock(object):
|
||
|
|
def lock(self):
|
||
|
|
pass
|
||
|
|
def unlock(self):
|
||
|
|
pass
|
||
|
|
def __enter__(self):
|
||
|
|
pass
|
||
|
|
def __exit__(self, *args):
|
||
|
|
pass
|
||
|
|
|
||
|
|
class FakeCondition(object):
|
||
|
|
def __init__(self, lock):
|
||
|
|
pass
|
||
|
|
def wait(self):
|
||
|
|
fatal();
|
||
|
|
def notify(self):
|
||
|
|
pass
|
||
|
|
def notify_all(self):
|
||
|
|
pass
|
||
|
|
def __enter__(self):
|
||
|
|
pass
|
||
|
|
def __exit__(self, *args):
|
||
|
|
pass
|
||
|
|
|
||
|
|
def __init__(self, taskmaster, num, stack_size) -> None:
|
||
|
|
self.taskmaster = taskmaster
|
||
|
|
self.max_workers = num
|
||
|
|
self.stack_size = stack_size
|
||
|
|
self.interrupted = InterruptState()
|
||
|
|
self.workers = []
|
||
|
|
|
||
|
|
# The `tm_lock` is what ensures that we only have one
|
||
|
|
# thread interacting with the taskmaster at a time. It
|
||
|
|
# also protects access to our state that gets updated
|
||
|
|
# concurrently. The `can_search_cv` is associated with
|
||
|
|
# this mutex.
|
||
|
|
self.tm_lock = (threading.Lock if self.max_workers > 1 else NewParallel.FakeLock)()
|
||
|
|
|
||
|
|
# Guarded under `tm_lock`.
|
||
|
|
self.jobs = 0
|
||
|
|
self.state = NewParallel.State.READY
|
||
|
|
|
||
|
|
# The `can_search_cv` is used to manage a leader /
|
||
|
|
# follower pattern for access to the taskmaster, and to
|
||
|
|
# awaken from stalls.
|
||
|
|
self.can_search_cv = (threading.Condition if self.max_workers > 1 else NewParallel.FakeCondition)(self.tm_lock)
|
||
|
|
|
||
|
|
# The queue of tasks that have completed execution. The
|
||
|
|
# next thread to obtain `tm_lock`` will retire them.
|
||
|
|
self.results_queue_lock = (threading.Lock if self.max_workers > 1 else NewParallel.FakeLock)()
|
||
|
|
self.results_queue = []
|
||
|
|
|
||
|
|
if self.taskmaster.trace:
|
||
|
|
self.trace = self._setup_logging()
|
||
|
|
else:
|
||
|
|
self.trace = False
|
||
|
|
|
||
|
|
def _setup_logging(self):
|
||
|
|
jl = logging.getLogger("Job")
|
||
|
|
jl.setLevel(level=logging.DEBUG)
|
||
|
|
jl.addHandler(self.taskmaster.trace.log_handler)
|
||
|
|
return jl
|
||
|
|
|
||
|
|
def trace_message(self, message) -> None:
|
||
|
|
# This grabs the name of the function which calls trace_message()
|
||
|
|
method_name = sys._getframe(1).f_code.co_name + "():"
|
||
|
|
thread_id=threading.get_ident()
|
||
|
|
self.trace.debug('%s.%s [Thread:%s] %s' % (type(self).__name__, method_name, thread_id, message))
|
||
|
|
|
||
|
|
def start(self) -> None:
|
||
|
|
if self.max_workers == 1:
|
||
|
|
self._work()
|
||
|
|
else:
|
||
|
|
self._start_worker()
|
||
|
|
while len(self.workers) > 0:
|
||
|
|
self.workers[0].join()
|
||
|
|
self.workers.pop(0)
|
||
|
|
self.taskmaster.cleanup()
|
||
|
|
|
||
|
|
def _maybe_start_worker(self) -> None:
|
||
|
|
if self.max_workers > 1 and len(self.workers) < self.max_workers:
|
||
|
|
if self.jobs >= len(self.workers):
|
||
|
|
self._start_worker()
|
||
|
|
|
||
|
|
def _start_worker(self) -> None:
|
||
|
|
prev_size = self._adjust_stack_size()
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Starting new worker thread")
|
||
|
|
self.workers.append(NewParallel.Worker(self))
|
||
|
|
self._restore_stack_size(prev_size)
|
||
|
|
|
||
|
|
def _adjust_stack_size(self):
|
||
|
|
try:
|
||
|
|
prev_size = threading.stack_size(self.stack_size * 1024)
|
||
|
|
return prev_size
|
||
|
|
except AttributeError as e:
|
||
|
|
# Only print a warning if the stack size has been
|
||
|
|
# explicitly set.
|
||
|
|
if explicit_stack_size is not None:
|
||
|
|
msg = "Setting stack size is unsupported by this version of Python:\n " + \
|
||
|
|
e.args[0]
|
||
|
|
SCons.Warnings.warn(SCons.Warnings.StackSizeWarning, msg)
|
||
|
|
except ValueError as e:
|
||
|
|
msg = "Setting stack size failed:\n " + str(e)
|
||
|
|
SCons.Warnings.warn(SCons.Warnings.StackSizeWarning, msg)
|
||
|
|
|
||
|
|
return None
|
||
|
|
|
||
|
|
def _restore_stack_size(self, prev_size) -> None:
|
||
|
|
if prev_size is not None:
|
||
|
|
threading.stack_size(prev_size)
|
||
|
|
|
||
|
|
def _work(self):
|
||
|
|
|
||
|
|
task = None
|
||
|
|
|
||
|
|
while True:
|
||
|
|
|
||
|
|
# Obtain `tm_lock`, granting exclusive access to the taskmaster.
|
||
|
|
with self.can_search_cv:
|
||
|
|
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Gained exclusive access")
|
||
|
|
|
||
|
|
# Capture whether we got here with `task` set,
|
||
|
|
# then drop our reference to the task as we are no
|
||
|
|
# longer interested in the actual object.
|
||
|
|
completed_task = (task is not None)
|
||
|
|
task = None
|
||
|
|
|
||
|
|
# We will only have `completed_task` set here if
|
||
|
|
# we have looped back after executing a task. If
|
||
|
|
# we have completed a task and find that we are
|
||
|
|
# stalled, we should speculatively indicate that
|
||
|
|
# we are no longer stalled by transitioning to the
|
||
|
|
# 'ready' state which will bypass the condition
|
||
|
|
# wait so that we immediately process the results
|
||
|
|
# queue and hopefully light up new
|
||
|
|
# work. Otherwise, stay stalled, and we will wait
|
||
|
|
# in the condvar. Some other thread will come back
|
||
|
|
# here with a completed task.
|
||
|
|
if self.state == NewParallel.State.STALLED and completed_task:
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Detected stall with completed task, bypassing wait")
|
||
|
|
self.state = NewParallel.State.READY
|
||
|
|
|
||
|
|
# Wait until we are neither searching nor stalled.
|
||
|
|
while self.state == NewParallel.State.SEARCHING or self.state == NewParallel.State.STALLED:
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Search already in progress, waiting")
|
||
|
|
self.can_search_cv.wait()
|
||
|
|
|
||
|
|
# If someone set the completed flag, bail.
|
||
|
|
if self.state == NewParallel.State.COMPLETED:
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Completion detected, breaking from main loop")
|
||
|
|
break
|
||
|
|
|
||
|
|
# Set the searching flag to indicate that a thread
|
||
|
|
# is currently in the critical section for
|
||
|
|
# taskmaster work.
|
||
|
|
#
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Starting search")
|
||
|
|
self.state = NewParallel.State.SEARCHING
|
||
|
|
|
||
|
|
# Bulk acquire the tasks in the results queue
|
||
|
|
# under the result queue lock, then process them
|
||
|
|
# all outside that lock. We need to process the
|
||
|
|
# tasks in the results queue before looking for
|
||
|
|
# new work because we might be unable to find new
|
||
|
|
# work if we don't.
|
||
|
|
results_queue = []
|
||
|
|
with self.results_queue_lock:
|
||
|
|
results_queue, self.results_queue = self.results_queue, results_queue
|
||
|
|
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message(f"Found {len(results_queue)} completed tasks to process")
|
||
|
|
for (rtask, rresult) in results_queue:
|
||
|
|
if rresult:
|
||
|
|
rtask.executed()
|
||
|
|
else:
|
||
|
|
if self.interrupted():
|
||
|
|
try:
|
||
|
|
raise SCons.Errors.BuildError(
|
||
|
|
rtask.targets[0], errstr=interrupt_msg)
|
||
|
|
except Exception:
|
||
|
|
rtask.exception_set()
|
||
|
|
|
||
|
|
# Let the failed() callback function arrange
|
||
|
|
# for the build to stop if that's appropriate.
|
||
|
|
rtask.failed()
|
||
|
|
|
||
|
|
rtask.postprocess()
|
||
|
|
self.jobs -= 1
|
||
|
|
|
||
|
|
# We are done with any task objects that were in
|
||
|
|
# the results queue.
|
||
|
|
results_queue.clear()
|
||
|
|
|
||
|
|
# Now, turn the crank on the taskmaster until we
|
||
|
|
# either run out of tasks, or find a task that
|
||
|
|
# needs execution. If we run out of tasks, go idle
|
||
|
|
# until results arrive if jobs are pending, or
|
||
|
|
# mark the walk as complete if not.
|
||
|
|
while self.state == NewParallel.State.SEARCHING:
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Searching for new tasks")
|
||
|
|
task = self.taskmaster.next_task()
|
||
|
|
|
||
|
|
if task:
|
||
|
|
# We found a task. Walk it through the
|
||
|
|
# task lifecycle. If it does not need
|
||
|
|
# execution, just complete the task and
|
||
|
|
# look for the next one. Otherwise,
|
||
|
|
# indicate that we are no longer searching
|
||
|
|
# so we can drop out of this loop, execute
|
||
|
|
# the task outside the lock, and allow
|
||
|
|
# another thread in to search.
|
||
|
|
try:
|
||
|
|
task.prepare()
|
||
|
|
except Exception:
|
||
|
|
task.exception_set()
|
||
|
|
task.failed()
|
||
|
|
task.postprocess()
|
||
|
|
else:
|
||
|
|
if not task.needs_execute():
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Found internal task")
|
||
|
|
task.executed()
|
||
|
|
task.postprocess()
|
||
|
|
else:
|
||
|
|
self.jobs += 1
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Found task requiring execution")
|
||
|
|
self.state = NewParallel.State.READY
|
||
|
|
self.can_search_cv.notify()
|
||
|
|
# This thread will be busy taking care of
|
||
|
|
# `execute`ing this task. If we haven't
|
||
|
|
# reached the limit, spawn a new thread to
|
||
|
|
# turn the crank and find the next task.
|
||
|
|
self._maybe_start_worker()
|
||
|
|
|
||
|
|
else:
|
||
|
|
# We failed to find a task, so this thread
|
||
|
|
# cannot continue turning the taskmaster
|
||
|
|
# crank. We must exit the loop.
|
||
|
|
if self.jobs:
|
||
|
|
# No task was found, but there are
|
||
|
|
# outstanding jobs executing that
|
||
|
|
# might unblock new tasks when they
|
||
|
|
# complete. Transition to the stalled
|
||
|
|
# state. We do not need a notify,
|
||
|
|
# because we know there are threads
|
||
|
|
# outstanding that will re-enter the
|
||
|
|
# loop.
|
||
|
|
#
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Found no task requiring execution, but have jobs: marking stalled")
|
||
|
|
self.state = NewParallel.State.STALLED
|
||
|
|
else:
|
||
|
|
# We didn't find a task and there are
|
||
|
|
# no jobs outstanding, so there is
|
||
|
|
# nothing that will ever return
|
||
|
|
# results which might unblock new
|
||
|
|
# tasks. We can conclude that the walk
|
||
|
|
# is complete. Update our state to
|
||
|
|
# note completion and awaken anyone
|
||
|
|
# sleeping on the condvar.
|
||
|
|
#
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Found no task requiring execution, and have no jobs: marking complete")
|
||
|
|
self.state = NewParallel.State.COMPLETED
|
||
|
|
self.can_search_cv.notify_all()
|
||
|
|
|
||
|
|
# We no longer hold `tm_lock` here. If we have a task,
|
||
|
|
# we can now execute it. If there are threads waiting
|
||
|
|
# to search, one of them can now begin turning the
|
||
|
|
# taskmaster crank in NewParallel.
|
||
|
|
if task:
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Executing task")
|
||
|
|
ok = True
|
||
|
|
try:
|
||
|
|
if self.interrupted():
|
||
|
|
raise SCons.Errors.BuildError(
|
||
|
|
task.targets[0], errstr=interrupt_msg)
|
||
|
|
task.execute()
|
||
|
|
except Exception:
|
||
|
|
ok = False
|
||
|
|
task.exception_set()
|
||
|
|
|
||
|
|
# Grab the results queue lock and enqueue the
|
||
|
|
# executed task and state. The next thread into
|
||
|
|
# the searching loop will complete the
|
||
|
|
# postprocessing work under the taskmaster lock.
|
||
|
|
#
|
||
|
|
if self.trace:
|
||
|
|
self.trace_message("Enqueueing executed task results")
|
||
|
|
with self.results_queue_lock:
|
||
|
|
self.results_queue.append((task, ok))
|
||
|
|
|
||
|
|
# Tricky state "fallthrough" here. We are going back
|
||
|
|
# to the top of the loop, which behaves differently
|
||
|
|
# depending on whether `task` is set. Do not perturb
|
||
|
|
# the value of the `task` variable if you add new code
|
||
|
|
# after this comment.
|
||
|
|
|
||
|
|
# Local Variables:
|
||
|
|
# tab-width:4
|
||
|
|
# indent-tabs-mode:nil
|
||
|
|
# End:
|
||
|
|
# vim: set expandtab tabstop=4 shiftwidth=4:
|