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Diffstat (limited to 'src/engine/SCons/Job.py')
| -rw-r--r-- | src/engine/SCons/Job.py | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/src/engine/SCons/Job.py b/src/engine/SCons/Job.py new file mode 100644 index 0000000..6d652bf --- /dev/null +++ b/src/engine/SCons/Job.py @@ -0,0 +1,435 @@ +"""SCons.Job + +This module defines the Serial and Parallel classes that execute tasks to +complete a build. The Jobs class provides a higher level interface to start, +stop, and wait on jobs. + +""" + +# +# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 The SCons Foundation +# +# Permission is hereby granted, free of charge, to any person obtaining +# a copy of this software and associated documentation files (the +# "Software"), to deal in the Software without restriction, including +# without limitation the rights to use, copy, modify, merge, publish, +# distribute, sublicense, and/or sell copies of the Software, and to +# permit persons to whom the Software is furnished to do so, subject to +# the following conditions: +# +# The above copyright notice and this permission notice shall be included +# in all copies or substantial portions of the Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY +# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE +# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. +# + +__revision__ = "src/engine/SCons/Job.py 4577 2009/12/27 19:44:43 scons" + +import os +import signal + +import SCons.Errors + +# The default stack size (in kilobytes) of the threads used to execute +# jobs in parallel. +# +# We use a stack size of 256 kilobytes. The default on some platforms +# is too large and prevents us from creating enough threads to fully +# parallelized the build. For example, the default stack size on linux +# is 8 MBytes. + +explicit_stack_size = None +default_stack_size = 256 + +interrupt_msg = 'Build interrupted.' + + +class InterruptState: + def __init__(self): + self.interrupted = False + + def set(self): + self.interrupted = True + + def __call__(self): + return self.interrupted + + +class Jobs: + """An instance of this class initializes N jobs, and provides + methods for starting, stopping, and waiting on all N jobs. + """ + + def __init__(self, num, taskmaster): + """ + create 'num' jobs using the given taskmaster. + + If 'num' is 1 or less, then a serial job will be used, + otherwise a parallel job with 'num' worker threads will + be used. + + The 'num_jobs' attribute will be set to the actual number of jobs + allocated. If more than one job is requested but the Parallel + class can't do it, it gets reset to 1. Wrapping interfaces that + care should check the value of 'num_jobs' after initialization. + """ + + self.job = None + if num > 1: + stack_size = explicit_stack_size + if stack_size is None: + stack_size = default_stack_size + + try: + self.job = Parallel(taskmaster, num, stack_size) + self.num_jobs = num + except NameError: + pass + if self.job is None: + self.job = Serial(taskmaster) + self.num_jobs = 1 + + def run(self, postfunc=lambda: None): + """Run the jobs. + + postfunc() will be invoked after the jobs has run. It will be + invoked even if the jobs are interrupted by a keyboard + interrupt (well, in fact by a signal such as either SIGINT, + SIGTERM or SIGHUP). The execution of postfunc() is protected + against keyboard interrupts and is guaranteed to run to + completion.""" + self._setup_sig_handler() + try: + self.job.start() + finally: + postfunc() + self._reset_sig_handler() + + def were_interrupted(self): + """Returns whether the jobs were interrupted by a signal.""" + return self.job.interrupted() + + def _setup_sig_handler(self): + """Setup an interrupt handler so that SCons can shutdown cleanly in + various conditions: + + a) SIGINT: Keyboard interrupt + b) SIGTERM: kill or system shutdown + c) SIGHUP: Controlling shell exiting + + We handle all of these cases by stopping the taskmaster. It + turns out that it very difficult to stop the build process + by throwing asynchronously an exception such as + KeyboardInterrupt. For example, the python Condition + variables (threading.Condition) and Queue's do not seem to + asynchronous-exception-safe. It would require adding a whole + bunch of try/finally block and except KeyboardInterrupt all + over the place. + + Note also that we have to be careful to handle the case when + SCons forks before executing another process. In that case, we + want the child to exit immediately. + """ + def handler(signum, stack, self=self, parentpid=os.getpid()): + if os.getpid() == parentpid: + self.job.taskmaster.stop() + self.job.interrupted.set() + else: + os._exit(2) + + self.old_sigint = signal.signal(signal.SIGINT, handler) + self.old_sigterm = signal.signal(signal.SIGTERM, handler) + try: + self.old_sighup = signal.signal(signal.SIGHUP, handler) + except AttributeError: + pass + + def _reset_sig_handler(self): + """Restore the signal handlers to their previous state (before the + call to _setup_sig_handler().""" + + signal.signal(signal.SIGINT, self.old_sigint) + signal.signal(signal.SIGTERM, self.old_sigterm) + try: + signal.signal(signal.SIGHUP, self.old_sighup) + except AttributeError: + pass + +class Serial: + """This class is used to execute tasks in series, and is more efficient + than Parallel, but is only appropriate for non-parallel builds. Only + one instance of this class should be in existence at a time. + + This class is not thread safe. + """ + + def __init__(self, taskmaster): + """Create a new serial job given a taskmaster. + + The taskmaster's next_task() method should return the next task + that needs to be executed, or None if there are no more tasks. The + taskmaster's executed() method will be called for each task when it + is successfully executed or failed() will be called if it failed to + execute (e.g. execute() raised an exception).""" + + self.taskmaster = taskmaster + self.interrupted = InterruptState() + + def start(self): + """Start the job. This will begin pulling tasks from the taskmaster + and executing them, and return when there are no more tasks. If a task + fails to execute (i.e. execute() raises an exception), then the job will + stop.""" + + while 1: + task = self.taskmaster.next_task() + + if task is None: + break + + try: + task.prepare() + if task.needs_execute(): + task.execute() + except: + if self.interrupted(): + try: + raise SCons.Errors.BuildError( + task.targets[0], errstr=interrupt_msg) + except: + task.exception_set() + else: + task.exception_set() + + # Let the failed() callback function arrange for the + # build to stop if that's appropriate. + task.failed() + else: + task.executed() + + task.postprocess() + self.taskmaster.cleanup() + + +# Trap import failure so that everything in the Job module but the +# Parallel class (and its dependent classes) will work if the interpreter +# doesn't support threads. +try: + import Queue + import threading +except ImportError: + pass +else: + class Worker(threading.Thread): + """A worker thread waits on a task to be posted to its request queue, + dequeues the task, executes it, and posts a tuple including the task + and a boolean indicating whether the task executed successfully. """ + + def __init__(self, requestQueue, resultsQueue, interrupted): + threading.Thread.__init__(self) + self.setDaemon(1) + self.requestQueue = requestQueue + self.resultsQueue = resultsQueue + self.interrupted = interrupted + self.start() + + def run(self): + while 1: + task = self.requestQueue.get() + + if task is None: + # The "None" value is used as a sentinel by + # ThreadPool.cleanup(). This indicates that there + # are no more tasks, so we should quit. + break + + try: + if self.interrupted(): + raise SCons.Errors.BuildError( + task.targets[0], errstr=interrupt_msg) + task.execute() + except: + task.exception_set() + ok = False + else: + ok = True + + self.resultsQueue.put((task, ok)) + + class ThreadPool: + """This class is responsible for spawning and managing worker threads.""" + + def __init__(self, num, stack_size, interrupted): + """Create the request and reply queues, and 'num' worker threads. + + One must specify the stack size of the worker threads. The + stack size is specified in kilobytes. + """ + self.requestQueue = Queue.Queue(0) + self.resultsQueue = Queue.Queue(0) + + try: + prev_size = threading.stack_size(stack_size*1024) + except AttributeError, e: + # Only print a warning if the stack size has been + # explicitly set. + if not explicit_stack_size is 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, e: + msg = "Setting stack size failed:\n " + str(e) + SCons.Warnings.warn(SCons.Warnings.StackSizeWarning, msg) + + # Create worker threads + self.workers = [] + for _ in range(num): + worker = Worker(self.requestQueue, self.resultsQueue, interrupted) + self.workers.append(worker) + + # Once we drop Python 1.5 we can change the following to: + #if 'prev_size' in locals(): + if 'prev_size' in locals().keys(): + threading.stack_size(prev_size) + + def put(self, task): + """Put task into request queue.""" + self.requestQueue.put(task) + + def get(self): + """Remove and return a result tuple from the results queue.""" + return self.resultsQueue.get() + + def preparation_failed(self, task): + self.resultsQueue.put((task, False)) + + def cleanup(self): + """ + Shuts down the thread pool, giving each worker thread a + chance to shut down gracefully. + """ + # For each worker thread, put a sentinel "None" value + # on the requestQueue (indicating that there's no work + # to be done) so that each worker thread will get one and + # terminate gracefully. + for _ in self.workers: + self.requestQueue.put(None) + + # Wait for all of the workers to terminate. + # + # If we don't do this, later Python versions (2.4, 2.5) often + # seem to raise exceptions during shutdown. This happens + # in requestQueue.get(), as an assertion failure that + # requestQueue.not_full is notified while not acquired, + # seemingly because the main thread has shut down (or is + # in the process of doing so) while the workers are still + # trying to pull sentinels off the requestQueue. + # + # Normally these terminations should happen fairly quickly, + # but we'll stick a one-second timeout on here just in case + # someone gets hung. + for worker in self.workers: + worker.join(1.0) + self.workers = [] + + class Parallel: + """This class is used to execute tasks in parallel, and is somewhat + less efficient than Serial, but is appropriate for parallel builds. + + This class is thread safe. + """ + + def __init__(self, taskmaster, num, stack_size): + """Create a new parallel job given a taskmaster. + + The taskmaster's next_task() method should return the next + task that needs to be executed, or None if there are no more + tasks. The taskmaster's executed() method will be called + for each task when it is successfully executed or failed() + will be called if the task failed to execute (i.e. execute() + raised an exception). + + Note: calls to taskmaster are serialized, but calls to + execute() on distinct tasks are not serialized, because + that is the whole point of parallel jobs: they can execute + multiple tasks simultaneously. """ + + self.taskmaster = taskmaster + self.interrupted = InterruptState() + self.tp = ThreadPool(num, stack_size, self.interrupted) + + self.maxjobs = num + + def start(self): + """Start the job. This will begin pulling tasks from the + taskmaster and executing them, and return when there are no + more tasks. If a task fails to execute (i.e. execute() raises + an exception), then the job will stop.""" + + jobs = 0 + + while 1: + # Start up as many available tasks as we're + # allowed to. + while jobs < self.maxjobs: + task = self.taskmaster.next_task() + if task is None: + break + + try: + # prepare task for execution + task.prepare() + except: + task.exception_set() + task.failed() + task.postprocess() + else: + if task.needs_execute(): + # dispatch task + self.tp.put(task) + jobs = 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 1: + task, ok = self.tp.get() + jobs = jobs - 1 + + if ok: + task.executed() + else: + if self.interrupted(): + try: + raise SCons.Errors.BuildError( + task.targets[0], errstr=interrupt_msg) + except: + 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() + +# Local Variables: +# tab-width:4 +# indent-tabs-mode:nil +# End: +# vim: set expandtab tabstop=4 shiftwidth=4: |