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"""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__
#
# 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__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
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:
try:
self.job = Parallel(taskmaster, num)
self.num_jobs = num
except NameError:
pass
if self.job is None:
self.job = Serial(taskmaster)
self.num_jobs = 1
def run(self):
"""run the job"""
try:
self.job.start()
except KeyboardInterrupt:
# mask any further keyboard interrupts so that scons
# can shutdown cleanly:
# (this only masks the keyboard interrupt for Python,
# child processes can still get the keyboard interrupt)
import signal
signal.signal(signal.SIGINT, signal.SIG_IGN)
raise
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). The taskmaster's
is_blocked() method will not be called. """
self.taskmaster = taskmaster
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()
task.execute()
except KeyboardInterrupt:
raise
except:
# Let the failed() callback function arrange for the
# build to stop if that's appropriate.
task.failed()
else:
task.executed()
# 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):
threading.Thread.__init__(self)
self.setDaemon(1)
self.requestQueue = requestQueue
self.resultsQueue = resultsQueue
self.start()
def run(self):
while 1:
task = self.requestQueue.get()
try:
task.execute()
except KeyboardInterrupt:
# be explicit here for test/interrupts.py
ok = False
except:
ok = 0
else:
ok = 1
self.resultsQueue.put((task, ok))
class ThreadPool:
"""This class is responsible for spawning and managing worker threads."""
def __init__(self, num):
"""Create the request and reply queues, and 'num' worker threads."""
self.requestQueue = Queue.Queue(0)
self.resultsQueue = Queue.Queue(0)
# Create worker threads
for i in range(num):
worker = Worker(self.requestQueue, self.resultsQueue)
def put(self, obj):
"""Put task into request queue."""
self.requestQueue.put(obj)
def get(self, block = 1):
"""Remove and return a result tuple from the results queue."""
return self.resultsQueue.get(block)
def get_nowait(self):
"""Remove and result a result tuple from the results queue
without blocking."""
return self.get(0)
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):
"""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). The
taskmaster's is_blocked() method should return true iff there are
more tasks, but they can't be executed until one or more other
tasks have been executed. next_task() will be called iff
is_blocked() returned false.
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.tp = ThreadPool(num)
self.jobs = 0
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."""
while 1:
if self.jobs < self.maxjobs:
task = self.taskmaster.next_task()
if task is None:
break
# prepare task for execution
try:
task.prepare()
except KeyboardInterrupt:
raise
except:
# Let the failed() callback function arrange for the
# build to stop if that's appropriate.
task.failed()
# dispatch task
self.tp.put(task)
self.jobs = self.jobs + 1
while 1:
try:
task, ok = self.tp.get_nowait()
except Queue.Empty:
if not (self.jobs is self.maxjobs or self.taskmaster.is_blocked()):
break
task, ok = self.tp.get()
self.jobs = self.jobs - 1
if ok:
task.executed()
else:
task.failed()
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