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docker-offlineimap/offlineimap/threadutil.py
Sebastian Spaeth 0cdfffa04d Don't always sleep while waiting for exited threads 
Rather than poll our exitthread Queue in a non-blocking fashion and
always sleep for 1 second inbetween, simply call it in a blocking
fashion which will return immediately when a thread has exited. This
is somewhat faster as we don't do unnecessary sleeps after a thread
exited.

Do note that we need to specify some timeout value here (the 60 chosen
is pretty arbitary, but what the value exactly is, is not that
important, it could be any positive value) in order to make the
Queue.get() call work with SIGINT (cf
http://bugs.python.org/issue1360).

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
2010-12-09 19:52:48 +01:00

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# Copyright (C) 2002, 2003 John Goerzen
# Thread support module
# <jgoerzen@complete.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
from threading import *
from StringIO import StringIO
from Queue import Queue, Empty
import sys, traceback, thread, time
from offlineimap.ui import UIBase # for getglobalui()
profiledir = None
def setprofiledir(newdir):
global profiledir
profiledir = newdir
######################################################################
# General utilities
######################################################################
def semaphorereset(semaphore, originalstate):
"""Wait until the semaphore gets back to its original state -- all acquired
resources released."""
for i in range(originalstate):
semaphore.acquire()
# Now release these.
for i in range(originalstate):
semaphore.release()
def semaphorewait(semaphore):
semaphore.acquire()
semaphore.release()
def threadsreset(threadlist):
for thr in threadlist:
thr.join()
class threadlist:
def __init__(self):
self.lock = Lock()
self.list = []
def add(self, thread):
self.lock.acquire()
try:
self.list.append(thread)
finally:
self.lock.release()
def remove(self, thread):
self.lock.acquire()
try:
self.list.remove(thread)
finally:
self.lock.release()
def pop(self):
self.lock.acquire()
try:
if not len(self.list):
return None
return self.list.pop()
finally:
self.lock.release()
def reset(self):
while 1:
thread = self.pop()
if not thread:
return
thread.join()
######################################################################
# Exit-notify threads
######################################################################
exitthreads = Queue(100)
inited = 0
def initexitnotify():
"""Initialize the exit notify system. This MUST be called from the
SAME THREAD that will call monitorloop BEFORE it calls monitorloop.
This SHOULD be called before the main thread starts any other
ExitNotifyThreads, or else it may miss the ability to catch the exit
status from them!"""
pass
def exitnotifymonitorloop(callback):
"""An infinite "monitoring" loop watching for finished ExitNotifyThread's.
:param callback: the function to call when a thread terminated. That
function is called with a single argument -- the
ExitNotifyThread that has terminated. The monitor will
not continue to monitor for other threads until
'callback' returns, so if it intends to perform long
calculations, it should start a new thread itself -- but
NOT an ExitNotifyThread, or else an infinite loop
may result.
Furthermore, the monitor will hold the lock all the
while the other thread is waiting.
:type callback: a callable function
"""
global exitthreads
while 1:
# Loop forever and call 'callback' for each thread that exited
try:
# we need a timeout in the get() call, so that ctrl-c can throw
# a SIGINT (http://bugs.python.org/issue1360). A timeout with empty
# Queue will raise `Empty`.
thrd = exitthreads.get(True, 60)
callback(thrd)
except Empty:
pass
def threadexited(thread):
"""Called when a thread exits."""
ui = UIBase.getglobalui()
if thread.getExitCause() == 'EXCEPTION':
if isinstance(thread.getExitException(), SystemExit):
# Bring a SystemExit into the main thread.
# Do not send it back to UI layer right now.
# Maybe later send it to ui.terminate?
raise SystemExit
ui.threadException(thread) # Expected to terminate
sys.exit(100) # Just in case...
os._exit(100)
elif thread.getExitMessage() == 'SYNC_WITH_TIMER_TERMINATE':
ui.terminate()
# Just in case...
sys.exit(100)
os._exit(100)
else:
ui.threadExited(thread)
class ExitNotifyThread(Thread):
"""This class is designed to alert a "monitor" to the fact that a thread has
exited and to provide for the ability for it to find out why."""
def run(self):
global exitthreads, profiledir
self.threadid = thread.get_ident()
try:
if not profiledir: # normal case
Thread.run(self)
else:
import profile
prof = profile.Profile()
try:
prof = prof.runctx("Thread.run(self)", globals(), locals())
except SystemExit:
pass
prof.dump_stats( \
profiledir + "/" + str(self.threadid) + "_" + \
self.getName() + ".prof")
except:
self.setExitCause('EXCEPTION')
if sys:
self.setExitException(sys.exc_info()[1])
sbuf = StringIO()
traceback.print_exc(file = sbuf)
self.setExitStackTrace(sbuf.getvalue())
else:
self.setExitCause('NORMAL')
if not hasattr(self, 'exitmessage'):
self.setExitMessage(None)
if exitthreads:
exitthreads.put(self, True)
def setExitCause(self, cause):
self.exitcause = cause
def getExitCause(self):
"""Returns the cause of the exit, one of:
'EXCEPTION' -- the thread aborted because of an exception
'NORMAL' -- normal termination."""
return self.exitcause
def setExitException(self, exc):
self.exitexception = exc
def getExitException(self):
"""If getExitCause() is 'EXCEPTION', holds the value from
sys.exc_info()[1] for this exception."""
return self.exitexception
def setExitStackTrace(self, st):
self.exitstacktrace = st
def getExitStackTrace(self):
"""If getExitCause() is 'EXCEPTION', returns a string representing
the stack trace for this exception."""
return self.exitstacktrace
def setExitMessage(self, msg):
"""Sets the exit message to be fetched by a subsequent call to
getExitMessage. This message may be any object or type except
None."""
self.exitmessage = msg
def getExitMessage(self):
"""For any exit cause, returns the message previously set by
a call to setExitMessage(), or None if there was no such message
set."""
return self.exitmessage
######################################################################
# Instance-limited threads
######################################################################
instancelimitedsems = {}
instancelimitedlock = Lock()
def initInstanceLimit(instancename, instancemax):
"""Initialize the instance-limited thread implementation to permit
up to intancemax threads with the given instancename."""
instancelimitedlock.acquire()
if not instancelimitedsems.has_key(instancename):
instancelimitedsems[instancename] = BoundedSemaphore(instancemax)
instancelimitedlock.release()
class InstanceLimitedThread(ExitNotifyThread):
def __init__(self, instancename, *args, **kwargs):
self.instancename = instancename
apply(ExitNotifyThread.__init__, (self,) + args, kwargs)
def start(self):
instancelimitedsems[self.instancename].acquire()
ExitNotifyThread.start(self)
def run(self):
try:
ExitNotifyThread.run(self)
finally:
if instancelimitedsems and instancelimitedsems[self.instancename]:
instancelimitedsems[self.instancename].release()
######################################################################
# Multi-lock -- capable of handling a single thread requesting a lock
# multiple times
######################################################################
class MultiLock:
def __init__(self):
self.lock = Lock()
self.statuslock = Lock()
self.locksheld = {}
def acquire(self):
"""Obtain a lock. Provides nice support for a single
thread trying to lock it several times -- as may be the case
if one I/O-using object calls others, while wanting to make it all
an atomic operation. Keeps a "lock request count" for the current
thread, and acquires the lock when it goes above zero, releases when
it goes below one.
This call is always blocking."""
# First, check to see if this thread already has a lock.
# If so, increment the lock count and just return.
self.statuslock.acquire()
try:
threadid = thread.get_ident()
if threadid in self.locksheld:
self.locksheld[threadid] += 1
return
else:
# This is safe because it is a per-thread structure
self.locksheld[threadid] = 1
finally:
self.statuslock.release()
self.lock.acquire()
def release(self):
self.statuslock.acquire()
try:
threadid = thread.get_ident()
if self.locksheld[threadid] > 1:
self.locksheld[threadid] -= 1
return
else:
del self.locksheld[threadid]
self.lock.release()
finally:
self.statuslock.release()
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