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# Copyright (C) 2005-2014 Bastian Kleineidam
#
# 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
Locking utility class.
"""
import threading
from . import log, LOG_THREAD
def get_lock(name, debug=False):
"""Get a new lock.
@param debug: if True, acquire() and release() will have debug messages
@type debug: boolean, default is False
@return: a lock object
@rtype: threading.Lock or DebugLock
"""
lock = threading.Lock()
# for thread debugging, use the DebugLock wrapper
if debug:
lock = DebugLock(lock, name)
return lock
class DebugLock:
"""Debugging lock class."""
def __init__(self, lock, name):
"""Store lock and name parameters."""
self.lock = lock
self.name = name
def acquire(self, blocking=1):
"""Acquire lock."""
threadname = threading.current_thread().name
log.debug(LOG_THREAD, "Acquire %s for %s", self.name, threadname)
self.lock.acquire(blocking)
log.debug(LOG_THREAD, "...acquired %s for %s", self.name, threadname)
def release(self):
"""Release lock."""
threadname = threading.current_thread().name
log.debug(LOG_THREAD, "Release %s for %s", self.name, threadname)
self.lock.release()
def get_semaphore(name, value=None, debug=False):
"""Get a new semaphore.
@param value: if not None, a BoundedSemaphore will be used
@type debug: int or None
@param debug: if True, acquire() and release() will have debug messages
@type debug: boolean, default is False
@return: a semaphore object
@rtype: threading.Semaphore or threading.BoundedSemaphore or DebugLock
"""
if value is None:
lock = threading.Semaphore()
else:
lock = threading.BoundedSemaphore(value)
if debug:
lock = DebugLock(lock, name)
return lock
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