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mutex_locker.cpp
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/***************************************************************************
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* mutex_locker.cpp - mutex locker helper
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*
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* Created: Thu Oct 04 16:14:30 2007
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* Copyright 2006-2007 Tim Niemueller [www.niemueller.de]
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*
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****************************************************************************/
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/* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version. A runtime exception applies to
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* this software (see LICENSE.GPL_WRE file mentioned below for details).
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* Read the full text in the LICENSE.GPL_WRE file in the doc directory.
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*/
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#include <core/threading/mutex_locker.h>
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#include <core/threading/mutex.h>
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namespace
fawkes {
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/** @class MutexLocker <core/threading/mutex_locker.h>
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* Mutex locking helper.
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* This class is a convenience function which can help you prevent a quite
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* a few headaches. Consider the following code.
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* @code
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* void my_function()
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* {
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* mutex->lock();
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* for (int i = 0; i < LIMIT; ++i) {
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* if ( failure ) {
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* mutex->unlock
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* }
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* }
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*
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* switch ( someval ) {
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* VALA:
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* mutex->unlock();
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* return;
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* VALB:
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* do_something();
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* }
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*
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* try {
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* do_function_that_throws_exceptions();
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* } catch (Exception &e) {
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* mutex->unlock();
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* throw;
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* }
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* mutex->unlock();
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* }
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* @endcode
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* This is not a complete list of examples but as you see if you have many
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* exit points in a function it becomes more and more work to have correct
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* locking behavior.
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*
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* This is a lot simpler with the MutexLocker. The MutexLocker locks the
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* given mutex on creation, and unlocks it in the destructor. If you now
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* have a mutex locker on the stack as integral type the destructor is
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* called automagically on function exit and thus the mutex is appropriately
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* unlocked.
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* The code would look like this:
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* @code
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* void my_function()
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* {
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* MutexLocker ml(mutex);
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* // do anything, no need to call mutex->lock()/unlock() if only has to be
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* // called on entering and exiting the function.
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* }
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* @endcode
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*
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* @ingroup Threading
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* @ingroup FCL
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*
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* @author Tim Niemueller
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*/
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/** Constructor.
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* @param mutex Mutex to lock/unlock appropriately.
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* @param initially_lock true to lock the mutex in the constructor, false to not lock
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*/
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MutexLocker::MutexLocker
(
RefPtr<Mutex>
mutex,
bool
initially_lock)
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{
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__rawmutex = 0;
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__refmutex = mutex;
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if
( initially_lock ) {
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__refmutex->lock();
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}
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__locked = initially_lock;
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}
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/** Constructor.
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* @param mutex Mutex to lock/unlock appropriately.
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* @param initially_lock true to lock the mutex in the constructor, false to not lock
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*/
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MutexLocker::MutexLocker
(
Mutex
*mutex,
bool
initially_lock)
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{
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__rawmutex = mutex;
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if
( initially_lock ) {
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__rawmutex->
lock
();
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}
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__locked = initially_lock;
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}
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/** Destructor */
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MutexLocker::~MutexLocker
()
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{
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if
( __locked ) {
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if
( __rawmutex) {
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__rawmutex->
unlock
();
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}
else
{
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__refmutex->unlock();
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}
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}
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}
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/** Lock this mutex, again.
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* Use this if you unlocked the mutex from the outside.
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*/
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void
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MutexLocker::relock
()
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{
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if
( __rawmutex ) {
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__rawmutex->
lock
();
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}
else
{
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__refmutex->lock();
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}
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__locked =
true
;
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}
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/** Unlock the mutex. */
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void
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MutexLocker::unlock
()
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{
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__locked =
false
;
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if
( __rawmutex ) {
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__rawmutex->
unlock
();
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}
else
{
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__refmutex->unlock();
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}
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}
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}
// end namespace fawkes
src
libs
core
threading
mutex_locker.cpp
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