PThreadMutex.c++
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上传日期:2022-04-05
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文件大小:4k
- //
- // OpenThread library, Copyright (C) 2002 - 2003 The Open Thread Group
- //
- // This library is free software; you can redistribute it and/or
- // modify it under the terms of the GNU Lesser General Public
- // License as published by the Free Software Foundation; either
- // version 2.1 of the License, or (at your option) any later version.
- //
- // This library 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
- // Lesser General Public License for more details.
- //
- // You should have received a copy of the GNU Lesser General Public
- // License along with this library; if not, write to the Free Software
- // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- //
- //
- // PThreadMutex.c++ - C++ Mutex class built on top of posix threads.
- // ~~~~~~~~~~~~~~~~
- //
- #include <unistd.h>
- #include <pthread.h>
- #include "../Mutex"
- #include "PThreadMutexPrivateData.h"
- using namespace OpenThreads;
- //----------------------------------------------------------------------------
- //
- // Decription: Constructor
- //
- // Use: public.
- //
- Mutex::Mutex() {
- pthread_mutexattr_t mutex_attr;
- pthread_mutexattr_init( &mutex_attr );
-
- PThreadMutexPrivateData *pd = new PThreadMutexPrivateData();
-
- #ifndef __linux__ // (not available until NPTL) [
- pthread_mutexattr_settype( &mutex_attr, PTHREAD_MUTEX_ERRORCHECK );
- #endif // ] __linux__
- #ifdef ALLOW_PRIORITY_SCHEDULING // [
- #ifdef __sun // [
- pthread_mutexattr_setprotocol(&mutex_attr, PTHREAD_PRIO_NONE);
- #endif // ] __sun
- //-------------------------------------------------------------------------
- // Initialization is a bit tricky, since we have to be able to be aware
- // that on many-to-many execution vehicle systems, we may run into
- // priority inversion deadlocks if a mutex is shared between threads
- // of differing priorities. Systems that do this should provide the
- // following protocol attributes to prevent deadlocks. Check at runtime.
- //
- // PRIO_INHERIT causes any thread locking the mutex to temporarily become
- // the same priority as the highest thread also blocked on the mutex.
- // Although more expensive, this is the prefered method.
- //
- // PRIO_PROTECT causes any thread locking the mutex to assume the priority
- // specified by setprioceiling. pthread_mutex_lock will fail if
- // the priority ceiling is lower than the thread's priority. Therefore,
- // the priority ceiling must be set to the max priority in order to
- // garantee no deadlocks will occur.
- //
- #if defined (_POSIX_THREAD_PRIO_INHERIT) || defined (_POSIX_THREAD_PRIO_PROTECT) // [
- if(sysconf(_POSIX_THREAD_PRIO_INHERIT)) {
-
- pthread_mutexattr_setprotocol(&mutex_attr, PTHREAD_PRIO_INHERIT);
-
- } else if (sysconf(_POSIX_THREAD_PRIO_PROTECT)) {
- int th_policy;
- struct sched_param th_param;
- pthread_getschedparam(pthread_self(), &th_policy, &th_param);
- pthread_mutexattr_setprotocol(&mutex_attr, PTHREAD_PRIO_PROTECT);
- pthread_mutexattr_setprioceiling(&mutex_attr,
- sched_get_priority_max(th_policy));
- }
- #endif // ] Priority Scheduling.
- #endif // ] ALLOW_PRIORITY_SCHEDULING
- pthread_mutex_init(&pd->mutex, &mutex_attr);
- _prvData = static_cast<void *>(pd);
- }
- //----------------------------------------------------------------------------
- //
- // Decription: Destructor
- //
- // Use: public.
- //
- Mutex::~Mutex() {
- PThreadMutexPrivateData *pd =
- static_cast<PThreadMutexPrivateData*>(_prvData);
- pthread_mutex_destroy(&pd->mutex);
- delete pd;
- }
- //----------------------------------------------------------------------------
- //
- // Decription: lock the mutex
- //
- // Use: public.
- //
- int Mutex::lock() {
- PThreadMutexPrivateData *pd =
- static_cast<PThreadMutexPrivateData*>(_prvData);
- return pthread_mutex_lock(&pd->mutex);
- }
- //----------------------------------------------------------------------------
- //
- // Decription: unlock the mutex
- //
- // Use: public.
- //
- int Mutex::unlock() {
- PThreadMutexPrivateData *pd =
- static_cast<PThreadMutexPrivateData*>(_prvData);
- return pthread_mutex_unlock(&pd->mutex);
- }
- //----------------------------------------------------------------------------
- //
- // Decription: test if the mutex may be locked
- //
- // Use: public.
- //
- int Mutex::trylock() {
- PThreadMutexPrivateData *pd =
- static_cast<PThreadMutexPrivateData*>(_prvData);
- return pthread_mutex_trylock(&pd->mutex);
- }