kc3-lang/libevent/evthread_pthread.c

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• Hash : 347952ff
  Author :
  Date : 2009-11-27T15:20:43
  

  Revise the locking API: deprecate the old locking callbacks and add trylock.
  
  Previously, there was no good way to request different kinds of lock
  (say, read/write vs writeonly or recursive vs nonrecursive), or for a
  lock function to signal failure (which would be important for a
  trylock mode).
  
  This patch revises the lock API to be a bit more useful.  The older
  lock calls are still supported for now.
  
  We also add a debugging mode to catch common errors in using the
  locking APIs.
  

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• evthread_pthread.c

• /*
   * Copyright 2009 Niels Provos and Nick Mathewson
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  #include "event-config.h"
  
  /* With glibc we need to define this to get PTHREAD_MUTEX_RECURSIVE. */
  #define _GNU_SOURCE
  #include <pthread.h>
  
  struct event_base;
  #include <event2/thread.h>
  
  #include <stdlib.h>
  #include "mm-internal.h"
  
  static pthread_mutexattr_t attr_recursive;
  
  static void *
  evthread_posix_lock_alloc(unsigned locktype)
  {
  	pthread_mutexattr_t *attr = NULL;
  	pthread_mutex_t *lock = mm_malloc(sizeof(pthread_mutex_t));
  	if (!lock)
  		return NULL;
  	if (locktype & EVTHREAD_LOCKTYPE_RECURSIVE)
  		attr = &attr_recursive;
  	if (pthread_mutex_init(lock, attr)) {
  		mm_free(lock);
  		return NULL;
  	}
  	return lock;
  }
  
  static void
  evthread_posix_lock_free(void *_lock, unsigned locktype)
  {
  	pthread_mutex_t *lock = _lock;
  	pthread_mutex_destroy(lock);
  	mm_free(lock);
  }
  
  static int
  evthread_posix_lock(unsigned mode, void *_lock)
  {
  	pthread_mutex_t *lock = _lock;
  	if (mode & EVTHREAD_TRY)
  		return pthread_mutex_trylock(lock);
  	else
  		return pthread_mutex_lock(lock);
  }
  
  static int
  evthread_posix_unlock(unsigned mode, void *_lock)
  {
  	pthread_mutex_t *lock = _lock;
  	return pthread_mutex_unlock(lock);
  }
  
  static unsigned long
  evthread_posix_get_id(void)
  {
  	union {
  		pthread_t thr;
  		unsigned long id;
  	} r;
  	r.thr = pthread_self();
  	return r.id;
  }
  
  int
  evthread_use_pthreads(void)
  {
  	struct evthread_lock_callbacks cbs = {
  		EVTHREAD_LOCK_API_VERSION,
  		EVTHREAD_LOCKTYPE_RECURSIVE,
  		evthread_posix_lock_alloc,
  		evthread_posix_lock_free,
  		evthread_posix_lock,
  		evthread_posix_unlock
  	};
  	/* Set ourselves up to get recursive locks. */
  	if (pthread_mutexattr_init(&attr_recursive))
  		return -1;
  	if (pthread_mutexattr_settype(&attr_recursive, PTHREAD_MUTEX_RECURSIVE))
  		return -1;
  
  	evthread_set_lock_callbacks(&cbs);
  	evthread_set_id_callback(evthread_posix_get_id);
  	return 0;
  }
  

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