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/*-------------------------------------------------------------------------
* C-Pluff, a plug-in framework for C
* Copyright 2007 Johannes Lehtinen
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*-----------------------------------------------------------------------*/
/** @file
* Posix implementation for generic mutex functions
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <pthread.h>
#include "cpluff.h"
#include "defines.h"
#include "util.h"
#include "internal.h"
#include "thread.h"
/* ------------------------------------------------------------------------
* Data types
* ----------------------------------------------------------------------*/
// A generic recursive mutex implementation
struct cpi_mutex_t {
/// The current lock count
int lock_count;
/// The underlying operating system mutex
pthread_mutex_t os_mutex;
/// The condition variable for signaling availability
pthread_cond_t os_cond_lock;
/// The condition variable for broadcasting a wake request
pthread_cond_t os_cond_wake;
/// The locking thread if currently locked
pthread_t os_thread;
};
/* ------------------------------------------------------------------------
* Function definitions
* ----------------------------------------------------------------------*/
CP_HIDDEN cpi_mutex_t * cpi_create_mutex(void) {
cpi_mutex_t *mutex;
if ((mutex = malloc(sizeof(cpi_mutex_t))) == NULL) {
return NULL;
}
memset(mutex, 0, sizeof(cpi_mutex_t));
if (pthread_mutex_init(&(mutex->os_mutex), NULL)) {
return NULL;
} else if (pthread_cond_init(&(mutex->os_cond_lock), NULL)) {
int ec;
ec = pthread_mutex_destroy(&(mutex->os_mutex));
assert(!ec);
return NULL;
} else if (pthread_cond_init(&(mutex->os_cond_wake), NULL)) {
int ec;
ec = pthread_mutex_destroy(&(mutex->os_mutex));
assert(!ec);
ec = pthread_cond_destroy(&(mutex->os_cond_wake));
assert(!ec);
return NULL;
}
return mutex;
}
CP_HIDDEN void cpi_destroy_mutex(cpi_mutex_t *mutex) {
int ec;
assert(mutex != NULL);
assert(mutex->lock_count == 0);
ec = pthread_mutex_destroy(&(mutex->os_mutex));
assert(!ec);
ec = pthread_cond_destroy(&(mutex->os_cond_lock));
assert(!ec);
ec = pthread_cond_destroy(&(mutex->os_cond_wake));
assert(!ec);
free(mutex);
}
static void lock_mutex(pthread_mutex_t *mutex) {
int ec;
if ((ec = pthread_mutex_lock(mutex))) {
cpi_fatalf(_("Could not lock a mutex due to error %d."), ec);
}
}
static void unlock_mutex(pthread_mutex_t *mutex) {
int ec;
if ((ec = pthread_mutex_unlock(mutex))) {
cpi_fatalf(_("Could not unlock a mutex due to error %d."), ec);
}
}
static void lock_mutex_holding(cpi_mutex_t *mutex) {
pthread_t self = pthread_self();
while (mutex->lock_count != 0
&& !pthread_equal(self, mutex->os_thread)) {
int ec;
if ((ec = pthread_cond_wait(&(mutex->os_cond_lock), &(mutex->os_mutex)))) {
cpi_fatalf(_("Could not wait for a condition variable due to error %d."), ec);
}
}
mutex->os_thread = self;
mutex->lock_count++;
}
CP_HIDDEN void cpi_lock_mutex(cpi_mutex_t *mutex) {
assert(mutex != NULL);
lock_mutex(&(mutex->os_mutex));
lock_mutex_holding(mutex);
unlock_mutex(&(mutex->os_mutex));
}
CP_HIDDEN void cpi_unlock_mutex(cpi_mutex_t *mutex) {
pthread_t self = pthread_self();
assert(mutex != NULL);
lock_mutex(&(mutex->os_mutex));
if (mutex->lock_count > 0
&& pthread_equal(self, mutex->os_thread)) {
if (--mutex->lock_count == 0) {
int ec;
if ((ec = pthread_cond_signal(&(mutex->os_cond_lock)))) {
cpi_fatalf(_("Could not signal a condition variable due to error %d."), ec);
}
}
} else {
cpi_fatalf(_("Internal C-Pluff error: Unauthorized attempt at unlocking a mutex."));
}
unlock_mutex(&(mutex->os_mutex));
}
CP_HIDDEN void cpi_wait_mutex(cpi_mutex_t *mutex) {
pthread_t self = pthread_self();
assert(mutex != NULL);
lock_mutex(&(mutex->os_mutex));
if (mutex->lock_count > 0
&& pthread_equal(self, mutex->os_thread)) {
int ec;
int lc = mutex->lock_count;
// Release mutex
mutex->lock_count = 0;
if ((ec = pthread_cond_signal(&(mutex->os_cond_lock)))) {
cpi_fatalf(_("Could not signal a condition variable due to error %d."), ec);
}
// Wait for signal
if ((ec = pthread_cond_wait(&(mutex->os_cond_wake), &(mutex->os_mutex)))) {
cpi_fatalf(_("Could not wait for a condition variable due to error %d."), ec);
}
// Re-acquire mutex and restore lock count for this thread
lock_mutex_holding(mutex);
mutex->lock_count = lc;
} else {
cpi_fatalf(_("Internal C-Pluff error: Unauthorized attempt at waiting on a mutex."));
}
unlock_mutex(&(mutex->os_mutex));
}
CP_HIDDEN void cpi_signal_mutex(cpi_mutex_t *mutex) {
pthread_t self = pthread_self();
assert(mutex != NULL);
lock_mutex(&(mutex->os_mutex));
if (mutex->lock_count > 0
&& pthread_equal(self, mutex->os_thread)) {
int ec;
// Signal the mutex
if ((ec = pthread_cond_broadcast(&(mutex->os_cond_wake)))) {
cpi_fatalf(_("Could not broadcast a condition variable due to error %d."), ec);
}
} else {
cpi_fatalf(_("Internal C-Pluff error: Unauthorized attempt at signaling a mutex."));
}
unlock_mutex(&(mutex->os_mutex));
}
#if !defined(NDEBUG)
CP_HIDDEN int cpi_is_mutex_locked(cpi_mutex_t *mutex) {
int locked;
lock_mutex(&(mutex->os_mutex));
locked = (mutex->lock_count != 0);
unlock_mutex(&(mutex->os_mutex));
return locked;
}
#endif
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