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#define _GNU_SOURCE
#define _XOPEN_SOURCE 600
#include "config.h"
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <assert.h>
#include <pthread.h>
#include <stdint.h>
#ifdef HAVE_STDATOMIC_H
# include <stdatomic.h>
#endif /* HAVE_STDATOMIC_H */
#include "error.h"
#include "lock.h"
#include "pci.h"
/**
* structure to define a lock
*/
struct pcilib_lock_s {
pthread_mutex_t mutex; /**< the pthread robust mutex */
pcilib_lock_flags_t flags; /**< flags to define the type of the mutex */
#ifdef HAVE_STDATOMIC_H
volatile atomic_uint refs; /**< approximate number of processes that hold the lock initialized, may desynchronize on crashes */
#else /* HAVE_STDATOMIC_H */
volatile uint32_t refs; /**< approximate number of processes that hold the lock initialized, may desynchronize on crashes */
#endif /* HAVE_STDATOMIC_H */
char name[]; /**< lock identifier */
};
int pcilib_init_lock(pcilib_lock_t *lock, pcilib_lock_flags_t flags, const char *lock_id) {
int err;
pthread_mutexattr_t attr;
assert(lock);
assert(lock_id);
memset(lock, 0, PCILIB_LOCK_SIZE);
if (strlen(lock_id) >= (PCILIB_LOCK_SIZE - offsetof(struct pcilib_lock_s, name))) {
pcilib_error("The supplied lock id (%s) is too long...", lock_id);
return PCILIB_ERROR_INVALID_ARGUMENT;
}
if ((err = pthread_mutexattr_init(&attr))!=0) {
pcilib_error("Can't initialize mutex attribute, errno %i", errno);
return PCILIB_ERROR_FAILED;
}
/* we declare the mutex as possibly shared amongst different processes*/
if ((err = pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED))!=0) {
pcilib_error("Can't configure a shared mutex attribute, errno %i", errno);
return PCILIB_ERROR_FAILED;
}
/* we set the mutex as robust, so it would be automatically unlocked if the application crash*/
if ((flags&PCILIB_LOCK_FLAG_PERSISTENT)==0) {
if ((err = pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_ROBUST))!=0) {
pcilib_error("Can't configure a robust mutex attribute, errno: %i", errno);
return PCILIB_ERROR_FAILED;
}
}
if ((err = pthread_mutex_init(&lock->mutex, &attr))!=0) {
pcilib_error("Can't create mutex, errno : %i",errno);
return PCILIB_ERROR_FAILED;
}
strcpy(lock->name, lock_id);
lock->refs = 1;
lock->flags = flags;
return 0;
}
void pcilib_free_lock(pcilib_lock_t *lock) {
int err;
assert(lock);
// if (lock->refs)
// pcilib_error("Forbidding to destroy the referenced mutex...");
if ((err = pthread_mutex_destroy(&lock->mutex))==-1)
pcilib_warning("Can't destroy POSIX mutex, errno %i",errno);
}
void pcilib_lock_ref(pcilib_lock_t *lock) {
assert(lock);
#ifdef HAVE_STDATOMIC_H
atomic_fetch_add_explicit(&lock->refs, 1, memory_order_relaxed);
#else /* HAVE_STDATOMIC_H */
lock->refs++;
#endif /* HAVE_STDATOMIC_H */
}
void pcilib_lock_unref(pcilib_lock_t *lock) {
assert(lock);
if (!lock->refs) {
pcilib_warning("Lock is not referenced");
return;
}
#ifdef HAVE_STDATOMIC_H
atomic_fetch_sub_explicit(&lock->refs, 1, memory_order_relaxed);
#else /* HAVE_STDATOMIC_H */
lock->refs--;
#endif /* HAVE_STDATOMIC_H */
}
size_t pcilib_lock_get_refs(pcilib_lock_t *lock) {
return lock->refs;
}
pcilib_lock_flags_t pcilib_lock_get_flags(pcilib_lock_t *lock) {
return lock->flags;
}
const char *pcilib_lock_get_name(pcilib_lock_t *lock) {
assert(lock);
if (lock->name[0]) return lock->name;
return NULL;
}
int pcilib_lock_custom(pcilib_lock_t *lock, pcilib_lock_flags_t flags, pcilib_timeout_t timeout) {
int err;
if (!lock) {
pcilib_error("The null lock pointer is passed to lock function");
return PCILIB_ERROR_INVALID_ARGUMENT;
}
struct timespec tm;
switch (timeout) {
case PCILIB_TIMEOUT_INFINITE:
/* the process will be hold till it can gain acquire the lock*/
err = pthread_mutex_lock(&lock->mutex);
break;
case PCILIB_TIMEOUT_IMMEDIATE:
/* the function returns immediatly if it can't acquire the lock*/
err = pthread_mutex_trylock(&lock->mutex);
break;
default:
/* the process will be hold till it can acquire the lock and timeout is not reached*/
clock_gettime(CLOCK_REALTIME, &tm);
tm.tv_nsec += 1000 * (timeout%1000000);
if (tm.tv_nsec < 1000000000)
tm.tv_sec += timeout/1000000;
else {
tm.tv_sec += 1 + timeout/1000000;
tm.tv_nsec -= 1000000000;
}
err = pthread_mutex_timedlock(&lock->mutex, &tm);
}
if (!err)
return 0;
switch (err) {
case EOWNERDEAD:
/*in the case an application with a lock acquired crashes, this lock becomes inconsistent. we have so to make it consistent again to use it again.*/
err = pthread_mutex_consistent(&lock->mutex);
if (err) {
pcilib_error("Failed to mark mutex as consistent, errno %i", err);
break;
}
return 0;
case ETIMEDOUT:
case EBUSY:
return PCILIB_ERROR_TIMEOUT;
default:
pcilib_error("Failed to obtain mutex, errno %i", err);
}
return PCILIB_ERROR_FAILED;
}
int pcilib_lock(pcilib_lock_t* lock) {
return pcilib_lock_custom(lock, PCILIB_LOCK_FLAGS_DEFAULT, PCILIB_TIMEOUT_INFINITE);
}
int pcilib_try_lock(pcilib_lock_t* lock) {
return pcilib_lock_custom(lock, PCILIB_LOCK_FLAGS_DEFAULT, PCILIB_TIMEOUT_IMMEDIATE);
}
void pcilib_unlock(pcilib_lock_t *lock) {
int err;
if (!lock)
return;
if ((err = pthread_mutex_unlock(&lock->mutex)) != 0) {
switch (err) {
case EPERM:
pcilib_error("Trying to unlock not locked mutex (%s) or the mutex which was locked by a different thread", lock->name);
break;
default:
pcilib_error("Can't unlock mutex, errno %i", err);
}
}
}
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