Add a mutex/condvar based semaphore implementation if sem_timedwait is unavailable

Fixes #214.
laforge/swu
Martin Willi 2012-08-20 16:58:15 +02:00
parent f39b3915cd
commit 907d3d0f1d
2 changed files with 69 additions and 2 deletions

View File

@ -409,6 +409,8 @@ dnl check if we can cancel threads
AC_CHECK_FUNCS(pthread_cancel)
dnl check if native rwlocks are available
AC_CHECK_FUNCS(pthread_rwlock_init)
dnl check if we have POSIX semaphore functions, including timed-wait
AC_CHECK_FUNCS(sem_timedwait)
LIBS=$saved_LIBS
AC_CHECK_FUNC(

View File

@ -13,10 +13,14 @@
* for more details.
*/
#include <semaphore.h>
#include <library.h>
#ifdef HAVE_SEM_TIMEDWAIT
#include <semaphore.h>
#else /* !HAVE_SEM_TIMEDWAIT */
#include <threading/condvar.h>
#endif /* HAVE_SEM_TIMEDWAIT */
#include "semaphore.h"
typedef struct private_semaphore_t private_semaphore_t;
@ -30,21 +34,50 @@ struct private_semaphore_t {
*/
semaphore_t public;
#ifdef HAVE_SEM_TIMEDWAIT
/**
* wrapped POSIX semaphore object
*/
sem_t sem;
#else /* !HAVE_SEM_TIMEDWAIT */
/**
* Mutex to lock count variable
*/
mutex_t *mutex;
/**
* Condvar to signal count increase
*/
condvar_t *cond;
/**
* Semaphore count value
*/
u_int count;
#endif /* HAVE_SEM_TIMEDWAIT */
};
METHOD(semaphore_t, wait_, void,
private_semaphore_t *this)
{
#ifdef HAVE_SEM_TIMEDWAIT
sem_wait(&this->sem);
#else /* !HAVE_SEM_TIMEDWAIT */
this->mutex->lock(this->mutex);
while (this->count == 0)
{
this->cond->wait(this->cond, this->mutex);
}
this->count--;
this->mutex->unlock(this->mutex);
#endif /* HAVE_SEM_TIMEDWAIT */
}
METHOD(semaphore_t, timed_wait_abs, bool,
private_semaphore_t *this, timeval_t tv)
{
#ifdef HAVE_SEM_TIMEDWAIT
timespec_t ts;
ts.tv_sec = tv.tv_sec;
@ -53,6 +86,20 @@ METHOD(semaphore_t, timed_wait_abs, bool,
/* there are errors other than ETIMEDOUT possible, but we consider them
* all as timeout */
return sem_timedwait(&this->sem, &ts) == -1;
#else /* !HAVE_SEM_TIMEDWAIT */
this->mutex->lock(this->mutex);
while (this->count == 0)
{
if (this->cond->timed_wait_abs(this->cond, this->mutex, tv))
{
this->mutex->unlock(this->mutex);
return TRUE;
}
}
this->count--;
this->mutex->unlock(this->mutex);
return FALSE;
#endif /* HAVE_SEM_TIMEDWAIT */
}
METHOD(semaphore_t, timed_wait, bool,
@ -72,13 +119,25 @@ METHOD(semaphore_t, timed_wait, bool,
METHOD(semaphore_t, post, void,
private_semaphore_t *this)
{
#ifdef HAVE_SEM_TIMEDWAIT
sem_post(&this->sem);
#else /* !HAVE_SEM_TIMEDWAIT */
this->mutex->lock(this->mutex);
this->count++;
this->mutex->unlock(this->mutex);
this->cond->signal(this->cond);
#endif /* HAVE_SEM_TIMEDWAIT */
}
METHOD(semaphore_t, destroy, void,
private_semaphore_t *this)
{
#ifdef HAVE_SEM_TIMEDWAIT
sem_destroy(&this->sem);
#else /* !HAVE_SEM_TIMEDWAIT */
this->cond->destroy(this->cond);
this->mutex->destroy(this->mutex);
#endif /* HAVE_SEM_TIMEDWAIT */
free(this);
}
@ -99,7 +158,13 @@ semaphore_t *semaphore_create(u_int value)
},
);
#ifdef HAVE_SEM_TIMEDWAIT
sem_init(&this->sem, 0, value);
#else /* !HAVE_SEM_TIMEDWAIT */
this->mutex = mutex_create(MUTEX_TYPE_DEFAULT);
this->cond = condvar_create(CONDVAR_TYPE_DEFAULT);
this->count = value;
#endif /* HAVE_SEM_TIMEDWAIT */
return &this->public;
}