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/*
* Copyright (C) 2011 Tobias Brunner
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program 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 General Public License
* for more details.
*/
#include <library.h>
#if defined(HAVE_CLOCK_GETTIME) && \
(defined(HAVE_CONDATTR_CLOCK_MONOTONIC) || \
defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC))
/* if we use MONOTONIC times, we can't use POSIX_SEMAPHORES since they use
* times based on CLOCK_REALTIME */
#undef HAVE_SEM_TIMEDWAIT
#endif /* HAVE_CLOCK_GETTIME && ... */
#ifdef HAVE_SEM_TIMEDWAIT
#include <semaphore.h>
#else /* !HAVE_SEM_TIMEDWAIT */
#include <threading/thread.h>
#include <threading/condvar.h>
#endif /* HAVE_SEM_TIMEDWAIT */
#include "semaphore.h"
typedef struct private_semaphore_t private_semaphore_t;
/**
* private data of a semaphore
*/
struct private_semaphore_t {
/**
* public interface
*/
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);
thread_cleanup_push((void*)this->mutex->unlock, this->mutex);
while (this->count == 0)
{
this->cond->wait(this->cond, this->mutex);
}
this->count--;
thread_cleanup_pop(TRUE);
#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;
ts.tv_nsec = tv.tv_usec * 1000;
/* 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);
thread_cleanup_push((void*)this->mutex->unlock, this->mutex);
while (this->count == 0)
{
if (this->cond->timed_wait_abs(this->cond, this->mutex, tv))
{
thread_cleanup_pop(TRUE);
return TRUE;
}
}
this->count--;
thread_cleanup_pop(TRUE);
return FALSE;
#endif /* HAVE_SEM_TIMEDWAIT */
}
METHOD(semaphore_t, timed_wait, bool,
private_semaphore_t *this, u_int timeout)
{
timeval_t tv, add;
add.tv_sec = timeout / 1000;
add.tv_usec = (timeout % 1000) * 1000;
time_monotonic(&tv);
timeradd(&tv, &add, &tv);
return timed_wait_abs(this, tv);
}
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);
}
/*
* Described in header
*/
semaphore_t *semaphore_create(u_int value)
{
private_semaphore_t *this;
INIT(this,
.public = {
.wait = _wait_,
.timed_wait = _timed_wait,
.timed_wait_abs = _timed_wait_abs,
.post = _post,
.destroy = _destroy,
},
);
#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;
}
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