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/*
* Copyright (c) 2006-2024 RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2010-10-26 Bernard the first version
*/
#include <pthread.h>
int pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
{
if (!attr)
return EINVAL;
return 0;
}
RTM_EXPORT(pthread_barrierattr_destroy);
int pthread_barrierattr_init(pthread_barrierattr_t *attr)
{
if (!attr)
return EINVAL;
*attr = PTHREAD_PROCESS_PRIVATE;
return 0;
}
RTM_EXPORT(pthread_barrierattr_init);
int pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr,
int *pshared)
{
if (!attr)
return EINVAL;
*pshared = (int)*attr;
return 0;
}
RTM_EXPORT(pthread_barrierattr_getpshared);
int pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
{
if (!attr)
return EINVAL;
if (pshared == PTHREAD_PROCESS_PRIVATE)
{
*attr = PTHREAD_PROCESS_PRIVATE;
return 0;
}
return EINVAL;
}
RTM_EXPORT(pthread_barrierattr_setpshared);
/**
* @brief Destroys a barrier object.
*
* The `pthread_barrier_destroy` function releases any resources associated
* with the specified barrier object. After a barrier has been destroyed,
* it cannot be used again unless it is reinitialized using `pthread_barrier_init`.
*
* @param[in] barrier
* A pointer to an initialized `pthread_barrier_t` object to be destroyed.
*
* @return
* - `0` on success.
* - `EINVAL` if the `barrier` is invalid or uninitialized.
* - `EBUSY` if there are threads currently blocked on the barrier.
*
* @note
* - Ensure that no threads are blocked on the barrier before calling this function.
* - Attempting to destroy a barrier that is still in use results in undefined behavior.
*
* @warning
* Destroying a barrier without ensuring it is no longer in use can lead to
* resource leaks or undefined program behavior.
*
* @see pthread_barrier_init, pthread_barrier_wait
*/
int pthread_barrier_destroy(pthread_barrier_t *barrier)
{
rt_err_t result;
if (!barrier)
return EINVAL;
/* Lock the internal mutex to safely check the barrier's state*/
result = pthread_mutex_lock(&(barrier->mutex));
if (result != 0)
return result;
/* Check if any threads are currently waiting on the barrier*/
if (barrier->count != 0)
{
pthread_mutex_unlock(&(barrier->mutex));
return EBUSY; /* Threads are still waiting*/
}
/* Free resources associated with the barrier*/
result = pthread_mutex_unlock(&(barrier->mutex));
if (result != 0)
{
return result; /* Return mutex unlock error*/
}
result = pthread_mutex_destroy(&(barrier->mutex));
if (result != 0)
{
return result; /* Return mutex destroy error*/
}
result = pthread_cond_destroy(&(barrier->cond));
return result;
}
RTM_EXPORT(pthread_barrier_destroy);
/**
* @brief Initializes a barrier for synchronizing threads.
*
* The `pthread_barrier_init` function initializes a barrier object
* that allows a specified number of threads to synchronize at a barrier point.
* Each thread waits at the barrier until the required number of threads have called
* `pthread_barrier_wait`.
*
* @param[out] barrier
* A pointer to the `pthread_barrier_t` object to be initialized.
* This object must not already be initialized.
*
* @param[in] attr
* A pointer to a `pthread_barrierattr_t` object that specifies
* attributes for the barrier (e.g., process-shared or process-private).
* If NULL, the default attributes are used.
*
* @param[in] count
* The number of threads that must call `pthread_barrier_wait`
* before any of them successfully return from the barrier.
*
* @return
* - `0` on success.
* - `EINVAL` if the `count` is zero or `barrier` is invalid.
*
* @note The barrier must be destroyed using `pthread_barrier_destroy`
* when it is no longer needed.
*
* @warning If `count` is set to zero, the behavior is undefined.
*
* @see pthread_barrier_wait, pthread_barrier_destroy
*/
int pthread_barrier_init(pthread_barrier_t *barrier,
const pthread_barrierattr_t *attr,
unsigned count)
{
if (!barrier)
return EINVAL;
if (attr && (*attr != PTHREAD_PROCESS_PRIVATE))
return EINVAL;
if (count == 0)
return EINVAL;
barrier->count = count;
pthread_cond_init(&(barrier->cond), NULL);
pthread_mutex_init(&(barrier->mutex), NULL);
return 0;
}
RTM_EXPORT(pthread_barrier_init);
/**
* @brief Synchronizes threads at a barrier.
*
* The `pthread_barrier_wait` function blocks the calling thread at the specified
* barrier until the required number of threads have reached the barrier. Once
* the required number of threads have called this function, all threads are
* unblocked and can proceed.
*
* @param[in] barrier
* A pointer to an initialized `pthread_barrier_t` object representing the barrier
* at which threads will synchronize.
*
* @return
* - `0` for all threads except one.
* - `EINVAL` - The `barrier` is invalid or uninitialized.
*
* @note
* - All threads participating in the barrier must call `pthread_barrier_wait`
* before any of them are released.
*
* @warning
* Ensure that the number of threads specified during the barrier's initialization
* matches the number of threads calling this function, otherwise the program
* may hang indefinitely.
*
* @see pthread_barrier_init, pthread_barrier_destroy
*/
int pthread_barrier_wait(pthread_barrier_t *barrier)
{
rt_err_t result;
if (!barrier)
return EINVAL;
result = pthread_mutex_lock(&(barrier->mutex));
if (result != 0)
return EINVAL;
if (barrier->count == 0)
result = EINVAL;
else
{
barrier->count -= 1;
if (barrier->count == 0) /* broadcast condition */
pthread_cond_broadcast(&(barrier->cond));
else
pthread_cond_wait(&(barrier->cond), &(barrier->mutex));
}
pthread_mutex_unlock(&(barrier->mutex));
return result;
}
RTM_EXPORT(pthread_barrier_wait);
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