Usage of releasesemaphore in C

The release_semaphore function in C is used to release the obtained semaphore so that other threads or processes can access shared resources. It increases the semaphore count by 1, allowing the blocking thread to continue execution.

Usage of release_semaphore in C

The release_semaphore function is used to release the obtained semaphore. It allows other threads or processes to continue accessing shared resources protected by semaphores.

grammar:

 <code class="cpp">int release_semaphore(sem_t *sem);</code>

parameter:

• sem : a pointer to a semaphore

Return value:

• Returns 0 when successful
• Returns -1 on failure (and set errno )

effect:

The release_semaphore function increases the count of the semaphore by 1. If the semaphore count is greater than 0, the blocked thread or process will continue to execute.

usage:

Typical usages are as follows:

 <code class="cpp">// 创建信号量sem_t sem; sem_init(&sem, 0, 0); // ... 获取信号量... // 释放信号量sem_post(&sem);</code>

Notes:

• It must be obtained before the semaphore is released.
• The count of the semaphore cannot be less than 0.
• The release_semaphore function is not thread-safe. Therefore, when using semaphores in a multithreaded environment, other synchronization primitives (such as mutexes) need to be used to protect access to semaphores.

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