sem_destroy

sem_destroy is a function in the C programming language that is used to destroy a named or unnamed semaphore.

Syntax:

#include <semaphore.h>

int sem_destroy(sem_t *sem);

Parameters:

- `sem`: Pointer to the semaphore that needs to be destroyed.

Return Value:

The sem_destroy function returns 0 on success, and -1 on failure.

Description:

The sem_destroy function is used to destroy a semaphore that was previously created using the sem_init or sem_open function. Once a semaphore has been destroyed, all threads waiting on it will be unblocked and any resources associated with it will be released.

Note:
- Before calling sem_destroy, all threads waiting on the semaphore must be unblocked.
- Once a semaphore has been destroyed, it cannot be used again until it is re-initialized using sem_init or sem_open.

Example:

#include <stdio.h>
#include <semaphore.h>
#include <pthread.h>

sem_t semaphore;

void* myThread(void* arg){
    sem_wait(&semaphore);
    printf("Thread is waiting on semaphore\n");
    sem_post(&semaphore);
    printf("Thread has finished waiting on semaphore\n");
    return NULL;
}

int main(){
    sem_init(&semaphore, 0, 1);
    pthread_t threadID;
    pthread_create(&threadID, NULL, &myThread, NULL);
    pthread_join(threadID, NULL);
    sem_destroy(&semaphore);
    printf("Semaphore has been destroyed\n");
    return 0;
}

In the above example, the sem_destroy function is called to destroy the semaphore after the thread has finished waiting on it.