75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/*
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* once.c
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*
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* Demonstrate the use of pthread_once() one-time
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* initialization.
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*/
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#include <pthread.h>
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#include "errors.h"
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pthread_once_t once_block = PTHREAD_ONCE_INIT;
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pthread_mutex_t mutex;
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/*
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* This is the one-time initialization routine. It will be
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* called exactly once, no matter how many calls to pthread_once
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* with the same control structure are made during the course of
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* the program.
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*/
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void
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once_init_routine(void)
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{
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int status;
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status = pthread_mutex_init(&mutex, NULL);
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if (status != 0)
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err_abort(status, "Init Mutex");
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}
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/*
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* Thread start routine that calls pthread_once.
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*/
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void*
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thread_routine(void* arg)
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{
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int status;
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status = pthread_once(&once_block, once_init_routine);
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if (status != 0)
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err_abort(status, "Once init");
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status = pthread_mutex_lock(&mutex);
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if (status != 0)
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err_abort(status, "Lock mutex");
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printf("thread_routine has locked the mutex.\n");
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status = pthread_mutex_unlock(&mutex);
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if (status != 0)
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err_abort(status, "Unlock mutex");
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return NULL;
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}
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int
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main(int argc, char* argv[])
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{
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pthread_t thread_id;
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char *input, buffer[64];
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int status;
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status = pthread_create(&thread_id, NULL, thread_routine, NULL);
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if (status != 0)
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err_abort(status, "Create thread");
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status = pthread_once(&once_block, once_init_routine);
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if (status != 0)
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err_abort(status, "Once init");
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status = pthread_mutex_lock(&mutex);
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if (status != 0)
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err_abort(status, "Lock mutex");
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printf("Main has locked the mutex.\n");
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status = pthread_mutex_unlock(&mutex);
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if (status != 0)
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err_abort(status, "Unlock mutex");
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status = pthread_join(thread_id, NULL);
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if (status != 0)
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err_abort(status, "Join thread");
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return 0;
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}
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