linux程序设计笔记--pthread--mutex

 互斥量：
 #include<pthread.h>
 int pthread_mutex_init(pthread_mutex_t*mutex,const pthread_mutexattr_t *mutex_attr);
 intpthread_mutex_lock(pthread_mutex_t *mutex);
 intpthread_mutex_unlock(pthread_mutex_t *mutex);
 intpthread_mutex_destroy(pthread_mutex_t *mutex);

例程：

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <string.h>

#include <pthread.h>

#include <semaphore.h>

void *thread_function(void *arg);

pthread_mutex_t work_mutex; /* protects both work_area andtime_to_exit */

#define WORK_SIZE 1024

char work_area[WORK_SIZE];

int time_to_exit = 0;

int main() {

     int res;

    pthread_t a_thread;

    void *thread_result;

    res = pthread_mutex_init(&work_mutex, NULL);

    if (res != 0) {

        perror("Mutex initialization failed");

        exit(EXIT_FAILURE);

    }

    res = pthread_create(&a_thread, NULL, thread_function,NULL);

    if (res != 0) {

        perror("Thread creation failed");

        exit(EXIT_FAILURE);

    }

    pthread_mutex_lock(&work_mutex);

    printf("Input some text. Enter 'end' to finish\n");

    while(!time_to_exit) {

        fgets(work_area, WORK_SIZE, stdin);

        pthread_mutex_unlock(&work_mutex);

        while(1) {

            pthread_mutex_lock(&work_mutex);

            if (work_area[0] != '\0') {

                pthread_mutex_unlock(&work_mutex);

                sleep(1);

            } else {

                break;

            }

        }

    }

    pthread_mutex_unlock(&work_mutex);

    printf("\nWaiting for thread to finish...\n");

    res = pthread_join(a_thread, &thread_result);

    if (res != 0) {

        perror("Thread join failed");

        exit(EXIT_FAILURE);

    }

    printf("Thread joined\n");

    pthread_mutex_destroy(&work_mutex);

    exit(EXIT_SUCCESS);

}

void *thread_function(void *arg) {

    sleep(1);

    pthread_mutex_lock(&work_mutex);

    while(strncmp("end", work_area, 3) != 0) {

        printf("You input %d characters\n",strlen(work_area) -1);

        work_area[0] = '\0';

        pthread_mutex_unlock(&work_mutex);

        sleep(1);

        pthread_mutex_lock(&work_mutex);

        while (work_area[0] == '\0' ) {

            pthread_mutex_unlock(&work_mutex);

            sleep(1);

            pthread_mutex_lock(&work_mutex);

        }

    }

    time_to_exit = 1;

    work_area[0] = '\0';

    pthread_mutex_unlock(&work_mutex);

    pthread_exit(0);

}