Linux多线程使用互斥量同步线程

#include <pthread.h> 
int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr); 
 
int pthread_mutex_lock(pthread_mutex_t *mutex); 
 
int pthread_mutex_unlock(pthread_mutex_t *mutex); 
 
int pthread_mutex_destroy(pthread_mutex_t *mutex); 

、#include <unistd.h> 
#include <pthread.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <string.h> 
 
 
//声明线程函数和互斥量 
void* thread_func(void *msg); 
pthread_mutex_t mutex; 
 
 
#define MSG_SIZE 512 
 
 
int main() 
{ 
  int res = -1; 
  pthread_t thread; 
  void *thread_result = NULL; 
  char msg[MSG_SIZE] = {'\0'}; 
  //初始化互斥量，使用默认的互斥量属性 
  res = pthread_mutex_init(&mutex, NULL); 
  if(res != 0) 
  { 
    perror("pthread_mutex_init failed\n"); 
    exit(EXIT_FAILURE); 
  } 
  //创建子线程，并把msg作为线程函数的参数传递给thread_func 
  res = pthread_create(&thread, NULL, thread_func, msg); 
  if(res != 0) 
  { 
    perror("pthread_create failed\n"); 
    exit(EXIT_FAILURE); 
  } 
  //输入字符串，以串‘end'结束 
  printf("Input some test. Enter 'end' to finish\n"); 
  //把互斥量mutex加锁，以确保同一时间只有该线程可以访问msg中的数据 
  pthread_mutex_lock(&mutex); 
  while(strcmp("end\n", msg) != 0) 
  { 
    if(strncmp("TEST", msg, 4) == 0) 
    { 
      strcpy(msg, "copy_data\n"); 
    } 
    else 
    { 
      fgets(msg, MSG_SIZE, stdin); 
    } 
    //把互斥量mutex解锁，让其他的线程可以访问msg中的数据 
    pthread_mutex_unlock(&mutex); 
    sleep(1);//休眠1秒再继续循环，让其他线程有执行的机会 
    pthread_mutex_lock(&mutex); 
  } 
  pthread_mutex_unlock(&mutex); 
  printf("\nWaiting for thread finish...\n"); 
  //等待子线程结束 
  res = pthread_join(thread, &thread_result); 
  if(res != 0) 
  { 
    perror("pthread_join failed\n"); 
    exit(EXIT_FAILURE); 
  } 
  printf("Thread joined\n"); 
  //清理互斥量 
  pthread_mutex_destroy(&mutex); 
  exit(EXIT_SUCCESS); 
} 
void* thread_func(void *msg) 
{ 
  int i = 0; 
  char *ptr = msg; 
  sleep(1); 
  //把互斥量mutex加锁，以确保同一时间只有该线程可以访问msg中的数据 
  pthread_mutex_lock(&mutex); 
  while(strcmp("end\n", msg) != 0) 
  { 
    //把小写字母变成大写 
    for(i = 0; ptr[i] != '\0'; ++i) 
    { 
      if(ptr[i] >= 'a' && ptr[i] <='z') 
      { 
        ptr[i] -= 'a' - 'A'; 
      } 
    } 
    printf("You input %d characters\n", i-1); 
    printf("To uppercase: %s\n", ptr); 
    //把互斥量mutex解锁，让其他的线程可以访问msg中的数据 
    pthread_mutex_unlock(&mutex); 
    sleep(1);//休眠1秒再继续循环，让其他线程有执行的机会 
    pthread_mutex_lock(&mutex); 
  } 
  pthread_mutex_unlock(&mutex); 
  //退出线程 
  pthread_exit(NULL); 
}