linux 进程间通信系列7，使用pthread mutex

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/shm.h>

#include <pthread.h>

#include <sys/wait.h>

int main(){

  pthread_mutex_t *m;

  pthread_mutexattr_t mat;

  int shmid;

  pid_t pid;

  shmid = shmget(IPC_PRIVATE, sizeof(pthread_mutex_t), 0600);

  if(shmid < 0){

    perror("shmget");

    return 1;

  }

  m = (pthread_mutex_t*)shmat(shmid, NULL, 0);

  //准备设定mutex的attribute

  pthread_mutexattr_init(&mat);

  //利用mutex进行进程间的通信

  //底下这句没有的话，这个mutex只在本进程间有作用

  if(pthread_mutexattr_setpshared(&mat, PTHREAD_PROCESS_SHARED) != 0){

    perror("pthread_mutexattr_setpshared");

    return 1;

  }

  pthread_mutex_init(m, &mat);

  pid = fork();

  printf("[%s] before pthread_mutex_lock()\n",

	 pid == 0 ? "child" : "parent");

  if(pthread_mutex_lock(m) != 0){

    perror("pthread_mutex_lock");

    return 1;

  }

  printf("[%s] press enter\n", pid == 0 ? "child" : "parent");

  getchar();

  if(pthread_mutex_unlock(m) != 0){

    perror("pthread_mutex_unlock");

    return 1;

  }

  printf("[%s] after pthread_mutex_lock()\n",

	 pid == 0 ? "child" : "parent");

  shmdt(m);

  if(pid != 0){

    wait(NULL);//wait child process to complete

    printf("[%s] after wait()\n", pid == 0 ? "child" : "parent");

    //delete shared memery

    if(shmctl(shmid, IPC_RMID, NULL) != 0){

      perror("shmctl");

      return 1;

    }

  }

  return 0;

}

github源代码

编译方法：

g++ -g process-41-pthread-mutex.cpp -std=c++11 -pthread

运行结果：

[parent] before pthread_mutex_lock()

[parent] press enter

[child] before pthread_mutex_lock()

敲回车

[parent] after pthread_mutex_lock()

[child] press enter

敲回车

[child] after pthread_mutex_lock()

[parent] after wait()

巴特西

c/c++ linux 进程间通信系列7，使用pthread mutex

linux 进程间通信系列7，使用pthread mutex

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