pthread_mutex»¥³âËø¶à½ø³Ì¹²Ïí

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

typedef struct _FOO
{
 int nCount;
 int nData;
}FOO,*PFOO;

int main(int argc,char *argv[])
{
 FOO *ptr;
 pid_t pid;

 pthread_mutexattr_t mutexattr;
 pthread_mutex_t mutex;

 pthread_mutexattr_init(&mutexattr);
 pthread_mutexattr_setpshared(&mutexattr,PTHREAD_PROCESS_SHARED); //ÉèÖÃΪ½ø³Ì¹²Ïí
 
 pthread_mutex_init(&mutex,&mutexattr);
 
 ptr = (PFOO)mmap(NULL,sizeof(FOO),PROT_READ | PROT_WRITE,MAP_SHARED|MAP_ANON,-1,0); //ÄäÃûÄÚ´æÓ³Éä，Èø¸×Ó½ø³Ì¶¼²Ù×÷ptrÖ¸ÏòµÄÄÚ´æÇø，Èç¹û²»Ê¹Óù²ÏíÄÚ´æ，Ôò¸¸×Ó½ø³ÌµÄptrÖ¸ÏòµÄÊǸ÷×ÔµÄÄÚ´æ¿Õ¼ä
 ptr->nCount = 1;
 ptr->nData = 2;
 printf("%d,%d\n",ptr->nCount,ptr->nData);
 if( (pid = fork()) < 0)
 {
  printf("fork error\n");
  return -1;
 } 
 else if( 0 == pid)  //×Ó½ø³Ì
 {
  for(int i = 0;i<3;i++)
  {
   pthread_mutex_lock(&mutex);
   ptr->nCount++;
   printf("child ++ === %d\n",ptr->nCount);
   pthread_mutex_unlock(&mutex);
   usleep(1000);
  }
 }
 else    //¸¸½ø³Ì
 {
  for(int i = 0;i<3;i++)
  {
   pthread_mutex_lock(&mutex);
   ptr->nCount += 2;
   printf("parent +2 === %d\n",ptr->nCount);
   pthread_mutex_unlock(&mutex);
   usleep(1000);
  } 
 }
 waitpid(pid,NULL,0);
 munmap(NULL,sizeof(FOO));
 return 0;
}