prg8_5.c

配套光盘网络编程进程间的通信,网络编程进程间的通信是一本很经典的好书

#include <stdlib.h>
#include <semaphore.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/stat.h>

pthread_rwlock_t  rwlock = PTHREAD_RWLOCK_INITIALIZER;
pthread_t  tid1,tid2;
void *thread1(void*),*thread2(void*);

int main(int argc,char **argv)
{
  void *status;
  pthread_setconcurrency(2);
  pthread_create(&tid1,NULL,thread1,NULL);
  sleep(1);
  pthread_create(&tid2,NULL,thread2,NULL);
  pthread_join(tid2,&status);
  if (status != PTHREAD_CANCELED)
    printf("thread2 status= %p\n",status);
  pthread_join(tid1,&status);
  if (status != NULL)
    printf("thread1 status = %p\n",status);
  pthread_rwlock_destroy(&rwlock);
  exit(0);
}

void *thread1(void *arg)
{
	pthread_rwlock_rdlock(&rwlock);
	printf("thread1() got a read lock\n");
	sleep(3);
	pthread_cancel(tid2);
        sleep(3);
	pthread_rwlock_unlock(&rwlock);
	return (NULL);
}

void *thread2(void *arg)
{
	printf("thread2() trying to obtain a write lock\n");
	pthread_rwlock_wrlock(&rwlock);
	printf("thread2() got a write lock\n");
	sleep(1);
	pthread_rwlock_unlock(&rwlock);
	return (NULL);
}