消费者与生产者线程同步程序

 

/*producer-customer.c*/
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<fcntl.h>
#include<pthread.h>
#include<errno.h>
#include<semaphore.h>
#include<sys/ipc.h>

#define MYFIFO  "/tmp/myfifo" //缓冲区有名管道的名字
#define BUFFER_SIZE  3   //缓冲区的单元数
#define UNIT_SIZE  5   //每个单元的大小
#define RUN_TIME  30
#define DELAY_TIME_LEVELS 5.0
int fd;
time_t end_time;
sem_t mutex,full,avail;

void *producer(void *arg);
void *customer(void *arg);
int main()
{
 pthread_t thrd_prd_id,thrd_cst_id;
 pthread_t mon_th_id;
 int ret;
 srand(time(NULL));
 end_time=time(NULL)+RUN_TIME;
 /*创建有名管道*/
 if((mkfifo(MYFIFO,O_CREAT|O_EXCL)<0)&&(errno!=EEXIST))
 {
  printf("cannot create fifo\n");
  return errno;
 }
 /*打开管道*/
 fd=open(MYFIFO,O_RDWR);
 if(fd==-1)
 {
  printf("open fifo error\n");
  return fd;
 }
 /*初始化互斥信号量为1*/
 ret=sem_init(&mutex,0,1);
 /*初始化avail信号量为N*/
 ret+=sem_init(&avail,0,BUFFER_SIZE);
 /*初始化full信号量0*/
 ret+=sem_init(&full,0,0);
 if(ret!=0)
 {
  printf("any semaphore initalization failed\n");
  return ret;
 }
 /*创建两个线程*/
 ret=pthread_create(&thrd_prd_id,NULL,producer,NULL);
 if(ret!=0)
 {
  printf("Create producer thread error\n");
  return ret;
 }
 ret=pthread_create(&thrd_cst_id,NULL,customer,NULL);
 if(ret!=0)
 {
  printf("Create customer thread error\n");
  return ret;
 }
 pthread_join(thrd_prd_id,NULL);
 pthread_join(thrd_cst_id,NULL);
 close(fd);
 unlink(MYFIFO);
 return 0;
}
 
/*生产者线程*/
void *producer(void *arg)
{
 int real_write;
 int delay_time=0;
 while(time(NULL)<end_time)
 {
  delay_time=(int)(rand()*DELAY_TIME_LEVELS/(RAND_MAX)/2.0)+1;
  sleep(delay_time);
  /*P操作信号量avail和mutex*/
  sem_wait(&avail);
  sem_wait(&mutex);
  printf("\nproducer:delay=%d\n",delay_time);
  /*生产者写入数据*/
  if((real_write=write(fd,"hello",UNIT_SIZE))==-1)
  {
   if(errno==EAGAIN)
    printf("the fifo has not ben read yet.please try later");
  }
  else
  {
   printf("Write %d to the fifo\n",real_write);
  }
  /*V操作信号量full和mutex*/
  sem_post(&full);
  sem_post(&mutex);
 }
 pthread_exit(NULL);
} 
 
/*消费者线程*/
void *customer(void *arg)
{
 int real_read;
 unsigned char read_buffer[UNIT_SIZE];
 int delay_time=0;
 while(time(NULL)<end_time)
 {
  delay_time=(int)(rand()*DELAY_TIME_LEVELS/(RAND_MAX))+1;
  sleep(delay_time);
  /*P操作信号量full和mutex*/
  sem_wait(&full);
  sem_wait(&mutex);
  printf("\ncustomer:delay=%d\n",delay_time);
  /*消费者数据*/
  if((real_read=read(fd,read_buffer,UNIT_SIZE))==-1)
  {
   if(errno==EAGAIN)
    printf("no data yet\n");
  }
  printf("read %s from FIFO\n",read_buffer);
  /*V操作信号量avail和mutex*/
  sem_post(&avail);
  sem_post(&mutex);
 }
 pthread_exit(NULL);
}