生产者与消费者

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/types.h>
#include <time.h>
#include <fcntl.h>
#include <semaphore.h>
#include <sys/ipc.h>
#include <errno.h>
#define MYFIFO "myfifo"
#define BUFFER_SIZE 3
#define UNIT_SIZE 5
#define RUN_TIME 30
#define DELAY_TIME_LEVELS 5.0

void *producer(void *arg);
void *customer(void *arg);

int fd;
time_t end_time;
sem_t mutex,full,avail;

int main()
{
int ret;
pthread_t thrd_prd_id,thrd_cst_id;

srand(time(NULL));
end_time = time(NULL) + RUN_TIME;

/*创建有名管道*/
if((mkfifo(MYFIFO,0644) < 0) && (errno != EEXIST))
{
perror("mkfifo error!");
exit(-1);
}

/*打开管道*/
fd = open(MYFIFO,O_RDWR);
if(fd == -1)
{
perror("open fifo error");
exit(-1);
}

/*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信号量为0*/
ret += sem_init(&full,0,0);

if(ret != 0)
{
perror("sem_init error");
exit(-1);
}

/*创建两个线程*/
ret = pthread_create(&thrd_prd_id,NULL,producer,NULL);
if(ret != 0)
{
perror("producer pthread_create error");
exit(-1);
}

ret = pthread_create(&thrd_cst_id,NULL,customer,NULL);
if(ret != 0)
{
perror("customer pthread_create error");
exit(-1);
}

pthread_join(thrd_prd_id,NULL);
pthread_join(thrd_cst_id,NULL);
close(fd);
unlink(MYFIFO);

return 0;
}

void *producer(void *arg) //生产者线程
{
int real_write;
int delay_time;

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 have delayed %d seconds\n",delay_time);

/*生产者写入数据*/
if((real_write = write(fd,"hello",UNIT_SIZE)) == -1)
{
if(errno == EAGAIN)
{
printf("The buffer is full,please wait for reading!\n");
}
}
else
{
printf("producer writes %d bytes to the FIFO\n",real_write);
printf("Now,the buffer left %d spaces!\n",avail);
}
/*V操作信号量full 和 mutex*/
sem_post(&full);
sem_post(&mutex);
}
pthread_exit(NULL);
}

void *customer(void *arg) //消费者线程
{
unsigned char read_buffer[UNIT_SIZE];
int real_read;
int delay_time;

while(time(NULL) < end_time)
{
delay_time = (int)(rand() * DELAY_TIME_LEVELS/RAND_MAX/2.0) + 1;
sleep(delay_time);

sem_wait(&full); //P操作信号量full和mutex
sem_wait(&mutex);
memset(read_buffer,0,UNIT_SIZE);
printf("\nCustomer have delayed %d seconds\n",delay_time);

if((real_read = read(fd,read_buffer,UNIT_SIZE)) == -1)
{
if(errno == EAGAIN)
{
printf("The buffer is empty,please wait for writing!\n");
}
}
else
{
printf("customer reads %d bytes from the FIFO\n",real_read);
}

sem_post(&avail); //V操作信号量 avail 和 mutex
sem_post(&mutex);
}

pthread_exit(NULL);
}