读者写者算法

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <semaphore.h>
#include <pthread.h>

#define READER 3
#define WRITER 2

sem_t rmutex,wmutex;

int readercount=0;
int number=0;
int reader_id=0,writer_id=0;

void *Reader()
{
    int readernum=++reader_id;
    while(1)
    {
        sem_wait(&rmutex);  
        if(readercount!=0)
            sem_wait(&wmutex);
        readercount++;
        sem_post(&rmutex);

        printf("读者%d读数为%d\n",readernum,number);
        sleep(2);
        sem_wait(&rmutex);
        readercount--;
        if(readercount==0)
            sem_post(&wmutex);
        sem_post(&rmutex);
    }
}


void *Writer()
{
    int writernum=++writer_id;
    while(1)
    {
        sem_wait(&wmutex);
        number++;
        printf("写者%d写入数为%d\n",writernum,number);
        sleep(3);
        sem_post(&wmutex);
    }
}

int main()
{
    pthread_t reader[READER],writer[WRITER];
    int t1,t2;
    int init1=sem_init(&rmutex,0,3);
    int init2=sem_init(&wmutex,0,2);
    for(int i=0;i<READER;i++)
    {
        t1=pthread_create(&reader[i],NULL,Reader,NULL);
        if(t1!=0)
        {
            printf("reader %d fail to create\n",i);
            exit(1);
        }
    }
    for(int i=0;i<WRITER;i++)
    {
        t2=pthread_create(&writer[i],NULL,Writer,NULL);
        if(t2!=0)
        {
            printf("writer %d fail to create\n",i);
            exit(1);
        }
    }
    for(int i=0;i<READER;i++)
    {
        pthread_join(reader[i],NULL);
    }
    for(int i=0;i<WRITER;i++)
    {
        pthread_join(writer[i],NULL);
    }
    return 0;
}