读者-写者问题（三种实现方案）

最新推荐文章于 2024-04-21 03:33:12 发布

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最新推荐文章于 2024-04-21 03:33:12 发布 · 5k 阅读

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第一种 读者优先方案：

#include<pthread.h>
#include<semaphore.h>
#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<string>
using namespace std;
sem_t rmutex,wmutex;
int readcount=0,writecount=0,count=0;
void *write(void *id){
     sem_wait(&wmutex);
           printf("%s: count为 %d , ",(char *)id,count); //CS代码
           count++;                                       //CS代码
           printf("writecount为 %d , ",writecount); //CS代码
           printf("readcount为 %d \n",readcount); //CS代码
     sem_post(&wmutex);
}

void *read(void *id){
      sem_wait(&rmutex);
          if(readcount==0) sem_wait(&wmutex);
          readcount++;
      sem_post(&rmutex);

      printf("%s：count为 %d , ",(char *)id,count); //CS代码
      printf("writecount为 %d , ",writecount); //CS代码
      printf("readcount为 %d \n",readcount); //CS代码

      sem_wait(&rmutex);
          readcount--;
          if(readcount==0) sem_post(&wmutex);
      sem_post(&rmutex);
}

int main() {
    pthread_t ti