用c++設計哲學家進餐問題的求解

ZHUO_SIR發表於2018-05-22
C++
#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
#include<iostream>
#include<unistd.h>
#include<semaphore.h>
#define N 5
#define LEFT i
#define RIGHT (i+1)%N
using namespace std;
class Semaphore{
   private:
      sem_t sem;
   public:
      Semaphore(int value=1){
          sem_init(&sem,0,value);
      }
      void P(){
          sem_wait(&sem);
      }
      void V(){
          sem_post(&sem);
      }
};
Semaphore mutex[N];
pthread_t thread[N];
int id[N];
int add=0;
void* solve(void*param){
    int i =*((int*)param);
    while(true){
       if(add>=30){
          cout<<"noodles is over"<<endl;
          break;
       }
       cout<<"philo"<<i<<"  thinking"<<endl;
       if(i%2==0){
          mutex[LEFT].P();
          mutex[RIGHT].P();
          cout<<"philo"<<i<<"  eatting"<<endl;
          add++;
          cout<<add<<endl;
          mutex[RIGHT].V();
          mutex[LEFT].V();
       }else{
          mutex[RIGHT].P();
          mutex[LEFT].P();
          cout<<"philo"<<i<<"  eatting"<<endl;
          add++;
          cout<<add<<endl;
          mutex[LEFT].V();
          mutex[RIGHT].V();
       }
       sleep(1);
    }
}
void thread_create(){
   int tmp;
   for(int i=0; i<N; i++){
      tmp=pthread_create(&thread[i],NULL,solve,&id[i]);
      if(tmp!=0){
          cout<<"thread"<<i<<"error"<<endl;
      }
   }
}
void thread_wait(){
    for(int i=0; i<N; i++){
       pthread_join(thread[i],NULL);
    }
}
int main(){
    for(int i=0; i<N; i++){
        id[i]=i;
    }
    thread_create();
    thread_wait();
    return 0;
}

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