理发师问题的信号量实现

barber.c

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

#define CHAIR_NUM 3
#define SOFA_NUM 4
#define CAPACITY 20
#define CUSTOMER_NUM 20
#define thread_sum (1 + CHAIR_NUM + CUSTOMER_NUM)

#define customer_say(sentence)    printf("%d:" sentence "\n", id);
#define true 1

sem_t capacity, sofa, chair, coord, have_customer, cut_finish, payment, receipt;

void* customer(void* arg) {
    int id = *((int*)arg)-(1 + CHAIR_NUM);
    customer_say("I want to enter");
    sem_wait(&capacity);
    customer_say("I enter, now I want a sofa");
    sem_wait(&sofa);
    customer_say("I get sofa, now I want a chair");
    sem_wait(&chair);
    sem_post(&sofa);
    customer_say("I get a chair, I want haircut");
    sem_post(&have_customer);
    sem_wait(&cut_finish);
    customer_say("I get haircut, now I want to pay");
    sem_post(&chair);
    sem_post(&payment);
    sem_wait(&receipt);
    customer_say("pay finish, I can leave now");
    sem_post(&capacity);
    customer_say("done");
}

void* barber(void* arg) {
    while(true) {
        sem_wait(&have_customer);
        sem_wait(&coord);
        puts("I'm working on haircut");
        sleep(0.5);
        sem_post(&cut_finish);
        sem_post(&coord);
    }
}

void* cashier(void* arg) {
    while(true) {
        sem_wait(&payment);
        sem_wait(&coord);
        sleep(0.1);
        puts("payment finish");
        sem_post(&receipt);
        sem_post(&coord);
    }
}

int main()
{
    sem_init(&capacity, 0, CAPACITY);
    sem_init(&sofa, 0, SOFA_NUM);
    sem_init(&chair, 0, CHAIR_NUM);
    sem_init(&coord, 0, CHAIR_NUM);
    sem_init(&have_customer, 0, 0);
    sem_init(&cut_finish, 0, 0);
    sem_init(&payment, 0, 0);
    sem_init(&receipt, 0, 0);
    
    pthread_t pthread_all[thread_sum];
    pthread_create(&pthread_all[0], NULL, cashier, NULL);
    int end = CHAIR_NUM + 1;
    for (int i = 1; i < end; i++) {
        pthread_create(&pthread_all[i], NULL, barber, NULL);
    }
    end = 1 + CHAIR_NUM + CUSTOMER_NUM;
    for (int i = 1 + CHAIR_NUM; i < end; i++) {
        pthread_create(&pthread_all[i], NULL, customer, (void*)&i);
    }
    for (int i = 1 + CHAIR_NUM; i < end; i++) {
        pthread_join(pthread_all[i], NULL);
    }
}