IPC 经典问题：Sleeping Barber Problem

完整代码实现：
#include <stdio.h>

#include <unistd.h>

#include <time.h>

#include <stdlib.h>

#include <pthread.h>

#include <semaphore.h>

#define CUSTOMER_NUMBER 20

void *customer(void *param);

void *barber(void *param);

int seat_num = 5;

int interval[CUSTOMER_NUMBER] = {100, 100, 200, 100, 250, 400, 200, 100, 200, 700, 100, 200, 600, 100, 250, 400, 200, 100, 200, 700};

sem_t cust_ready;

sem_t barber_ready;

sem_t mutex;

int main(int argc, char *argv[]) {

	pthread_t barberid;

	pthread_t clientids[CUSTOMER_NUMBER];

    sem_init(&mutex,0,1);

    sem_init(&barber_ready,0,0);

    sem_init(&cust_ready,0,0);

    pthread_create(&barberid, NULL, barber, NULL);

    for (int i = 0; i < CUSTOMER_NUMBER; i++){

        usleep(interval[i]*1000);

        time_t t = time(NULL);

        struct tm tm = *localtime(&t);

        pthread_create(&clientids[i], NULL, customer, NULL);

        printf("%d:%d:%d: One customer comes, now there are %d seats left now\n", tm.tm_hour, tm.tm_min, tm.tm_sec, seat_num);

    }

}

void *barber(void *param) {

    int worktime = 500;

    while(1) {

        sem_wait(&cust_ready);

        sem_wait(&mutex);

        seat_num += 1;

        time_t t = time(NULL);

        struct tm tm = *localtime(&t);

        printf("%d:%d:%d: Barber works, there are %d seats left now\n", tm.tm_hour, tm.tm_min, tm.tm_sec, seat_num);

        usleep(worktime*1000);

        t = time(NULL);

        tm = *localtime(&t);

        printf("%d:%d:%d: Barber has cut hair, there are %d seats left now\n", tm.tm_hour, tm.tm_min, tm.tm_sec, seat_num);

        sem_post(&barber_ready);

        sem_post(&mutex);

    }

}

void *customer(void *param) {

    sem_wait(&mutex);

    if(seat_num > 0){

        seat_num --;

        time_t t = time(NULL);

        struct tm tm = *localtime(&t);

        printf("%d:%d:%d: One customer comes, now there are %d seats left now\n", tm.tm_hour, tm.tm_min, tm.tm_sec, seat_num);

        sem_post(&cust_ready);

        sem_post(&mutex);

        sem_wait(&barber_ready);

        t = time(NULL);

        tm = *localtime(&t);

        printf("%d:%d:%d: One customer leaves with haircut, now there are %d seats left now\n", tm.tm_hour, tm.tm_min, tm.tm_sec, seat_num);

    } else {

        time_t t = time(NULL);

        struct tm tm = *localtime(&t);

        printf("%d:%d:%d: One customer leaves with no haircut\n", tm.tm_hour, tm.tm_min, tm.tm_sec);

        sem_post(&mutex);

    }

}
巴特西

IPC 经典问题：Sleeping Barber Problem

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