linux条件变量 信号量

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

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
int ready = 0;

void* producer(void* arg) {
    pthread_mutex_lock(&mutex);
    ready = 1;
    pthread_cond_signal(&cond);
    pthread_mutex_unlock(&mutex);
    return NULL;
}

void* consumer(void* arg) {
    pthread_mutex_lock(&mutex);
    while (!ready) {
        pthread_cond_wait(&cond, &mutex);
    }
    printf("Consumer: Data is ready!\n");
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
    pthread_t producer_thread, consumer_thread;
    pthread_create(&producer_thread, NULL, producer, NULL);
    pthread_create(&consumer_thread, NULL, consumer, NULL);
    pthread_join(producer_thread, NULL);
    pthread_join(consumer_thread, NULL);
    return 0;
}

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

sem_t sem;

void* thread_func(void* arg) {
    sem_wait(&sem);
    printf("Thread entered critical section.\n");
    // Critical section
    sem_post(&sem);
    return NULL;
}

int main() {
    sem_init(&sem, 0, 3); // Allow 3 threads in critical section at a time
    pthread_t threads[10];
    for (int i = 0; i < 10; ++i) {
        pthread_create(&threads[i], NULL, thread_func, NULL);
    }
    for (int i = 0; i < 10; ++i) {
        pthread_join(threads[i], NULL);
    }
    sem_destroy(&sem);
    return 0;
}