【Linux】线程同步 -- 条件变量 | 生产者消费者模型 | 自旋锁 |读写锁

在Linux环境下，可以使用条件变量(pthread\_cond\_t)、互斥锁(pthread\_mutex\_t)和自旋锁(spinlock)等来实现线程同步。以下是实现生产者和消费者模型的例子：

#include <stdio.h>
#include <pthread.h>
 
#define BUFFER_SIZE 1
 
int buffer[BUFFER_SIZE];
int read_index = 0;
int write_index = 0;
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t not_full = PTHREAD_COND_INITIALIZER;
pthread_cond_t not_empty = PTHREAD_COND_INITIALIZER;
 
void* producer(void* arg) {
    int i;
    for (i = 0; i < BUFFER_SIZE; i++) {
        pthread_mutex_lock(&mutex);
        while ((write_index + 1) % BUFFER_SIZE == read_index) {
            pthread_cond_wait(&not_full, &mutex);
        }
        buffer[write_index] = i;
        write_index = (write_index + 1) % BUFFER_SIZE;
        pthread_cond_signal(&not_empty);
        pthread_mutex_unlock(&mutex);
    }
    return NULL;
}
 
void* consumer(void* arg) {
    int i;
    for (i = 0; i < BUFFER_SIZE; i++) {
        pthread_mutex_lock(&mutex);
        while (write_index == read_index) {
            pthread_cond_wait(&not_empty, &mutex);
        }
        printf("Consumed: %d\n", buffer[read_index]);
        read_index = (read_index + 1) % BUFFER_SIZE;
        pthread_cond_signal(&not_full);
        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;
}

在这个例子中，我们使用了条件变量not_full和not_empty来同步生产者和消费者。当缓冲区满时，生产者等待not_full条件，当缓冲区为空时，消费者等待not_empty条件。一旦条件满足，相应的pthread_cond_signal函数被调用来唤醒其他线程。

注意，这里使用了一个有界缓冲区来演示生产者消费者模型，大小为1，以简化示例。在实际应用中，缓冲区大小可以根据需要进行调整。