Linux系统编程（十）线程池

 

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <string.h>
#include <signal.h>
#include <errno.h>

#define DEFAULT_TIME 10
#define DEFAULT_THREAD_VARY 10
#define MIN_WAIT_TASK_NUM 10


typedef struct threadpool_task {
    void *(*function)(void *);
    void *arg;
} threadpool_task_t;

typedef struct threadpool {
    pthread_mutex_t lock;                // 锁住本结构体
    pthread_mutex_t thread_counter;        // 记录忙状态线程个数的锁
    
    pthread_cond_t queue_not_full;        // 任务队列满时，添加任务的线程阻塞，等待此条件变量
    pthread_cond_t queue_not_empty;        // 任务队列不为空，通知等待任务的线程
    
    pthread_t *threads;                    // 存放线程池中的线程号tid
    pthread_t adjust_tid;                // 存管理线程tid
    threadpool_task_t *task_queue;        // 任务队列数组
    
    int min_thr_num;                    // 线程池最小线程数
    int max_thr_num;                    // 线程池最大线程数
    int live_thr_num;                    // 当前存活线程数
    int busy_thr_num;                    // 忙状态线程个数
    int wait_exit_thr_num;                // 要销毁的线程个数
    
    int queue_front;                    // task_queue队头下标
    int queue_rear;                        // task_queue队尾下标
    int queue_size;                        // task_queue队中实际任务数
    int queue_max_size;                    // task_queue队列可容纳任务数量上限
    
    int shutdown;                        // 线程池使用状态
} threadpool_t;

int is_thread_alive(pthread_t tid)
{
    int kill_rc = pthread_kill(tid, 0);
    if(kill_rc == ESRCH)
        return 0;
    else
        return -1;
}

int threadpool_free(threadpool_t *pool)
{
    if(pool == NULL)
        return -1;

    if(pool->task_queue)
        free(pool->task_queue);

    if(pool->threads)
    {
        free(pool->threads);
        pthread_mutex_lock(&(pool->lock));
        pthread_mutex_destroy(&(pool->lock));
        pthread_mutex_lock(&(pool->thread_counter));    
        pthread_mutex_destroy(&(pool->thread_counter));
        pthread_cond_destroy(&(pool->queue_not_empty));
        pthread_cond_destroy(&(pool->queue_not_full));
    }
    free(pool);
    pool = NULL;

    return 0;
}

int threadpool_destory(threadpool_t *pool)
{
    int i;
    if(pool == NULL)
        return -1;

    pool->shutdown = 1;

    pthread_join(pool->adjust_tid, NULL);

    for(i = 0; i < pool->live_thr_num; i++)
        pthread_cond_broadcast(&(pool->queue_not_empty));

    for(i = 0; i < pool->live_thr_num; i++)
        pthread_join(pool->threads[i], NULL);

    threadpool_free(pool);

    return 0;
}

void *threadpool_thread(void *threadpool)
{
    threadpool_t *pool = (threadpool_t *)threadpool;
    threadpool_task_t task;

    while(1)
    {
        pthread_mutex_lock(&(pool->lock));

        while((pool->queue_size == 0) && (!pool->shutdown)){
            printf("thread 0x%lx is waiting\n", pthread_self());
            pthread_cond_wait(&(pool->queue_not_empty), &(pool->lock));

            if(pool->wait_exit_thr_num > 0){
                pool->wait_exit_thr_num--;

                if(pool->live_thr_num > pool->min_thr_num){
                    printf("thread 0x%lx is exsiting\n", pthread_self());
                    pool->live_thr_num--;
                    pthread_mutex_unlock(&(pool->lock));
                    pthread_exit(NULL);
                }

            }
        }

        if(pool->shutdown){
            pthread_mutex_unlock(&(pool->lock));
            printf("thread 0x%lx is existing\n", pthread_self());
            pthread_detach(pthread_self());
            pthread_exit(NULL);
        }

        task.function = pool->task_queue[pool->queue_front].function;
        task.arg = pool->task_queue[pool->queue_front].arg;

        pool->queue_front = (pool->queue_front + 1) % pool->queue_max_size;
        pool->queue_size--;

        pthread_cond_broadcast(&(pool->queue_not_full));

        pthread_mutex_unlock(&(pool->lock));

        printf("thread 0x%lx start working\n", pthread_self());

        (*(task.function))(task.arg);

        printf("thread 0x%lx end working\n", pthread_self());
        pthread_mutex_lock(&(pool->thread_counter));
        pool->busy_thr_num--;
        pthread_mutex_unlock(&(pool->thread_counter));
    }

    pthread_exit(NULL);
}


void *adjust_thread(void *threadpool)
{
    threadpool_t *pool = (threadpool_t *)threadpool;
    int i;
    while(!pool->shutdown) {
        
        sleep(DEFAULT_TIME);

        pthread_mutex_lock(&(pool->lock));
        int queue_size = pool->queue_size;
        int live_thr_num = pool->live_thr_num;
        pthread_mutex_unlock(&(pool->lock));

        pthread_mutex_lock(&(pool->thread_counter));
        int busy_thr_num = pool->busy_thr_num;
        pthread_mutex_unlock(&(pool->thread_counter));
        
        if(queue_size >= MIN_WAIT_TASK_NUM && live_thr_num < pool->max_thr_num)
        {
            pthread_mutex_lock(&(pool->lock));
            int add = 0;
            
            for(i = 0; i < pool->max_thr_num && add < DEFAULT_THREAD_VARY && 
                            pool->live_thr_num < pool->max_thr_num; i++) {
                if(pool->threads[i] == 0 || !is_thread_alive(pool->threads[i])) {
                    pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void*)pool);
                    add++;
                    pool->live_thr_num++;
                }
            }
            pthread_mutex_unlock(&(pool->lock));
        }

        if((busy_thr_num *2) < live_thr_num && live_thr_num > pool->min_thr_num){
            pthread_mutex_lock(&(pool->lock));
            pool->wait_exit_thr_num = DEFAULT_THREAD_VARY;
            pthread_mutex_unlock(&(pool->lock));

            for(i = 0; i < DEFAULT_THREAD_VARY; i++){
                pthread_cond_signal(&(pool->queue_not_empty));
            }
        }
    }
    return NULL;
}

threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size)
{
    int i;
    threadpool_t *pool = NULL;
    do{
        if((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL){
            printf("malloc threadpool fail");
            break;
        }

        pool->min_thr_num = min_thr_num;
        pool->max_thr_num = max_thr_num;
        pool->busy_thr_num = 0;
        pool->live_thr_num = min_thr_num;
        pool->queue_size = 0;
        pool->queue_max_size = queue_max_size;
        pool->queue_front = 0;
        pool->queue_rear = 0;
        pool->shutdown = 0;

        pool->threads = (pthread_t *)malloc(sizeof(pthread_t)*max_thr_num);
        if(pool->threads == NULL)
        {
            printf("malloc threads fail\n");
            break;
        }
        memset(pool->threads, 0, sizeof(pthread_t)*max_thr_num);

        pool->task_queue = (threadpool_task_t*)malloc(sizeof(threadpool_task_t)*queue_max_size);
        if(pool->task_queue == NULL)
        {
            printf("mallc task_queue fail\n");
            break;
        }

        if(pthread_mutex_init(&(pool->lock), NULL) != 0
                || pthread_mutex_init(&(pool->thread_counter), NULL) != 0
                || pthread_cond_init(&(pool->queue_not_empty), NULL) != 0
                || pthread_cond_init(&(pool->queue_not_full), NULL) != 0 )
        {
            printf("init mutex or cond fail\n");
            break;
        }
        
        for(i = 0; i < min_thr_num; i++)
        {
            pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void*)pool);
            printf("start thread 0x%lx...\n", pool->threads[i]);
        }

        pthread_create(&(pool->adjust_tid), NULL, adjust_thread, (void*)pool);

        return pool;
    
    }while(0);
    
    threadpool_free(pool);

    return NULL;
}

void threadpool_add(threadpool_t *pool, void *(*func)(void*arg), void *arg)
{
    pthread_mutex_lock(&(pool->lock));

    // fang zhi qiang suo
    while((pool->queue_size == pool->queue_max_size) && (!pool->shutdown))
        pthread_cond_wait(&(pool->queue_not_full), &(pool->lock));

    if(pool->shutdown){
        pthread_cond_broadcast(&(pool->queue_not_empty));
        pthread_mutex_unlock(&(pool->lock));
    }

    if(pool->task_queue[pool->queue_rear].arg != NULL)
        pool->task_queue[pool->queue_rear].arg = NULL;

    pool->task_queue[pool->queue_rear].function = func;
    pool->task_queue[pool->queue_rear].arg = arg;
    pool->queue_rear = (pool->queue_rear + 1) % pool->queue_max_size;
    pool->queue_size++;

    pthread_cond_signal(&(pool->queue_not_empty));
    pthread_mutex_unlock(&(pool->lock));

}

void *process(void *arg)
{
    printf("thread 0x%lx working on task %p\n", pthread_self(), arg);
    sleep(1);
    printf("task %p is end\n", arg);
    return NULL;
}

int main(int argc, char** argv)
{
    threadpool_t *thp = threadpool_create(3, 100, 100);

    int num[20];
    for(int i = 0; i < 20; i++)
    {
        num[i] = i;
        threadpool_add(thp, process, (void*)&num[i]);
    
    
    }
    sleep(10);
    threadpool_destory(thp);

    return 0;
}