/* 头文件：threadpool.h*/
#ifndef _TP_H_INCLUDED_
#define _TP_H_INCLUDED_
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>
#include <assert.h>
typedef struct worker {
void * (*process) (void *arg);
void *arg;
struct worker *next;
} threadpool_item_t;
typedef struct {
pthread_mutex_t queue_lock;
pthread_cond_t queue_ready;
threadpool_item_t *queue_head;
int shutdown; /*是否销毁线程池*/
pthread_t *threadid;
int max_thread_num;/*线程池中允许的活动线程数目*/
int cur_queue_size; /*当前等待队列的任务数目*/
} threadpool_t;
void pool_init (int max_thread_num);
int pool_destroy ();
int pool_add_worker (void * (*process) (void *arg), void *arg);
static void * thread_routine (void *arg);
#endif
/*具体实现：threadpool.c*/
#include "threadpool.h"
static threadpool_t *pool = NULL;
/*初始化线程池*/
void pool_init (int max_thread_num) {
pool = (threadpool_t *) malloc (sizeof (threadpool_t));
pthread_mutex_init (&(pool->queue_lock), NULL);
pthread_cond_init (&(pool->queue_ready), NULL);
pool->queue_head = NULL;
pool->max_thread_num = max_thread_num;
pool->cur_queue_size = 0;
pool->shutdown = 0;
pool->threadid = (pthread_t *) malloc (max_thread_num * sizeof (pthread_t));
int i;
for (i = 0; i < max_thread_num; i++) {
pthread_create (&(pool->threadid[i]), NULL, thread_routine, NULL);
}
}
/*向线程池中加入任务*/
int pool_add_worker (void *(*process) (void *arg), void *arg) {
/*构造一个新任务*/
threadpool_item_t *newworker = (threadpool_item_t *) malloc (sizeof (threadpool_item_t));
newworker->process = process;
newworker->arg = arg;
newworker->next = NULL;
pthread_mutex_lock (&(pool->queue_lock));
/*将任务加入到等待队列中*/
threadpool_item_t *member = pool->queue_head;
if (member != NULL) {
while (member->next != NULL) member = member->next;
member->next = newworker;
} else{
pool->queue_head = newworker;
}
assert (pool->queue_head != NULL);
pool->cur_queue_size++;
pthread_mutex_unlock (&(pool->queue_lock));
/*唤醒一个等待线程*/
pthread_cond_signal (&(pool->queue_ready));
return 0;
}
/*销毁线程池，等待队列中的任务不会再被执行，但是正在运行的线程会一直把任务运行完后再退出*/
int pool_destroy () {
if (pool->shutdown) return -1;/*防止两次调用*/
pool->shutdown = 1;
/*唤醒所有等待线程，线程池要销毁了*/
pthread_cond_broadcast (&(pool->queue_ready));
/*阻塞等待线程退出，否则就成僵尸了*/
int i;
for (i = 0; i < pool->max_thread_num; i++) {
pthread_join (pool->threadid[i], NULL);
}
free (pool->threadid);
/*销毁等待队列*/
threadpool_item_t *head = NULL;
while (pool->queue_head != NULL)
{
head = pool->queue_head;
pool->queue_head = pool->queue_head->next;
free (head);
}
/*销毁条件变量和互斥量*/
pthread_mutex_destroy(&(pool->queue_lock));
pthread_cond_destroy(&(pool->queue_ready));
free (pool);
pool=NULL;
return 0;
}
/*线程主函数*/
static void * thread_routine (void *arg) {
printf ("starting thread %lu\n", pthread_self ());
while (1) {
pthread_mutex_lock (&(pool->queue_lock));
/*如果等待队列为0并且不销毁线程池，则处于阻塞状态;*/
while (pool->cur_queue_size == 0 && !pool->shutdown)
{
printf ("thread %lu is waiting\n", pthread_self ());
pthread_cond_wait (&(pool->queue_ready), &(pool->queue_lock));
}
/*线程池要销毁了*/
if (pool->shutdown) {
/*遇到break,continue,return等跳转语句，千万不要忘记先解锁*/
pthread_mutex_unlock (&(pool->queue_lock));
printf ("thread %lu will exit\n", pthread_self ());
pthread_exit (NULL);
}
printf ("thread %lu is starting to work\n", pthread_self ());
assert (pool->cur_queue_size != 0);
assert (pool->queue_head != NULL);
/*队列长度减去1，并取出链表中的头元素*/
pool->cur_queue_size--;
threadpool_item_t *worker = pool->queue_head;
pool->queue_head = worker->next;
pthread_mutex_unlock (&(pool->queue_lock)); //解锁
/*调用回调函数，执行任务*/
(*(worker->process)) (worker->arg);
free (worker);
worker = NULL;
}
}
/* 下面是测试代码 */
void * myprocess (void *arg)
{
printf ("threadid is 0x%x, working on task %d\n", pthread_self (),*(int *) arg);
sleep (1);/*休息一秒，延长任务的执行时间*/
return NULL;
}
int main (int argc, char **argv)
{
pool_init (3);/*线程池中最多三个活动线程*/
/*连续向池中投入10个任务*/
int *workingnum = (int *) malloc (sizeof (int) * 10);
int i;
for (i = 0; i < 10; i++)
{
workingnum[i] = i;
pool_add_worker (myprocess, &workingnum[i]);
}
/*等待所有任务完成*/ sleep (5);
/*销毁线程池*/ pool_destroy ();
free(workingnum);
workingnum = NULL;
return 0;
}
编译,运行：
$ gcc -std=c99 -o threadpool threadpool.h threadpool.c -lpthread
$ ./threadpool
starting thread 1115277632
thread 1115277632 is starting to work
threadid is 1115277632, working on task 0
starting thread 1125767488
thread 1125767488 is starting to work
threadid is 1125767488, working on task 1
starting thread 1136257344
thread 1136257344 is starting to work
threadid is 1136257344, working on task 2
thread 1115277632 is starting to work
threadid is 1115277632, working on task 3
thread 1125767488 is starting to work
threadid is 1125767488, working on task 4
thread 1136257344 is starting to work
threadid is 1136257344, working on task 5
thread 1115277632 is starting to work
threadid is 1115277632, working on task 6
thread 1125767488 is starting to work
threadid is 1125767488, working on task 7
thread 1136257344 is starting to work
threadid is 1136257344, working on task 8
thread 1115277632 is starting to work
threadid is 1115277632, working on task 9
thread 1125767488 is waiting
thread 1136257344 is waiting
thread 1115277632 is waiting
thread 1125767488 will exit
thread 1136257344 will exit
thread 1115277632 will exit