一个线程池的简单的实现

线程池实现：

contion.h

#ifndef _CONDITION_H_
#define _CONDITION_H_


#include <pthread.h>


typedef struct condition
{
pthread_mutex_t pmutex;
pthread_cond_t pcond;
} condition_t;


int condition_init(condition_t *cond);
int condition_lock(condition_t *cond);
int condition_unlock(condition_t *cond);
int condition_wait(condition_t *cond);
int condition_timedwait(condition_t *cond, const struct timespec *abstime);
int condition_signal(condition_t *cond);
int condition_broadcast(condition_t *cond);
int condition_destroy(condition_t *cond);


#endif /* _CONDITION_H_ */

condition.c

#include "condition.h"


int condition_init(condition_t *cond)
{
int status;
if ((status = pthread_mutex_init(&cond->pmutex, NULL)))
return status;


if ((status = pthread_cond_init(&cond->pcond, NULL)))
return status;


return 0;
}


int condition_lock(condition_t *cond)
{
return pthread_mutex_lock(&cond->pmutex);
}


int condition_unlock(condition_t *cond)
{
return pthread_mutex_unlock(&cond->pmutex);
}


int condition_wait(condition_t *cond)
{
return pthread_cond_wait(&cond->pcond, &cond->pmutex);
}


int condition_timedwait(condition_t *cond, const struct timespec *abstime)
{
return pthread_cond_timedwait(&cond->pcond, &cond->pmutex, abstime);
}




int condition_signal(condition_t *cond)
{
return pthread_cond_signal(&cond->pcond);
}


int condition_broadcast(condition_t* cond)
{
return pthread_cond_broadcast(&cond->pcond);
}


int condition_destroy(condition_t* cond)
{
int status;
if ((status = pthread_mutex_destroy(&cond->pmutex)))
return status;


if ((status = pthread_cond_destroy(&cond->pcond)))
return status;


return 0;
}

threadpool.h

#ifndef _THREAD_POOL_H_
#define _THREAD_POOL_H_


#include "condition.h"


// 任务结构体,将任务放入队列由线程池中的线程来执行
typedef struct task
{
void *(*run)(void *arg); // 任务回调函数
void *arg; // 回调函数参数
struct task *next;
} task_t;


// 线程池结构体
typedef struct threadpool
{
condition_t ready; //任务准备就绪或者线程池销毁通知
task_t *first; //任务队列头指针
task_t *last; //任务队列尾指针
int counter; //线程池中当前线程数
int idle; //线程池中当前正在等待任务的线程数
int max_threads; //线程池中最大允许的线程数
int quit; //销毁线程池的时候置1
} threadpool_t;


// 初始化线程池
void threadpool_init(threadpool_t *pool, int threads);
// 往线程池中添加任务
void threadpool_add_task(threadpool_t *pool, void *(*run)(void *arg), void *arg);
// 销毁线程池
void threadpool_destroy(threadpool_t *pool);


#endif /* _THREAD_POOL_H_ */

threadpool.c

#include "threadpool.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <time.h>


void *thread_routine(void *arg)
{
struct timespec abstime;
int timeout;
printf("thread 0x%x is starting\n", (int)pthread_self());
threadpool_t *pool = (threadpool_t *)arg;
while (1)
{
timeout = 0;
condition_lock(&pool->ready);
pool->idle++;
// 等待队列有任务到来或者线程池销毁通知
while (pool->first == NULL && !pool->quit)
{
printf("thread 0x%x is waiting\n", (int)pthread_self());
//condition_wait(&pool->ready);
clock_gettime(CLOCK_REALTIME, &abstime);
abstime.tv_sec += 2;
int status = condition_timedwait(&pool->ready, &abstime);
if (status == ETIMEDOUT)
{
printf("thread 0x%x is wait timed out\n", (int)pthread_self());
timeout = 1;
break;
}
}


// 等待到条件，处于工作状态
pool->idle--;


// 等待到任务
if (pool->first != NULL)
{
// 从队头取出任务
task_t *t = pool->first;
pool->first = t->next;
// 执行任务需要一定的时间，所以要先解锁，以便生产者进程
// 能够往队列中添加任务，其它消费者线程能够进入等待任务
condition_unlock(&pool->ready);
t->run(t->arg);
free(t);
condition_lock(&pool->ready);
}
// 如果等待到线程池销毁通知, 且任务都执行完毕
if (pool->quit && pool->first == NULL)
{
pool->counter--;
if (pool->counter == 0)
condition_signal(&pool->ready);


condition_unlock(&pool->ready);
// 跳出循环之前要记得解锁
break;
}


if (timeout && pool->first == NULL)
{
pool->counter--;
condition_unlock(&pool->ready);
// 跳出循环之前要记得解锁
break;
}
condition_unlock(&pool->ready);
}


printf("thread 0x%x is exting\n", (int)pthread_self());
return NULL;


}


// 初始化线程池
void threadpool_init(threadpool_t *pool, int threads)
{
// 对线程池中的各个字段初始化
condition_init(&pool->ready);
pool->first = NULL;
pool->last = NULL;
pool->counter = 0;
pool->idle = 0;
pool->max_threads = threads;
pool->quit = 0;
}


// 往线程池中添加任务
void threadpool_add_task(threadpool_t *pool, void *(*run)(void *arg), void *arg)
{
// 生成新任务
task_t *newtask = (task_t *)malloc(sizeof(task_t));
newtask->run = run;
newtask->arg = arg;
newtask->next = NULL;


condition_lock(&pool->ready);
// 将任务添加到队列
if (pool->first == NULL)
pool->first = newtask;
else
pool->last->next = newtask;
pool->last = newtask;


// 如果有等待线程，则唤醒其中一个
if (pool->idle > 0)
condition_signal(&pool->ready);
else if (pool->counter < pool->max_threads)
{
// 没有等待线程，并且当前线程数不超过最大线程数，则创建一个新线程
pthread_t tid;
pthread_create(&tid, NULL, thread_routine, pool);
pool->counter++;
}
condition_unlock(&pool->ready);
}


// 销毁线程池
void threadpool_destroy(threadpool_t *pool)
{
if (pool->quit)
{
return;
}
condition_lock(&pool->ready);
pool->quit = 1;
if (pool->counter > 0)
{
if (pool->idle > 0)
condition_broadcast(&pool->ready);


// 处于执行任务状态中的线程，不会收到广播
// 线程池需要等待执行任务状态中的线程全部退出


while (pool->counter > 0)
condition_wait(&pool->ready);
}
condition_unlock(&pool->ready);
condition_destroy(&pool->ready);




}

main.c

#include "threadpool.h"
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>


void* mytask(void *arg)
{
printf("thread 0x%x is working on task %d\n", (int)pthread_self(), *(int*)arg);
sleep(1);
free(arg);
return NULL;
}


int main(void)
{
threadpool_t pool;
threadpool_init(&pool, 3);


int i;
for (i=0; i<10; i++)
{
int *arg = (int *)malloc(sizeof(int));
*arg = i;
threadpool_add_task(&pool, mytask, arg);
}


//sleep(15);
threadpool_destroy(&pool);
return 0;
}

makefile:

.PHONY:clean
CC=gcc
CFLAGS=-Wall -g
ALL=main
all:$(ALL)
OBJS=threadpool.o main.o condition.o
.c.o:
$(CC) $(CFLAGS) -c $<


main:$(OBJS)
$(CC) $(CFLAGS) $^ -o $@ -lpthread -lrt


clean:
rm -f $(ALL) *.o