utlis 线程池

The thread pool structure must be mastered
万变不离其宗,Still the familiar producer-consumer pattern,Still the familiar mutex+Condition variables implement semaphore semantics,Notifies the worker thread to fetch data from the task queue,still familiarflagThe flag bit controls the worker thread to exit.非常熟悉!

	struct NWORKER *workers;  //执行队列
	struct NJOB *waiting_jobs;//任务队列
	pthread_mutex_t jobs_mtx; //互斥锁
	pthread_cond_t jobs_cond; //条件变量

The interaction between the worker thread and the main thread is the task queue,

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

#include <pthread.h>

//Why use macros,宏==模板了,Different types can be manipulated
//头插
#define LL_ADD(item, list) do {
       \ item->prev = NULL; \ item->next = list; \ list = item; \ } while(0)
//删除某个节点
#define LL_REMOVE(item, list) do {
       \ if (item->prev != NULL) item->prev->next = item->next; \ if (item->next != NULL) item->next->prev = item->prev; \ if (list == item) list = item->next; \ item->prev = item->next = NULL; \ } while(0)

//执行
typedef struct NWORKER {
    
	pthread_t thread;
	int terminate;
	struct NWORKQUEUE *workqueue; //回指指针,指向所有workerShared task queue
	struct NWORKER *prev;
	struct NWORKER *next;
} nWorker;
//任务
typedef struct NJOB {
    
	void (*job_function)(struct NJOB *job);
	void *user_data;
	struct NJOB *prev;
	struct NJOB *next;
} nJob;
//Pool component management
typedef struct NWORKQUEUE {
    
	struct NWORKER *workers;  //执行队列
	struct NJOB *waiting_jobs;//任务队列
	pthread_mutex_t jobs_mtx; //互斥锁
	pthread_cond_t jobs_cond; //条件变量
} nWorkQueue;

typedef nWorkQueue nThreadPool;

static void *ntyWorkerThread(void *ptr) {
    
	nWorker *worker = (nWorker*)ptr;

	while (1) {
    
		pthread_mutex_lock(&worker->workqueue->jobs_mtx);

		while (worker->workqueue->waiting_jobs == NULL) {
    
			if (worker->terminate) break;
			pthread_cond_wait(&worker->workqueue->jobs_cond, &worker->workqueue->jobs_mtx);
		}

		if (worker->terminate) {
    
			pthread_mutex_unlock(&worker->workqueue->jobs_mtx);
			break;
		}
		
		nJob *job = worker->workqueue->waiting_jobs;
		if (job != NULL) {
    
			LL_REMOVE(job, worker->workqueue->waiting_jobs);
		}
		
		pthread_mutex_unlock(&worker->workqueue->jobs_mtx);

		if (job == NULL) continue;

		job->job_function(job);
	}

	free(worker);
	pthread_exit(NULL);
}



int ntyThreadPoolCreate(nThreadPool *workqueue, int numWorkers) {
    

	if (numWorkers < 1) numWorkers = 1;
	memset(workqueue, 0, sizeof(nThreadPool));
	
	pthread_cond_t blank_cond = PTHREAD_COND_INITIALIZER;
	memcpy(&workqueue->jobs_cond, &blank_cond, sizeof(workqueue->jobs_cond));
	
	pthread_mutex_t blank_mutex = PTHREAD_MUTEX_INITIALIZER;
	memcpy(&workqueue->jobs_mtx, &blank_mutex, sizeof(workqueue->jobs_mtx));

	int i = 0;
	for (i = 0;i < numWorkers;i ++) {
    
		nWorker *worker = (nWorker*)malloc(sizeof(nWorker));
		if (worker == NULL) {
    
			perror("malloc");
			return 1;
		}

		memset(worker, 0, sizeof(nWorker));
		worker->workqueue = workqueue;

		int ret = pthread_create(&worker->thread, NULL, ntyWorkerThread, (void *)worker);
		if (ret) {
    
			
			perror("pthread_create");
			free(worker);

			return 1;
		}

		LL_ADD(worker, worker->workqueue->workers);
	}

	return 0;
}


void ntyThreadPoolShutdown(nThreadPool *workqueue) {
    
	nWorker *worker = NULL;

	for (worker = workqueue->workers;worker != NULL;worker = worker->next) {
    
		worker->terminate = 1;
	}

	pthread_mutex_lock(&workqueue->jobs_mtx);

	workqueue->workers = NULL;
	workqueue->waiting_jobs = NULL;

	pthread_cond_broadcast(&workqueue->jobs_cond);

	pthread_mutex_unlock(&workqueue->jobs_mtx);
	
}

void ntyThreadPoolQueue(nThreadPool *workqueue, nJob *job) {
    

	pthread_mutex_lock(&workqueue->jobs_mtx);

	LL_ADD(job, workqueue->waiting_jobs);
	
	pthread_cond_signal(&workqueue->jobs_cond);
	pthread_mutex_unlock(&workqueue->jobs_mtx);
	
}




/************************** debug thread pool **************************/
//sdk --> software develop kit
// 提供SDK给其他开发者使用

#if 1

#define KING_MAX_THREAD 80
#define KING_COUNTER_SIZE 1000

void king_counter(nJob *job) {
    

	int index = *(int*)job->user_data;

	printf("index : %d, selfid : %lu\n", index, pthread_self());
	
	free(job->user_data);
	free(job);
}



int main(int argc, char *argv[]) {
    

	nThreadPool pool;

	ntyThreadPoolCreate(&pool, KING_MAX_THREAD);
	
	int i = 0;
	for (i = 0;i < KING_COUNTER_SIZE;i ++) {
    
		nJob *job = (nJob*)malloc(sizeof(nJob));
		if (job == NULL) {
    
			perror("malloc");
			exit(1);
		}
		
		job->job_function = king_counter;
		job->user_data = malloc(sizeof(int));
		*(int*)job->user_data = i;

		ntyThreadPoolQueue(&pool, job);
		
	}

	getchar();
	printf("\n");

	
}

#endif