一、问题描述
现在以C/S架构为例，客户端向服务器端发送要查找的数字，服务器端启动线程中的线程进行相应的查询，将查询结果显示出来。
二、实现方案
1. 整个工程以client、server、lib组织，如下图所示：
2. 进入lib，
socket.h、socket.c
/**
@file socket.h
@brief Socket API header file
TCP socket utility functions, it provides simple functions that helps
to build TCP client/server.
@author wangzhicheng
*/
#ifndef SOCKET_H
#define SOCKET_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <resolv.h>
#include <fcntl.h>
#define MAX_CONNECTION 20
int TCPServerInit(int port, int *serverfd);
int TCPServerWaitConnection(int serverfd, int *clientfd, char *clientaddr);
int TCPServerSelect(int* serverfdlist, int num, int *clientfd, char *clientaddr);
int TCPClientInit(int *clientfd);
int TCPClientConnect(const int clientfd, const char *addr, int port);
int TCPNonBlockRead(int clientfd, char* buf, int size);
int TCPBlockRead(int clientfd, char* buf, int size);
int TCPWrite(int clientfd, char* buf, int size);
void TCPClientClose(int sockfd);
void TCPServerClose(int sockfd);
#endif
socket.c
#include "socket.h"
/*
* @brief initialize TCP server
* @port port number for socket
* @serverfd server socket fd
* return server socked fd for success, on error return error code
* */
int TCPServerInit(int port, int *serverfd) {
struct sockaddr_in dest;
// create socket , same as client
*serverfd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if(*serverfd < 0) return -1;
/// initialize structure dest
memset((void*)&dest, '\0', sizeof(dest));
dest.sin_family = PF_INET;
dest.sin_port = htons(port);
dest.sin_addr.s_addr = INADDR_ANY;
// Assign a port number to socket
bind( *serverfd, (struct sockaddr*)&dest, sizeof(dest));
return *serverfd;
}
/*
* @brief wait client connect
* @serverfd server socket fd
* @clientfd client socket fd
* @clientaddr client address which connect to server
* return client fd, on error return error code
* */
int TCPServerWaitConnection(int serverfd, int *clientfd, char *clientaddr) {
struct sockaddr_in client_addr;
socklen_t addrlen = sizeof(client_addr);
// make it listen to socket
listen( serverfd, 20);
// Wait and Accept connection
*clientfd = accept(serverfd, (struct sockaddr*)&client_addr, &addrlen);
strcpy( clientaddr, (const char *)( inet_ntoa( client_addr.sin_addr)));
return *clientfd;
}
/*
* @brief initialize TCP client
* @clientfd client socket fd
* return client socked fd for success, on error return error code
*/
int TCPClientInit(int *clientfd) {
*clientfd = socket(PF_INET, SOCK_STREAM, 0);
return *clientfd;
}
/*
* @brief connect to TCP server
* @clientfd client socket fd
* @addr server address
* @port server port number
* return 0 for success, on error -1 is returned
*/
int TCPClientConnect(const int clientfd, const char *addr, int port) {
struct sockaddr_in dest;
// initialize value in dest
memset(&dest, '\0', sizeof(dest));
dest.sin_family = PF_INET;
dest.sin_port = htons(port);
inet_aton(addr, &dest.sin_addr);
// Connecting to server
return connect(clientfd, (struct sockaddr*)&dest, sizeof(dest));
}
/*
* @brief non-block read from TCP socket
* @clientfd socket fd
* @buf input buffer
* @size buffer size
* return the length of read data
*/
int TCPNonBlockRead(int clientfd, char* buf, int size) {
int opts;
opts = fcntl(clientfd, F_GETFL);
opts = (opts | O_NONBLOCK);
fcntl(clientfd, F_SETFL, opts);
return recv(clientfd, buf, size, 0);
}
/*
* @brief block read from TCP socket
* @clientfd socket fd
* @buf input buffer
* @size buf size
* return the length of read data
*/
int TCPBlockRead(int clientfd, char* buf, int size) {
int opts;
opts = fcntl(clientfd, F_GETFL);
opts = (opts & ~O_NONBLOCK);
fcntl(clientfd, F_SETFL, opts);
return recv(clientfd, buf, size, 0);
}
/*
* @brief write to TCP socket
* @clientfd socket fd
* @buf output buf
* @size output buf length
* return the length of the actual written data, -1: disconnected
*/
int TCPWrite(int clientfd, char* buf, int size) {
int len= 0;
/* set socket to nonblock */
int ret = fcntl(clientfd, F_GETFL);
ret |= O_NONBLOCK;
if (fcntl(clientfd, F_SETFL, ret) < 0 ) {
printf("set socket to nonblock fail [%d] !\n", errno);
}
len = send(clientfd, buf, size, MSG_NOSIGNAL);
return len;
}
/*
* @brief close the tcp connection
* @sockfd socket fd
* return none
*/
void TCPConnectionClose(int sockfd) {
close(sockfd);
}
threadpool.h
#ifndef THREADPOOL_H
#define THREADPOOL_H
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
struct job
{
void* (*callback_function)(void *arg); //线程回调函数
void *arg; //回调函数参数
struct job *next;
};
struct threadpool
{
int thread_num; //线程池中开启线程的个数
int queue_max_num; //队列中最大job的个数
struct job *head; //指向job的头指针
struct job *tail; //指向job的尾指针
pthread_t *pthreads; //线程池中所有线程的pthread_t
pthread_mutex_t mutex; //互斥信号量
pthread_cond_t queue_empty; //队列为空的条件变量
pthread_cond_t queue_not_empty; //队列不为空的条件变量
pthread_cond_t queue_not_full; //队列不为满的条件变量
int queue_cur_num; //队列当前的job个数
int queue_close; //队列是否已经关闭
int pool_close; //线程池是否已经关闭
};
//================================================================================================
//函数名： threadpool_init
//函数描述： 初始化线程池
//输入： [in] thread_num 线程池开启的线程个数
// [in] queue_max_num 队列的最大job个数
//输出： 无
//返回： 成功：线程池地址 失败：NULL
//================================================================================================
struct threadpool* threadpool_init(int thread_num, int queue_max_num);
//================================================================================================
//函数名： threadpool_add_job
//函数描述： 向线程池中添加任务
//输入： [in] pool 线程池地址
// [in] callback_function 回调函数
// [in] arg 回调函数参数
//输出： 无
//返回： 成功：0 失败：-1
//================================================================================================
int threadpool_add_job(struct threadpool *pool, void* (*callback_function)(void *arg), void *arg);
//================================================================================================
//函数名： threadpool_destroy
//函数描述： 销毁线程池
//输入： [in] pool 线程池地址
//输出： 无
//返回： 成功：0 失败：-1
//================================================================================================
int threadpool_destroy(struct threadpool *pool);
//================================================================================================
//函数名： threadpool_function
//函数描述： 线程池中线程函数
//输入： [in] arg 线程池地址
//输出： 无
//返回： 无
//================================================================================================
void* threadpool_function(void* arg);
#endif
threadpool.c
#include "threadpool.h"
struct threadpool* threadpool_init(int thread_num, int queue_max_num) {
struct threadpool *pool = NULL;
do
{
pool = malloc(sizeof(struct threadpool));
if (NULL == pool)
{
printf("failed to malloc threadpool!\n");
break;
}
pool->thread_num = thread_num;
pool->queue_max_num = queue_max_num;
pool->queue_cur_num = 0;
pool->head = NULL;
pool->tail = NULL;
if (pthread_mutex_init(&(pool->mutex), NULL))
{
printf("failed to init mutex!\n");
break;
}
if (pthread_cond_init(&(pool->queue_empty), NULL))
{
printf("failed to init queue_empty!\n");
break;
}
if (pthread_cond_init(&(pool->queue_not_empty), NULL))
{
printf("failed to init queue_not_empty!\n");
break;
}
if (pthread_cond_init(&(pool->queue_not_full), NULL))
{
printf("failed to init queue_not_full!\n");
break;
}
pool->pthreads = malloc(sizeof(pthread_t) * thread_num);
if (NULL == pool->pthreads)
{
printf("failed to malloc pthreads!\n");
break;
}
pool->queue_close = 0;
pool->pool_close = 0;
int i;
for (i = 0; i < pool->thread_num; ++i)
{
pthread_create(&(pool->pthreads[i]), NULL, threadpool_function, (void *)pool);
}
return pool;
} while (0);
return NULL;
}
int threadpool_add_job(struct threadpool* pool, void* (*callback_function)(void *arg), void *arg) {
if(pool == NULL || callback_function == NULL || arg == NULL) return -1;
pthread_mutex_lock(&(pool->mutex));
while ((pool->queue_cur_num == pool->queue_max_num) && !(pool->queue_close || pool->pool_close))
{
pthread_cond_wait(&(pool->queue_not_full), &(pool->mutex)); //队列满的时候就等待
}
if (pool->queue_close || pool->pool_close) //队列关闭或者线程池关闭就退出
{
pthread_mutex_unlock(&(pool->mutex));
return -1;
}
struct job *pjob =(struct job*) malloc(sizeof(struct job));
if (NULL == pjob)
{
pthread_mutex_unlock(&(pool->mutex));
return -1;
}
pjob->callback_function = callback_function;
pjob->arg = arg;
pjob->next = NULL;
if (pool->head == NULL)
{
pool->head = pool->tail = pjob;
pthread_cond_broadcast(&(pool->queue_not_empty)); //队列空的时候，有任务来时就通知线程池中的线程：队列非空
}
else
{
pool->tail->next = pjob;
pool->tail = pjob;
}
pool->queue_cur_num++;
pthread_mutex_unlock(&(pool->mutex));
return 0;
}
void* threadpool_function(void* arg) {
struct threadpool *pool = (struct threadpool*)arg;
struct job *pjob = NULL;
while (1) //死循环
{
pthread_mutex_lock(&(pool->mutex));
while ((pool->queue_cur_num == 0) && !pool->pool_close) //队列为空时，就等待队列非空
{
pthread_cond_wait(&(pool->queue_not_empty), &(pool->mutex));
}
if (pool->pool_close) //线程池关闭，线程就退出
{
pthread_mutex_unlock(&(pool->mutex));
pthread_exit(NULL);
}
pool->queue_cur_num--;
pjob = pool->head;
if (pool->queue_cur_num == 0)
{
pool->head = pool->tail = NULL;
}
else
{
pool->head = pjob->next;
}
if (pool->queue_cur_num == 0)
{
pthread_cond_signal(&(pool->queue_empty)); //队列为空，就可以通知threadpool_destroy函数，销毁线程函数
}
if (pool->queue_cur_num == pool->queue_max_num - 1)
{
pthread_cond_broadcast(&(pool->queue_not_full)); //队列非满，就可以通知threadpool_add_job函数，添加新任务
}
pthread_mutex_unlock(&(pool->mutex));
(*(pjob->callback_function))(pjob->arg); //线程真正要做的工作，回调函数的调用
free(pjob);
pjob = NULL;
}
}
int threadpool_destroy(struct threadpool *pool) {
if(pool == NULL) return -1;
pthread_mutex_lock(&(pool->mutex));
if (pool->queue_close || pool->pool_close) //线程池已经退出了，就直接返回
{
pthread_mutex_unlock(&(pool->mutex));
return -1;
}
pool->queue_close = 1; //置队列关闭标志
while (pool->queue_cur_num != 0)
{
pthread_cond_wait(&(pool->queue_empty), &(pool->mutex)); //等待队列为空
}
pool->pool_close = 1; //置线程池关闭标志
pthread_mutex_unlock(&(pool->mutex));
pthread_cond_broadcast(&(pool->queue_not_empty)); //唤醒线程池中正在阻塞的线程
pthread_cond_broadcast(&(pool->queue_not_full)); //唤醒添加任务的threadpool_add_job函数
int i;
for (i = 0; i < pool->thread_num; ++i)
{
pthread_join(pool->pthreads[i], NULL); //等待线程池的所有线程执行完毕
}
pthread_mutex_destroy(&(pool->mutex)); //清理资源
pthread_cond_destroy(&(pool->queue_empty));
pthread_cond_destroy(&(pool->queue_not_empty));
pthread_cond_destroy(&(pool->queue_not_full));
free(pool->pthreads);
struct job *p;
while (pool->head != NULL)
{
p = pool->head;
pool->head = p->next;
free(p);
}
free(pool);
return 0;
}
3.进入client
client.c
/*************************************************************************
> File Name: test.c
> Author: wangzhicheng
> Mail:
> Created Time: Fri 03 Oct 2014 09:43:59 PM WST
************************************************************************/
#include "socket.h"
const char * serveraddr = "127.0.0.1";
#define TCPPORT 4001
int main() {
int clientfd = -1;
char buf[256];
strcpy(buf, "1");
if(TCPClientInit(&clientfd) < 0) {
perror("client init failed...!\n");
exit(EXIT_FAILURE);
}
if(TCPClientConnect(clientfd, serveraddr, TCPPORT)) {
perror("can not connect to server...!\n");
exit(EXIT_FAILURE);
}
if(TCPWrite(clientfd, buf, strlen(buf) == 1)) {
printf("send successfully...!\n");
}
else printf("send failed...!\n");
return 0;
}
Makefile
CC=gcc
LIBRARY=../lib
CFLAGS=-I$(LIBRARY)
CXXFLAGS=
OBJS1=client.o socket.o
all: client
client: $(OBJS1)
$(CC) -o $@ $(OBJS1)
socket.o: $(LIBRARY)/socket.c
$(CC) -c $(LIBRARY)/socket.c
clean:
rm *.o client > /dev/null 2>&1
4. 进入server
server.c
/*************************************************************************
> File Name: server.c
>
> Created Time: Sat 04 Oct 2014 09:46:30 PM WST
************************************************************************/
#include "socket.h"
#include "threadpool.h"
#define TCPPORT 4001
#define SIZE 256
#define N 10
int array[N] = {1, 2, 6, 8, 12, 88, 208, 222, 688, 1018};
int find(int low, int high, int m) {
int mid;
if(low <= high) {
mid = (low + high) >> 1;
if(array[mid] == m) return 1;
else if(array[mid] > m) return find(low, mid - 1, m);
else return find(mid + 1, high, m);
}
return 0;
}
void* work(void* arg)
{
int *p = (int *) arg;
int m = *p;
if(find(0, N - 1, m)) printf("%d has been found...!\n", m);
else printf("%d has not been found...!\n", m);
sleep(1);
}
int main() {
int serverfd = -1, clientfd = -1;
char clientaddr[SIZE];
char buf[SIZE];
int num;
struct threadpool *pool = NULL;
TCPServerInit(TCPPORT, &serverfd);
if(serverfd < 0) {
perror("server init failed...!\n");
exit(EXIT_FAILURE);
}
pool = threadpool_init(10, 20);
while(1) {
TCPServerWaitConnection(serverfd, &clientfd, clientaddr);
if(clientfd < 0) {
perror("can not connect the clients...!\n");
exit(EXIT_FAILURE);
}
if(TCPBlockRead(clientfd, buf, SIZE) <= 0) {
perror("can not read from client...!\n");
sleep(1);
}
else {
num = atoi(buf);
threadpool_add_job(pool, work, &num);
}
}
threadpool_destroy(pool);
return 0;
}
Makefile
CC=gcc
LIBRARY=../lib
CFLAGS=-I$(LIBRARY)
CXXFLAGS=
OBJS1=server.o socket.o threadpool.o
all: server
server: $(OBJS1)
$(CC) -o $@ $(OBJS1) -lpthread
socket.o: $(LIBRARY)/socket.c
$(CC) -c $(LIBRARY)/socket.c
threadpool.o: $(LIBRARY)/threadpool.c
$(CC) -c $(LIBRARY)/threadpool.c
clean:
rm *.o client > /dev/null 2>&1
三、测试
四、有关线程池的说明
当线程池被创建时，线程池中有些“空”的线程，即不执行任务，每当一个任务被加入进来时，任务就被组织成任务队列，线程按照队列队头出，队尾进的原则取出头任务执行。
任务队列中所含任务数必须控制在一个上限内，超过上限时，任务被阻塞。当所有任务被执行完，销毁线程池。
