多线程并发服务器-CFANZ编程社区

一、多线程并发服务器

1.设计思路

服务器端
主线程：
socket()创建套接字文件描述符
bind()绑定端口
listen()监听客户端
accept()等待客户端连接
pthread_create()创建子线程
子线程：
实现与客户端的通信

客户端
socket()创建套接字
connect()实现与服务器的通信
close()关闭套接字

多线程并发服务器_多线程并发服务器

2.注意事项

线程如有共享数据，考虑线程同步
服务于客户端线程退出时，退出处理。（退出值，分离态）
系统负载，随着链接客户端增加，导致其它线程不能及时得到CPU

二、代码实现

（1）server.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 

#include "wrap.h"

#define MAXLINE 8192
#define SERV_PORT 8000

struct s_info {                     
    //定义一个结构体, 将地址结构跟cfd捆绑
    struct sockaddr_in cliaddr;
    int connfd;
};

void *do_work(void *arg)
{
    int n,i;
    struct s_info *ts = (struct s_info*)arg;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];     
    //#define INET_ADDRSTRLEN 16  可用"[+d"查看

    while (1) {
        n = Read(ts->connfd, buf, MAXLINE);                    
        //读客户端
        if (n == 0) {
            printf("the client %d closed...\n", ts->connfd);
            break;                                              
            //跳出循环,关闭cfd
        }
        printf("received from %s at PORT %d\n",
                inet_ntop(AF_INET, &(*ts).cliaddr.sin_addr, str, sizeof(str)),
                ntohs((*ts).cliaddr.sin_port));                 
                //打印客户端信息(IP/PORT)

        for (i = 0; i < n; i++) 
            buf[i] = toupper(buf[i]);//小写-->大写

        Write(STDOUT_FILENO, buf, n);                           
        //写出至屏幕
        Write(ts->connfd, buf, n);                             
        //回写给客户端
    }
    Close(ts->connfd);

    return (void *)0;//pthread——exit(0);
}

int main(void)
{
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    int listenfd, connfd;
    pthread_t tid;
    struct s_info ts[256];      //根据最大线程数创建自定义结构体数组.
    int i = 0;

    listenfd = Socket(AF_INET, SOCK_STREAM, 0);                     //创建一个socket, 得到lfd

    bzero(&servaddr, sizeof(servaddr));                             //地址结构清零
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);                   //指定本地任意IP
    servaddr.sin_port = htons(SERV_PORT);                           //指定端口号 8000

    Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)); //绑定

    Listen(listenfd, 128);      //设置同一时刻链接服务器上限数

    printf("Accepting client connect ...\n");

    while (1) {
        cliaddr_len = sizeof(cliaddr);
        connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);   //阻塞监听客户端链接请求
        ts[i].cliaddr = cliaddr;//客户端的地址结构
        ts[i].connfd = connfd;

        /* 达到线程最大数时，pthread_create出错处理, 增加服务器稳定性 */
        pthread_create(&tid, NULL, do_work, (void*)&ts[i]);
        pthread_detach(tid);                                                    //子线程分离,防止僵线程产生.
        i++;
    }

    return 0;
}

（2）client.c

#include 
#include 
#include 
#include 
#include 
#include "wrap.h"

#define MAXLINE 80
#define SERV_PORT 8000

int main(int argc, char *argv[])
{
  struct sockaddr_in servaddr;
  char buf[MAXLINE];
  int sockfd, n;

  sockfd = Socket(AF_INET, SOCK_STREAM, 0);

  bzero(&servaddr, sizeof(servaddr));
  servaddr.sin_family = AF_INET;
  inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr.s_addr);
  servaddr.sin_port = htons(SERV_PORT);

  Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

  while (fgets(buf, MAXLINE, stdin) != NULL) {
    Write(sockfd, buf, strlen(buf));
    n = Read(sockfd, buf, MAXLINE);
    if (n == 0)
      printf("the other side has been closed.\n");
    else
      Write(STDOUT_FILENO, buf, n);
  }

  Close(sockfd);

  return 0;
}

（3）wrap.h

#ifndef __WRAP_H_
#define __WRAP_H_

void perr_exit(const char *s);
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr);
int Bind(int fd, const struct sockaddr *sa, socklen_t salen);
int Connect(int fd, const struct sockaddr *sa, socklen_t salen);
int Listen(int fd, int backlog);
int Socket(int family, int type, int protocol);
ssize_t Read(int fd, void *ptr, size_t nbytes);
ssize_t Write(int fd, const void *ptr, size_t nbytes);
int Close(int fd);
ssize_t Readn(int fd, void *vptr, size_t n);
ssize_t Writen(int fd, const void *vptr, size_t n);
ssize_t my_read(int fd, char *ptr);
ssize_t Readline(int fd, void *vptr, size_t maxlen);

#endif

（4）wrap.c

#include 
#include 
#include 
#include 
#include 

void perr_exit(const char *s)
{
    perror(s);
    exit(-1);
}

int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr)
{
    int n;

again:
    if ((n = accept(fd, sa, salenptr)) < 0) {
        if ((errno == ECONNABORTED) || (errno == EINTR))
            goto again;
        else
            perr_exit("accept error");
    }
    return n;
}

int Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
    int n;

    if ((n = bind(fd, sa, salen)) < 0)
        perr_exit("bind error");

    return n;
}

int Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
    int n;

    if ((n = connect(fd, sa, salen)) < 0)
        perr_exit("connect error");

    return n;
}

int Listen(int fd, int backlog)
{
    int n;

    if ((n = listen(fd, backlog)) < 0)
        perr_exit("listen error");

    return n;
}

int Socket(int family, int type, int protocol)
{
    int n;

    if ((n = socket(family, type, protocol)) < 0)
        perr_exit("socket error");

    return n;
}

ssize_t Read(int fd, void *ptr, size_t nbytes)
{
    ssize_t n;

again:
    if ( (n = read(fd, ptr, nbytes)) == -1) {
        if (errno == EINTR)
            goto again;
        else
            return -1;
    }
    return n;
}

ssize_t Write(int fd, const void *ptr, size_t nbytes)
{
    ssize_t n;

again:
    if ( (n = write(fd, ptr, nbytes)) == -1) {
        if (errno == EINTR)
            goto again;
        else
            return -1;
    }
    return n;
}

int Close(int fd)
{
    int n;
    if ((n = close(fd)) == -1)
        perr_exit("close error");

    return n;
}

/*参三: 应该读取的字节数*/
ssize_t Readn(int fd, void *vptr, size_t n)
{
    size_t  nleft;              //usigned int 剩余未读取的字节数
    ssize_t nread;              //int 实际读到的字节数
    char   *ptr;

    ptr = vptr;
    nleft = n;

    while (nleft > 0) {
        if ((nread = read(fd, ptr, nleft)) < 0) {
            if (errno == EINTR)
                nread = 0;
            else
                return -1;
        } else if (nread == 0)
            break;

        nleft -= nread;
        ptr += nread;
    }
    return n - nleft;
}

ssize_t Writen(int fd, const void *vptr, size_t n)
{
    size_t nleft;
    ssize_t nwritten;
    const char *ptr;

    ptr = vptr;
    nleft = n;
    while (nleft > 0) {
        if ( (nwritten = write(fd, ptr, nleft)) <= 0) {
            if (nwritten < 0 && errno == EINTR)
                nwritten = 0;
            else
                return -1;
        }

        nleft -= nwritten;
        ptr += nwritten;
    }
    return n;
}

static ssize_t my_read(int fd, char *ptr)
{
    static int read_cnt;
    static char *read_ptr;
    static char read_buf[100];

    if (read_cnt <= 0) {
again:
        if ( (read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0) {
            if (errno == EINTR)
                goto again;
            return -1;
        } else if (read_cnt == 0)
            return 0;
        read_ptr = read_buf;
    }
    read_cnt--;
    *ptr = *read_ptr++;

    return 1;
}

ssize_t Readline(int fd, void *vptr, size_t maxlen)
{
    ssize_t n, rc;
    char    c, *ptr;

    ptr = vptr;
    for (n = 1; n < maxlen; n++) {
        if ( (rc = my_read(fd, &c)) == 1) {
            *ptr++ = c;
            if (c  == '\n')
                break;
        } else if (rc == 0) {
            *ptr = 0;
            return n - 1;
        } else
            return -1;
    }
    *ptr  = 0;

    return n;
}

（5）makefile

src = $(wildcard *.c)
obj = $(patsubst %.c, %.o, $(src))

all: server client

server: server.o wrap.o
  gcc server.o wrap.o -o server -Wall -lpthread
client: client.o wrap.o
  gcc client.o wrap.o -o client -Wall -lpthread

%.o:%.c
  gcc -c $< -Wall 

.PHONY: clean all
clean: 
  -rm -rf server client $(obj)