本章将带你掌握异步IO事件处理原理。

5-1 通过fork的方式实现高性能网络服务器

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fork_tcp_server1.c

  1. #include <stdio.h>
  2. #include <unistd.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5. #include <sys/socket.h>
  6. #include <netinet/in.h>
  8. #define PORT 8888
  9. #define MESSAGE_SIZE 1024
  11. int main(){
  13.   int ret = -1;
  15.   int pid;
  16.   int socket_fd = -1;
  18.   int curpos = 0;
  19.   int backlog = 10;
  20.   int flag;
  22.   struct sockaddr_in local_addr, remote_addr;
  24.   //create a tcp socket
  25.   socket_fd = socket(AF_INET, SOCK_STREAM, 0);
  26.   if ( socket_fd == -1 ){
  27.     perror("create socket error");
  28.     exit(1);
  29.   }
  31.   //set option of socket
  32.   ret = setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (char *)&flag, sizeof(flag));
  33.   if ( ret == -1 ){
  34.     perror("setsockopt error");
  35.   }
  37.   //set local address
  38.   local_addr.sin_family = AF_INET;
  39.   local_addr.sin_port = htons(PORT);
  40.   local_addr.sin_addr.s_addr = INADDR_ANY;
  41.   bzero(&(local_addr.sin_zero), 8);
  43.   //bind socket
  44.   ret = bind(socket_fd, (struct sockaddr *)&local_addr, sizeof(struct sockaddr_in));
  45.   if(ret == -1 ) {
  46.     perror("bind error");
  47.     exit(1);
  48.   }
  50.   ret = listen(socket_fd, backlog);
  51.   if ( ret == -1 ){
  52.     perror("listen error");
  53.     exit(1);
  54.   }
  56.   //create a sub process
  57.   pid = fork();
  59.   for(;;){
  61.     //子进程
  62.     if( pid==0 ){ 
  64.       int accept_fd = -1;
  65.       char in_buf[MESSAGE_SIZE] = {0,};
  67.       int addr_len = sizeof( struct sockaddr_in );
  68.       //accept an new connection
  69.       accept_fd = accept( socket_fd, (struct sockaddr *)&remote_addr, &addr_len );
  71.       for(;;){
  73.         memset(in_buf, 0, MESSAGE_SIZE);
  75.         ret = recv(accept_fd ,&in_buf, MESSAGE_SIZE, 0);
  76.         if(ret == 0){
  77.           break; 
  78.         } 
  80.         printf( "receive message:%s\n", in_buf );
  81.         send(accept_fd, (void*)in_buf, MESSAGE_SIZE, 0);
  83.       }
  85.       printf("close client connection...\n");
  86.       close(accept_fd);
  88.     } 
  90.     //parent process
  91.     sleep(1000);
  93.   }
  95.   if(pid != 0 ){
  96.     printf("quit server...\n");
  97.     close(socket_fd);
  98.   }
  100.   return 0;
  101. }

fork_tcp_server2.c

  1. #include <stdio.h>
  2. #include <unistd.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5. #include <sys/socket.h>
  6. #include <netinet/in.h>
  8. #define PORT 8111
  9. #define MESSAGE_SIZE 1024
  11. int main(){
  13.   int ret = -1;
  15.   int pid;
  16.   int socket_fd = -1;
  17.   int accept_fd = -1;
  19.   int curpos = 0;
  20.   int backlog = 10;
  21.   int flag = 1;
  23.   struct sockaddr_in local_addr, remote_addr;
  25.   //create a tcp socket
  26.   socket_fd = socket(AF_INET, SOCK_STREAM, 0);
  27.   if ( socket_fd == -1 ){
  28.     perror("create socket error");
  29.     exit(1);
  30.   }
  32.   //set option of socket
  33.   ret = setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));
  34.   if ( ret == -1 ){
  35.     perror("setsockopt error");
  36.   }
  38.   //set local address
  39.   local_addr.sin_family = AF_INET;
  40.   local_addr.sin_port = htons(PORT);
  41.   local_addr.sin_addr.s_addr = INADDR_ANY;
  42.   bzero(&(local_addr.sin_zero), 8);
  44.   //bind socket
  45.   ret = bind(socket_fd, (struct sockaddr *)&local_addr, sizeof(struct sockaddr_in));
  46.   if(ret == -1 ) {
  47.     perror("bind error");
  48.     exit(1);
  49.   }
  51.   ret = listen(socket_fd, backlog);
  52.   if ( ret == -1 ){
  53.     perror("listen error");
  54.     exit(1);
  55.   }
  57.   for(;;){
  59.     int addr_len = sizeof( struct sockaddr_in );
  61.     //accept an new connection, block......
  62.     accept_fd = accept( socket_fd, (struct sockaddr *)&remote_addr, &addr_len );
  64.     //create a sub process
  65.     pid = fork();
  67.     //子进程
  68.     if( pid==0 ){ 
  70.       char in_buf[MESSAGE_SIZE] = {0,};
  72.       for(;;){
  74.         memset(in_buf, 0, MESSAGE_SIZE);
  76.         ret = recv(accept_fd ,&in_buf, MESSAGE_SIZE, 0);
  77.         if(ret == 0){
  78.           break; 
  79.         } 
  81.         printf( "receive message:%s\n", in_buf );
  82.         send(accept_fd, (void*)in_buf, MESSAGE_SIZE, 0);
  84.       }
  86.       printf("close client connection...\n");
  87.       close(accept_fd);
  89.     } 
  91.     //parent process
  93.   }
  95.   if(pid != 0 ){
  96.     printf("quit server...\n");
  97.     close(socket_fd);
  98.   }
  100.   return 0;
  101. }

5-2 通过select实现高性能服务器

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  1. #include <stdio.h>
  2. #include <unistd.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5. #include <fcntl.h>
  6. #include <sys/socket.h>
  7. #include <netinet/in.h>
  9. #define PORT 8888
  10. #define FD_SIZE 1024
  11. #define MESSAGE_SIZE 1024
  13. int main(){
  15.   int ret = -1;
  17.   int pid;
  18.   int accept_fd = -1;
  19.   int socket_fd = -1;
  20.   int accept_fds[FD_SIZE] = {-1, };
  22.   int curpos = -1;
  23.   int maxpos = 0;
  24.   int backlog = 10;
  25.   int flags = 1; //open REUSEADDR option
  27.   int max_fd = -1;
  28.   fd_set fd_sets;
  29.   int events=0;
  31.   struct sockaddr_in local_addr, remote_addr;
  33.   //create a tcp socket
  34.   socket_fd = socket(AF_INET, SOCK_STREAM, 0);
  35.   if ( socket_fd == -1 ){
  36.     perror("create socket error");
  37.     exit(1);
  38.   }
  40.   //set option of socket
  41.   ret = setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &flags, sizeof(flags));
  42.   if ( ret == -1 ){
  43.     perror("setsockopt error");
  44.   }
  46.   //NONBLOCK
  47.   flags = fcntl(socket_fd, F_GETFL, 0);
  48.   fcntl(socket_fd, F_SETFL, flags | O_NONBLOCK);
  50.   //set local address
  51.   local_addr.sin_family = AF_INET;
  52.   local_addr.sin_port = htons(PORT);
  53.   local_addr.sin_addr.s_addr = INADDR_ANY;
  54.   bzero(&(local_addr.sin_zero), 8);
  56.   //bind socket
  57.   ret = bind(socket_fd, (struct sockaddr *)&local_addr, sizeof(struct sockaddr_in));
  58.   if(ret == -1 ) {
  59.     perror("bind error");
  60.     exit(1);
  61.   }
  63.   ret = listen(socket_fd, backlog);
  64.   if ( ret == -1 ){
  65.     perror("listen error");
  66.     exit(1);
  67.   }
  69.   max_fd = socket_fd; //每次都重新设置 max_fd
  70.   for(int i=0; i< FD_SIZE; i++){
  71.     accept_fds[i] = -1; 
  72.   }  
  74.   for(;;) {
  76.     FD_ZERO(&fd_sets); //清空sets
  77.     FD_SET(socket_fd, &fd_sets); //将socket_fd 添加到sets
  79.     for(int k=0; k < maxpos; k++){
  80.       if(accept_fds[k] != -1){
  81.         if(accept_fds[k] > max_fd){
  82.           max_fd = accept_fds[k]; 
  83.         }
  84.         printf("fd:%d, k:%d, max_fd:%d\n", accept_fds[k], k, max_fd);
  85.         FD_SET(accept_fds[k], &fd_sets); //继续向sets添加fd
  86.       }
  87.     }
  89.     //遍历所有的fd
  90.     events = select( max_fd + 1, &fd_sets, NULL, NULL, NULL );
  91.     if(events < 0) {
  92.       perror("select");
  93.       break;
  94.     }else if(events == 0){
  95.       printf("select time out ......");
  96.       continue;
  97.     }else if( events ){
  99.       printf("events:%d\n", events);
  101.       if( FD_ISSET(socket_fd, &fd_sets)){ // 如果来的是新连接
  102.         printf("listen event :1\n");
  104.         int a = 0;
  105.         for( ; a < FD_SIZE; a++){
  106.           if(accept_fds[a] == -1){
  107.             curpos = a;
  108.             break;
  109.           }
  110.         }
  112.         if(a == FD_SIZE){
  113.           printf("the connection is full!\n");
  114.           continue;
  115.         }
  117.         int addr_len = sizeof( struct sockaddr_in );
  118.         accept_fd = accept(socket_fd, (struct sockaddr *)&remote_addr, &addr_len); //创建一个新连接的fd
  120.         int flags = fcntl(accept_fd, F_GETFL, 0); //取出新连接的 fd 的相关选项
  121.         fcntl(accept_fd, F_SETFL, flags|O_NONBLOCK); //设置为非阻塞
  123.         accept_fds[curpos] = accept_fd;
  125.         if(curpos+1 > maxpos){
  126.           maxpos = curpos + 1; 
  127.         }
  129.         if(accept_fd > max_fd){
  130.           max_fd = accept_fd; 
  131.         }
  133.         printf("new connection fd:%d, curpos = %d \n",accept_fd, curpos);
  134.       }
  136.       for(int j=0; j < maxpos; j++ ){
  137.         if( (accept_fds[j] != -1) && FD_ISSET(accept_fds[j], &fd_sets)){ //有事件时
  138.           printf("accept event :%d, accept_fd: %d\n",j, accept_fds[j]);
  139.           char in_buf[MESSAGE_SIZE];
  140.           memset(in_buf, 0, MESSAGE_SIZE);
  141.           int ret = recv(accept_fds[j], &in_buf, MESSAGE_SIZE, 0);
  142.           if(ret == 0){
  143.             close(accept_fds[j]);
  144.             accept_fds[j] = -1;
  145.           } 
  147.           printf( "receive message:%s\n", in_buf );
  148.           send(accept_fds[j], (void*)in_buf, MESSAGE_SIZE, 0);
  149.         }
  150.       }
  151.     }
  152.   }
  154.   printf("quit server...\n");
  155.   close(socket_fd);
  157.   return 0;
  158. }

5-3 再论select函数

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