接着上文IO多路複用(一)-- Select、Poll、Epoll,接下來將演示一個TCP回射程序,源代碼來自於該博文https://www.cnblogs.com/Anker...,在這裏將其進行了整合,突出select、poll和epoll不一樣方法之間的比較,可是代碼的結構相同,爲了突出方法之間的差異,可能有的代碼改動的並不合理,實際中使用並不是這麼寫。html
該程序的主要邏輯以下:c++
服務器: 1. 開啓服務器套接字 2. 將服務器套接字加入要監聽的集合中(select的fd_set、poll的pollfd、epoll調用epoll_ctl) 3. 進入循環,調用IO多路複用的API函數(select/poll/epoll_create),若是有事件產生: 3.1. 服務器套接字產生的事件,添加新的客戶端到監聽集合中 3.2. 客戶端套接字產生的事件,讀取數據,並立馬回傳給客戶端 客戶端: 1. 開啓客戶端套接字 2. 將客戶端套接字和標準輸入文件描述符加入要監聽的集合中(select的fd_set、poll的pollfd、epoll調用epoll_ctl) 3. 進入循環,調用IO多路複用的API函數(select/poll/epoll_create),若是有事件產生: 3.1. 客戶端套接字產生的事件,則讀取數據,將其輸出到控制檯 3.2. 標準輸入文件描述符產生的事件,則讀取數據,將其經過客戶端套接字傳給服務器
具體代碼以下,首先是頭文件git
//multiplexing.h #ifndef MULTIPLEXING_H #define MULTIPLEXING_H #include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <netinet/in.h> #include <sys/socket.h> #include <poll.h> #include <unistd.h> #include <sys/types.h> #include <arpa/inet.h> #include <sys/select.h> #include <sys/epoll.h> #include <unistd.h> using namespace std; #define MAXLINE 1024 class Multiplexing { protected: static const int DEFAULT_IO_MAX = 10; //默認的最大文件描述符 static const int INFTIM = -1; int io_max; //記錄最大文件描述符 int listenfd; //監聽句柄 public: Multiplexing() { this->io_max = DEFAULT_IO_MAX; } Multiplexing(int max, int listenfd) { this->io_max = max; this->listenfd = listenfd; } ~Multiplexing() {} virtual void server_do_multiplexing() = 0; //服務端io多路複用 virtual void client_do_multiplexing() = 0; //客戶端io多路複用 virtual void handle_client_msg() = 0; //處理客戶端消息 virtual bool accept_client_proc() = 0; //接收客戶端鏈接 virtual bool add_event(int confd, int event) = 0; virtual int wait_event() = 0; // 等待事件 }; //-----------------select------------------------- class MySelect : public Multiplexing { private: fd_set* allfds; //句柄集合 int* clifds; //客戶端集合 int maxfd; //記錄句柄的最大值 int cli_cnt; //客戶端個數 public: MySelect() : Multiplexing() { allfds = NULL; clifds = NULL; maxfd = 0; cli_cnt = 0; } MySelect(int max, int listenfd); ~MySelect() { if (allfds) { delete allfds; allfds = NULL; } if (clifds) { delete clifds; clifds = NULL; } } void server_do_multiplexing(); void client_do_multiplexing(); void handle_client_msg(); bool accept_client_proc(); bool add_event(int confd, int event); bool init_event(); //每次調用select前都要從新設置文件描述符 int wait_event(); // 等待事件 }; //-----------------poll------------------------- typedef struct pollfd Pollfd; class MyPoll : public Multiplexing { private: Pollfd* clientfds; //poll中使用pollfd結構體指定一個被監視的文件描述符 int max_index; //記錄當前clientfds數組中使用的最大下標 public: MyPoll() : Multiplexing() { clientfds = NULL; max_index = -1; } MyPoll(int max, int listenfd); ~MyPoll() { if (clientfds) { delete clientfds; clientfds = NULL; } } void server_do_multiplexing(); void client_do_multiplexing(); void handle_client_msg(); bool accept_client_proc(); bool add_event(int confd, int event); int wait_event(); // 等待事件 }; //-----------------epoll------------------------- typedef struct epoll_event Epoll_event; class MyEpoll : public Multiplexing { private: int epollfd; //epoll的句柄,用來管理多個文件描述符 Epoll_event *events; //事件數組 int nready; //在handle_client_msg函數中用到,傳給handle_client_msg函數的當前事件的個數 public: MyEpoll() : Multiplexing() { events = NULL; epollfd = -1; } MyEpoll(int max, int listenfd); ~MyEpoll() { if (events) { delete events; events = NULL; } } void server_do_multiplexing(); void client_do_multiplexing(); void handle_client_msg(); bool accept_client_proc(); bool add_event(int confd, int event); bool delete_event(int confd, int event); int wait_event(); // 等待事件 }; #endif // !MULTIPLEXING_H
而後是函數的實現,從各個函數的實現能夠看到select、poll、epoll在使用過程當中的區別,具體看代碼註釋github
//multiplexing.cpp #include "multiplexing.h" //--------------------------select------------------ MySelect::MySelect(int max, int listenfd) : Multiplexing(max, listenfd) { this->allfds = new fd_set[this->io_max]; this->clifds = new int[this->io_max]; if (NULL == this->allfds || NULL == this->clifds) { perror("initialization failed!"); exit(-1); } this->cli_cnt = 0; this->maxfd = 0; //初始化客戶鏈接描述符 int i; for (i = 0; i < io_max; i++) { this->clifds[i] = -1; } } void MySelect::server_do_multiplexing() { int nready = 0; int i = 0; while (1) { //從新初始化fd_set集合 -- 這裏與poll不一樣 init_event(); /*開始輪詢接收處理服務端和客戶端套接字*/ nready = wait_event(); if (-1 == nready) return; if (0 == nready) continue; if (FD_ISSET(this->listenfd, this->allfds)) { /*監聽客戶端請求*/ if (!accept_client_proc()) //處理鏈接請求 continue; if (--nready <= 0) //說明此時產生的事件個數小於等於1,因此沒必要再處理下面的客戶鏈接信息 continue; } /*接受處理客戶端消息*/ handle_client_msg(); } } void MySelect::client_do_multiplexing() { char sendline[MAXLINE], recvline[MAXLINE]; int n; this->maxfd = -1; int nready = -1; if (this->io_max < 2) { perror("please increase the max number of io!"); exit(1); } //添加鏈接描述符 if (!add_event(this->listenfd, -1)) { perror("add event error!"); exit(1); } //添加標準輸入描述符 if (!add_event(STDIN_FILENO, -1)) { perror("add event error!"); exit(1); } while (1) { //從新初始化fd_set集合 -- 這裏與poll不一樣 init_event(); //等待事件產生 nready = wait_event(); if (-1 == nready) return; if (0 == nready) continue; //是否有客戶信息準備好 if (FD_ISSET(this->listenfd, this->allfds)) { n = read(this->listenfd, recvline, MAXLINE); if (n <= 0) { fprintf(stderr, "client: server is closed.\n"); close(this->listenfd); return; } write(STDOUT_FILENO, recvline, n); } //測試標準輸入是否準備好 if (FD_ISSET(STDIN_FILENO, this->allfds)) { n = read(STDIN_FILENO, sendline, MAXLINE); if (n <= 0) { shutdown(this->listenfd, SHUT_WR); continue; } write(this->listenfd, sendline, n); } } } bool MySelect::init_event() { FD_ZERO(this->allfds); //從新設置文件描述符 /*添加監聽套接字*/ FD_SET(this->listenfd, this->allfds); this->maxfd = this->listenfd; int i; int clifd = -1; /*添加客戶端套接字*/ for (i = 0; i < this->cli_cnt; i++) { clifd = this->clifds[i]; /*去除無效的客戶端句柄*/ if (clifd != -1) { FD_SET(clifd, this->allfds); } this->maxfd = (clifd > this->maxfd ? clifd : this->maxfd); } } bool MySelect::accept_client_proc() { struct sockaddr_in cliaddr; socklen_t cliaddrlen; cliaddrlen = sizeof(cliaddr); int connfd; //接受新的鏈接 if ((connfd = accept(this->listenfd, (struct sockaddr*)&cliaddr, &cliaddrlen)) == -1) { if (errno == EINTR) return false; else { perror("accept error:"); exit(1); } } fprintf(stdout, "accept a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port); return add_event(connfd, -1); //添加新的描述符 } bool MySelect::add_event(int connfd, int event) { //在select中event並無做用 //將新的鏈接描述符添加到數組中 int i = 0; for (i = 0; i < io_max; i++) { if (this->clifds[i] < 0) { this->clifds[i] = connfd; this->cli_cnt++; break; } } if (i == io_max) { fprintf(stderr, "too many clients.\n"); return false; } //將新的描述符添加到讀描述符集合中 FD_SET(connfd, this->allfds); if (connfd > this->maxfd) this->maxfd = connfd; return true; } void MySelect::handle_client_msg() { int i = 0, n = 0; int clifd; char buf[MAXLINE]; memset(buf, 0, MAXLINE); //處理信息 for (i = 0; i <= this->cli_cnt; i++) { clifd = this->clifds[i]; if (clifd < 0) { continue; } /*判斷客戶端套接字是否有數據*/ if (FD_ISSET(clifd, this->allfds)) { //接收客戶端發送的信息 n = read(clifd, buf, MAXLINE); if (n <= 0) { /*n==0表示讀取完成,客戶都關閉套接字*/ FD_CLR(clifd, this->allfds); close(clifd); this->clifds[i] = -1; continue; } //回寫數據 printf("recv buf is :%s\n", buf); write(clifd, buf, n); return; } } } int MySelect::wait_event() { struct timeval tv; /*每次調用select前都要從新設置文件描述符和時間,由於事件發生後,文件描述符和時間都被內核修改啦*/ tv.tv_sec = 30; tv.tv_usec = 0; /*開始輪詢接收處理服務端和客戶端套接字*/ int nready = select(this->maxfd + 1, this->allfds, NULL, NULL, &tv); if (nready == -1) { fprintf(stderr, "select error:%s.\n", strerror(errno)); } if (nready == 0) { fprintf(stdout, "select is timeout.\n"); } return nready; } //-----------------poll------------------------- MyPoll::MyPoll(int max, int listenfd) : Multiplexing(max, listenfd) { this->clientfds = new Pollfd[this->io_max]; //初始化客戶鏈接描述符 int i; for (i = 0; i < io_max; i++) { this->clientfds[i].fd = -1; } this->max_index = -1; } void MyPoll::server_do_multiplexing() { int sockfd; int i; int nready; this->max_index = -1; //注意:須要將監聽描述符添加在第一個位置 if (!add_event(this->listenfd, POLLIN)) { perror("add listen event error!"); return; } //循環處理 while (1) { //等待事件,獲取可用描述符的個數 nready = wait_event(); if (nready == -1) { return; } if (nready == 0) { continue; } //測試監聽描述符是否準備好 if (this->clientfds[0].revents & POLLIN) { if (!accept_client_proc()) //處理鏈接請求 continue; if (--nready <= 0) //說明此時產生的事件個數小於等於1,因此沒必要再處理下面的客戶鏈接信息 continue; } //處理客戶鏈接 handle_client_msg(); } } void MyPoll::client_do_multiplexing() { char sendline[MAXLINE], recvline[MAXLINE]; int n; this->max_index = -1; int nready = -1; if (this->io_max < 2) { perror("please increase the max number of io!"); exit(1); } //添加鏈接描述符 if (!add_event(this->listenfd, POLLIN)) { perror("add event error!"); exit(1); } //添加標準輸入描述符 if (!add_event(STDIN_FILENO, POLLIN)) { perror("add event error!"); exit(1); } while (1) { //等待事件產生 nready = wait_event(); if (-1 == nready) return; if (0 == nready) continue; //是否有客戶信息準備好 if (this->clientfds[0].revents & POLLIN) { n = read(this->listenfd, recvline, MAXLINE); if (n <= 0) { fprintf(stderr, "client: server is closed.\n"); close(this->listenfd); return; } write(STDOUT_FILENO, recvline, n); } //測試標準輸入是否準備好 if (this->clientfds[1].revents & POLLIN) { n = read(STDIN_FILENO, sendline, MAXLINE); if (n <= 0) { shutdown(this->listenfd, SHUT_WR); continue; } write(this->listenfd, sendline, n); } } } bool MyPoll::accept_client_proc() { struct sockaddr_in cliaddr; socklen_t cliaddrlen; cliaddrlen = sizeof(cliaddr); int connfd; //接受新的鏈接 if ((connfd = accept(this->listenfd, (struct sockaddr*)&cliaddr, &cliaddrlen)) == -1) { if (errno == EINTR) return false; else { perror("accept error:"); exit(1); } } fprintf(stdout, "accept a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port); return add_event(connfd, POLLIN); //添加新的描述符 } bool MyPoll::add_event(int connfd, int event) { //將新的鏈接描述符添加到數組中 int i; for (i = 0; i < io_max; i++) { if (this->clientfds[i].fd < 0) { this->clientfds[i].fd = connfd; break; } } if (i == io_max) { fprintf(stderr, "too many clients.\n"); return false; } //將新的描述符添加到讀描述符集合中 this->clientfds[i].events = event; if (i > this->max_index) this->max_index = i; return true; } void MyPoll::handle_client_msg() { int i, n; char buf[MAXLINE]; memset(buf, 0, MAXLINE); //處理信息 for (i = 1; i <= this->max_index; i++) { if (this->clientfds[i].fd < 0) continue; //測試客戶描述符是否準備好 if (this->clientfds[i].revents & POLLIN) { //接收客戶端發送的信息 n = read(this->clientfds[i].fd, buf, MAXLINE); if (n <= 0) { close(this->clientfds[i].fd); this->clientfds[i].fd = -1; continue; } write(STDOUT_FILENO, buf, n); //向客戶端發送buf write(this->clientfds[i].fd, buf, n); } } } int MyPoll::wait_event() { /*開始輪詢接收處理服務端和客戶端套接字*/ int nready = nready = poll(this->clientfds, this->max_index + 1, INFTIM); if (nready == -1) { fprintf(stderr, "poll error:%s.\n", strerror(errno)); } if (nready == 0) { fprintf(stdout, "poll is timeout.\n"); } return nready; } //------------------------epoll--------------------------- MyEpoll::MyEpoll(int max, int listenfd) : Multiplexing(max, listenfd) { this->events = new Epoll_event[this->io_max]; //建立一個描述符 this->epollfd = epoll_create(this->io_max); } void MyEpoll::server_do_multiplexing() { int i, fd; int nready; char buf[MAXLINE]; memset(buf, 0, MAXLINE); //添加監聽描述符事件 if (!add_event(this->listenfd, EPOLLIN)) { perror("add event error!"); exit(1); } while (1) { //獲取已經準備好的描述符事件 nready = wait_event(); this->nready = nready; if (-1 == nready) return; if (0 == nready) continue; //進行遍歷 /**這裏和poll、select都不一樣,由於並不能直接判斷監聽的事件是否產生, 因此須要一個for循環遍歷,這個for循環+判斷相似於poll中 if (FD_ISSET(this->listenfd, this->allfds))、 select中的if (this->clientfds[0].revents & POLLIN) 這裏只是儘可能寫的跟poll、select中的結構相似, 可是實際代碼中,不該該這麼寫,這麼寫多加了一個for循環**/ for (i = 0; i < nready; i++) { fd = events[i].data.fd; //根據描述符的類型和事件類型進行處理 if ((fd == this->listenfd) && (events[i].events & EPOLLIN)) { //監聽事件 /*監聽客戶端請求*/ if (!accept_client_proc()) //處理鏈接請求 continue; //說明此時產生的事件個數小於等於1,因此沒必要再處理下面的客戶鏈接信息 if (--nready <= 0) continue; } } //處理客戶端事件 handle_client_msg(); } close(epollfd); } bool MyEpoll::accept_client_proc() { struct sockaddr_in cliaddr; socklen_t cliaddrlen; cliaddrlen = sizeof(cliaddr); int connfd; //接受新的鏈接 if ((connfd = accept(this->listenfd, (struct sockaddr*)&cliaddr, &cliaddrlen)) == -1) { if (errno == EINTR) return false; else { perror("accept error:"); exit(1); } } fprintf(stdout, "accept a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port); return add_event(connfd, EPOLLIN); //添加新的描述符 } void MyEpoll::client_do_multiplexing() { char sendline[MAXLINE], recvline[MAXLINE]; int n; int nready = -1; int i, fd; if (this->io_max < 2) { perror("please increase the max number of io!"); exit(1); } //添加鏈接描述符 if (!add_event(this->listenfd, POLLIN)) { perror("add event error!"); exit(1); } //添加標準輸入描述符 if (!add_event(STDIN_FILENO, POLLIN)) { perror("add event error!"); exit(1); } while (1) { //等待事件產生 nready = wait_event(); if (-1 == nready) return; if (0 == nready) continue; for (i = 0; i < nready; i++) { fd = events[i].data.fd; //根據描述符的類型和事件類型進行處理 if ((fd == this->listenfd) && (events[i].events & EPOLLIN)) { //監聽事件 n = read(this->listenfd, recvline, MAXLINE); if (n <= 0) { fprintf(stderr, "client: server is closed.\n"); close(this->listenfd); return; } write(STDOUT_FILENO, recvline, n); } else { n = read(STDIN_FILENO, sendline, MAXLINE); if (n <= 0) { shutdown(this->listenfd, SHUT_WR); continue; } write(this->listenfd, sendline, n); } } } } bool MyEpoll::add_event(int connfd, int event) { //將新的描述符添加到讀描述符集合中 Epoll_event ev; ev.events = event; ev.data.fd = connfd; return epoll_ctl(this->epollfd, EPOLL_CTL_ADD, connfd, &ev) == 0; } void MyEpoll::handle_client_msg() { int i, fd; char buf[MAXLINE]; memset(buf, 0, MAXLINE); //處理信息 for (i = 0; i <= this->nready; i++) { fd = this->events[i].data.fd; if (fd == this->listenfd) continue; if (events[i].events & EPOLLIN) { int n = read(fd, buf, MAXLINE); if (n <= 0) { perror("read error:"); close(fd); delete_event(fd, EPOLLIN); } else { write(STDOUT_FILENO, buf, n); //向客戶端發送buf write(fd, buf, strlen(buf)); } } } } int MyEpoll::wait_event() { /*開始輪詢接收處理服務端和客戶端套接字*/ int nready = epoll_wait(this->epollfd, this->events, this->io_max, INFTIM);; if (nready == -1) { fprintf(stderr, "poll error:%s.\n", strerror(errno)); } if (nready == 0) { fprintf(stdout, "poll is timeout.\n"); } return nready; } bool MyEpoll::delete_event(int fd, int state) { Epoll_event ev; ev.events = state; ev.data.fd = fd; return epoll_ctl(this->epollfd, EPOLL_CTL_DEL, fd, &ev) == 0; }
#include "multiplexing.h" #define IPADDRESS "127.0.0.1" #define PORT 8787 #define LISTENQ 5 #define OPEN_MAX 1000 //函數聲明 //建立套接字並進行綁定 static int socket_bind(const char* ip, int port); int main(int argc, char *argv[]) { int listenfd = socket_bind(IPADDRESS, PORT); if (listenfd < 0) { perror("socket bind error"); return 0; } listen(listenfd, LISTENQ); // 改動此處,調用不一樣的IO複用函數 MySelect mltp(OPEN_MAX, listenfd); //MyPoll mltp(OPEN_MAX, listenfd); //MyEpoll mltp(OPEN_MAX, listenfd); mltp.server_do_multiplexing(); //處理服務端 return 0; } static int socket_bind(const char* ip, int port) { int listenfd; struct sockaddr_in servaddr; listenfd = socket(AF_INET, SOCK_STREAM, 0); if (listenfd == -1) { perror("socket error:"); exit(1); } bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; inet_pton(AF_INET, ip, &servaddr.sin_addr); servaddr.sin_port = htons(port); if (bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1) { perror("bind error: "); exit(1); } return listenfd; }
#include "multiplexing.h" #define MAXLINE 1024 #define IPADDRESS "127.0.0.1" #define SERV_PORT 8787 static void handle_connection(int sockfd); int main(int argc, char *argv[]) { int sockfd; struct sockaddr_in servaddr; sockfd = socket(AF_INET, SOCK_STREAM, 0); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(SERV_PORT); inet_pton(AF_INET, IPADDRESS, &servaddr.sin_addr); connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)); // 改動此處,調用不一樣的IO複用函數 MySelect mltp(2, sockfd); //MyPoll mltp(2, sockfd); //MyEpoll mltp(2, sockfd); poll.client_do_multiplexing(); // 處理客戶端 return 0; }
服務端:segmentfault
客戶端:數組
完整代碼能夠訪問筆者github: https://github.com/yearsj/Cli...
IO多路複用之poll總結socket
做者: yearsj轉載請註明出處:https://segmentfault.com/a/11...測試