第16章 非阻塞式I/O

执行时间：

        停等版本（完全阻塞）  》  select加阻塞I/O版本  》  fork多进程版本（Linux下多线程也应该差不多）  》  非阻塞I/O版本

非阻塞读写

#include "../Gnet.h"void do_client(int connfd){    char to[MAX_LINE], fr[MAX_LINE];    char *toiptr, *tooptr, *friptr, *froptr;    int val, stdineof, maxfd, n, nwritten;    fd_set rset, wset;    val = fcntl(connfd, F_GETFL, 0);    fcntl(connfd, F_SETFL, val|O_NONBLOCK);    val = fcntl(STDIN_FILENO, F_GETFL, 0);    fcntl(STDIN_FILENO, F_SETFL, val|O_NONBLOCK);    val = fcntl(STDOUT_FILENO, F_GETFL, 0);    fcntl(STDOUT_FILENO, F_SETFL, val|O_NONBLOCK);    toiptr = tooptr = to;    friptr = froptr = fr;    stdineof = 0;    maxfd = MAX(MAX(STDIN_FILENO, STDOUT_FILENO), connfd);    while(1)    {        FD_ZERO(&rset);        FD_ZERO(&wset);        if(stdineof==0 && toiptr<&to[MAX_LINE])//标准输入->套接字 还有数据要发送&&缓冲区还有容量            FD_SET(STDIN_FILENO, &rset);        if(friptr<&fr[MAX_LINE])//套接字->标准输出 缓冲区还有空闲            FD_SET(connfd, &rset);        if(tooptr!=toiptr)            FD_SET(connfd, &wset);        if(froptr!=friptr)            FD_SET(STDOUT_FILENO, &wset);        select(maxfd+1,&rset,&wset,NULL,NULL);        if(FD_ISSET(STDIN_FILENO, &rset))        {            if((n = read(STDIN_FILENO, toiptr, &to[MAX_LINE]-toiptr)) < 0)            {                if(errno != EWOULDBLOCK)                    perr_exit("read error on stdin");            }            else if(n == 0)            {                fprintf(stderr,"EOF on stdin\n");                stdineof = 1;                if(tooptr == toiptr)                    shutdown(connfd, SHUT_WR);            }            else            {                fprintf(stderr, "read %d bytes from stdin\n", n);                toiptr += n;                FD_SET(connfd, &wset);            }        }        if(FD_ISSET(connfd, &rset))        {            if((n = read(connfd, friptr, &fr[MAX_LINE]-friptr)) < 0)            {                if(errno != EWOULDBLOCK)                    perr_exit("read error on socker");            }            else if(n == 0)            {                fprintf(stderr, "EOF on socket\n");                if(stdineof)                    return;                else                    perr_exit("server terminated prematurely");            }            else            {                fprintf(stderr, "read %d bytes from socket\n", n);                friptr += n;                FD_SET(STDOUT_FILENO, &wset);            }        }        if(FD_ISSET(STDOUT_FILENO, &wset) && ((n = friptr-froptr) > 0 ))        {            if((nwritten = write(STDOUT_FILENO, froptr, n)) < 0)            {                if(errno != EWOULDBLOCK)                    perr_exit("write error to stdout");            }            else            {                fprintf(stderr, "wrote %d bytes to stdout\n", nwritten);                froptr += nwritten;                if(froptr == friptr)                    froptr = friptr = fr;            }        }        if(FD_ISSET(connfd, &wset) && ((n = toiptr-tooptr) > 0))        {            if((nwritten = write(connfd, tooptr, n)) < 0)            {                if(errno != EWOULDBLOCK)                    perr_exit("write error to socket");            }            else            {                fprintf(stderr, "wrote %d bytes to socket\n", nwritten);                tooptr += nwritten;                if(tooptr == toiptr)                {                    toiptr = tooptr = to;                    if(stdineof)                        shutdown(connfd, SHUT_WR);                }            }        }    }}    int main(int argc, const char* argv[])    {        int connfd;        struct sockaddr_in server_addr;        if(argc < 2)            perr_exit("usage : client <IPaddress>");        connfd = Socket(AF_INET, SOCK_STREAM, 0);        memset(&server_addr, 0, sizeof(server_addr));        server_addr.sin_family = AF_INET;        server_addr.sin_port = htons(SERVER_PORT);        inet_pton(AF_INET, argv[1], &server_addr.sin_addr);        Connect(connfd, (struct sockaddr*)&server_addr, sizeof(server_addr));        do_client(connfd);        return 0;}

多进程版本

#include "../Gnet.h"void do_client(int connfd){    char buf[MAX_LINE];    pid_t pid;    if((pid = fork()) == 0)    {        while(Readline(connfd, buf, MAX_LINE) > 0)            fputs(buf, stdout);        kill(getppid(), SIGTERM);        exit(0);    }    else    {        while(fgets(buf, MAX_LINE, stdin) != NULL)            Write(connfd, buf, strlen(buf));        shutdown(connfd, SHUT_WR);        pause();    }}int main(int argc, const char* argv[]){    int connfd;    struct sockaddr_in server_addr;    if(argc < 2)        perr_exit("usage : client <IPaddress>");    connfd = Socket(AF_INET, SOCK_STREAM, 0);    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_port = htons(SERVER_PORT);    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);    Connect(connfd, (struct sockaddr*)&server_addr, sizeof(server_addr));    do_client(connfd);    return 0;}

github:https://github.com/gongluck/unp-notes