IO多路複用之epoll（二）

前一篇介紹了epoll的LT模式，LT模式注意epollout事件在資料全部寫成功後需要取消關注，

或者更改為EPOLLIN。

而這次epoll的ET模式，要注意的是在讀和寫的過程中要在循環中寫完或者讀完所有資料，

確定不要丢掉一些資料。

因為epoll ET模式隻在兩種邊緣更改的時候觸發，對于讀事件隻在核心緩沖區由空變為

非空通知一次使用者，對于寫事件，核心緩沖區隻在由滿變為非滿的情況通知使用者一次。

下面是代碼

int main()

{

int eventsize = 20;

struct epoll_event * epoll_eventsList = (struct epoll_event *)malloc(sizeof(struct epoll_event)

*eventsize);

//打開一個空的描述符

int idlefd = open("/dev/null",O_RDONLY|O_CLOEXEC);

cout << "idlefd" <<idlefd <<endl;

//生成listen描述符

int listenfd = socket(PF_INET, SOCK_CLOEXEC | SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);

if(listenfd < 0)

ERR_EXIT("socketfd");

}

//初始化位址資訊

struct sockaddr_in servaddr;

memset(&servaddr,0 ,sizeof(struct sockaddr_in));

servaddr.sin_family = AF_INET;

servaddr.sin_port = htons(6667);

servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

int on = 1;

if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)

ERR_EXIT("setsockopt");

if(bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)))

ERR_EXIT("bindError");

if (listen(listenfd, SOMAXCONN) < 0)

ERR_EXIT("listen");

//記錄用戶端連接配接對應的socket

std::vector<int> clients;

//建立epollfd, 用于管理epoll事件表

int epollfd;

epollfd = epoll_create1(EPOLL_CLOEXEC);

struct epoll_event event;

event.data.fd = listenfd;

event.events = EPOLLIN|EPOLLET;

//将listenfd加入到epollfd管理的表裡

epoll_ctl(epollfd, EPOLL_CTL_ADD, listenfd, &event);

//用于接收新連接配接的用戶端位址

struct sockaddr_in peeraddr;

socklen_t peerlen;

int connfd;

//為了簡單起見寫了個很大的數組，根據檔案描述符存儲内容

//其實很多項目代碼采epoll.data.ptr回調具體的讀寫

vector<string> recievebuf;

for(int i = 0 ; i < 22222; i++)

recievebuf.push_back("");

while(1)

int nready = epoll_wait(epollfd, epoll_eventsList, eventsize, -1);

if (nready == -1)

if (errno == EINTR)

continue;

ERR_EXIT("epoll_wait");

if (nready == 0)

//大小不夠重新開辟

if ((size_t)nready == eventsize)

if(eventsize * 2 >= 22222)

ERR_EXIT("too many fds");

struct epoll_event * epoll_eventsList2 = (struct epoll_event *)malloc(sizeof(struct epoll_event) * 

eventsize *2);

if(epoll_eventsList2)

memcpy(epoll_eventsList2,epoll_eventsList,sizeof(struct epoll_event) * eventsize);

eventsize = eventsize * 2;

free(epoll_eventsList);

epoll_eventsList = epoll_eventsList2;

for (int i = 0; i < nready; ++i)

//判斷wait傳回的events數組狀态是否正常

if ((epoll_eventsList[i].events & EPOLLERR) ||

(epoll_eventsList[i].events & EPOLLHUP))

fprintf (stderr, "epoll error\n");

close (epoll_eventsList[i].data.fd);

if (epoll_eventsList[i].data.fd == listenfd)

peerlen = sizeof(peeraddr);

//ET模式accept放在while循環裡

do

connfd = ::accept4(listenfd, (struct sockaddr*)&peeraddr,

&peerlen, SOCK_NONBLOCK | SOCK_CLOEXEC);

if(connfd <= 0)

break;

std::cout<<"ip="<<inet_ntoa(peeraddr.sin_addr)<<

" port="<<ntohs(peeraddr.sin_port)<<std::endl;

clients.push_back(connfd);

//将connd加入epoll表裡，關注讀事件

event.data.fd = connfd;

event.events = EPOLLIN |EPOLLET;

epoll_ctl(epollfd, EPOLL_CTL_ADD, connfd, &event);

cout << "loop" <<endl;

cout << "loop" << connfd << endl;

}while(1);

//accept失敗，判斷是否接收全所有的fd

cout << connfd << endl;

if (connfd == -1){

if (errno != EAGAIN && errno != ECONNABORTED

&& errno != EPROTO && errno != EINTR)

cout << "error" <<endl;

ERR_EXIT("accept");

//所有請求都處理完成

cout << "continue"<<endl;

}//endif

else if(epoll_eventsList[i].events & EPOLLIN)

connfd = epoll_eventsList[i].data.fd;

if(connfd > 22222)

close(connfd);

event = epoll_eventsList[i];

epoll_ctl(epollfd, EPOLL_CTL_DEL, connfd, &event);

clients.erase(std::remove(clients.begin(), clients.end(), connfd), clients.end());

char buf[1024] = {0};

if(connfd < 0)

int ret = 0;

int total = 0;

std::string strtemp;

cout << "begin read" <<endl;

ret = read(connfd, buf, 1024);

if(ret <= 0)

strtemp += string(buf);

total += ret;

memset(buf, 0, 1024);

if(ret < 1024)

}//endwhile(1)

cout << "end read" <<endl;

recievebuf[connfd] = strtemp.c_str();

cout << "buff data :" << recievebuf[connfd]<<endl; 

if(ret == -1)

if((errno == EAGAIN) ||

(errno == EWOULDBLOCK))

//由于核心緩沖區空了，下次有資料到來是會觸發epollin

ERR_EXIT("read");

}//endif ret == -1

//連接配接斷開

if(ret == 0)

std::cout<<"client close"<<std::endl;

cout << "turn to write" << endl;

//更改為寫模式

event.events = EPOLLOUT | EPOLLET;

epoll_ctl(epollfd, EPOLL_CTL_MOD, connfd, &event);

cout << "epoll mod change success" << endl;

}//end elif

else //寫事件

if(epoll_eventsList[i].events & EPOLLOUT)

cout << "begin write" <<endl;

int count = 0;

int totalsend = 0;

char buf[1024];

strcpy(buf, recievebuf[connfd].c_str());

cout << "write buff" <<buf<<endl;

int totalcount = strlen(buf);

int pos = 0;

count = write(epoll_eventsList[i].data.fd, buf + pos, totalcount);

cout << "write count:" << count;

if(count < 0)

if(count < totalcount)

totalcount = totalcount - count;

pos += count;

else

}//end while

if(count == -1)

//由于核心緩沖區滿了

//于核心緩沖區滿了

ERR_EXIT("write");

if(count == 0)

clients.erase(std::remove(clients.begin(), clients.end(), connfd), 

clients.end());

}//end eles 寫事件

源代碼下載下傳位址：http://download.csdn.net/detail/secondtonone1/9486222