epoll相对于poll和select这两个多路复用的I/O模型更加的高效。epoll的函数很简单，麻烦的地方在于水平触发和边沿触发。
用张图来说明下
ET(边沿)只是在状态反转时触发，比如从不可读到可读。而LT(水平)就是如果可读，就会一直触发。所以在使用ET的时候要做一些额外的处理，比如可读的，一直把缓冲区读完，进入不可读状态，下次来数据才会触发。
下面贴出代码，只是一个简单的练习的例子
socketheads.h
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#ifndef SOCKETHEADS_H
#define SOCKETHEADS_H
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif //SOCKETHEADS_H
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zepoll.h
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#ifndef EPOLL_H
#define EPOLL_H
#include <sys/epoll.h>
#include <unistd.h>
/**
* @brief The Epoll class 对epoll的封装
*/
class Epoll
{
public:
/**
*
*/
enum EPOLL_OP {ADD = EPOLL_CTL_ADD, MOD = EPOLL_CTL_MOD, DEL = EPOLL_CTL_DEL};
/**
* 最大的连接数和最大的回传事件数
*/
Epoll(int _max = 30, int maxevents = 20);
~Epoll();
int create();
int add(int fd, epoll_event *event);
int mod(int fd, epoll_event *event);
int del(int fd, epoll_event *event);
void setTimeout(int timeout);
void setMaxEvents(int maxevents);
int wait();
const epoll_event* events() const;
const epoll_event& operator[](int index)
{
return backEvents[index];
}
private:
bool isValid() const;
int max;
int epoll_fd;
int epoll_timeout;
int epoll_maxevents;
epoll_event *backEvents;
};
#endif //EPOLL_H
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zepoll.cpp
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#include "zepoll.h"
Epoll::Epoll(int _max, int maxevents):max(_max),
epoll_fd(-1),
epoll_timeout(0),
epoll_maxevents(maxevents),
backEvents(0)
{
}
Epoll::~Epoll()
{
if (isValid()) {
close(epoll_fd);
}
delete[] backEvents;
}
inline
bool Epoll::isValid() const
{
return epoll_fd > 0;
}
inline
void Epoll::setTimeout(int timeout)
{
epoll_timeout = timeout;
}
inline
void Epoll::setMaxEvents(int maxevents)
{
epoll_maxevents = maxevents;
}
inline
const epoll_event* Epoll::events() const
{
return backEvents;
}
int Epoll::create()
{
epoll_fd = ::epoll_create(max);
if (isValid()) {
backEvents = new epoll_event[epoll_maxevents];
}
return epoll_fd;
}
int Epoll::add(int fd, epoll_event *event)
{
if (isValid()) {
return ::epoll_ctl(epoll_fd, ADD, fd, event);
}
return -1;
}
int Epoll::mod(int fd, epoll_event *event)
{
if (isValid()) {
return ::epoll_ctl(epoll_fd, MOD, fd, event);
}
return -1;
}
int Epoll::del(int fd, epoll_event *event)
{
if (isValid()) {
return ::epoll_ctl(epoll_fd, DEL, fd, event);
}
return -1;
}
int Epoll::wait()
{
if (isValid()) {
return ::epoll_wait(epoll_fd, backEvents, epoll_maxevents, epoll_timeout);
}
return -1;
}
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task.h
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/********************************************************************
* author 周翔
* e-mail 604487178@qq.com
* blog http://blog.csdn.net/zhx6044
**********************************************************************/
#ifndef TASK_H
#define TASK_H
#include <string>
#include <socketheads.h>
/**
* @brief The Task class 任务类
*/
class Task
{
public:
typedef enum {CONNECT = 0, DISCONNECT, TALKING} TASKFLAG;
Task(const std::string &message, TASKFLAG flag = TALKING);
const std::string& getMessage() const;
TASKFLAG getFlag() const;
void setIP(in_addr _ip);
int getS_fd() const;
void setS_fd(int _fd);
std::string getData() const;
private:
std::string m_message;
TASKFLAG m_flag;
in_addr ip;
int s_fd;
};
#endif // TASK_H
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task.cpp
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/********************************************************************
* author 周翔
* e-mail 604487178@qq.com
* blog http://blog.csdn.net/zhx6044
**********************************************************************/
#include "task.h"
Task::Task(const std::string &message, TASKFLAG flag):
m_message(message),
m_flag(flag)
{
}
const std::string& Task::getMessage() const
{
return m_message;
}
Task::TASKFLAG Task::getFlag() const
{
return m_flag;
}
void Task::setIP(in_addr _ip)
{
ip = _ip;
}
int Task::getS_fd() const
{
return s_fd;
}
void Task::setS_fd(int _fd)
{
s_fd = _fd;
}
std::string Task::getData() const
{
std::string re;
if (m_flag == CONNECT) {
re = ::inet_ntoa(ip) + std::string("----->") + "CONNECT! " + m_message;
} else {
if (m_flag == DISCONNECT) {
re = ::inet_ntoa(ip) + std::string("----->") + "DISCONNECT " + m_message;;
} else {
re = ::inet_ntoa(ip) + std::string("----->Talk:") + m_message;
}
}
return re;
}
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epoll_server.h
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#ifndef EPOLL_SERVER_H
#define EPOLL_SERVER_H
#include <map>
#include <list>
#include "zepoll.h"
#include "socketheads.h"
#include "task.h"
typedef std::pair<int, in_addr> FDtoIP;
/**
* @brief The Epoll_server class 服务器
*/
class Epoll_server
{
public:
Epoll_server(int port);
~Epoll_server();
int bind();
int listen();
void poweroff();
bool states() const;
private:
enum {BLOCKLOG = 5};
bool isValid() const;
int acceptSocketEpoll();
int readSocketEpoll(const epoll_event &ev);
int writeSocketEpoll(const epoll_event &ev);
void doTask(const Task &t);
int _port;
int server_socket_fd;
Epoll *_epoll;
sockaddr_in server_addr;
sockaddr_in client_addr;
epoll_event m_event;
bool on;
static int setNonblocking(int socket_fd);
std::list<FDtoIP> fd_IP;
};
#endif //EPOLL_SERVER_H
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epoll_server.cpp
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#include "epoll_server.h"
#include <iostream>
//static char welcom[] = "welcom to my epoll_server";
//static char sorry[] = "Sorry! This is a simple demo,so not any function!";
//static char buf[BUFSIZ];
Epoll_server::Epoll_server(int port):_port(port),
server_socket_fd(-1),
_epoll(0),
on(true)
{
}
Epoll_server::~Epoll_server()
{
if (isValid()) {
::close(server_socket_fd);
}
delete _epoll;
}
inline
bool Epoll_server::isValid() const
{
return server_socket_fd > 0;
}
inline
void Epoll_server::poweroff()
{
on = false;
}
inline
bool Epoll_server::states() const
{
return on;
}
int Epoll_server::setNonblocking(int socket_fd)
{
int opts;
opts = fcntl(socket_fd, F_GETFL);
if (opts < 0) {
return -1;
} else
{
opts = opts | O_NONBLOCK;
if (fcntl(socket_fd, F_SETFL, opts) < 0) {
return -1;
}
}
return 0;
}
void Epoll_server::doTask(const Task &t)
{
std::list<FDtoIP>::iterator ite = fd_IP.begin();
std::list<FDtoIP>::iterator ite1 = fd_IP.end();
for (;ite != fd_IP.end();++ite) {
if ((*ite).first != t.getS_fd()) {
memset(&m_event, '\0', sizeof(m_event));
m_event.events = EPOLLOUT | EPOLLET;
Task *c = new Task(t);
c->setS_fd((*ite).first);
m_event.data.ptr = static_cast<void*>(c);
_epoll->mod((*ite).first, &m_event);
} else {
ite1 = ite;
}
}
if (t.getFlag() == Task::DISCONNECT) {
if (ite1 != fd_IP.end()) {
fd_IP.erase(ite1);
}
}
}
/**
* @brief Epoll_server::acceptSocketEpoll 有用户接入
* @return
*/
int Epoll_server::acceptSocketEpoll()
{
socklen_t len = sizeof(struct sockaddr_in);
int connect_fd;
while ((connect_fd = ::accept(server_socket_fd,
(struct sockaddr*)(&client_addr), &len)) > 0) {
if (setNonblocking(connect_fd) < 0) {
::close(connect_fd);
continue;
}
m_event.data.fd = connect_fd;
m_event.events = EPOLLIN | EPOLLET;
if (_epoll->add(connect_fd, &m_event) < 0) {
::close(connect_fd);
continue;
} else {
fd_IP.push_back(FDtoIP(connect_fd, client_addr.sin_addr));
Task t("come in", Task::CONNECT);
t.setIP(client_addr.sin_addr);
t.setS_fd(connect_fd);
doTask(t);
}
}
if (connect_fd == -1 && errno != EAGAIN && errno != ECONNABORTED
&& errno != EPROTO && errno !=EINTR) {
return -1;
}
return 0;
}
int Epoll_server::readSocketEpoll(const epoll_event &ev)
{
int n = 0;
int nread = 0;
char buf[BUFSIZ]={'\0'};
while ((nread = ::read(ev.data.fd, buf + n, BUFSIZ-1)) > 0) {
n += nread;
}
if (nread == -1 && errno != EAGAIN) {
return -1;
}
std::list<FDtoIP>::iterator ite = fd_IP.begin();
for (;ite != fd_IP.end();++ite) {
if ((*ite).first == ev.data.fd) {
break;
}
}
if (nread == 0) {
strcpy(buf, " disconet left ");
Task t(buf,Task::DISCONNECT);
t.setIP(client_addr.sin_addr);
t.setS_fd((*ite).first);
doTask(t);
} else {
Task t(buf,Task::TALKING);
t.setIP(client_addr.sin_addr);
t.setS_fd((*ite).first);
doTask(t);
}
// Task *t = new Task(buf,Task::DISCONNECT);
// t->setIP((*ite).second);
// t->setS_fd((*ite).first);
// m_event.data.fd = ev.data.fd;
// m_event.events = ev.events;
return 0;//_epoll->mod(m_event.data.fd, &m_event);
}
int Epoll_server::writeSocketEpoll(const epoll_event &ev)
{
Task *t = static_cast<Task*>(ev.data.ptr);
const char* buf = t->getData().data();
int nwrite = 0, data_size = strlen(buf);
int fd = t->getS_fd();
int n = data_size;
delete t;
while (n > 0) {
nwrite = ::write(fd, buf + data_size - n, n);
if (nwrite < 0) {
if (nwrite == -1 && errno != EAGAIN) {
return -1;
}
break;
}
n -= nwrite;
}
memset(&m_event, '\0', sizeof(m_event));
// m_event.events &= ~EPOLLOUT;
m_event.events = EPOLLIN | EPOLLET;
m_event.data.fd = fd;
if (_epoll->mod(fd, &m_event) < 0) {
::close(m_event.data.fd);
return -1;
}
return 0;
}
/**
* @brief Epoll_server::bind
* @return
*/
int Epoll_server::bind()
{
server_socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (server_socket_fd < 0) {
return -1;
}
setNonblocking(server_socket_fd);
_epoll = new Epoll();
if (_epoll->create() < 0) {
return -1;
}
memset(&m_event, '\0', sizeof(m_event));
m_event.data.fd = server_socket_fd;
m_event.events = EPOLLIN | EPOLLET;
_epoll->add(server_socket_fd, &m_event);
memset(&server_addr, 0 ,sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
server_addr.sin_port = htons(_port);
return ::bind(server_socket_fd, (struct sockaddr*)(&server_addr), sizeof(struct sockaddr));
}
int Epoll_server::listen()
{
if (isValid()) {
if (::listen(server_socket_fd, BLOCKLOG) < 0) {
return -1;
} else {
int num;
while (on) {
num = _epoll->wait();
for (int i = 0;i < num;++i) {
/**
* 接受连接的连接，把她加入到epoll中
*/
if ((*_epoll)[i].data.fd == server_socket_fd) {
if (acceptSocketEpoll() < 0) {
break;
}
continue;
}
/**
* EPOLLIN event
*/
if ((*_epoll)[i].events & EPOLLIN) {
if (readSocketEpoll((*_epoll)[i]) < 0) {
break;
}
continue;
}
/**
* EPOLLOUT event
*/
if ((*_epoll)[i].events & EPOLLOUT) {
if (writeSocketEpoll((*_epoll)[i]) < 0) {
break;
}
}
}
}
}
}
return -1;
}
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main.cpp
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#include "epoll_server.h"
#include <iostream>
int main(int /*argc*/, char const **/*argv[]*/)
{
std::cout << "server" << std::endl;
Epoll_server s(18090);
if (s.bind() < 0) {
return -1;
}
return s.listen();
}
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客户端用qt简单的写了一个
客户端服务端代码：epoll_chatroom.zip
http://love.junzimu.com/archives/2660
来源：https://www.cnblogs.com/findumars/p/4973114.html