1

安装方法，源码包有说明：https://github.com/Qihoo360/evpp

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2

tcp回声服务器（官方示例）

#include <evpp/tcp_server.h>
#include <evpp/buffer.h>
#include <evpp/tcp_conn.h>#ifdef _WIN32
#include "../../winmain-inl.h"
#endifvoid OnMessage(const evpp::TCPConnPtr& conn,evpp::Buffer* msg) {std::string s = msg->NextAllString();LOG_INFO << "Received a message [" << s << "]";conn->Send(s);if (s == "quit" || s == "exit") {conn->Close();}
}void OnConnection(const evpp::TCPConnPtr& conn) {if (conn->IsConnected()) {LOG_INFO << "Accept a new connection from " << conn->remote_addr();} else {LOG_INFO << "Disconnected from " << conn->remote_addr();}
}int main(int argc, char* argv[]) {std::string port = "9099";if (argc == 2) {port = argv[1];}std::string addr = std::string("0.0.0.0:") + port;evpp::EventLoop loop;evpp::TCPServer server(&loop, addr, "TCPEcho", 0);server.SetMessageCallback(&OnMessage);server.SetConnectionCallback(&OnConnection);server.Init();server.Start();loop.Run();return 0;
}

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3

evpp::TCPServer类（主要）

#include <evpp/tcp_server.h>

#pragma once#include "evpp/inner_pre.h"
#include "evpp/event_loop.h"
#include "evpp/event_loop_thread_pool.h"
#include "evpp/tcp_callbacks.h"#include "evpp/thread_dispatch_policy.h"
#include "evpp/server_status.h"#include <map>namespace evpp {class Listener;// We can use this class to create a TCP server.
// The typical usage is :
//      1. Create a TCPServer object
//      2. Set the message callback and connection callback
//      3. Call TCPServer::Init()
//      4. Call TCPServer::Start()
//      5. Process TCP client connections and messages in callbacks
//      6. At last call Server::Stop() to stop the whole server
//
// The examples code is as bellow:
// <code>
//     std::string addr = "0.0.0.0:9099";
//     int thread_num = 4;
//     evpp::EventLoop loop;
//     evpp::TCPServer server(&loop, addr, "TCPEchoServer", thread_num);
//     server.SetMessageCallback([](const evpp::TCPConnPtr& conn,
//                                  evpp::Buffer* msg) {
//         // Do something with the received message
//         conn->Send(msg); // At here, we just send the received message back.
//     });
//     server.SetConnectionCallback([](const evpp::TCPConnPtr& conn) {
//         if (conn->IsConnected()) {
//             LOG_INFO << "A new connection from " << conn->remote_addr();
//         } else {
//             LOG_INFO << "Lost the connection from " << conn->remote_addr();
//         }
//     });
//     server.Init();
//     server.Start();
//     loop.Run();
// </code>
//
class EVPP_EXPORT TCPServer : public ThreadDispatchPolicy, public ServerStatus {
public:typedef std::function<void()> DoneCallback;// @brief The constructor of a TCPServer.// @param loop -// @param listen_addr - The listening address with "ip:port" format// @param name - The name of this object// @param thread_num - The working thread countTCPServer(EventLoop* loop,const std::string& listen_addr/*ip:port*/,const std::string& name,uint32_t thread_num);~TCPServer();// @brief Do the initialization works here.//  It will create a nonblocking TCP socket, and bind with the give address//  then listen on it. If there is anything wrong it will return false.// @return bool - True if anything goes wellbool Init();// @brief Start the TCP server and we can accept new connections now.// @return bool - True if anything goes wellbool Start();// @brief Stop the TCP server// @param cb - the callback cb will be invoked when//  the TCP server is totally stoppedvoid Stop(DoneCallback cb = DoneCallback());// @brief Reinitialize some data fields after a forkvoid AfterFork();public:// Set a connection event relative callback when the TCPServer// receives a new connection or an exist connection breaks down.// When these two events happened, the value of the parameter in the callback is://      1. Received a new connection : TCPConn::IsConnected() == true//      2. An exist connection broken down : TCPConn::IsDisconnecting() == truevoid SetConnectionCallback(const ConnectionCallback& cb) {conn_fn_ = cb;}// Set the message callback to handle the messages from remote clientvoid SetMessageCallback(MessageCallback cb) {msg_fn_ = cb;}public:const std::string& listen_addr() const {return listen_addr_;}
private:void StopThreadPool();void StopInLoop(DoneCallback on_stopped_cb);void RemoveConnection(const TCPConnPtr& conn);void HandleNewConn(evpp_socket_t sockfd, const std::string& remote_addr/*ip:port*/, const struct sockaddr_in* raddr);EventLoop* GetNextLoop(const struct sockaddr_in* raddr);
private:EventLoop* loop_;  // the listening loopconst std::string listen_addr_; // ip:portconst std::string name_;std::unique_ptr<Listener> listener_;std::shared_ptr<EventLoopThreadPool> tpool_;ConnectionCallback conn_fn_;MessageCallback msg_fn_;DoneCallback stopped_cb_;// always in the listening loop threaduint64_t next_conn_id_ = 0;typedef std::map<uint64_t/*the id of the connection*/, TCPConnPtr> ConnectionMap;ConnectionMap connections_;
};
}

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4

std::function回调类型
part3中的两个evpp::TCPServer类的成员函数（设置回调函数）
void SetConnectionCallback(const ConnectionCallback& cb)
void SetMessageCallback(MessageCallback cb)
其回调类型在源码 #include "evpp/tcp_callbacks.h"

#pragma once#include "evpp/inner_pre.h"namespace evpp {
class Buffer;
class TCPConn;typedef std::shared_ptr<TCPConn> TCPConnPtr;
typedef std::function<void()> TimerCallback;// When a connection established, broken down, connecting failed, this callback will be called
// This is called from a work-thread this is not the listening thread probably
typedef std::function<void(const TCPConnPtr&)> ConnectionCallback;typedef std::function<void(const TCPConnPtr&)> CloseCallback;
typedef std::function<void(const TCPConnPtr&)> WriteCompleteCallback;
typedef std::function<void(const TCPConnPtr&, size_t)> HighWaterMarkCallback;typedef std::function<void(const TCPConnPtr&, Buffer*)> MessageCallback;namespace internal {
inline void DefaultConnectionCallback(const TCPConnPtr&) {}
inline void DefaultMessageCallback(const TCPConnPtr&, Buffer*) {}
}}

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5

evpp::EventLoop类

evpp::EventLoop类是IO事件的驱动内核。这个类是event_base类的包装器，但不仅仅是一个包装器。它通过简单的方式，运行IO事件驱动循环。一个线程一个循环。

在evpp::TCPServer对象设置完回调函数及调用Init()、Start()之后，必须执行IO事件线程Run()，如part2示例。

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6

以上是evpp tcp网络库的大致用法。udp、http用法参照源码。

evpp语法采用C++11的特性，大量使用std::string，而不是char*独占天；使用std::stringstream，而不是sprintf；易读的Lambda,而不是函数指针等等。满满的C++11诚意。http库更是可以弥补C++开发http服务器效率低的问题。膜拜360大佬们！