Asio tcp异步例子

1.什么是asio?
Asio是一个用于网络底层I / O编程的跨平台C ++开发的网络编程库，支持同步与异步的网络开发。
2.asio有哪些优点?
简单易用、跨平台、可以用于大型项目中。
3.Asio的io_service作用?
io_service实例同底层操作系统的IO服务进行交互,是asio框架中的调度器，所有异步io事件都是通过它来分发处理的。Io_service提供了两个方法post和run，post向任务队列中投递任务，run是执行队列中的任务，直到全部执行完毕，并且run可以被N个线程调用。Io_service是完全线程安全的队列

4.以下asio常用的函数?
async_connect(endpoint)：//这个函数用异步的方式连接到一个地址。
async_accept(socket,accept_handler) //接收新客户端连接。
read(stream, buffer [, extra options])//同步读取方法。
async_read(stream, buffer [, extra options], handler)//异步读取方法。
write(stream, buffer [, extra options]) //同步发送。
async_write(stream, buffer [, extra options], handler) //异步发送。

Asio聊天室例子:
服务器端:

//chat_message.h
#ifndef CHAT_MESSAGE_HPP
#define CHAT_MESSAGE_HPP
#include "Header.h"
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include "stdafx.h"class chat_message {
public:enum { header_length = sizeof(Header) };enum { max_body_length = 512 };chat_message(){}const char *data() const { return data_; }char *data() { return data_; }std::size_t length() const { return header_length + m_header.bodySize; }const char *body() const { return data_ + header_length; }char *body() { return data_ + header_length; }int type() const { return m_header.type; }std::size_t body_length() const { return m_header.bodySize; }void setMessage(int messageType, const void *buffer, size_t bufferSize) {assert(bufferSize <= max_body_length);m_header.bodySize = bufferSize;m_header.type = messageType;std::memcpy(body(), buffer, bufferSize);std::memcpy(data(), &m_header, sizeof(m_header));}void setMessage(int messageType, const std::string& buffer) {setMessage(messageType, buffer.data(), buffer.size());}bool decode_header() {std::memcpy(&m_header, data(), header_length);if (m_header.bodySize > max_body_length) {std::cout << "body size " << m_header.bodySize << " " << m_header.type<< std::endl;return false;}return true;}
private:char data_[header_length + max_body_length];Header m_header;
};#endif

//Header.h#ifndef FND_STRUCT_HEADER_H
#define FND_STRUCT_HEADER_H
#include <string>
struct Header{int bodySize;int type;
};
enum MessageType
{MT_BIND_NAME = 1,MT_CHAT_INFO = 2, MT_ROOM_INFO = 3, };
struct BindName{char name[32];int nameLen;
};
struct ChatInformation {char information[256];int infoLen;
};
struct RoomInformation {BindName name;ChatInformation chat;
};
bool parseMessage(const std::string &input, int *type, std::string &outbuffer);
#endif//Header.cpp
#include "stdafx.h"
#include "Header.h"
#include <cstdlib>
#include <cstring>
#include <iostream>
bool parseMessage(const std::string &input, int *type, std::string &outbuffer) {auto pos = input.find_first_of(" ");if (pos == std::string::npos)return false;if (pos == 0)return false;auto command = input.substr(0, pos);if (command == "BindName") {std::string name = input.substr(pos + 1);if (name.size() > 32)return false;if (type)*type = MT_BIND_NAME;BindName bindInfo;bindInfo.nameLen = name.size();std::memcpy(&(bindInfo.name), name.data(), name.size());auto buffer = reinterpret_cast<const char *>(&bindInfo);outbuffer.assign(buffer, buffer + sizeof(bindInfo));return true;} else if (command == "Chat") {std::string chat = input.substr(pos + 1);if (chat.size() > 256)return false;ChatInformation info;info.infoLen = chat.size();std::memcpy(&(info.information), chat.data(), chat.size());auto buffer = reinterpret_cast<const char *>(&info);outbuffer.assign(buffer, buffer + sizeof(info));if (type)*type = MT_CHAT_INFO;return true;}return false;
}

//chat.cpp
#include "chat_message.h"
#include <asio.hpp>
#include <chrono>
#include <deque>
#include <iostream>
#include <list>
#include <memory>
#include <set>
#include <thread>
#include <utility>
#include <mutex>
#include <cstdlib>
#include "stdafx.h"using boost::asio::ip::tcp;
typedef std::deque<chat_message> chat_message_queue;
std::chrono::system_clock::time_point base;
class chat_session;
typedef std::shared_ptr<chat_session> chat_session_ptr;
class chat_room {
public:chat_room(boost::asio::io_service& io_service) : m_strand(io_service) {}
public:void join(chat_session_ptr);void leave(chat_session_ptr);void deliver(const chat_message&);
private:boost::asio::io_service::strand m_strand;//strand提供串行执行, 能够保证线程安全, 同时被post或dispatch的方法, 不会被并发的执行. std::set<chat_session_ptr> participants_;enum { max_recent_msgs = 100 };chat_message_queue recent_msgs_;
};class chat_session : public std::enable_shared_from_this<chat_session> {
public:chat_session(tcp::socket socket, chat_room &room): socket_(std::move(socket)),room_(room),m_strand(socket_.get_io_service()){}void start() {room_.join(shared_from_this()); //加入房间do_read_header();//读取数据包头}void deliver(const chat_message &msg){m_strand.post([this,msg]{bool write_in_progress = !write_msgs_.empty();write_msgs_.push_back(msg);if (!write_in_progress){do_write();}});}private:void do_read_header(){auto self(shared_from_this());boost::asio::async_read(socket_,boost::asio::buffer(read_msg_.data(),chat_message::header_length), //读取头数据8个字节m_strand.wrap([this,self](boost::system::error_code ec, std::size_t){if ( !ec && read_msg_.decode_header()){ do_read_body();//合法的头部的话，进行内容的读取。} else {std::cout << "player leave the room\n";room_.leave(shared_from_this());}}));}void do_read_body() {auto self(shared_from_this());boost::asio::async_read(socket_,boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),//内容的读取，async_read相当于读取缓存数据，按长度一次读取大小多少，直到读取完成。m_strand.wrap([this,self](boost::system::error_code ec, std::size_t) {if (!ec) {handleMessage();do_read_header();} else {room_.leave(shared_from_this());}}));}void handleMessage() {auto n = std::chrono::system_clock::now() - base;std::cout << "i'm in " << std::this_thread::get_id() << " time "<< std::chrono::duration_cast<std::chrono::milliseconds>(n).count() << std::endl;std::this_thread::sleep_for(std::chrono::milliseconds(3));if (read_msg_.type() == MT_BIND_NAME) {//设定昵称const BindName* bind = reinterpret_cast<const BindName*>(read_msg_.body());m_name.assign(bind->name, bind->name + bind->nameLen);} else if (read_msg_.type() == MT_CHAT_INFO) {const ChatInformation* chat = reinterpret_cast<const ChatInformation*>(read_msg_.body());m_chatInformation.assign(chat->information, chat->information + chat->infoLen);auto rinfo = buildRoomInfo();chat_message msg;msg.setMessage(MT_ROOM_INFO,&rinfo, sizeof(rinfo));room_.deliver(msg); //对当前房间发送消息} else {}}void do_write() { //发送数据auto self(shared_from_this());boost::asio::async_write(socket_, boost::asio::buffer(write_msgs_.front().data(),write_msgs_.front().length()),m_strand.wrap([this, self](boost::system::error_code ec, std::size_t) {if (!ec) {write_msgs_.pop_front();if (!write_msgs_.empty()) {do_write();}} else {room_.leave(shared_from_this());}}));}tcp::socket socket_;chat_room &room_;chat_message read_msg_;chat_message_queue write_msgs_;std::string m_name;std::string m_chatInformation;boost::asio::io_service::strand m_strand;RoomInformation buildRoomInfo() const {RoomInformation info;info.name.nameLen = m_name.size();std::memcpy(info.name.name, m_name.data(), m_name.size());info.chat.infoLen = m_chatInformation.size();std::memcpy(info.chat.information, m_chatInformation.data(),m_chatInformation.size());return info;}
};//加入房间void chat_room::join(chat_session_ptr participant) {m_strand.post([this, participant]{participants_.insert(participant);for (const auto& msg : recent_msgs_)participant->deliver(msg); //对所有端广播});}//离开房间void chat_room::leave(chat_session_ptr participant) {m_strand.post([this,participant]{participants_.erase(participant);});}void chat_room::deliver(const chat_message &msg) {m_strand.post([this, msg]{recent_msgs_.push_back(msg);while (recent_msgs_.size() > max_recent_msgs)recent_msgs_.pop_front();for (auto& participant : participants_)participant->deliver(msg);});}class chat_server {
public:chat_server(boost::asio::io_service &io_service,const tcp::endpoint &endpoint): acceptor_(io_service, endpoint), socket_(io_service), room_(io_service) {do_accept();}private:void do_accept() {acceptor_.async_accept(socket_, [this](boost::system::error_code ec) {if (!ec) {auto session =std::make_shared<chat_session>(std::move(socket_), room_);session->start();//新客户端开始接收数据包}do_accept(); //创建新连接进行等待});}tcp::acceptor acceptor_;tcp::socket socket_;chat_room room_;
};int _tmain(int argc, char *argv[])
{try {base = std::chrono::system_clock::now();boost::asio::io_service io_service;std::list<chat_server> servers;tcp::endpoint endpoint(tcp::v4(), 9000);servers.emplace_back(io_service, endpoint);std::vector<std::thread> threadGroup;for(int i = 0; i < 5; ++i) {threadGroup.emplace_back([&io_service, i]{std::cout << i << " name is " << std::this_thread::get_id() << std::endl;io_service.run();});}io_service.run();for(auto& v : threadGroup) v.join();} catch (std::exception &e) {std::cout << "Exception: " << e.what();}return 0;
}

客户端：

//client.cpp#include "chat_message.h"
#include <asio.hpp>
#include <chrono>
#include <deque>
#include <iostream>
#include <list>
#include <memory>
#include <set>
#include <thread>
#include <utility>
#include <mutex>
#include <cstdlib>
#include "stdafx.h"using boost::asio::ip::tcp;
typedef std::deque<chat_message> chat_message_queue;
class chat_client {
public:chat_client(boost::asio::io_service &io_service,tcp::resolver::iterator endpoint_iterator): io_service_(io_service), socket_(io_service) {do_connect(endpoint_iterator);}void write(const chat_message &msg) {io_service_.post([this, msg]() {bool write_in_progress = !write_msgs_.empty();write_msgs_.push_back(msg);if (!write_in_progress) {do_write();}});}void close() {io_service_.post([this]() { socket_.close(); });}private:void do_connect(tcp::resolver::iterator endpoint_iterator) {boost::asio::async_connect(socket_, endpoint_iterator,[this](boost::system::error_code ec, tcp::resolver::iterator) {if (!ec) {do_read_header();}});}void do_read_header() {boost::asio::async_read(socket_,boost::asio::buffer(read_msg_.data(), chat_message::header_length),[this](boost::system::error_code ec, std::size_t /*length*/) {if (!ec && read_msg_.decode_header()) {do_read_body();} else {socket_.close();}});}void do_read_body() {boost::asio::async_read(socket_, boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),[this](boost::system::error_code ec, std::size_t /*length*/) {if (!ec) {if (read_msg_.body_length() == sizeof(RoomInformation) &&read_msg_.type() == MT_ROOM_INFO) {const RoomInformation *info =reinterpret_cast<const RoomInformation *>(read_msg_.body());std::cout << "client: '";assert(info->name.nameLen <= sizeof(info->name.name));std::cout.write(info->name.name, info->name.nameLen);std::cout << "' says '";assert(info->chat.infoLen <= sizeof(info->chat.information));std::cout.write(info->chat.information, info->chat.infoLen);std::cout << "'\n";}do_read_header();} else {socket_.close();}});}void do_write() {boost::asio::async_write(socket_, boost::asio::buffer(write_msgs_.front().data(),write_msgs_.front().length()),[this](boost::system::error_code ec, std::size_t /*length*/) {if (!ec) {write_msgs_.pop_front();if (!write_msgs_.empty()) {do_write();}} else {socket_.close();}});}private:boost::asio::io_service &io_service_;tcp::socket socket_;chat_message read_msg_;chat_message_queue write_msgs_;
};
int _tmain(int argc, char* argv[])
{
try {boost::asio::io_service io_service;tcp::resolver resolver(io_service);boost::asio::ip::tcp::resolver::query query("localhost", "9000");auto endpoint_iterator = resolver.resolve(query);chat_client c(io_service, endpoint_iterator);std::thread t([&io_service]() { io_service.run(); });char line[chat_message::max_body_length + 1];// ctrl-dwhile (std::cin.getline(line, chat_message::max_body_length + 1)) {chat_message msg;auto type = 0;std::string input(line, line + std::strlen(line));std::string output;if(parseMessage(input, &type, output)) {msg.setMessage(type, output.data(), output.size());c.write(msg);std::cout << "write message for server " << output.size() << std::endl;}}c.close();t.join();} catch (std::exception &e) {std::cerr << "Exception: " << e.what() << "\n";}return 0;
}

运行结果：

QQ图片20181127135440.png

参考链接
http://www.cnblogs.com/zhiranok/archive/2011/09/04/boost_asio_io_service_CPP.html

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