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Java中多线程Reactor模式的实现

程序员文章站 2022-03-10 13:19:48
目录1、 主服务器2、io请求handler+线程池3、客户端多线程reactor模式旨在分配多个reactor每一个reactor独立拥有一个selector,在网络通信中大体设计为负责连接的主re...

多线程reactor模式旨在分配多个reactor每一个reactor独立拥有一个selector,在网络通信中大体设计为负责连接的主reactor,其中在主reactor的run函数中若selector检测到了连接事件的发生则dispatch该事件。

让负责管理连接的handler处理连接,其中在这个负责连接的handler处理器中创建子handler用以处理io请求。这样一来连接请求与io请求分开执行提高通道的并发量。同时多个reactor带来的好处是多个selector可以提高通道的检索速度

1、 主服务器

package com.crazymakercircle.reactormodel;

import com.crazymakercircle.niodemoconfig;
import com.crazymakercircle.util.logger;

import java.io.ioexception;
import java.net.inetsocketaddress;
import java.nio.channels.selectionkey;
import java.nio.channels.selector;
import java.nio.channels.serversocketchannel;
import java.nio.channels.socketchannel;
import java.util.iterator;
import java.util.set;
import java.util.concurrent.atomic.atomicinteger;


class multithreadechoserverreactor {
    serversocketchannel serversocket;
    atomicinteger next = new atomicinteger(0);
    selector bossselector = null;
    reactor bossreactor = null;
    //selectors集合,引入多个selector选择器
    //多个选择器可以更好的提高通道的并发量
    selector[] workselectors = new selector[2];
    //引入多个子反应器
    //如果cpu是多核的可以开启多个子reactor反应器,这样每一个子reactor反应器还可以独立分配一个线程。
    //每一个线程可以单独绑定一个单独的selector选择器以提高通道并发量
    reactor[] workreactors = null;

    multithreadechoserverreactor() throws ioexception {

        bossselector = selector.open();
        //初始化多个selector选择器
        workselectors[0] = selector.open();
        workselectors[1] = selector.open();
        serversocket = serversocketchannel.open();

        inetsocketaddress address =
                new inetsocketaddress(niodemoconfig.socket_server_ip,
                        niodemoconfig.socket_server_port);
        serversocket.socket().bind(address);
        //非阻塞
        serversocket.configureblocking(false);

        //第一个selector,负责监控新连接事件
        selectionkey sk =
                serversocket.register(bossselector, selectionkey.op_accept);
        //附加新连接处理handler处理器到selectionkey(选择键)
        sk.attach(new acceptorhandler());

        //处理新连接的反应器
        bossreactor = new reactor(bossselector);

        //第一个子反应器,一子反应器负责一个选择器
        reactor subreactor1 = new reactor(workselectors[0]);
        //第二个子反应器,一子反应器负责一个选择器
        reactor subreactor2 = new reactor(workselectors[1]);
        workreactors = new reactor[]{subreactor1, subreactor2};
    }

    private void startservice() {
        new thread(bossreactor).start();
        // 一子反应器对应一条线程
        new thread(workreactors[0]).start();
        new thread(workreactors[1]).start();
    }

    //反应器
    class reactor implements runnable {
        //每条线程负责一个选择器的查询
        final selector selector;

        public reactor(selector selector) {
            this.selector = selector;
        }

        public void run() {
            try {
                while (!thread.interrupted()) {
                    //单位为毫秒
                    //每隔一秒列出选择器感应列表
                    selector.select(1000);
                    set<selectionkey> selectedkeys = selector.selectedkeys();
                    if (null == selectedkeys || selectedkeys.size() == 0) {
                        //如果列表中的通道注册事件没有发生那就继续执行
                        continue;
                    }
                    iterator<selectionkey> it = selectedkeys.iterator();
                    while (it.hasnext()) {
                        //reactor负责dispatch收到的事件
                        selectionkey sk = it.next();
                        dispatch(sk);
                    }
                    //清楚掉已经处理过的感应事件,防止重复处理
                    selectedkeys.clear();
                }
            } catch (ioexception ex) {
                ex.printstacktrace();
            }
        }


        void dispatch(selectionkey sk) {
            runnable handler = (runnable) sk.attachment();
            //调用之前attach绑定到选择键的handler处理器对象
            if (handler != null) {
                handler.run();
            }
        }
    }


    // handler:新连接处理器
    class acceptorhandler implements runnable {
        public void run() {
        try {
                socketchannel channel = serversocket.accept();
                logger.info("接收到一个新的连接");

                if (channel != null) {
                    int index = next.get();
                    logger.info("选择器的编号:" + index);
                    selector selector = workselectors[index];
                    new multithreadechohandler(selector, channel);
                }
            } catch (ioexception e) {
                e.printstacktrace();
            }
            if (next.incrementandget() == workselectors.length) {
                next.set(0);
            }
        }
    }


    public static void main(string[] args) throws ioexception {
        multithreadechoserverreactor server =
                new multithreadechoserverreactor();
        server.startservice();
    }

}

按上述的设计思想,在主服务器中实际上设计了三个reactor,一个主reactor专门负责连接请求并配已单独的selector,但是三个reactor的线程run函数是做的相同的功能,都是根据每个线程内部的selector进行检索事件列表,若注册的监听事件发生了则调用dispactch分发到每个reactor对应的handler。

这里需要注意的一开始其实只有负责连接事件的主reactor在注册selector的时候给相应的key配了一个acceptorhandler()。

 //第一个selector,负责监控新连接事件
        selectionkey sk =
                serversocket.register(bossselector, selectionkey.op_accept);
        //附加新连接处理handler处理器到selectionkey(选择键)
        sk.attach(new acceptorhandler());

但是reactor的run方法里若相应的selector key发生了便要dispatch到一个handler。这里其他两个子reactor的handler在哪里赋值的呢?其实在处理连接请求的reactor中便创建了各个子handler,如下代码所示:
主handler中先是根据服务器channel创建出客服端channel,在进行子selector与channel的绑定。

                   int index = next.get();
                   logger.info("选择器的编号:" + index);
                   selector selector = workselectors[index];
                   new multithreadechohandler(selector, channel);

2、io请求handler+线程池

package com.crazymakercircle.reactormodel;


import com.crazymakercircle.util.logger;

import java.io.ioexception;
import java.nio.bytebuffer;
import java.nio.channels.selectionkey;
import java.nio.channels.selector;
import java.nio.channels.socketchannel;
import java.util.concurrent.executorservice;
import java.util.concurrent.executors;

class multithreadechohandler implements runnable {
    final socketchannel channel;
    final selectionkey sk;
    final bytebuffer bytebuffer = bytebuffer.allocate(1024);
    static final int recieving = 0, sending = 1;
    int state = recieving;
    //引入线程池
    static executorservice pool = executors.newfixedthreadpool(4);

    multithreadechohandler(selector selector, socketchannel c) throws ioexception {
        channel = c;
        channel.configureblocking(false);

        //唤醒选择,防止register时 boss线程被阻塞,netty 处理方式比较优雅,会在同一个线程注册事件,避免阻塞boss
        selector.wakeup();

        //仅仅取得选择键,后设置感兴趣的io事件
        sk = channel.register(selector, 0);
        //将本handler作为sk选择键的附件,方便事件dispatch
        sk.attach(this);
        //向sk选择键注册read就绪事件
        sk.interestops(selectionkey.op_read);

        //唤醒选择,是的op_read生效
        selector.wakeup();
        logger.info("新的连接 注册完成");

    }

    public void run() {
        //异步任务,在独立的线程池中执行
        pool.execute(new asynctask());
    }

    //异步任务,不在reactor线程中执行
    public synchronized void asyncrun() {
        try {
            if (state == sending) {
                //写入通道
                channel.write(bytebuffer);

                //写完后,准备开始从通道读,bytebuffer切换成写模式
                bytebuffer.clear();
                //写完后,注册read就绪事件
                sk.interestops(selectionkey.op_read);
                //写完后,进入接收的状态
                state = recieving;
            } else if (state == recieving) {
                //从通道读
                int length = 0;
                while ((length = channel.read(bytebuffer)) > 0) {
                    logger.info(new string(bytebuffer.array(), 0, length));
                }
                //读完后,准备开始写入通道,bytebuffer切换成读模式
                bytebuffer.flip();
                //读完后,注册write就绪事件
                sk.interestops(selectionkey.op_write);
                //读完后,进入发送的状态
                state = sending;
            }
            //处理结束了, 这里不能关闭select key,需要重复使用
            //sk.cancel();
        } catch (ioexception ex) {
            ex.printstacktrace();
        }
    }

    //异步任务的内部类
    class asynctask implements runnable {
        public void run() {
            multithreadechohandler.this.asyncrun();
        }
    }
}

3、客户端

在处理io请求的handler中采用了线程池,已达到异步处理的目的。

package com.crazymakercircle.reactormodel;

import com.crazymakercircle.niodemoconfig;
import com.crazymakercircle.util.dateutil;
import com.crazymakercircle.util.logger;

import java.io.ioexception;
import java.net.inetsocketaddress;
import java.nio.bytebuffer;
import java.nio.channels.selectionkey;
import java.nio.channels.selector;
import java.nio.channels.socketchannel;
import java.util.iterator;
import java.util.scanner;
import java.util.set;

/**
 * create by 尼恩 @ 疯狂创客圈
 **/
public class echoclient {

    public void start() throws ioexception {

        inetsocketaddress address =
                new inetsocketaddress(niodemoconfig.socket_server_ip,
                        niodemoconfig.socket_server_port);

        // 1、获取通道(channel)
        socketchannel socketchannel = socketchannel.open(address);
        logger.info("客户端连接成功");
        // 2、切换成非阻塞模式
        socketchannel.configureblocking(false);
        //不断的自旋、等待连接完成,或者做一些其他的事情
        while (!socketchannel.finishconnect()) {

        }
        logger.tcfo("客户端启动成功!");

        //启动接受线程
        processer processer = new processer(socketchannel);
        new thread(processer).start();

    }

    static class processer implements runnable {
        final selector selector;
        final socketchannel channel;

        processer(socketchannel channel) throws ioexception {
            //reactor初始化
            selector = selector.open();
            this.channel = channel;
            channel.register(selector,
                    selectionkey.op_read | selectionkey.op_write);
        }

        public void run() {
            try {
                while (!thread.interrupted()) {
                    selector.select();
                    set<selectionkey> selected = selector.selectedkeys();
                    iterator<selectionkey> it = selected.iterator();
                    while (it.hasnext()) {
                        selectionkey sk = it.next();
                        if (sk.iswritable()) {
                            bytebuffer buffer = bytebuffer.allocate(niodemoconfig.send_buffer_size);

                            scanner scanner = new scanner(system.in);
                            logger.tcfo("请输入发送内容:");
                            if (scanner.hasnext()) {
                                socketchannel socketchannel = (socketchannel) sk.channel();
                                string next = scanner.next();
                                buffer.put((dateutil.getnow() + " >>" + next).getbytes());
                                buffer.flip();
                                // 操作三:发送数据
                                socketchannel.write(buffer);
                                buffer.clear();
                            }

                        }
                        if (sk.isreadable()) {
                            // 若选择键的io事件是“可读”事件,读取数据
                            socketchannel socketchannel = (socketchannel) sk.channel();

                            //读取数据
                            bytebuffer bytebuffer = bytebuffer.allocate(1024);
                            int length = 0;
                            while ((length = socketchannel.read(bytebuffer)) > 0) {
                                bytebuffer.flip();
                                logger.info("server echo:" + new string(bytebuffer.array(), 0, length));
                                bytebuffer.clear();
                            }

                        }
                        //处理结束了, 这里不能关闭select key,需要重复使用
                        //selectionkey.cancel();
                    }
                    selected.clear();
                }
            } catch (ioexception ex) {
                ex.printstacktrace();
            }
        }
    }

    public static void main(string[] args) throws ioexception {
        new echoclient().start();
    }
}

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