Java网络编程- IO多路复用(多Reactor)(主从式Reactor)
来源:互联网 发布:全程软件测试 编辑:程序博客网 时间:2024/06/07 00:50
1. 介绍
本篇文章将IO多路复用(多线程)中的单Reactor+多线程网络模型做了改进,
把Reactor拆成两个角色Main Reactor及Sub Reactor,以提升效能与资源利用率。
Main Reactor:负责监听外部的连线请求,并派发给Acceptor处理。故Main Reactor中的selector只有注册OP_ACCEPT事件,也只能监听OP_ACCEPT事件。
Acceptor接受连线后会给client绑定一个Handler并注册IO事件到Sub Reactor上监听,
对于有多个Sub Reactor的情况下,IO事件选择注册给哪个Sub Reactor则是采用Round-robin的机制来分配。
Sub Reactor:負責監聽IO事件,並派發IO事件給Handler處理。Sub Reactor線程的數量可以設置為CPU核心數。
2. 网络模型
3. 源代码
Main Reactor
[TCPReactor.Java]
-
- package server;
-
- 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.util.Iterator;
- import java.util.Set;
-
- public class TCPReactor implements Runnable {
-
- private final ServerSocketChannel ssc;
- private final Selector selector;
-
- public TCPReactor(int port) throws IOException {
- selector = Selector.open();
- ssc = ServerSocketChannel.open();
- InetSocketAddress addr = new InetSocketAddress(port);
- ssc.socket().bind(addr);
- ssc.configureBlocking(false);
- SelectionKey sk = ssc.register(selector, SelectionKey.OP_ACCEPT);
- sk.attach(new Acceptor(ssc));
- }
-
- @Override
- public void run() {
- while (!Thread.interrupted()) {
- System.out.println("mainReactor waiting for new event on port: "
- + ssc.socket().getLocalPort() + "...");
- try {
- if (selector.select() == 0)
- continue;
- } catch (IOException e) {
- e.printStackTrace();
- }
- Set<SelectionKey> selectedKeys = selector.selectedKeys();
- Iterator<SelectionKey> it = selectedKeys.iterator();
- while (it.hasNext()) {
- dispatch((SelectionKey) (it.next()));
- it.remove();
- }
- }
- }
-
-
-
-
-
- private void dispatch(SelectionKey key) {
- Runnable r = (Runnable) (key.attachment());
- if (r != null)
- r.run();
- }
-
- }
Acceptor
[Acceptor.java]-
- package server;
-
- import java.io.IOException;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.Selector;
- import java.nio.channels.ServerSocketChannel;
- import java.nio.channels.SocketChannel;
-
- public class Acceptor implements Runnable {
-
- private final ServerSocketChannel ssc;
- private final int cores = Runtime.getRuntime().availableProcessors();
- private final Selector[] selectors = new Selector[cores];
- private int selIdx = 0;
- private TCPSubReactor[] r = new TCPSubReactor[cores];
- private Thread[] t = new Thread[cores];
-
- public Acceptor(ServerSocketChannel ssc) throws IOException {
- this.ssc = ssc;
-
- for (int i = 0; i < cores; i++) {
- selectors[i] = Selector.open();
- r[i] = new TCPSubReactor(selectors[i], ssc, i);
- t[i] = new Thread(r[i]);
- t[i].start();
- }
- }
-
- @Override
- public synchronized void run() {
- try {
- SocketChannel sc = ssc.accept();
- System.out.println(sc.socket().getRemoteSocketAddress().toString()
- + " is connected.");
-
- if (sc != null) {
- sc.configureBlocking(false);
- r[selIdx].setRestart(true);
- selectors[selIdx].wakeup();
- SelectionKey sk = sc.register(selectors[selIdx],
- SelectionKey.OP_READ);
- selectors[selIdx].wakeup();
- r[selIdx].setRestart(false);
- sk.attach(new TCPHandler(sk, sc));
- if (++selIdx == selectors.length)
- selIdx = 0;
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
-
- }
Sub Reactor
Sub Reactor在实作上有个重点要注意,
当一个监听中而阻塞住的selector由于Acceptor需要注册新的IO事件到该selector上时,
Acceptor会调用selector的wakeup()函数唤醒阻塞住的selector,以注册新IO事件后再继续监听。
但Sub Reactor中循环调用selector.select()的线程回圈可能会因为循环太快,导致selector被唤醒后再度于IO事件成功注册前被调用selector.select()而阻塞住,
因此我们需要给Sub Reactor线程循环设置一个flag来控制,
让selector被唤醒后不会马上进入下回合调用selector.select()的Sub Reactor线程循环,
等待我们将新的IO事件注册完之后才能让Sub Reactor线程继续运行。
[TCPSubReactor.java]
- package server;
-
- import java.io.IOException;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.Selector;
- import java.nio.channels.ServerSocketChannel;
- import java.util.Iterator;
- import java.util.Set;
-
- public class TCPSubReactor implements Runnable {
-
- private final ServerSocketChannel ssc;
- private final Selector selector;
- private boolean restart = false;
- int num;
-
- public TCPSubReactor(Selector selector, ServerSocketChannel ssc, int num) {
- this.ssc = ssc;
- this.selector = selector;
- this.num = num;
- }
-
- @Override
- public void run() {
- while (!Thread.interrupted()) {
-
-
-
- System.out.println("waiting for restart");
- while (!Thread.interrupted() && !restart) {
- try {
- if (selector.select() == 0)
- continue;
- } catch (IOException e) {
- e.printStackTrace();
- }
- Set<SelectionKey> selectedKeys = selector.selectedKeys();
- Iterator<SelectionKey> it = selectedKeys.iterator();
- while (it.hasNext()) {
- dispatch((SelectionKey) (it.next()));
- it.remove();
- }
- }
- }
- }
-
-
-
-
- private void dispatch(SelectionKey key) {
- Runnable r = (Runnable) (key.attachment());
- if (r != null)
- r.run();
- }
-
- public void setRestart(boolean restart) {
- this.restart = restart;
- }
- }
Handler
[TCPHandler.java]
-
- package server;
-
- import java.io.IOException;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.SocketChannel;
- import java.util.concurrent.LinkedBlockingQueue;
- import java.util.concurrent.ThreadPoolExecutor;
- import java.util.concurrent.TimeUnit;
-
- public class TCPHandler implements Runnable {
-
- private final SelectionKey sk;
- private final SocketChannel sc;
- private static final int THREAD_COUNTING = 10;
- private static ThreadPoolExecutor pool = new ThreadPoolExecutor(
- THREAD_COUNTING, THREAD_COUNTING, 10, TimeUnit.SECONDS,
- new LinkedBlockingQueue<Runnable>());
-
- HandlerState state;
-
- public TCPHandler(SelectionKey sk, SocketChannel sc) {
- this.sk = sk;
- this.sc = sc;
- state = new ReadState();
- pool.setMaximumPoolSize(32);
- }
-
- @Override
- public void run() {
- try {
- state.handle(this, sk, sc, pool);
-
- } catch (IOException e) {
- System.out.println("[Warning!] A client has been closed.");
- closeChannel();
- }
- }
-
- public void closeChannel() {
- try {
- sk.cancel();
- sc.close();
- } catch (IOException e1) {
- e1.printStackTrace();
- }
- }
-
- public void setState(HandlerState state) {
- this.state = state;
- }
- }
状态介面
[HandlerState.java]
- package server;
-
- import java.io.IOException;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.SocketChannel;
- import java.util.concurrent.ThreadPoolExecutor;
-
- public interface HandlerState {
-
- public void changeState(TCPHandler h);
-
- public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,
- ThreadPoolExecutor pool) throws IOException ;
- }
状态实现类
[ReadState.java]- package server;
-
- import java.io.IOException;
- import java.nio.ByteBuffer;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.SocketChannel;
- import java.util.concurrent.ThreadPoolExecutor;
-
- public class ReadState implements HandlerState{
-
- private SelectionKey sk;
-
- public ReadState() {
- }
-
- @Override
- public void changeState(TCPHandler h) {
-
- h.setState(new WorkState());
- }
-
- @Override
- public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,
- ThreadPoolExecutor pool) throws IOException {
- this.sk = sk;
-
- byte[] arr = new byte[1024];
- ByteBuffer buf = ByteBuffer.wrap(arr);
-
- int numBytes = sc.read(buf);
- if(numBytes == -1)
- {
- System.out.println("[Warning!] A client has been closed.");
- h.closeChannel();
- return;
- }
- String str = new String(arr);
- if ((str != null) && !str.equals(" ")) {
- h.setState(new WorkState());
- pool.execute(new WorkerThread(h, str));
- System.out.println(sc.socket().getRemoteSocketAddress().toString()
- + " > " + str);
- }
-
- }
-
-
-
-
- synchronized void process(TCPHandler h, String str) {
-
-
- h.setState(new WriteState());
- this.sk.interestOps(SelectionKey.OP_WRITE);
- this.sk.selector().wakeup();
- }
-
-
-
-
- class WorkerThread implements Runnable {
-
- TCPHandler h;
- String str;
-
- public WorkerThread(TCPHandler h, String str) {
- this.h = h;
- this.str=str;
- }
-
- @Override
- public void run() {
- process(h, str);
- }
-
- }
- }
[WorkState.java]- package server;
-
- import java.io.IOException;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.SocketChannel;
- import java.util.concurrent.ThreadPoolExecutor;
-
- public class WorkState implements HandlerState {
-
- public WorkState() {
- }
-
- @Override
- public void changeState(TCPHandler h) {
-
- h.setState(new WriteState());
- }
-
- @Override
- public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,
- ThreadPoolExecutor pool) throws IOException {
-
-
- }
-
- }
[WriteState.java]- package server;
-
- import java.io.IOException;
- import java.nio.ByteBuffer;
- import java.nio.channels.SelectionKey;
- import java.nio.channels.SocketChannel;
- import java.util.concurrent.ThreadPoolExecutor;
-
- public class WriteState implements HandlerState{
-
- public WriteState() {
- }
-
- @Override
- public void changeState(TCPHandler h) {
-
- h.setState(new ReadState());
- }
-
- @Override
- public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,
- ThreadPoolExecutor pool) throws IOException {
-
-
- String str = "Your message has sent to "
- + sc.socket().getLocalSocketAddress().toString() + "\r\n";
- ByteBuffer buf = ByteBuffer.wrap(str.getBytes());
-
- while (buf.hasRemaining()) {
- sc.write(buf);
- }
-
- h.setState(new ReadState());
- sk.interestOps(SelectionKey.OP_READ);
- sk.selector().wakeup();
- }
- }
主程序
[Main.java]- package server;
-
- import java.io.IOException;
-
- public class Main {
-
-
- public static void main(String[] args) {
-
- try {
- TCPReactor reactor = new TCPReactor(1333);
- new Thread(reactor).start();
- } catch (IOException e) {
-
- e.printStackTrace();
- }
- }
-
- }
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