上文说到单线程的reactor模式 reactor模式:单线程的reactor模式
单线程的reactor模式并没有解决IO和CPU处理速度不匹配问题,所以多线程的reactor模式引入线程池的概念,把耗时的IO操作交由线程池处理,处理完了之后再同步到selectionkey中,服务器架构图如下
上文(reactor模式:单线程的reactor模式)提到,以read和send阶段IO最为频繁,所以多线程的reactor版本里,把这2个阶段单独拎出来。
下面看看代码实现
// Reactor線程 (该类与单线程的处理基本无变动) 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); // 在ServerSocketChannel綁定監聽端口 ssc.configureBlocking(false); // 設置ServerSocketChannel為非阻塞 SelectionKey sk = ssc.register(selector, SelectionKey.OP_ACCEPT); // ServerSocketChannel向selector註冊一個OP_ACCEPT事件,然後返回該通道的key sk.attach(new Acceptor(selector, ssc)); // 給定key一個附加的Acceptor對象 } @Override public void run() { while (!Thread.interrupted()) { // 在線程被中斷前持續運行 System.out.println("Waiting for new event on port: " + ssc.socket().getLocalPort() + "..."); try { if (selector.select() == 0) // 若沒有事件就緒則不往下執行 continue; } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } Set<SelectionKey> selectedKeys = selector.selectedKeys(); // 取得所有已就緒事件的key集合 Iterator<SelectionKey> it = selectedKeys.iterator(); while (it.hasNext()) { dispatch((SelectionKey) (it.next())); // 根據事件的key進行調度 it.remove(); } } } /* * name: dispatch(SelectionKey key) * description: 調度方法,根據事件綁定的對象開新線程 */ private void dispatch(SelectionKey key) { Runnable r = (Runnable) (key.attachment()); // 根據事件之key綁定的對象開新線程 if (r != null) r.run(); } }
// 接受連線請求線程 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 Selector selector; public Acceptor(Selector selector, ServerSocketChannel ssc) { this.ssc=ssc; this.selector=selector; } @Override public void run() { try { SocketChannel sc= ssc.accept(); // 接受client連線請求 System.out.println(sc.socket().getRemoteSocketAddress().toString() + " is connected."); if(sc!=null) { sc.configureBlocking(false); // 設置為非阻塞 SelectionKey sk = sc.register(selector, SelectionKey.OP_READ); // SocketChannel向selector註冊一個OP_READ事件,然後返回該通道的key selector.wakeup(); // 使一個阻塞住的selector操作立即返回 sk.attach(new TCPHandler(sk, sc)); // 給定key一個附加的TCPHandler對象 } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
// Handler線程 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>()); // 線程池 HandlerState state; // 以狀態模式實現Handler public TCPHandler(SelectionKey sk, SocketChannel sc) { this.sk = sk; this.sc = sc; state = new ReadState(); // 初始狀態設定為READING pool.setMaximumPoolSize(32); // 設置線程池最大線程數 } @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; } }
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 ; }
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) { // TODO Auto-generated method stub h.setState(new WorkState()); } @Override public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, ThreadPoolExecutor pool) throws IOException { // read() this.sk = sk; // non-blocking下不可用Readers,因為Readers不支援non-blocking byte[] arr = new byte[1024]; ByteBuffer buf = ByteBuffer.wrap(arr); int numBytes = sc.read(buf); // 讀取字符串 if(numBytes == -1) { System.out.println("[Warning!] A client has been closed."); h.closeChannel(); return; } String str = new String(arr); // 將讀取到的byte內容轉為字符串型態 if ((str != null) && !str.equals(" ")) { h.setState(new WorkState()); // 改變狀態(READING->WORKING) pool.execute(new WorkerThread(h, str)); // do process in worker thread System.out.println(sc.socket().getRemoteSocketAddress().toString() + " > " + str); } } /* * 執行邏輯處理之函數 */ synchronized void process(TCPHandler h, String str) { // do process(decode, logically process, encode).. // .. h.setState(new WriteState()); // 改變狀態(WORKING->SENDING) this.sk.interestOps(SelectionKey.OP_WRITE); // 通過key改變通道註冊的事件 this.sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回 } /* * 工作者線程 */ 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); } } }
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) { // TODO Auto-generated method stub h.setState(new WriteState()); } @Override public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, ThreadPoolExecutor pool) throws IOException { // TODO Auto-generated method stub } }
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) { // TODO Auto-generated method stub h.setState(new ReadState()); } @Override public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, ThreadPoolExecutor pool) throws IOException { // send() // get message from message queue String str = "Your message has sent to " + sc.socket().getLocalSocketAddress().toString() + "\r\n"; ByteBuffer buf = ByteBuffer.wrap(str.getBytes()); // wrap自動把buf的position設為0,所以不需要再flip() while (buf.hasRemaining()) { sc.write(buf); // 回傳給client回應字符串,發送buf的position位置 到limit位置為止之間的內容 } h.setState(new ReadState()); // 改變狀態(SENDING->READING) sk.interestOps(SelectionKey.OP_READ); // 通過key改變通道註冊的事件 sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回 } }
package server; import java.io.IOException; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub try { TCPReactor reactor = new TCPReactor(1333); reactor.run(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
总的来说,多线程版本的reactor是为了解决单线程reactor版本的IO和CPU处理速度不匹配问题,从而达到高效处理的目的
参考文章:
https://blog.csdn.net/yehjordan/article/details/51017025