reactor模式：多线程的reactor模式
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
1 // Reactor線程 （该类与单线程的处理基本无变动） 2 package server; 3 4 import java.io.IOException; 5 import java.net.InetSocketAddress; 6 import java.nio.channels.SelectionKey; 7 import java.nio.channels.Selector; 8 import java.nio.channels.ServerSocketChannel; 9 import java.util.Iterator; 10 import java.util.Set; 11 12 public class TCPReactor implements Runnable { 13 14 private final ServerSocketChannel ssc; 15 private final Selector selector; 16 17 public TCPReactor(int port) throws IOException { 18 selector = Selector.open(); 19 ssc = ServerSocketChannel.open(); 20 InetSocketAddress addr = new InetSocketAddress(port); 21 ssc.socket().bind(addr); // 在ServerSocketChannel綁定監聽端口 22 ssc.configureBlocking(false); // 設置ServerSocketChannel為非阻塞 23 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 24 sk.attach(new Acceptor(selector, ssc)); // 給定key一個附加的Acceptor對象 25 } 26 27 @Override 28 public void run() { 29 while (!Thread.interrupted()) { // 在線程被中斷前持續運行 30 System.out.println("Waiting for new event on port: " + ssc.socket().getLocalPort() + "..."); 31 try { 32 if (selector.select() == 0) // 若沒有事件就緒則不往下執行 33 continue; 34 } catch (IOException e) { 35 // TODO Auto-generated catch block 36 e.printStackTrace(); 37 } 38 Set<SelectionKey> selectedKeys = selector.selectedKeys(); // 取得所有已就緒事件的key集合 39 Iterator<SelectionKey> it = selectedKeys.iterator(); 40 while (it.hasNext()) { 41 dispatch((SelectionKey) (it.next())); // 根據事件的key進行調度 42 it.remove(); 43 } 44 } 45 } 46 47 /* 48 * name: dispatch(SelectionKey key) 49 * description: 調度方法，根據事件綁定的對象開新線程 50 */ 51 private void dispatch(SelectionKey key) { 52 Runnable r = (Runnable) (key.attachment()); // 根據事件之key綁定的對象開新線程 53 if (r != null) 54 r.run(); 55 } 56 57 }
1 // 接受連線請求線程 2 package server; 3 4 import java.io.IOException; 5 import java.nio.channels.SelectionKey; 6 import java.nio.channels.Selector; 7 import java.nio.channels.ServerSocketChannel; 8 import java.nio.channels.SocketChannel; 9 10 public class Acceptor implements Runnable { 11 12 private final ServerSocketChannel ssc; 13 private final Selector selector; 14 15 public Acceptor(Selector selector, ServerSocketChannel ssc) { 16 this.ssc=ssc; 17 this.selector=selector; 18 } 19 20 @Override 21 public void run() { 22 try { 23 SocketChannel sc= ssc.accept(); // 接受client連線請求 24 System.out.println(sc.socket().getRemoteSocketAddress().toString() + " is connected."); 25 26 if(sc!=null) { 27 sc.configureBlocking(false); // 設置為非阻塞 28 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 29 selector.wakeup(); // 使一個阻塞住的selector操作立即返回 30 sk.attach(new TCPHandler(sk, sc)); // 給定key一個附加的TCPHandler對象 31 } 32 33 } catch (IOException e) { 34 // TODO Auto-generated catch block 35 e.printStackTrace(); 36 } 37 } 38 39 40 }
1 // Handler線程 2 package server; 3 4 import java.io.IOException; 5 import java.nio.channels.SelectionKey; 6 import java.nio.channels.SocketChannel; 7 import java.util.concurrent.LinkedBlockingQueue; 8 import java.util.concurrent.ThreadPoolExecutor; 9 import java.util.concurrent.TimeUnit; 10 11 public class TCPHandler implements Runnable { 12 13 private final SelectionKey sk; 14 private final SocketChannel sc; 15 private static final int THREAD_COUNTING = 10; 16 private static ThreadPoolExecutor pool = new ThreadPoolExecutor( 17 THREAD_COUNTING, THREAD_COUNTING, 10, TimeUnit.SECONDS, 18 new LinkedBlockingQueue<Runnable>()); // 線程池 19 20 HandlerState state; // 以狀態模式實現Handler 21 22 public TCPHandler(SelectionKey sk, SocketChannel sc) { 23 this.sk = sk; 24 this.sc = sc; 25 state = new ReadState(); // 初始狀態設定為READING 26 pool.setMaximumPoolSize(32); // 設置線程池最大線程數 27 } 28 29 @Override 30 public void run() { 31 try { 32 state.handle(this, sk, sc, pool); 33 34 } catch (IOException e) { 35 System.out.println("[Warning!] A client has been closed."); 36 closeChannel(); 37 } 38 } 39 40 public void closeChannel() { 41 try { 42 sk.cancel(); 43 sc.close(); 44 } catch (IOException e1) { 45 e1.printStackTrace(); 46 } 47 } 48 49 public void setState(HandlerState state) { 50 this.state = state; 51 } 52 } 53 54
1 package server; 2 3 import java.io.IOException; 4 import java.nio.channels.SelectionKey; 5 import java.nio.channels.SocketChannel; 6 import java.util.concurrent.ThreadPoolExecutor; 7 8 public interface HandlerState { 9 10 public void changeState(TCPHandler h); 11 12 public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, 13 ThreadPoolExecutor pool) throws IOException ; 14 }
1 package server; 2 3 import java.io.IOException; 4 import java.nio.ByteBuffer; 5 import java.nio.channels.SelectionKey; 6 import java.nio.channels.SocketChannel; 7 import java.util.concurrent.ThreadPoolExecutor; 8 9 public class ReadState implements HandlerState{ 10 11 private SelectionKey sk; 12 13 public ReadState() { 14 } 15 16 @Override 17 public void changeState(TCPHandler h) { 18 // TODO Auto-generated method stub 19 h.setState(new WorkState()); 20 } 21 22 @Override 23 public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, 24 ThreadPoolExecutor pool) throws IOException { // read() 25 this.sk = sk; 26 // non-blocking下不可用Readers，因為Readers不支援non-blocking 27 byte[] arr = new byte[1024]; 28 ByteBuffer buf = ByteBuffer.wrap(arr); 29 30 int numBytes = sc.read(buf); // 讀取字符串 31 if(numBytes == -1) 32 { 33 System.out.println("[Warning!] A client has been closed."); 34 h.closeChannel(); 35 return; 36 } 37 String str = new String(arr); // 將讀取到的byte內容轉為字符串型態 38 if ((str != null) && !str.equals(" ")) { 39 h.setState(new WorkState()); // 改變狀態(READING->WORKING) 40 pool.execute(new WorkerThread(h, str)); // do process in worker thread 41 System.out.println(sc.socket().getRemoteSocketAddress().toString() 42 + " > " + str); 43 } 44 45 } 46 47 /* 48 * 執行邏輯處理之函數 49 */ 50 synchronized void process(TCPHandler h, String str) { 51 // do process(decode, logically process, encode).. 52 // .. 53 h.setState(new WriteState()); // 改變狀態(WORKING->SENDING) 54 this.sk.interestOps(SelectionKey.OP_WRITE); // 通過key改變通道註冊的事件 55 this.sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回 56 } 57 58 /* 59 * 工作者線程 60 */ 61 class WorkerThread implements Runnable { 62 63 TCPHandler h; 64 String str; 65 66 public WorkerThread(TCPHandler h, String str) { 67 this.h = h; 68 this.str=str; 69 } 70 71 @Override 72 public void run() { 73 process(h, str); 74 } 75 76 } 77 }
1 package server; 2 3 import java.io.IOException; 4 import java.nio.channels.SelectionKey; 5 import java.nio.channels.SocketChannel; 6 import java.util.concurrent.ThreadPoolExecutor; 7 8 public class WorkState implements HandlerState { 9 10 public WorkState() { 11 } 12 13 @Override 14 public void changeState(TCPHandler h) { 15 // TODO Auto-generated method stub 16 h.setState(new WriteState()); 17 } 18 19 @Override 20 public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, 21 ThreadPoolExecutor pool) throws IOException { 22 // TODO Auto-generated method stub 23 24 } 25 26 }
1 package server; 2 3 import java.io.IOException; 4 import java.nio.ByteBuffer; 5 import java.nio.channels.SelectionKey; 6 import java.nio.channels.SocketChannel; 7 import java.util.concurrent.ThreadPoolExecutor; 8 9 public class WriteState implements HandlerState{ 10 11 public WriteState() { 12 } 13 14 @Override 15 public void changeState(TCPHandler h) { 16 // TODO Auto-generated method stub 17 h.setState(new ReadState()); 18 } 19 20 @Override 21 public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc, 22 ThreadPoolExecutor pool) throws IOException { // send() 23 // get message from message queue 24 25 String str = "Your message has sent to " 26 + sc.socket().getLocalSocketAddress().toString() + "\r\n"; 27 ByteBuffer buf = ByteBuffer.wrap(str.getBytes()); // wrap自動把buf的position設為0，所以不需要再flip() 28 29 while (buf.hasRemaining()) { 30 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 31 } 32 33 h.setState(new ReadState()); // 改變狀態(SENDING->READING) 34 sk.interestOps(SelectionKey.OP_READ); // 通過key改變通道註冊的事件 35 sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回 36 } 37 }
1 package server; 2 3 import java.io.IOException; 4 5 public class Main { 6 7 8 public static void main(String[] args) { 9 // TODO Auto-generated method stub 10 try { 11 TCPReactor reactor = new TCPReactor(1333); 12 reactor.run(); 13 } catch (IOException e) { 14 // TODO Auto-generated catch block 15 e.printStackTrace(); 16 } 17 } 18 19 }
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
