reactor模式：主从式reactor
前面两篇文章提到
NIO的server模式只有5个阶段，但是，NIO的selectionkey里确实有个accept事件，所以，为了区别，衍生出了主reactor和从reactor
并且，从reactor可以根据服务器的负荷，新增多个从reactor进行请求处理
服务器架构如下图
这个就是完整版的reactor模式的架构图了，目前使用到了reactor模式的框架（如netty），基本用的模式就是这个
代码实现：
1 // Reactor線程 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; // mainReactor用的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(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("mainReactor waiting for new event on port: " 31 + ssc.socket().getLocalPort() + "..."); 32 try { 33 if (selector.select() == 0) // 若沒有事件就緒則不往下執行 34 continue; 35 } catch (IOException e) { 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; // mainReactor監聽的socket通道 13 private final int cores = Runtime.getRuntime().availableProcessors(); // 取得CPU核心數 14 private final Selector[] selectors = new Selector[cores]; // 創建核心數個selector給subReactor用 15 private int selIdx = 0; // 當前可使用的subReactor索引 16 private TCPSubReactor[] r = new TCPSubReactor[cores]; // subReactor線程 17 private Thread[] t = new Thread[cores]; // subReactor線程 18 19 public Acceptor(ServerSocketChannel ssc) throws IOException { 20 this.ssc = ssc; 21 // 創建多個selector以及多個subReactor線程 22 for (int i = 0; i < cores; i++) { 23 selectors[i] = Selector.open(); 24 r[i] = new TCPSubReactor(selectors[i], ssc, i); 25 t[i] = new Thread(r[i]); 26 t[i].start(); 27 } 28 } 29 30 @Override 31 public synchronized void run() { 32 try { 33 SocketChannel sc = ssc.accept(); // 接受client連線請求 34 System.out.println(sc.socket().getRemoteSocketAddress().toString() 35 + " is connected."); 36 37 if (sc != null) { 38 sc.configureBlocking(false); // 設置為非阻塞 39 r[selIdx].setRestart(true); // 暫停線程 40 selectors[selIdx].wakeup(); // 使一個阻塞住的selector操作立即返回 41 SelectionKey sk = sc.register(selectors[selIdx], 42 SelectionKey.OP_READ); // SocketChannel向selector[selIdx]註冊一個OP_READ事件，然後返回該通道的key 43 selectors[selIdx].wakeup(); // 使一個阻塞住的selector操作立即返回 44 r[selIdx].setRestart(false); // 重啟線程 45 sk.attach(new TCPHandler(sk, sc)); // 給定key一個附加的TCPHandler對象 46 if (++selIdx == selectors.length) 47 selIdx = 0; 48 } 49 } catch (IOException e) { 50 e.printStackTrace(); 51 } 52 } 53 54 }
1 package server; 2 3 import java.io.IOException; 4 import java.nio.channels.SelectionKey; 5 import java.nio.channels.Selector; 6 import java.nio.channels.ServerSocketChannel; 7 import java.util.Iterator; 8 import java.util.Set; 9 10 public class TCPSubReactor implements Runnable { 11 12 private final ServerSocketChannel ssc; 13 private final Selector selector; 14 private boolean restart = false; 15 int num; 16 17 public TCPSubReactor(Selector selector, ServerSocketChannel ssc, int num) { 18 this.ssc = ssc; 19 this.selector = selector; 20 this.num = num; 21 } 22 23 @Override 24 public void run() { 25 while (!Thread.interrupted()) { // 在線程被中斷前持續運行 26 //System.out.println("ID:" + num 27 // + " subReactor waiting for new event on port: " 28 // + ssc.socket().getLocalPort() + "..."); 29 System.out.println("waiting for restart"); 30 while (!Thread.interrupted() && !restart) { // 在線程被中斷前以及被指定重啟前持續運行 31 try { 32 if (selector.select() == 0) 33 continue; // 若沒有事件就緒則不往下執行 34 } catch (IOException e) { 35 e.printStackTrace(); 36 } 37 Set<SelectionKey> selectedKeys = selector.selectedKeys(); // 取得所有已就緒事件的key集合 38 Iterator<SelectionKey> it = selectedKeys.iterator(); 39 while (it.hasNext()) { 40 dispatch((SelectionKey) (it.next())); // 根據事件的key進行調度 41 it.remove(); 42 } 43 } 44 } 45 } 46 47 /* 48 * name: dispatch(SelectionKey key) description: 調度方法，根據事件綁定的對象開新線程 49 */ 50 private void dispatch(SelectionKey key) { 51 Runnable r = (Runnable) (key.attachment()); // 根據事件之key綁定的對象開新線程 52 if (r != null) 53 r.run(); 54 } 55 56 public void setRestart(boolean restart) { 57 this.restart = restart; 58 } 59 }
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 }
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 }
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); } } }
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 }
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 } }
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 new Thread(reactor).start(); 13 } catch (IOException e) { 14 // TODO Auto-generated catch block 15 e.printStackTrace(); 16 } 17 } 18 19 }
总的来说，主从式reactor比多线程的reactor先进的地方在于：
1.主reactor是一个线程，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。
而处理请求是其他N个不同的线程，即从reactor
2.可以根据请求的密集度来调控从reactor的个数
参考文章：
https://blog.csdn.net/yehjordan/article/details/51026045
