reactor模式：多執行緒的reactor模式
阿新 • • 發佈：2019-01-03
單執行緒的reactor模式並沒有解決IO和CPU處理速度不匹配問題，所以多執行緒的reactor模式引入執行緒池的概念，把耗時的IO操作交由執行緒池處理，處理完了之後再同步到selectionkey中，伺服器架構圖如下
上文（reactor模式：單執行緒的reactor模式）提到，以read和send階段IO最為頻繁，所以多執行緒的reactor版本里，把這2個階段單獨拎出來。
下面看看程式碼實現
// Reactor執行緒 （該類與單執行緒的處理基本無變動） 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繫結監聽埠 ssc.configureBlocking(false); // 設定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物件 } @Override public void run() { while (!Thread.interrupted()) { // 線上程被中斷前持續執行 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進行排程 it.remove(); } } } /* * name: dispatch(SelectionKey key) * description: 排程方法，根據事件繫結的物件開新執行緒 */ private void dispatch(SelectionKey key) { Runnable r = (Runnable) (key.attachment()); // 根據事件之key繫結的物件開新執行緒 if (r != null) r.run(); } }
// 接受連線請求執行緒 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); // 設定為非阻塞 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物件 } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
// Handler執行緒 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>()); // 執行緒池 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); // 設定執行緒池最大執行緒數 } @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);
}
}
/*
* 執行邏輯處理之函式
*/
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
}
/*
* 工作者執行緒
*/
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回應字串，傳送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();
}
}
} 總的來說，多執行緒版本的reactor是為了解決單執行緒reactor版本的IO和CPU處理速度不匹配問題，從而達到高效處理的目的
參考文章：
https://blog.csdn.net/yehjordan/article/details/51017025