NIO-Reactor模式介绍 nioreactor多线程socket
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2022-05-04 21:40:54
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Reactor模式常用于java nio编程中，跟生产者消费者模式有点类似，可以认为是只有一个线程的生产者消费者模型，netty底层也是使用Reactor模式作为nio部分的开发
一个简单的Reactor模式
Reactor.java
Handler.java
以上模式在正常非阻塞IO的情况效果还可以，但是要提供效率，可以使用多线程处理 io之后的业务逻辑，下面看一下多线程Reactor模式
多线程Reactor模式
ReactorWithPool.java
HandlerWithPool.java
一个简单的Reactor模式
Reactor.java
package com.gbcom.protocol.nio.core;
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.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
/**
* 反应器模式，适合nio编码，类似事件驱动编程方式，适合非阻塞IO
*
* 相比较传统的生产者消费者模式，，由于结合nio，不需要开启多个消费者线程，仅仅需要开启一个Reactor线程进行轮询
* 性能会更高，（reactor 模式 必须结合 nio 也就是 非阻塞的模式使用）
*
*
* netty 使用 reactor模式nio部分的编码
* @author SYZ
* @date 2016-11-1 上午10:52:58
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.Reactor
*/
class Reactor implements Runnable {
final Selector selector;
final ServerSocketChannel serverSocket;
Reactor(int port) throws IOException {
selector = Selector.open();
serverSocket = ServerSocketChannel.open();
serverSocket.socket().bind(new InetSocketAddress(port));
serverSocket.configureBlocking(false);
SelectionKey sk = serverSocket.register(selector,
SelectionKey.OP_ACCEPT);
sk.attach(new Acceptor());
}
/*
* Alternatively, use explicit SPI provider: SelectorProvider p =
* SelectorProvider.provider(); selector = p.openSelector(); serverSocket =
* p.openServerSocketChannel();
*/
// class Reactor continued
public void run() { // normally in a new Thread
try {
while (!Thread.interrupted()) {
selector.select(); //select这个函数是block，
Set selected = selector.selectedKeys();
Iterator it = selected.iterator();
while (it.hasNext())
dispatch((SelectionKey) (it.next()));
selected.clear();
}
} catch (IOException ex) { /* ... */
}
}
void dispatch(SelectionKey k) {
Runnable r = (Runnable) (k.attachment());
if (r != null)
r.run();
}
// class Reactor continued //接收者处理方法
class Acceptor implements Runnable {
// inner
public void run() {
try {
SocketChannel c = serverSocket.accept();//1.select()方法仅仅通知有事件到来， 真正的接受 还是要使用 accept
//每个客户端 应该只执行一次，也就是 new Handler 会重新注册到该select中，以后不会再重复创建了。。。（待测试）
if (c != null)
new Handler(selector, c);
} catch (IOException ex) { /* ... */
}
}
}
/**
* Test: (Reactor.main)
* @param args
* @throws IOException
*/
public static void main(String args[]) throws IOException{
System.out.println(SelectionKey.OP_ACCEPT);
Reactor reactor = new Reactor(1107);
Thread t = new Thread(reactor);
// t.setDaemon(true);
t.start();
}
}
Handler.java
package com.gbcom.protocol.nio.core;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
/**
* 请求的处理，sk.attach(this);是关键，，也就是直接添加到 选择器中，，如果有事件到来，，直接会调用run方法
*
* 注意 该方法并没有开启线程处理
*
* @author SYZ
* @date 2016-11-1 上午11:08:04
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.Handler
*/
final class Handler implements Runnable {
final SocketChannel socket;
final SelectionKey sk;
ByteBuffer input = ByteBuffer.allocate(0);
ByteBuffer output = ByteBuffer.allocate(100);
static final int READING = 0, SENDING = 1;
int state = READING;
Handler(Selector sel, SocketChannel c) throws IOException {
socket = c;
c.configureBlocking(false);
// Optionally try first read now
sk = socket.register(sel, 0);//把channel 注册到选择器中
sk.attach(this);// 添加到 select中,公用 reactor中的selector线程
sk.interestOps(SelectionKey.OP_READ);
sel.wakeup();// 立即执行
}
boolean inputIsComplete() {
return false; /* ... */
}
boolean outputIsComplete() {
return false; /* ... */
}
void process() {
System.out.println("process!");
/* ... */
}
// class Handler continued
public void run() {
try {
if (state == READING)
read();//IO的read是非阻塞的，但是逻辑是同步，所以有耗时的可能
else if (state == SENDING)
send();
} catch (IOException ex) { /* ... */
}
}
void read() throws IOException {
socket.read(input);
if (inputIsComplete()) {
process();
state = SENDING;// Normally also do first write now
sk.interestOps(SelectionKey.OP_WRITE);
// 设计模式方式
/*
* sk.attach(new Sender()); sk.interest(SelectionKey.OP_WRITE);
* sk.selector().wakeup();
*/
}
}
void send() throws IOException {
socket.write(output);
if (outputIsComplete())
sk.cancel();
}
/**
* 简单封装，并没有使用
* @author SYZ
* @date 2016-11-1 上午11:21:38
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.Sender
*/
class Sender implements Runnable {
public void run() { // ...
try {
socket.write(output);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (outputIsComplete())
sk.cancel();
}
}
}
以上模式在正常非阻塞IO的情况效果还可以，但是要提供效率，可以使用多线程处理 io之后的业务逻辑，下面看一下多线程Reactor模式
多线程Reactor模式
ReactorWithPool.java
package com.gbcom.protocol.nio.core;
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.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
/**
* 反应器的多线程版本，
*
* http://gee.cs.oswego.edu Multiple Reactor Threads " Using Reactor Pools Use
* to match CPU and IO rates Static or dynamic construction " Each with own
* Selector, Thread, dispatch loop Main acceptor distributes to other reacto
*
*
* 选择器也会资源紧张（未深究），所以可以创建多个
* @author SYZ
* @date 2016-11-1 上午11:46:49
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.ReactorWithPool
*/
class ReactorWithPool implements Runnable {
final Selector mainSelector;
Selector[] subselectors = new Selector[10];//业务逻辑相关的选择器，，如何创建？？
// also create threads
int next = 0;
final ServerSocketChannel serverSocket;
ReactorWithPool(int port) throws IOException {
mainSelector = Selector.open();
for(int i=0;i<10;i++){ //add by myself
subselectors[i] = Selector.open();
}
serverSocket = ServerSocketChannel.open();
serverSocket.socket().bind(new InetSocketAddress(port));
serverSocket.configureBlocking(false);
SelectionKey sk = serverSocket.register(mainSelector,
SelectionKey.OP_ACCEPT);
sk.attach(new Acceptor());
}
/*
* Alternatively, use explicit SPI provider: SelectorProvider p =
* SelectorProvider.provider(); selector = p.openSelector(); serverSocket =
* p.openServerSocketChannel();
*/
// class Reactor continued
public void run() { // normally in a new Thread
try {
while (!Thread.interrupted()) {
mainSelector.select();
Set selected = mainSelector.selectedKeys();
Iterator it = selected.iterator();
while (it.hasNext())
dispatch((SelectionKey) (it.next()));
selected.clear();
}
} catch (IOException ex) { /* ... */
}
}
void dispatch(SelectionKey k) {
Runnable r = (Runnable) (k.attachment());
if (r != null)
r.run();
}
// class Reactor continued //接收者处理方法
class Acceptor implements Runnable {
// inner
public void run() {
try {
SocketChannel connection = serverSocket.accept();
if (connection != null)
new Handler(subselectors[next], connection);
if (++next == subselectors.length)
next = 0;
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* Test: (Reactor.main)
*
* @param args
* @throws IOException
*/
public static void main(String args[]) throws IOException {
System.out.println(SelectionKey.OP_ACCEPT);
ReactorWithPool reactor = new ReactorWithPool(1107);
Thread t = new Thread(reactor);
t.setDaemon(true);
t.start();
}
}
HandlerWithPool.java
package com.gbcom.protocol.nio.core;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import EDU.oswego.cs.dl.util.concurrent.PooledExecutor;
/**
* 使用线程池处理read之后的事情，主要包括业务逻辑，
* 注意是处理IO read完之后的事情，不是处理IO的读写操作，适用于业务逻辑比较复杂的情况，
*
* 解决逻辑耗时问题
*
* @author SYZ
* @date 2016-11-1 上午11:33:03
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.HandlerWithPool
*/
public class HandlerWithPool implements Runnable{
// uses util.concurrent thread pool
static PooledExecutor pool = new PooledExecutor();
static final int PROCESSING = 3;
final SocketChannel socket;
final SelectionKey sk;
ByteBuffer input = ByteBuffer.allocate(0);
ByteBuffer output = ByteBuffer.allocate(100);
static final int READING = 0, SENDING = 1;
int state = READING;
HandlerWithPool(Selector sel, SocketChannel c) throws IOException {
socket = c;
c.configureBlocking(false);
// Optionally try first read now
sk = socket.register(sel, 0);
sk.attach(this);// 添加到 select中,公用 reactor中的selector线程
sk.interestOps(SelectionKey.OP_READ);
sel.wakeup();// 立即执行
}
boolean inputIsComplete() {
return false; /* ... */
}
boolean outputIsComplete() {
return false; /* ... */
}
void process() {
System.out.println("process!");
/* ... */
}
// class Handler continued
public void run() {
try {
if (state == READING)
read();
else if (state == SENDING)
send();
} catch (IOException ex) { /* ... */
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
synchronized void read() throws IOException, InterruptedException {
socket.read(input);//非阻塞，模式，直接获取了数据，
if (inputIsComplete()) {
state = PROCESSING;
pool.execute(new Processer());
}
}
synchronized void processAndHandOff() {
process();
state = SENDING; // or rebind attachment
sk.interestOps(SelectionKey.OP_WRITE);
}
class Processer implements Runnable {
public void run() { processAndHandOff(); }
}
void send() throws IOException {
socket.write(output);
if (outputIsComplete())
sk.cancel();
}
/**
* 简单封装，并没有使用
* @author SYZ
* @date 2016-11-1 上午11:21:38
* @version 1.0.0
* @see com.gbcom.protocol.nio.core.Sender
*/
class Sender implements Runnable {
public void run() { // ...
try {
socket.write(output);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (outputIsComplete())
sk.cancel();
}
}
}