/*
* Copyright 2012 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.channel;
import static io.netty.channel.DefaultChannelPipeline.logger;
import io.netty.buffer.ByteBufAllocator;
import io.netty.util.DefaultAttributeMap;
import io.netty.util.Recycler;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.EventExecutorGroup;
import io.netty.util.internal.StringUtil;
import java.net.SocketAddress;
final class DefaultChannelHandlerContext extends DefaultAttributeMap implements ChannelHandlerContext {
volatile DefaultChannelHandlerContext next; //指向后面一个handlercontext
volatile DefaultChannelHandlerContext prev; //指向前面一个handlercontext
private final boolean inbound; //标示当前DefaultChannelHandlerContext所封装的handler是否是一个inbound
private final boolean outbound; //标示当前DefaultChannelHandlerContext所封装的handler是否是一个outbound
private final AbstractChannel channel; //所属的channel
//所属的pipline,pipline中把所有的DefaultChannelHandlerContext组成了一个链表
private final DefaultChannelPipeline pipeline;
private final String name;//名字
private final ChannelHandler handler; //包含的hander
private boolean removed;
// Will be set to null if no child executor should be used, otherwise it will be set to the
// child executor.
//如果没有使用child 执行器，那么这里将被设置为null,否则将赋值为child executor
final EventExecutor executor;
private ChannelFuture succeededFuture;
// Lazily instantiated tasks used to trigger events to a handler with different executor.
private Runnable invokeChannelReadCompleteTask;
private Runnable invokeReadTask;
private Runnable invokeFlushTask;
private Runnable invokeChannelWritableStateChangedTask;
DefaultChannelHandlerContext(DefaultChannelPipeline pipeline, EventExecutorGroup group, String name,
ChannelHandler handler) {
//参数检查
if (name == null) {
throw new NullPointerException("name");
}
if (handler == null) {
throw new NullPointerException("handler");
}
channel = pipeline.channel;
this.pipeline = pipeline;
this.name = name;
this.handler = handler;
//todo:这里的group赋值过程的代码需要好好看看
if (group != null) {
// Pin one of the child executors once and remember it so that the same child executor
// is used to fire events for the same channel.
EventExecutor childExecutor = pipeline.childExecutors.get(group);
if (childExecutor == null) {
childExecutor = group.next();
pipeline.childExecutors.put(group, childExecutor);
}
executor = childExecutor;
} else {
executor = null;
}
inbound = handler instanceof ChannelInboundHandler;
outbound = handler instanceof ChannelOutboundHandler;
}
/**
* Invocation initiated by {@link DefaultChannelPipeline#teardownAll()}}.
*/
void teardown() {
EventExecutor executor = executor();
if (executor.inEventLoop()) {
teardown0();
} else {
executor.execute(new Runnable() {
@Override
public void run() {
teardown0();
}
});
}
}
private void teardown0() {
DefaultChannelHandlerContext prev = this.prev;
if (prev != null) {
synchronized (pipeline) {
pipeline.remove0(this);
}
prev.teardown();
}
}
@Override
public Channel channel() {
return channel;
}
@Override
public ChannelPipeline pipeline() {
return pipeline;
}
@Override
public ByteBufAllocator alloc() {
return channel().config().getAllocator();
}
@Override
public EventExecutor executor() {
if (executor == null) {
return channel().eventLoop();
} else {
return executor;
}
}
@Override
public ChannelHandler handler() {
return handler;
}
@Override
public String name() {
return name;
}
//触发ChannelRegister事件，按照从head ---> tail的顺序寻找inbonud，并依次触发
@Override
public ChannelHandlerContext fireChannelRegistered() {
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelRegistered();
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeChannelRegistered();
}
});
}
return this;
}
private void invokeChannelRegistered() {
try {
((ChannelInboundHandler) handler).channelRegistered(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelHandlerContext fireChannelUnregistered() {
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelUnregistered();
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeChannelUnregistered();
}
});
}
return this;
}
private void invokeChannelUnregistered() {
try {
((ChannelInboundHandler) handler).channelUnregistered(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
//从head-->tail的顺序，寻找inbound并依次触发
@Override
public ChannelHandlerContext fireChannelActive() {
//先找到当前ChannelHandlerContext的下一个ChannelHandlerContext
final DefaultChannelHandlerContext next = findContextInbound();
//得到执行器
EventExecutor executor = next.executor();
/**
* 1.首先executor.inEventLoop()方法判断当前线程是不是netty创建的
*/
//调用上面得到的next的真正的invokeChannelActive
if (executor.inEventLoop()) {
next.invokeChannelActive();
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeChannelActive();
}
});
}
return this;
}
/**
* 注意这里pipline里面的handler是如何链式调用的：
* 1.pipline里面通过 DefaultChannelHandlerContext next，DefaultChannelHandlerContext prev这两个属性把add到pipline
* 的所有handler组装成一个双向链表
* 2.调用真正handler的channelActive方法，同时把当前DefaultChannelHandlerContext对象当做参数传入进去
* 3.我们来看handler默认实现的channelActive方法：
*
* @Override public void channelActive(ChannelHandlerContext ctx) throws Exception {
* ctx.fireChannelActive();
* }
* 默认实现就是调用传入参数的ctx.fireChannelActive()方法，该方法又会重复
* 4.如果在handler对应的方法里面不调用ctx.fireChannelActive();那么循环终止
*/
private void invokeChannelActive() {
try {
((ChannelInboundHandler) handler).channelActive(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelHandlerContext fireChannelInactive() {
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelInactive();
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeChannelInactive();
}
});
}
return this;
}
private void invokeChannelInactive() {
try {
((ChannelInboundHandler) handler).channelInactive(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelHandlerContext fireExceptionCaught(final Throwable cause) {
if (cause == null) {
throw new NullPointerException("cause");
}
final DefaultChannelHandlerContext next = this.next;
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeExceptionCaught(cause);
} else {
try {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeExceptionCaught(cause);
}
});
} catch (Throwable t) {
if (logger.isWarnEnabled()) {
logger.warn("Failed to submit an exceptionCaught() event.", t);
logger.warn("The exceptionCaught() event that was failed to submit was:", cause);
}
}
}
return this;
}
private void invokeExceptionCaught(final Throwable cause) {
try {
handler.exceptionCaught(this, cause);
} catch (Throwable t) {
if (logger.isWarnEnabled()) {
logger.warn(
"An exception was thrown by a user handler's " +
"exceptionCaught() method while handling the following exception:", cause);
}
}
}
@Override
public ChannelHandlerContext fireUserEventTriggered(final Object event) {
if (event == null) {
throw new NullPointerException("event");
}
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeUserEventTriggered(event);
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeUserEventTriggered(event);
}
});
}
return this;
}
private void invokeUserEventTriggered(Object event) {
try {
((ChannelInboundHandler) handler).userEventTriggered(this, event);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
/**
* @param msg 从源代码看，这个代表的是Server accpet后产生的netty封装的NioSocketChannel对象
* @return
*/
@Override
public ChannelHandlerContext fireChannelRead(final Object msg) {
if (msg == null) {
throw new NullPointerException("msg");
}
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelRead(msg);
} else {
executor.execute(new Runnable() {
@Override
public void run() {
next.invokeChannelRead(msg);
}
});
}
return this;
}
private void invokeChannelRead(Object msg) {
try {
((ChannelInboundHandler) handler).channelRead(this, msg);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelHandlerContext fireChannelReadComplete() {
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelReadComplete();
} else {
Runnable task = next.invokeChannelReadCompleteTask;
if (task == null) {
next.invokeChannelReadCompleteTask = task = new Runnable() {
@Override
public void run() {
next.invokeChannelReadComplete();
}
};
}
executor.execute(task);
}
return this;
}
private void invokeChannelReadComplete() {
try {
((ChannelInboundHandler) handler).channelReadComplete(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelHandlerContext fireChannelWritabilityChanged() {
final DefaultChannelHandlerContext next = findContextInbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeChannelWritabilityChanged();
} else {
Runnable task = next.invokeChannelWritableStateChangedTask;
if (task == null) {
next.invokeChannelWritableStateChangedTask = task = new Runnable() {
@Override
public void run() {
next.invokeChannelWritabilityChanged();
}
};
}
executor.execute(task);
}
return this;
}
private void invokeChannelWritabilityChanged() {
try {
((ChannelInboundHandler) handler).channelWritabilityChanged(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelFuture bind(SocketAddress localAddress) {
return bind(localAddress, newPromise());
}
@Override
public ChannelFuture connect(SocketAddress remoteAddress) {
return connect(remoteAddress, newPromise());
}
@Override
public ChannelFuture connect(SocketAddress remoteAddress, SocketAddress localAddress) {
return connect(remoteAddress, localAddress, newPromise());
}
@Override
public ChannelFuture disconnect() {
return disconnect(newPromise());
}
@Override
public ChannelFuture close() {
return close(newPromise());
}
@Override
public ChannelFuture deregister() {
return deregister(newPromise());
}
//bind事件是从tail(是一个Inbound) --->head(是一个Outbound),寻找Outbound并依次触发
@Override
public ChannelFuture bind(final SocketAddress localAddress, final ChannelPromise promise) {
if (localAddress == null) {
throw new NullPointerException("localAddress");
}
validatePromise(promise, false);
//从tail ---> head找Outbound执行
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeBind(localAddress, promise);
} else {
safeExecute(executor, new Runnable() {
@Override
public void run() {
next.invokeBind(localAddress, promise);
}
}, promise, null);
}
return promise;
}
private void invokeBind(SocketAddress localAddress, ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).bind(this, localAddress, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
@Override
public ChannelFuture connect(SocketAddress remoteAddress, ChannelPromise promise) {
return connect(remoteAddress, null, promise);
}
@Override
public ChannelFuture connect(
final SocketAddress remoteAddress, final SocketAddress localAddress, final ChannelPromise promise) {
if (remoteAddress == null) {
throw new NullPointerException("remoteAddress");
}
validatePromise(promise, false);
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeConnect(remoteAddress, localAddress, promise);
} else {
safeExecute(executor, new Runnable() {
@Override
public void run() {
next.invokeConnect(remoteAddress, localAddress, promise);
}
}, promise, null);
}
return promise;
}
private void invokeConnect(SocketAddress remoteAddress, SocketAddress localAddress, ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).connect(this, remoteAddress, localAddress, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
@Override
public ChannelFuture disconnect(final ChannelPromise promise) {
validatePromise(promise, false);
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
// Translate disconnect to close if the channel has no notion of disconnect-reconnect.
// So far, UDP/IP is the only transport that has such behavior.
if (!channel().metadata().hasDisconnect()) {
next.invokeClose(promise);
} else {
next.invokeDisconnect(promise);
}
} else {
safeExecute(executor, new Runnable() {
@Override
public void run() {
if (!channel().metadata().hasDisconnect()) {
next.invokeClose(promise);
} else {
next.invokeDisconnect(promise);
}
}
}, promise, null);
}
return promise;
}
private void invokeDisconnect(ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).disconnect(this, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
@Override
public ChannelFuture close(final ChannelPromise promise) {
validatePromise(promise, false);
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeClose(promise);
} else {
safeExecute(executor, new Runnable() {
@Override
public void run() {
next.invokeClose(promise);
}
}, promise, null);
}
return promise;
}
private void invokeClose(ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).close(this, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
@Override
public ChannelFuture deregister(final ChannelPromise promise) {
validatePromise(promise, false);
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeDeregister(promise);
} else {
safeExecute(executor, new Runnable() {
@Override
public void run() {
next.invokeDeregister(promise);
}
}, promise, null);
}
return promise;
}
private void invokeDeregister(ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).deregister(this, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
//从tail --> head的顺序寻找outbound,并依次调用read方法
@Override
public ChannelHandlerContext read() {
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeRead();
} else {
Runnable task = next.invokeReadTask;
if (task == null) {
next.invokeReadTask = task = new Runnable() {
@Override
public void run() {
next.invokeRead();
}
};
}
executor.execute(task);
}
return this;
}
private void invokeRead() {
try {
((ChannelOutboundHandler) handler).read(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelFuture write(Object msg) {
return write(msg, newPromise());
}
@Override
public ChannelFuture write(final Object msg, final ChannelPromise promise) {
if (msg == null) {
throw new NullPointerException("msg");
}
validatePromise(promise, true);
write(msg, false, promise);
return promise;
}
private void invokeWrite(Object msg, ChannelPromise promise) {
try {
((ChannelOutboundHandler) handler).write(this, msg, promise);
} catch (Throwable t) {
notifyOutboundHandlerException(t, promise);
}
}
@Override
public ChannelHandlerContext flush() {
final DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeFlush();
} else {
Runnable task = next.invokeFlushTask;
if (task == null) {
next.invokeFlushTask = task = new Runnable() {
@Override
public void run() {
next.invokeFlush();
}
};
}
safeExecute(executor, task, channel.voidPromise(), null);
}
return this;
}
private void invokeFlush() {
try {
((ChannelOutboundHandler) handler).flush(this);
} catch (Throwable t) {
notifyHandlerException(t);
}
}
@Override
public ChannelFuture writeAndFlush(Object msg, ChannelPromise promise) {
if (msg == null) {
throw new NullPointerException("msg");
}
validatePromise(promise, true);
write(msg, true, promise);
return promise;
}
private void write(Object msg, boolean flush, ChannelPromise promise) {
DefaultChannelHandlerContext next = findContextOutbound();
EventExecutor executor = next.executor();
if (executor.inEventLoop()) {
next.invokeWrite(msg, promise);
if (flush) {
next.invokeFlush();
}
} else {
int size = channel.estimatorHandle().size(msg);
if (size > 0) {
ChannelOutboundBuffer buffer = channel.unsafe().outboundBuffer();
// Check for null as it may be set to null if the channel is closed already
if (buffer != null) {
buffer.incrementPendingOutboundBytes(size);
}
}
safeExecute(executor, WriteTask.newInstance(next, msg, size, flush, promise), promise, msg);
}
}
@Override
public ChannelFuture writeAndFlush(Object msg) {
return writeAndFlush(msg, newPromise());
}
private static void notifyOutboundHandlerException(Throwable cause, ChannelPromise promise) {
// only try to fail the promise if its not a VoidChannelPromise, as
// the VoidChannelPromise would also fire the cause through the pipeline
if (promise instanceof VoidChannelPromise) {
return;
}
if (!promise.tryFailure(cause)) {
if (logger.isWarnEnabled()) {
logger.warn("Failed to fail the promise because it's done already: {}", promise, cause);
}
}
}
private void notifyHandlerException(Throwable cause) {
if (inExceptionCaught(cause)) {
if (logger.isWarnEnabled()) {
logger.warn(
"An exception was thrown by a user handler " +
"while handling an exceptionCaught event", cause);
}
return;
}
invokeExceptionCaught(cause);
}
private static boolean inExceptionCaught(Throwable cause) {
do {
StackTraceElement[] trace = cause.getStackTrace();
if (trace != null) {
for (StackTraceElement t : trace) {
if (t == null) {
break;
}
if ("exceptionCaught".equals(t.getMethodName())) {
return true;
}
}
}
cause = cause.getCause();
} while (cause != null);
return false;
}
@Override
public ChannelPromise newPromise() {
return new DefaultChannelPromise(channel(), executor());
}
@Override
public ChannelProgressivePromise newProgressivePromise() {
return new DefaultChannelProgressivePromise(channel(), executor());
}
@Override
public ChannelFuture newSucceededFuture() {
ChannelFuture succeededFuture = this.succeededFuture;
if (succeededFuture == null) {
this.succeededFuture = succeededFuture = new SucceededChannelFuture(channel(), executor());
}
return succeededFuture;
}
@Override
public ChannelFuture newFailedFuture(Throwable cause) {
return new FailedChannelFuture(channel(), executor(), cause);
}
private void validatePromise(ChannelPromise promise, boolean allowVoidPromise) {
if (promise == null) {
throw new NullPointerException("promise");
}
if (promise.isDone()) {
throw new IllegalArgumentException("promise already done: " + promise);
}
if (promise.channel() != channel()) {
throw new IllegalArgumentException(String.format(
"promise.channel does not match: %s (expected: %s)", promise.channel(), channel()));
}
if (promise.getClass() == DefaultChannelPromise.class) {
return;
}
if (!allowVoidPromise && promise instanceof VoidChannelPromise) {
throw new IllegalArgumentException(
StringUtil.simpleClassName(VoidChannelPromise.class) + " not allowed for this operation");
}
if (promise instanceof AbstractChannel.CloseFuture) {
throw new IllegalArgumentException(
StringUtil.simpleClassName(AbstractChannel.CloseFuture.class) + " not allowed in a pipeline");
}
}
private DefaultChannelHandlerContext findContextInbound() {
/**
* inbound时候，从head往tail遍历handle,并找出这些handle里面所有inbound类型的handle,
* 一直遍历到TailHandle,TailHandle是netty默认实现的一个inbound类型的handle，这个TailHandle默认实现的
* ChannelInboundHandler接口都是空方法，所以当调用到tail对应的方法的时候，调用链就会终止
*/
DefaultChannelHandlerContext ctx = this;
do {
ctx = ctx.next;
} while (!ctx.inbound);
return ctx;
}
private DefaultChannelHandlerContext findContextOutbound() {
DefaultChannelHandlerContext ctx = this;
do {
ctx = ctx.prev;
} while (!ctx.outbound);
return ctx;
}
@Override
public ChannelPromise voidPromise() {
return channel.voidPromise();
}
void setRemoved() {
removed = true;
}
@Override
public boolean isRemoved() {
return removed;
}
private static void safeExecute(EventExecutor executor, Runnable runnable, ChannelPromise promise, Object msg) {
try {
executor.execute(runnable);
} catch (Throwable cause) {
try {
promise.setFailure(cause);
} finally {
if (msg != null) {
ReferenceCountUtil.release(msg);
}
}
}
}
static final class WriteTask implements Runnable {
private DefaultChannelHandlerContext ctx;
private Object msg;
private ChannelPromise promise;
private int size;
private boolean flush;
private static final Recycler<WriteTask> RECYCLER = new Recycler<WriteTask>() {
@Override
protected WriteTask newObject(Handle handle) {
return new WriteTask(handle);
}
};
private static WriteTask newInstance(
DefaultChannelHandlerContext ctx, Object msg, int size, boolean flush, ChannelPromise promise) {
WriteTask task = RECYCLER.get();
task.ctx = ctx;
task.msg = msg;
task.promise = promise;
task.size = size;
task.flush = flush;
return task;
}
private final Recycler.Handle handle;
private WriteTask(Recycler.Handle handle) {
this.handle = handle;
}
@Override
public void run() {
try {
if (size > 0) {
ChannelOutboundBuffer buffer = ctx.channel.unsafe().outboundBuffer();
// Check for null as it may be set to null if the channel is closed already
if (buffer != null) {
buffer.decrementPendingOutboundBytes(size);
}
}
ctx.invokeWrite(msg, promise);
if (flush) {
ctx.invokeFlush();
}
} finally {
// Set to null so the GC can collect them directly
ctx = null;
msg = null;
promise = null;
RECYCLER.recycle(this, handle);
}
}
}
}