/*
* 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.aio;
import io.netty.channel.Channel;
import io.netty.channel.EventLoop;
import java.nio.channels.CompletionHandler;
/**
* Special {@link CompletionHandler} which makes sure that the callback methods gets executed in the {@link EventLoop}
*/
public abstract class AioCompletionHandler<V, A extends Channel> implements CompletionHandler<V, A> {
/**
* See {@link CompletionHandler#completed(Object, Object)}
*/
protected abstract void completed0(V result, A channel);
/**
* Set {@link CompletionHandler#failed(Throwable, Object)}
*/
protected abstract void failed0(Throwable exc, A channel);
// According to JDK AIO documentation, the ExecutorService a user specified must not call the Runnable given by
// JDK AIO implementation directly. However, we violates that rull by calling Runnable.run() directly for
// optimization purposes, and it can result in infinite recursion in combination with the fact that the JDK AIO
// implementation often makes recursive invocations. Therefore, we must make sure we don't go too deep in the
// stack.
private static final int MAX_STACK_DEPTH = 8;
private static final ThreadLocal<Integer> STACK_DEPTH = new ThreadLocal<Integer>() {
@Override
protected Integer initialValue() {
return 0;
}
};
@Override
public final void completed(final V result, final A channel) {
EventLoop loop = channel.eventLoop();
if (loop.inEventLoop()) {
Integer d = STACK_DEPTH.get();
if (d < MAX_STACK_DEPTH) {
STACK_DEPTH.set(d + 1);
try {
completed0(result, channel);
} finally {
STACK_DEPTH.set(d);
}
} else {
// schedule it with a special runnable to make sure we keep the right
// order and exist the recursive call to prevent stackoverflow
loop.execute(new AioEventLoop.RecursionBreakingRunnable() {
@Override
public void run() {
completed0(result, channel);
}
});
}
} else {
loop.execute(new Runnable() {
@Override
public void run() {
completed0(result, channel);
}
});
}
}
@Override
public final void failed(final Throwable exc, final A channel) {
EventLoop loop = channel.eventLoop();
if (loop.inEventLoop()) {
Integer d = STACK_DEPTH.get();
if (d < MAX_STACK_DEPTH) {
STACK_DEPTH.set(d + 1);
try {
failed0(exc, channel);
} finally {
STACK_DEPTH.set(d);
}
} else {
// schedule it with a special runnable to make sure we keep the right
// order and exist the recursive call to prevent stackoverflow
loop.execute(new AioEventLoop.RecursionBreakingRunnable() {
@Override
public void run() {
failed0(exc, channel);
}
});
}
} else {
loop.execute(new Runnable() {
@Override
public void run() {
failed0(exc, channel);
}
});
}
}
}