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JDBC Driver for Google Cloud Spanner
/*
* 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 nl.topicus.jdbc.shaded.io.netty.handler.timeout;
import nl.topicus.jdbc.shaded.io.netty.bootstrap.ServerBootstrap;
import nl.topicus.jdbc.shaded.io.netty.channel.Channel;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelDuplexHandler;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelFuture;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelFutureListener;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelHandlerContext;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelInitializer;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelOutboundHandlerAdapter;
import nl.topicus.jdbc.shaded.io.netty.channel.ChannelPromise;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
/**
* Raises a {@link WriteTimeoutException} when a write operation cannot finish in a certain period of time.
*
*
* // The connection is closed when a write operation cannot finish in 30 seconds.
*
* public class MyChannelInitializer extends {@link ChannelInitializer}<{@link Channel}> {
* public void initChannel({@link Channel} channel) {
* channel.pipeline().addLast("writeTimeoutHandler", new {@link WriteTimeoutHandler}(30);
* channel.pipeline().addLast("myHandler", new MyHandler());
* }
* }
*
* // Handler should handle the {@link WriteTimeoutException}.
* public class MyHandler extends {@link ChannelDuplexHandler} {
* {@code @Override}
* public void exceptionCaught({@link ChannelHandlerContext} ctx, {@link Throwable} cause)
* throws {@link Exception} {
* if (cause instanceof {@link WriteTimeoutException}) {
* // do something
* } else {
* super.exceptionCaught(ctx, cause);
* }
* }
* }
*
* {@link ServerBootstrap} bootstrap = ...;
* ...
* bootstrap.childHandler(new MyChannelInitializer());
* ...
*
* @see ReadTimeoutHandler
* @see IdleStateHandler
*/
public class WriteTimeoutHandler extends ChannelOutboundHandlerAdapter {
private static final long MIN_TIMEOUT_NANOS = TimeUnit.MILLISECONDS.toNanos(1);
private final long timeoutNanos;
/**
* A doubly-linked list to track all WriteTimeoutTasks
*/
private WriteTimeoutTask lastTask;
private boolean closed;
/**
* Creates a new instance.
*
* @param timeoutSeconds
* write timeout in seconds
*/
public WriteTimeoutHandler(int timeoutSeconds) {
this(timeoutSeconds, TimeUnit.SECONDS);
}
/**
* Creates a new instance.
*
* @param timeout
* write timeout
* @param unit
* the {@link TimeUnit} of {@code timeout}
*/
public WriteTimeoutHandler(long timeout, TimeUnit unit) {
if (unit == null) {
throw new NullPointerException("unit");
}
if (timeout <= 0) {
timeoutNanos = 0;
} else {
timeoutNanos = Math.max(unit.toNanos(timeout), MIN_TIMEOUT_NANOS);
}
}
@Override
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
if (timeoutNanos > 0) {
promise = promise.unvoid();
scheduleTimeout(ctx, promise);
}
ctx.write(msg, promise);
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
WriteTimeoutTask task = lastTask;
lastTask = null;
while (task != null) {
task.scheduledFuture.cancel(false);
WriteTimeoutTask prev = task.prev;
task.prev = null;
task.next = null;
task = prev;
}
}
private void scheduleTimeout(final ChannelHandlerContext ctx, final ChannelPromise promise) {
// Schedule a timeout.
final WriteTimeoutTask task = new WriteTimeoutTask(ctx, promise);
task.scheduledFuture = ctx.executor().schedule(task, timeoutNanos, TimeUnit.NANOSECONDS);
if (!task.scheduledFuture.isDone()) {
addWriteTimeoutTask(task);
// Cancel the scheduled timeout if the flush promise is complete.
promise.addListener(task);
}
}
private void addWriteTimeoutTask(WriteTimeoutTask task) {
if (lastTask == null) {
lastTask = task;
} else {
lastTask.next = task;
task.prev = lastTask;
lastTask = task;
}
}
private void removeWriteTimeoutTask(WriteTimeoutTask task) {
if (task == lastTask) {
// task is the tail of list
assert task.next == null;
lastTask = lastTask.prev;
if (lastTask != null) {
lastTask.next = null;
}
} else if (task.prev == null && task.next == null) {
// Since task is not lastTask, then it has been removed or not been added.
return;
} else if (task.prev == null) {
// task is the head of list and the list has at least 2 nodes
task.next.prev = null;
} else {
task.prev.next = task.next;
task.next.prev = task.prev;
}
task.prev = null;
task.next = null;
}
/**
* Is called when a write timeout was detected
*/
protected void writeTimedOut(ChannelHandlerContext ctx) throws Exception {
if (!closed) {
ctx.fireExceptionCaught(WriteTimeoutException.INSTANCE);
ctx.close();
closed = true;
}
}
private final class WriteTimeoutTask implements Runnable, ChannelFutureListener {
private final ChannelHandlerContext ctx;
private final ChannelPromise promise;
// WriteTimeoutTask is also a node of a doubly-linked list
WriteTimeoutTask prev;
WriteTimeoutTask next;
ScheduledFuture scheduledFuture;
WriteTimeoutTask(ChannelHandlerContext ctx, ChannelPromise promise) {
this.ctx = ctx;
this.promise = promise;
}
@Override
public void run() {
// Was not written yet so issue a write timeout
// The promise itself will be failed with a ClosedChannelException once the close() was issued
// See https://github.com/netty/netty/issues/2159
if (!promise.isDone()) {
try {
writeTimedOut(ctx);
} catch (Throwable t) {
ctx.fireExceptionCaught(t);
}
}
removeWriteTimeoutTask(this);
}
@Override
public void operationComplete(ChannelFuture future) throws Exception {
// scheduledFuture has already be set when reaching here
scheduledFuture.cancel(false);
removeWriteTimeoutTask(this);
}
}
}