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/*
 * 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:
 *
 *   https://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.handler.timeout;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOutboundHandlerAdapter;
import io.netty.channel.ChannelPromise;
import io.netty.util.internal.ObjectUtil;

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) { ObjectUtil.checkNotNull(unit, "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 { assert ctx.executor().inEventLoop(); WriteTimeoutTask task = lastTask; lastTask = null; while (task != null) { assert task.ctx.executor().inEventLoop(); 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) { assert task.ctx.executor().inEventLoop(); if (lastTask != null) { lastTask.next = task; task.prev = lastTask; } lastTask = task; } private void removeWriteTimeoutTask(WriteTimeoutTask task) { assert task.ctx.executor().inEventLoop(); 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); // Check if its safe to modify the "doubly-linked-list" that we maintain. If its not we will schedule the // modification so its picked up by the executor.. if (ctx.executor().inEventLoop()) { removeWriteTimeoutTask(this); } else { // So let's just pass outself to the executor which will then take care of remove this task // from the doubly-linked list. Schedule ourself is fine as the promise itself is done. // // This fixes https://github.com/netty/netty/issues/11053 assert promise.isDone(); ctx.executor().execute(this); } } } }




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