Java example source code file (ReadTimeoutHandler.java)

This example Java source code file (ReadTimeoutHandler.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

channelhandlercontext, channelinboundhandleradapter, exception, initialized, min_timeout_nanos, nullpointerexception, object, override, readtimeouthandler, readtimeouttask, runnable, scheduledfuture, threading, threads, throwable, timeunit

The ReadTimeoutHandler.java Java example source code

/*
 * 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.handler.timeout;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;

import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * Raises a {@link ReadTimeoutException} when no data was read within a certain
 * period of time.
 *
 * <pre>
 * // The connection is closed when there is no inbound traffic
 * // for 30 seconds.
 *
 * public class MyChannelInitializer extends {@link ChannelInitializer}<{@link Channel}> {
 *     public void initChannel({@link Channel} channel) {
 *         channel.pipeline().addLast("readTimeoutHandler", new {@link ReadTimeoutHandler}(30);
 *         channel.pipeline().addLast("myHandler", new MyHandler());
 *     }
 * }
 *
 * // Handler should handle the {@link ReadTimeoutException}.
 * public class MyHandler extends {@link ChannelDuplexHandler} {
 *     {@code @Override}
 *     public void exceptionCaught({@link ChannelHandlerContext} ctx, {@link Throwable} cause)
 *             throws {@link Exception} {
 *         if (cause instanceof {@link ReadTimeoutException}) {
 *             // do something
 *         } else {
 *             super.exceptionCaught(ctx, cause);
 *         }
 *     }
 * }
 *
 * {@link ServerBootstrap} bootstrap = ...;
 * ...
 * bootstrap.childHandler(new MyChannelInitializer());
 * ...
 * </pre>
 * @see WriteTimeoutHandler
 * @see IdleStateHandler
 */
public class ReadTimeoutHandler extends ChannelInboundHandlerAdapter {
    private static final long MIN_TIMEOUT_NANOS = TimeUnit.MILLISECONDS.toNanos(1);

    private final long timeoutNanos;

    private long lastReadTime;

    private volatile ScheduledFuture<?> timeout;

    private volatile int state; // 0 - none, 1 - Initialized, 2 - Destroyed;

    private volatile boolean reading;
    private boolean closed;

    /**
     * Creates a new instance.
     *
     * @param timeoutSeconds
     *        read timeout in seconds
     */
    public ReadTimeoutHandler(int timeoutSeconds) {
        this(timeoutSeconds, TimeUnit.SECONDS);
    }

    /**
     * Creates a new instance.
     *
     * @param timeout
     *        read timeout
     * @param unit
     *        the {@link TimeUnit} of {@code timeout}
     */
    public ReadTimeoutHandler(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 handlerAdded(ChannelHandlerContext ctx) throws Exception {
        if (ctx.channel().isActive() && ctx.channel().isRegistered()) {
            // channelActvie() event has been fired already, which means this.channelActive() will
            // not be invoked. We have to initialize here instead.
            initialize(ctx);
        } else {
            // channelActive() event has not been fired yet.  this.channelActive() will be invoked
            // and initialization will occur there.
        }
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        destroy();
    }

    @Override
    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
        // Initialize early if channel is active already.
        if (ctx.channel().isActive()) {
            initialize(ctx);
        }
        super.channelRegistered(ctx);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        // This method will be invoked only if this handler was added
        // before channelActive() event is fired.  If a user adds this handler
        // after the channelActive() event, initialize() will be called by beforeAdd().
        initialize(ctx);
        super.channelActive(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        destroy();
        super.channelInactive(ctx);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        reading = true;
        ctx.fireChannelRead(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        lastReadTime = System.nanoTime();
        reading = false;
        ctx.fireChannelReadComplete();
    }

    private void initialize(ChannelHandlerContext ctx) {
        // Avoid the case where destroy() is called before scheduling timeouts.
        // See: https://github.com/netty/netty/issues/143
        switch (state) {
        case 1:
        case 2:
            return;
        }

        state = 1;

        lastReadTime = System.nanoTime();
        if (timeoutNanos > 0) {
            timeout = ctx.executor().schedule(
                    new ReadTimeoutTask(ctx),
                    timeoutNanos, TimeUnit.NANOSECONDS);
        }
    }

    private void destroy() {
        state = 2;

        if (timeout != null) {
            timeout.cancel(false);
            timeout = null;
        }
    }

    /**
     * Is called when a read timeout was detected.
     */
    protected void readTimedOut(ChannelHandlerContext ctx) throws Exception {
        if (!closed) {
            ctx.fireExceptionCaught(ReadTimeoutException.INSTANCE);
            ctx.close();
            closed = true;
        }
    }

    private final class ReadTimeoutTask implements Runnable {

        private final ChannelHandlerContext ctx;

        ReadTimeoutTask(ChannelHandlerContext ctx) {
            this.ctx = ctx;
        }

        @Override
        public void run() {
            if (!ctx.channel().isOpen()) {
                return;
            }

            long nextDelay = timeoutNanos;
            if (!reading) {
                nextDelay -= System.nanoTime() - lastReadTime;
            }

            if (nextDelay <= 0) {
                // Read timed out - set a new timeout and notify the callback.
                timeout = ctx.executor().schedule(this, timeoutNanos, TimeUnit.NANOSECONDS);
                try {
                    readTimedOut(ctx);
                } catch (Throwable t) {
                    ctx.fireExceptionCaught(t);
                }
            } else {
                // Read occurred before the timeout - set a new timeout with shorter delay.
                timeout = ctx.executor().schedule(this, nextDelay, TimeUnit.NANOSECONDS);
            }
        }
    }
}