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Java example source code file (AbstractOioMessageChannel.java)

This example Java source code file (AbstractOioMessageChannel.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

abstractoiochannel, abstractoiomessagechannel, arraylist, channelconfig, channelpipeline, ioexception, override, throwable, util

The AbstractOioMessageChannel.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.channel.oio;

import io.netty.channel.Channel;
import io.netty.channel.ChannelConfig;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.RecvByteBufAllocator;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Abstract base class for OIO which reads and writes objects from/to a Socket
 */
public abstract class AbstractOioMessageChannel extends AbstractOioChannel {

    private final List<Object> readBuf = new ArrayList();

    protected AbstractOioMessageChannel(Channel parent) {
        super(parent);
    }

    @Override
    protected void doRead() {
        if (!readPending) {
            // We have to check readPending here because the Runnable to read could have been scheduled and later
            // during the same read loop readPending was set to false.
            return;
        }
        // In OIO we should set readPending to false even if the read was not successful so we can schedule
        // another read on the event loop if no reads are done.
        readPending = false;

        final ChannelConfig config = config();
        final ChannelPipeline pipeline = pipeline();
        final RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
        allocHandle.reset(config);

        boolean closed = false;
        Throwable exception = null;
        try {
            do {
                // Perform a read.
                int localRead = doReadMessages(readBuf);
                if (localRead == 0) {
                    break;
                }
                if (localRead < 0) {
                    closed = true;
                    break;
                }

                allocHandle.incMessagesRead(localRead);
            } while (allocHandle.continueReading());
        } catch (Throwable t) {
            exception = t;
        }

        boolean readData = false;
        int size = readBuf.size();
        if (size > 0) {
            readData = true;
            for (int i = 0; i < size; i++) {
                readPending = false;
                pipeline.fireChannelRead(readBuf.get(i));
            }
            readBuf.clear();
            allocHandle.readComplete();
            pipeline.fireChannelReadComplete();
        }

        if (exception != null) {
            if (exception instanceof IOException) {
                closed = true;
            }

            pipeline.fireExceptionCaught(exception);
        }

        if (closed) {
            if (isOpen()) {
                unsafe().close(unsafe().voidPromise());
            }
        } else if (readPending || config.isAutoRead() || !readData && isActive()) {
            // Reading 0 bytes could mean there is a SocketTimeout and no data was actually read, so we
            // should execute read() again because no data may have been read.
            read();
        }
    }

    /**
     * Read messages into the given array and return the amount which was read.
     */
    protected abstract int doReadMessages(List<Object> msgs) throws Exception;
}

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