/*
 * Copyright (c) 2002-2018 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed 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 org.neo4j.driver.internal.async.inbound;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

public class MessageDecoder extends ByteToMessageDecoder
{
    private boolean readMessageBoundary;

    @Override
    public void channelRead( ChannelHandlerContext ctx, Object msg ) throws Exception
    {
        if ( msg instanceof ByteBuf )
        {
            // on every read check if input buffer is empty or not
            // if it is empty then it's a message boundary and full message is in the buffer
            readMessageBoundary = ((ByteBuf) msg).readableBytes() == 0;
        }
        super.channelRead( ctx, msg );
    }

    @Override
    protected void decode( ChannelHandlerContext ctx, ByteBuf in, List<Object> out )
    {
        if ( readMessageBoundary )
        {
            // now we have a complete message in the input buffer

            // increment ref count of the buffer and create it's duplicate that shares the content
            // duplicate will be the output of this decoded and input for the next one
            ByteBuf messageBuf = in.retainedDuplicate();

            // signal that whole message was read by making input buffer seem like it was fully read/consumed
            in.readerIndex( in.readableBytes() );

            // pass the full message to the next handler in the pipeline
            out.add( messageBuf );

            readMessageBoundary = false;
        }
    }
}

/*
 * Copyright (c) 2002-2018 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed 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 org.neo4j.driver.internal.async.inbound;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

public class MessageDecoder extends ByteToMessageDecoder
{
    private static final Cumulator DEFAULT_CUMULATOR = determineDefaultCumulator();

    private boolean readMessageBoundary;

    public MessageDecoder()
    {
        setCumulator( DEFAULT_CUMULATOR );
    }

    @Override
    public void channelRead( ChannelHandlerContext ctx, Object msg ) throws Exception
    {
        if ( msg instanceof ByteBuf )
        {
            // on every read check if input buffer is empty or not
            // if it is empty then it's a message boundary and full message is in the buffer
            readMessageBoundary = ((ByteBuf) msg).readableBytes() == 0;
        }
        super.channelRead( ctx, msg );
    }

    @Override
    protected void decode( ChannelHandlerContext ctx, ByteBuf in, List<Object> out )
    {
        if ( readMessageBoundary )
        {
            // now we have a complete message in the input buffer

            // increment ref count of the buffer and create it's duplicate that shares the content
            // duplicate will be the output of this decoded and input for the next one
            ByteBuf messageBuf = in.retainedDuplicate();

            // signal that whole message was read by making input buffer seem like it was fully read/consumed
            in.readerIndex( in.readableBytes() );

            // pass the full message to the next handler in the pipeline
            out.add( messageBuf );

            readMessageBoundary = false;
        }
    }

    private static Cumulator determineDefaultCumulator()
    {
        String value = System.getProperty( "messageDecoderCumulator", "" );
        if ( "merge".equals( value ) )
        {
            return MERGE_CUMULATOR;
        }
        return COMPOSITE_CUMULATOR;
    }
}

Use composite cumulator for message decoding