alluxio.network.protocol.RPCMessageEncoder.java Source code

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Here is the source code for alluxio.network.protocol.RPCMessageEncoder.java

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/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.network.protocol;

import alluxio.network.protocol.databuffer.DataBuffer;

import com.google.common.base.Preconditions;
import com.google.common.primitives.Longs;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.FileRegion;
import io.netty.handler.codec.MessageToMessageEncoder;

import java.util.List;

import javax.annotation.concurrent.ThreadSafe;

/**
 * Simple Netty encoder for RPCMessages.
 */
@ChannelHandler.Sharable
@ThreadSafe
public final class RPCMessageEncoder extends MessageToMessageEncoder<RPCMessage> {

    /**
     * Constructs a new {@link RPCMessageEncoder}.
     */
    public RPCMessageEncoder() {
    }

    @Override
    protected void encode(ChannelHandlerContext ctx, RPCMessage in, List<Object> out) throws Exception {
        RPCRequest.Type type = in.getType();

        long bodyBytes = 0;
        DataBuffer payload = null;

        if (in.hasPayload()) {
            payload = in.getPayloadDataBuffer();
            bodyBytes = payload.getLength();
        }

        int lengthBytes = Longs.BYTES;
        int typeBytes = type.getEncodedLength();
        int messageBytes = in.getEncodedLength();

        int headerBytes = lengthBytes + typeBytes + messageBytes;
        long frameBytes = headerBytes + bodyBytes;

        // Write the header info into a buffer.
        // The format is: [frame length][message type][message][(optional) data]
        ByteBuf buffer = ctx.alloc().buffer();
        buffer.writeLong(frameBytes);
        type.encode(buffer);
        in.encode(buffer);

        // Output the header buffer.
        out.add(buffer);

        if (payload != null && bodyBytes > 0) {
            Object output = payload.getNettyOutput();
            Preconditions.checkArgument(output instanceof ByteBuf || output instanceof FileRegion,
                    "The payload must be a ByteBuf or a FileRegion.");
            out.add(output);
        }
    }
}