org.apache.spark.network.shuffle.protocol.BlockTransferMessage.java Source code

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Here is the source code for org.apache.spark.network.shuffle.protocol.BlockTransferMessage.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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 org.apache.spark.network.shuffle.protocol;

import java.nio.ByteBuffer;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;

import org.apache.spark.network.protocol.Encodable;
import org.apache.spark.network.shuffle.protocol.mesos.RegisterDriver;
import org.apache.spark.network.shuffle.protocol.mesos.ShuffleServiceHeartbeat;

/**
 * Messages handled by the {@link org.apache.spark.network.shuffle.ExternalShuffleBlockHandler}, or
 * by Spark's NettyBlockTransferService.
 *
 * At a high level:
 *   - OpenBlock is handled by both services, but only services shuffle files for the external
 *     shuffle service. It returns a StreamHandle.
 *   - UploadBlock is only handled by the NettyBlockTransferService.
 *   - RegisterExecutor is only handled by the external shuffle service.
 */
public abstract class BlockTransferMessage implements Encodable {
    protected abstract Type type();

    /** Preceding every serialized message is its type, which allows us to deserialize it. */
    public enum Type {
        OPEN_BLOCKS(0), UPLOAD_BLOCK(1), REGISTER_EXECUTOR(2), STREAM_HANDLE(3), REGISTER_DRIVER(4), HEARTBEAT(5);

        private final byte id;

        Type(int id) {
            assert id < 128 : "Cannot have more than 128 message types";
            this.id = (byte) id;
        }

        public byte id() {
            return id;
        }
    }

    // NB: Java does not support static methods in interfaces, so we must put this in a static class.
    public static class Decoder {
        /** Deserializes the 'type' byte followed by the message itself. */
        public static BlockTransferMessage fromByteBuffer(ByteBuffer msg) {
            ByteBuf buf = Unpooled.wrappedBuffer(msg);
            byte type = buf.readByte();
            switch (type) {
            case 0:
                return OpenBlocks.decode(buf);
            case 1:
                return UploadBlock.decode(buf);
            case 2:
                return RegisterExecutor.decode(buf);
            case 3:
                return StreamHandle.decode(buf);
            case 4:
                return RegisterDriver.decode(buf);
            case 5:
                return ShuffleServiceHeartbeat.decode(buf);
            default:
                throw new IllegalArgumentException("Unknown message type: " + type);
            }
        }
    }

    /** Serializes the 'type' byte followed by the message itself. */
    public ByteBuffer toByteBuffer() {
        // Allow room for encoded message, plus the type byte
        ByteBuf buf = Unpooled.buffer(encodedLength() + 1);
        buf.writeByte(type().id);
        encode(buf);
        assert buf.writableBytes() == 0 : "Writable bytes remain: " + buf.writableBytes();
        return buf.nioBuffer();
    }
}