alluxio.network.protocol.RPCBlockReadResponse.java Source code

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Here is the source code for alluxio.network.protocol.RPCBlockReadResponse.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 alluxio.network.protocol.databuffer.DataNettyBuffer;

import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.primitives.Longs;
import com.google.common.primitives.Shorts;
import io.netty.buffer.ByteBuf;

import javax.annotation.concurrent.ThreadSafe;

/**
 * This represents the response of a {@link RPCBlockReadRequest}.
 *
 * Since 1.5.0, this also represents the response of a {@link RPCUnderFileSystemBlockReadRequest}.
 */
@ThreadSafe
public final class RPCBlockReadResponse extends RPCResponse {
    private final long mBlockId;
    private final long mOffset;
    private final long mLength;
    private final DataBuffer mData;
    private final Status mStatus;

    /**
     * Constructs a new RPC response of a {@link RPCBlockReadRequest} or a
     * {@link RPCUnderFileSystemBlockReadRequest}.
     *
     * @param blockId the id of the block
     * @param offset the block offset that the read began at
     * @param length the number of bytes read
     * @param data the data for the response
     * @param status the status of the response
     */
    public RPCBlockReadResponse(long blockId, long offset, long length, DataBuffer data, Status status) {
        mBlockId = blockId;
        mOffset = offset;
        mLength = length;
        mData = data;
        mStatus = status;
    }

    @Override
    public Type getType() {
        return Type.RPC_BLOCK_READ_RESPONSE;
    }

    /**
     * Creates a {@link RPCBlockReadResponse} object that indicates an error for the given
     * {@link RPCBlockReadRequest}.
     *
     * @param request the {@link RPCBlockReadRequest} to generated
     * the {@link RPCBlockReadResponse} for
     * @param status the {@link alluxio.network.protocol.RPCResponse.Status} for the response
     * @return The generated {@link RPCBlockReadResponse} object
     */
    public static RPCBlockReadResponse createErrorResponse(final RPCBlockReadRequest request, final Status status) {
        Preconditions.checkArgument(status != Status.SUCCESS);
        // The response has no payload, so length must be 0.
        return new RPCBlockReadResponse(request.getBlockId(), request.getOffset(), 0, null, status);
    }

    /**
     * Creates a {@link RPCBlockReadResponse} object that indicates an error for the given
     * {@link RPCUnderFileSystemBlockReadRequest}.
     *
     * @param request the {@link RPCUnderFileSystemBlockReadRequest} to generate
     *        the {@link RPCBlockReadResponse} for
     * @param status the {@link alluxio.network.protocol.RPCResponse.Status} for the response
     * @return The generated {@link RPCBlockReadResponse} object
     */
    public static RPCBlockReadResponse createErrorResponse(final RPCUnderFileSystemBlockReadRequest request,
            final Status status) {
        Preconditions.checkArgument(status != Status.SUCCESS);
        // The response has no payload, so length must be 0.
        return new RPCBlockReadResponse(request.getBlockId(), request.getOffset(), 0, null, status);
    }

    /**
     * Decodes the input {@link ByteBuf} into a {@link RPCBlockReadResponse} object and returns it.
     *
     * @param in the input {@link ByteBuf}
     * @return The decoded RPCBlockReadResponse object
     */
    public static RPCBlockReadResponse decode(ByteBuf in) {
        long blockId = in.readLong();
        long offset = in.readLong();
        long length = in.readLong();
        short status = in.readShort();

        DataBuffer data = null;
        if (length > 0) {
            // use DataNettyBuffer instead of DataByteBuffer to avoid copying
            data = new DataNettyBuffer(in, (int) length);
        }
        return new RPCBlockReadResponse(blockId, offset, length, data, Status.fromShort(status));
    }

    @Override
    public int getEncodedLength() {
        // 3 longs (mBLockId, mOffset, mLength) + 1 short (mStatus)
        return Longs.BYTES * 3 + Shorts.BYTES;
    }

    @Override
    public void encode(ByteBuf out) {
        out.writeLong(mBlockId);
        out.writeLong(mOffset);
        out.writeLong(mLength);
        out.writeShort(mStatus.getId());
        // The actual payload is not encoded here, since the RPCMessageEncoder will transfer it in a
        // more efficient way.
    }

    @Override
    public DataBuffer getPayloadDataBuffer() {
        return mData;
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(this).add("blockId", mBlockId).add("offset", mOffset).add("length", mLength)
                .add("status", mStatus).toString();
    }

    /**
     * @return the id of the block
     */
    public long getBlockId() {
        return mBlockId;
    }

    /**
     * @return the number of bytes read
     */
    public long getLength() {
        return mLength;
    }

    /**
     * @return the block offset that the read began at
     */
    public long getOffset() {
        return mOffset;
    }

    @Override
    public Status getStatus() {
        return mStatus;
    }
}