alluxio.network.protocol.RPCFileReadResponse.java Source code

Introduction

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

Source

/*
 * 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 RPCFileReadRequest}.
 */
@ThreadSafe
public final class RPCFileReadResponse extends RPCResponse {
    private final long mTempUfsFileId;
    private final long mOffset;
    private final long mLength;
    private final DataBuffer mData;
    private final Status mStatus;

    /**
     * Constructs a new RPC response of a {@link RPCFileReadRequest}.
     *
     * @param tempUfsFileId the worker specific id of the ufs file to read
     * @param offset the file 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 RPCFileReadResponse(long tempUfsFileId, long offset, long length, DataBuffer data, Status status) {
        mTempUfsFileId = tempUfsFileId;
        mOffset = offset;
        mLength = length;
        mData = data;
        mStatus = status;
    }

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

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

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

        DataBuffer data = null;
        if (length > 0) {
            data = new DataNettyBuffer(in, (int) length);
        }
        return new RPCFileReadResponse(tempUfsFileId, offset, length, data, Status.fromShort(status));
    }

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

    @Override
    public void encode(ByteBuf out) {
        out.writeLong(mTempUfsFileId);
        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("tempUfsFileId", mTempUfsFileId).add("offset", mOffset)
                .add("length", mLength).add("status", mStatus).toString();
    }

    @Override
    public void validate() {
        Preconditions.checkState(mOffset >= 0, "Offset cannot be negative: %s", mOffset);
        Preconditions.checkState(mLength >= 0, "Length cannot be negative: %s", mLength);
    }

    /**
     * @return the worker specific id of the ufs file
     */
    public long getTempUfsFileId() {
        return mTempUfsFileId;
    }

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

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

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

    /**
     * @return if the message indicates the reader has reached the end of the file
     */
    public boolean isEOF() {
        return mLength == 0;
    }
}