alluxio.network.protocol.RPCFileReadRequest.java Source code

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Here is the source code for alluxio.network.protocol.RPCFileReadRequest.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 com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.primitives.Longs;
import io.netty.buffer.ByteBuf;

import javax.annotation.concurrent.ThreadSafe;

/**
 * This represents an RPC request to read a file from an under file system from an Alluxio worker.
 * The file must have been previously opened through an RPC call.
 */
@ThreadSafe
public final class RPCFileReadRequest extends RPCRequest {
    private final long mTempUfsFileId;
    private final long mOffset;
    private final long mLength;

    /**
     * Constructs a new RPC request to read a file from an under file system from an Alluxio worker.
     *
     * @param tempUfsFileId the worker specific id of the ufs file to read
     * @param offset the relative file offset to begin reading at
     * @param length the number of bytes to read
     */
    public RPCFileReadRequest(long tempUfsFileId, long offset, long length) {
        mTempUfsFileId = tempUfsFileId;
        mOffset = offset;
        mLength = length;
    }

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

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

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

    @Override
    public void encode(ByteBuf out) {
        out.writeLong(mTempUfsFileId);
        out.writeLong(mOffset);
        out.writeLong(mLength);
    }

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

    @Override
    public String toString() {
        return Objects.toStringHelper(this).add("tempUfsFileId", mTempUfsFileId).add("offset", mOffset)
                .add("length", mLength).toString();
    }

    /**
     * @return the temporary under file system file id
     */
    public long getTempUfsFileId() {
        return mTempUfsFileId;
    }

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

    /**
     * @return the file offset to begin reading at
     */
    public long getOffset() {
        return mOffset;
    }
}