alluxio.client.block.stream.LocalFilePacketWriter.java Source code

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Here is the source code for alluxio.client.block.stream.LocalFilePacketWriter.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.client.block.stream;

import alluxio.Configuration;
import alluxio.PropertyKey;
import alluxio.client.block.BlockWorkerClient;
import alluxio.worker.block.io.LocalFileBlockWriter;

import com.google.common.base.Preconditions;
import io.netty.buffer.ByteBuf;

import java.io.IOException;

import javax.annotation.concurrent.NotThreadSafe;

/**
 * A local packet writer that simply writes packets to a local file.
 */
@NotThreadSafe
public final class LocalFilePacketWriter implements PacketWriter {
    private static final long PACKET_SIZE = Configuration.getBytes(PropertyKey.USER_LOCAL_WRITER_PACKET_SIZE_BYTES);
    private static final long FILE_BUFFER_BYTES = Configuration.getBytes(PropertyKey.USER_FILE_BUFFER_BYTES);

    /** The position to write the next byte at. */
    private long mPos = 0;
    /** The number of bytes reserved on the block worker to hold the block. */
    private long mPosReserved = 0;
    private final long mBlockId;
    private final LocalFileBlockWriter mWriter;
    private final BlockWorkerClient mBlockWorkerClient;
    private boolean mClosed = false;

    /**
     * Creates an instance of {@link LocalFilePacketWriter}. This requires the block to be locked
     * beforehand.
     *
     * @param blockWorkerClient the block worker client, not owned by this class
     * @param blockId the block ID
     * @param tier the target tier
     * @throws IOException if it fails to create the packet writer
     * @return the {@link LocalFilePacketWriter} created
     */
    public static LocalFilePacketWriter create(BlockWorkerClient blockWorkerClient, long blockId, int tier)
            throws IOException {
        return new LocalFilePacketWriter(blockWorkerClient, blockId, tier);
    }

    @Override
    public long pos() {
        return mPos;
    }

    @Override
    public int packetSize() {
        return (int) PACKET_SIZE;
    }

    @Override
    public void writePacket(final ByteBuf buf) throws IOException {
        try {
            Preconditions.checkState(!mClosed, "PacketWriter is closed while writing packets.");
            int sz = buf.readableBytes();
            ensureReserved(mPos + sz);
            mPos += sz;
            Preconditions.checkState(buf.readBytes(mWriter.getChannel(), sz) == sz);
        } finally {
            buf.release();
        }
    }

    @Override
    public void cancel() throws IOException {
        close();
    }

    @Override
    public void flush() {
    }

    @Override
    public void close() throws IOException {
        if (mClosed) {
            return;
        }
        try {
            mWriter.close();
        } finally {
            mClosed = true;
        }
    }

    /**
     * Creates an instance of {@link LocalFilePacketWriter}.
     *
     * @param blockWorkerClient the block worker client, not owned by this class
     * @param blockId the block ID
     * @param tier the target tier
     * @throws IOException if it fails to create the packet writer
     */
    private LocalFilePacketWriter(BlockWorkerClient blockWorkerClient, long blockId, int tier) throws IOException {
        String blockPath = blockWorkerClient.requestBlockLocation(blockId, FILE_BUFFER_BYTES, tier);
        mWriter = new LocalFileBlockWriter(blockPath);
        mPosReserved += FILE_BUFFER_BYTES;
        mBlockId = blockId;
        mBlockWorkerClient = blockWorkerClient;
    }

    /**
     * Reserves enough space in the block worker.
     *
     * @param pos the pos of the file/block to reserve to
     * @throws IOException if it fails to reserve the space
     */
    private void ensureReserved(long pos) throws IOException {
        if (pos <= mPosReserved) {
            return;
        }
        long toReserve = Math.max(pos - mPosReserved, FILE_BUFFER_BYTES);
        mBlockWorkerClient.requestSpace(mBlockId, toReserve);
        mPosReserved += toReserve;
    }
}