alluxio.worker.netty.DataServerUfsBlockReadHandler.java Source code

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Here is the source code for alluxio.worker.netty.DataServerUfsBlockReadHandler.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.worker.netty;

import alluxio.metrics.MetricsSystem;
import alluxio.network.protocol.RPCProtoMessage;
import alluxio.network.protocol.databuffer.DataBuffer;
import alluxio.network.protocol.databuffer.DataNettyBufferV2;
import alluxio.proto.dataserver.Protocol;
import alluxio.worker.block.BlockWorker;
import alluxio.worker.block.io.BlockReader;

import com.codahale.metrics.Counter;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.concurrent.ExecutorService;

import javax.annotation.concurrent.NotThreadSafe;

/**
 * This handler handles UFS block read request. Check more information in
 * {@link DataServerReadHandler}.
 */
@NotThreadSafe
final class DataServerUfsBlockReadHandler extends DataServerReadHandler {
    private static final Logger LOG = LoggerFactory.getLogger(DataServerUfsBlockReadHandler.class);

    /** The Block Worker. */
    private final BlockWorker mWorker;

    /**
     * The block read request internal representation.
     */
    private final class UfsBlockReadRequestInternal extends ReadRequestInternal {
        final BlockReader mBlockReader;

        /**
         * Creates an instance of {@link UfsBlockReadRequestInternal}.
         *
         * @param request the block read request
         * @throws Exception if it fails to create the object
         */
        UfsBlockReadRequestInternal(Protocol.ReadRequest request) throws Exception {
            super(request.getId(), request.getOffset(), request.getOffset() + request.getLength());
            mBlockReader = mWorker.readUfsBlock(request.getSessionId(), mId, mStart, request.getNoCache());
            // Note that we do not need to seek to offset since the block worker is created at the offset.
        }

        @Override
        public void close() {
            if (mBlockReader != null) {
                try {
                    mBlockReader.close();
                } catch (Exception e) {
                    LOG.warn("Failed to close block reader for block {}.", mId);
                }
            }
        }
    }

    /**
     * Creates an instance of {@link DataServerReadHandler}.
     *
     * @param executorService the executor service to run {@link PacketReader}s
     * @param blockWorker the block worker
     */
    public DataServerUfsBlockReadHandler(ExecutorService executorService, BlockWorker blockWorker) {
        super(executorService);
        mWorker = blockWorker;
    }

    @Override
    protected boolean acceptMessage(Object object) {
        if (!super.acceptMessage(object)) {
            return false;
        }
        Protocol.ReadRequest request = ((RPCProtoMessage) object).getMessage().getMessage();
        return request.getType() == Protocol.RequestType.UFS_BLOCK;
    }

    @Override
    protected void initializeRequest(Protocol.ReadRequest request) throws Exception {
        mRequest = new UfsBlockReadRequestInternal(request);
    }

    @Override
    protected DataBuffer getDataBuffer(Channel channel, long offset, int len) throws IOException {
        BlockReader blockReader = ((UfsBlockReadRequestInternal) mRequest).mBlockReader;
        // This buf is released by netty.
        ByteBuf buf = channel.alloc().buffer(len, len);
        try {
            while (buf.writableBytes() > 0 && blockReader.transferTo(buf) != -1) {
            }
            return new DataNettyBufferV2(buf);
        } catch (Throwable e) {
            buf.release();
            throw e;
        }
    }

    @Override
    protected void incrementMetrics(long bytesRead) {
        Metrics.BYTES_READ_UFS.inc(bytesRead);
    }

    /**
     * Class that contains metrics for BlockDataServerHandler.
     */
    private static final class Metrics {
        private static final Counter BYTES_READ_UFS = MetricsSystem.workerCounter("BytesReadUFS");

        private Metrics() {
        } // prevent instantiation
    }
}