alluxio.worker.netty.DataServerUFSFileReadHandler.java Source code

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Here is the source code for alluxio.worker.netty.DataServerUFSFileReadHandler.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.file.FileSystemWorker;

import com.codahale.metrics.Counter;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;

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

import javax.annotation.concurrent.NotThreadSafe;

/**
 * This handler handles file read request. Check more information in {@link DataServerReadHandler}.
 */
@NotThreadSafe
public final class DataServerUFSFileReadHandler extends DataServerReadHandler {
    /** The Block Worker which handles blocks stored in the Alluxio storage of the worker. */
    private final FileSystemWorker mWorker;

    /**
     * The block read request internal representation.
     */
    private final class FileReadRequestInternal extends ReadRequestInternal {
        /** The UFS input stream. No need to close. */
        final InputStream mInputStream;

        /**
         * Creates an instance of {@link FileReadRequestInternal}.
         *
         * @param request the block read request
         * @throws Exception if it fails to create the object
         */
        FileReadRequestInternal(Protocol.ReadRequest request) throws Exception {
            super(request.getId(), request.getOffset(), request.getOffset() + request.getLength());
            mInputStream = mWorker.getUfsInputStream(mId, mStart);
        }

        @Override
        public void close() {
        }
    }

    /**
     * Creates an instance of {@link DataServerUFSFileReadHandler}.
     *
     * @param executorService the executor service to run {@link PacketReader}s
     * @param worker the file system worker
     */
    public DataServerUFSFileReadHandler(ExecutorService executorService, FileSystemWorker worker) {
        super(executorService);
        mWorker = worker;
    }

    @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_FILE;
    }

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

    @Override
    protected DataBuffer getDataBuffer(Channel channel, long offset, int len) throws IOException {
        ByteBuf buf = channel.alloc().buffer(len, len);
        try {
            InputStream in = ((FileReadRequestInternal) mRequest).mInputStream;
            if (in != null) { // if we have not reached the end of the file
                while (buf.writableBytes() > 0 && buf.writeBytes(in, buf.writableBytes()) != -1) {
                }
            }
            if (buf.readableBytes() == 0) {
                buf.release();
                return null;
            }
            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
    }
}