alluxio.client.netty.NettyUnderFileSystemBlockReader.java Source code

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Here is the source code for alluxio.client.netty.NettyUnderFileSystemBlockReader.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.netty;

import alluxio.client.UnderFileSystemBlockReader;
import alluxio.client.file.FileSystemContext;
import alluxio.exception.ExceptionMessage;
import alluxio.metrics.MetricsSystem;
import alluxio.network.protocol.RPCBlockReadResponse;
import alluxio.network.protocol.RPCErrorResponse;
import alluxio.network.protocol.RPCMessage;
import alluxio.network.protocol.RPCResponse;
import alluxio.network.protocol.RPCUnderFileSystemBlockReadRequest;

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

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.util.concurrent.TimeUnit;

import javax.annotation.concurrent.NotThreadSafe;
import javax.annotation.concurrent.ThreadSafe;

/**
 * Read data from UFS on a data server using Netty.
 */
@NotThreadSafe
public final class NettyUnderFileSystemBlockReader implements UnderFileSystemBlockReader {
    private static final Logger LOG = LoggerFactory.getLogger(NettyUnderFileSystemBlockReader.class);

    private final FileSystemContext mContext;
    /** A reference to read response so we can explicitly release the resource after reading. */
    private RPCBlockReadResponse mReadResponse = null;

    /**
     * Creates a new {@link NettyUnderFileSystemBlockReader}.
     * @param context the file system context
     */
    public NettyUnderFileSystemBlockReader(FileSystemContext context) {
        mContext = context;
    }

    @Override
    public ByteBuffer read(InetSocketAddress address, long blockId, long offset, long length, long sessionId,
            boolean noCache) throws IOException {
        Channel channel = null;
        ClientHandler clientHandler = null;
        Metrics.NETTY_UFS_BLOCK_READ_OPS.inc();
        try {
            channel = mContext.acquireNettyChannel(address);
            if (!(channel.pipeline().last() instanceof ClientHandler)) {
                channel.pipeline().addLast(new ClientHandler());
            }
            clientHandler = (ClientHandler) channel.pipeline().last();
            SingleResponseListener listener = new SingleResponseListener();
            clientHandler.addListener(listener);

            ChannelFuture channelFuture = channel.writeAndFlush(
                    new RPCUnderFileSystemBlockReadRequest(blockId, offset, length, sessionId, noCache));
            channelFuture = channelFuture.sync();
            if (channelFuture.isDone() && !channelFuture.isSuccess()) {
                LOG.error("Failed to read from %s for block %d with error %s.", address.toString(), blockId,
                        channelFuture.cause());
                throw new IOException(channelFuture.cause());
            }

            RPCResponse response = listener.get(NettyClient.TIMEOUT_MS, TimeUnit.MILLISECONDS);

            switch (response.getType()) {
            case RPC_BLOCK_READ_RESPONSE:
                RPCBlockReadResponse blockResponse = (RPCBlockReadResponse) response;
                LOG.debug("Data {} from machine {} received", blockId, address);

                RPCResponse.Status status = blockResponse.getStatus();
                if (status == RPCResponse.Status.SUCCESS) {
                    // always clear the previous response before reading another one
                    close();
                    mReadResponse = blockResponse;
                    return blockResponse.getPayloadDataBuffer().getReadOnlyByteBuffer();
                }
                throw new IOException(status.getMessage() + " response: " + blockResponse);
            case RPC_ERROR_RESPONSE:
                RPCErrorResponse error = (RPCErrorResponse) response;
                throw new IOException(error.getStatus().getMessage());
            default:
                throw new IOException(ExceptionMessage.UNEXPECTED_RPC_RESPONSE.getMessage(response.getType(),
                        RPCMessage.Type.RPC_BLOCK_READ_RESPONSE));
            }
        } catch (Exception e) {
            Metrics.NETTY_UFS_BLOCK_READ_FAILURES.inc();
            try {
                if (channel != null) {
                    channel.close().sync();
                }
            } catch (InterruptedException ee) {
                throw new RuntimeException(ee);
            }
            throw new IOException(e);
        } finally {
            if (clientHandler != null) {
                clientHandler.removeListeners();
            }
            if (channel != null) {
                mContext.releaseNettyChannel(address, channel);
            }
        }
    }

    /**
     * {@inheritDoc}
     *
     * Releases the underlying buffer of previous/current read response.
     */
    @Override
    public void close() throws IOException {
        if (mReadResponse != null) {
            mReadResponse.getPayloadDataBuffer().release();
            mReadResponse = null;
        }
    }

    /**
     * Class that contains metrics about {@link NettyUnderFileSystemBlockReader}.
     */
    @ThreadSafe
    private static final class Metrics {
        private static final Counter NETTY_UFS_BLOCK_READ_OPS = MetricsSystem.clientCounter("NettyUFSBlockReadOps");
        private static final Counter NETTY_UFS_BLOCK_READ_FAILURES = MetricsSystem
                .clientCounter("NettyUFSBlockReadFailures");

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