alluxio.client.netty.NettyRemoteBlockReader.java Source code

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Here is the source code for alluxio.client.netty.NettyRemoteBlockReader.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.Constants;
import alluxio.client.RemoteBlockReader;
import alluxio.exception.ExceptionMessage;
import alluxio.network.protocol.RPCBlockReadRequest;
import alluxio.network.protocol.RPCBlockReadResponse;
import alluxio.network.protocol.RPCErrorResponse;
import alluxio.network.protocol.RPCMessage;
import alluxio.network.protocol.RPCResponse;

import io.netty.bootstrap.Bootstrap;
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;

/**
 * Read data from remote data server using Netty.
 */
@NotThreadSafe
public final class NettyRemoteBlockReader implements RemoteBlockReader {
    private static final Logger LOG = LoggerFactory.getLogger(Constants.LOGGER_TYPE);

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

    /**
     * Creates a new {@link NettyRemoteBlockReader}.
     *
     * TODO(gene): Creating a new remote block reader may be expensive, so consider a connection pool.
     */
    public NettyRemoteBlockReader() {
        mHandler = new ClientHandler();
        mClientBootstrap = NettyClient.createClientBootstrap(mHandler);
    }

    /**
     * Constructor.
     *
     * @param clientBootstrap bootstrap class of the client channel
     * @param clientHandler handler of the client channel
     */
    public NettyRemoteBlockReader(Bootstrap clientBootstrap, ClientHandler clientHandler) {
        mClientBootstrap = clientBootstrap;
        mHandler = clientHandler;
    }

    @Override
    public ByteBuffer readRemoteBlock(InetSocketAddress address, long blockId, long offset, long length,
            long lockId, long sessionId) throws IOException {
        SingleResponseListener listener = null;
        try {
            ChannelFuture f = mClientBootstrap.connect(address).sync();

            LOG.info("Connected to remote machine {}", address);
            Channel channel = f.channel();
            listener = new SingleResponseListener();
            mHandler.addListener(listener);
            channel.writeAndFlush(new RPCBlockReadRequest(blockId, offset, length, lockId, sessionId));

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

            switch (response.getType()) {
            case RPC_BLOCK_READ_RESPONSE:
                RPCBlockReadResponse blockResponse = (RPCBlockReadResponse) response;
                LOG.info("Data {} from remote 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) {
            throw new IOException(e);
        } finally {
            if (listener != null) {
                mHandler.removeListener(listener);
            }
        }
    }

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