com.onion.master.MasterBlockReader.java Source code

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Here is the source code for com.onion.master.MasterBlockReader.java

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/*
 * Licensed to the University of California, Berkeley under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License. You may obtain a
 * copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.onion.master;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import tachyon.Constants;
import tachyon.client.RemoteBlockReader;
import tachyon.network.protocol.*;

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

/**
 * Read data from from worker data server using Netty.
 */
public final class MasterBlockReader 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;

    public MasterBlockReader() {
        mHandler = new ClientHandler();
        mClientBootstrap = NettyClient.createClientBootstrap(mHandler);
    }

    public ByteBuffer readRemoteBlock(InetSocketAddress address, long blockId, long offset, long length)
            throws IOException {

        try {
            ChannelFuture f = mClientBootstrap.connect(address).sync();

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

            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();
            }
        } catch (Exception e) {
            throw new IOException(e);
        }
    }

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