oz.hadoop.yarn.api.FsByteBufferPersister.java Source code

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Here is the source code for oz.hadoop.yarn.api.FsByteBufferPersister.java

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/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed 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 oz.hadoop.yarn.api;

import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

/**
 * @author Oleg Zhurakousky
 *
 */
public class FsByteBufferPersister {

    private final static Log logger = LogFactory.getLog(FsByteBufferPersister.class);

    private final Map<String, WritableByteChannel> outputChannels;

    private final FileSystem fileSystem;

    /**
     * 
     * @param fileNamingStrategy
     */
    public FsByteBufferPersister() {
        this.outputChannels = new HashMap<String, WritableByteChannel>();
        Configuration configuration = new Configuration();
        try {
            this.fileSystem = FileSystem.get(configuration);
        } catch (Exception e) {
            throw new IllegalStateException(
                    "Failed to create an instance of FsPersistingApplicationContainerProcessor", e);
        }
        if (logger.isDebugEnabled()) {
            logger.debug("Successfully created FsPersistingApplicationContainerProcessor");
        }
    }

    /**
     * 
     * @param dataBuffer
     */
    public void persist(String dataIdentifier, ByteBuffer dataBuffer) {
        WritableByteChannel outputChannel = this.outputChannels.get(dataIdentifier);
        if (outputChannel == null) {
            String fileName = this.generateFileName(dataIdentifier);
            try {
                OutputStream os = this.fileSystem.create(new Path(fileName), true);
                outputChannel = Channels.newChannel(os);
                this.outputChannels.put(dataIdentifier, outputChannel);
            } catch (Exception e) {
                throw new IllegalStateException(
                        "Failed to create FSDataOutputStream with fileIdentifier '" + dataIdentifier + "'", e);
            }
        }
        dataBuffer.rewind();
        try {
            outputChannel.write(dataBuffer);
        } catch (Exception e) {
            throw new IllegalStateException("Failed to write data to channel", e);
        }
    }

    /**
     * 
     * @param fileIdentifier
     * @return
     */
    private String generateFileName(String fileIdentifier) {
        UUID uuid = UUID.randomUUID();
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd_HH-mm-ss");
        String fileName = fileIdentifier + "_" + df.format(new Date()) + "_" + uuid.toString().substring(24);
        return fileName;
    }

}