com.datatorrent.contrib.enrich.FSLoader.java Source code

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Here is the source code for com.datatorrent.contrib.enrich.FSLoader.java

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/**
 * Licensed to the Apache Software Foundation (ASF) 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.datatorrent.contrib.enrich;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.commons.io.IOUtils;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import com.esotericsoftware.kryo.NotNull;
import com.google.common.collect.Maps;
import com.datatorrent.lib.db.cache.CacheManager;
import com.datatorrent.lib.util.FieldInfo;

/**
 * This implementation of {@link BackendLoader} loads the data from a given file
 * into memory cache and serves queries from the cache. When this is set as
 * primaryCache in {@link CacheManager}, CacheManager can call
 * {@link #loadInitialData()} periodically to reload the file. NOTE: This loader
 * should be used with caution as all the data present in the file is loaded in
 * memory because of which the memory consumption may go up.
 *
 * @since 3.4.0
 */
@InterfaceStability.Evolving
public abstract class FSLoader extends ReadOnlyBackup {
    @NotNull
    private String fileName;

    private transient Path filePath;
    private transient FileSystem fs;
    private transient boolean connected;

    private static final Logger logger = LoggerFactory.getLogger(FSLoader.class);

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    @Override
    public Map<Object, Object> loadInitialData() {
        Map<Object, Object> result = null;
        FSDataInputStream in = null;
        BufferedReader bin = null;
        try {
            result = Maps.newHashMap();
            in = fs.open(filePath);
            bin = new BufferedReader(new InputStreamReader(in));
            String line;
            while ((line = bin.readLine()) != null) {
                try {
                    Map<String, Object> tuple = extractFields(line);
                    if (tuple != null && !tuple.isEmpty()) {
                        result.put(getKey(tuple), getValue(tuple));
                    }
                } catch (Exception parseExp) {
                    logger.info("Unable to parse line {}", line);
                }
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            if (bin != null) {
                IOUtils.closeQuietly(bin);
            }
            if (in != null) {
                IOUtils.closeQuietly(in);
            }
            try {
                fs.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        logger.debug("loading initial data {}", result.size());
        return result;
    }

    /**
     * This method is called by {@link #loadInitialData()} to extract values from
     * a record. Concrete implementations override this method to parse a record
     * and convert it to Map of field names and values OR simply returns null to
     * skip the records.
     * 
     * @param line
     *          A single record from file
     * @return a map with field name and value. Null value if returned is ignored
     */
    abstract Map<String, Object> extractFields(String line);

    private Object getValue(Map<String, Object> tuple) {
        ArrayList<Object> includeTuple = new ArrayList<Object>();
        for (FieldInfo s : includeFieldInfo) {
            includeTuple.add(tuple.get(s.getColumnName()));
        }
        return includeTuple;
    }

    private Object getKey(Map<String, Object> tuple) {
        ArrayList<Object> list = new ArrayList<Object>();
        for (FieldInfo key : lookupFieldInfo) {
            list.add(tuple.get(key.getColumnName()));
        }
        return list;
    }

    @Override
    public Object get(Object key) {
        return null;
    }

    @Override
    public List<Object> getAll(List<Object> keys) {
        return null;
    }

    @Override
    public void connect() throws IOException {
        Configuration conf = new Configuration();
        this.filePath = new Path(fileName);
        this.fs = FileSystem.newInstance(filePath.toUri(), conf);
        if (!fs.isFile(filePath)) {
            throw new IOException("Provided path " + fileName + " is not a file");
        }
        connected = true;
    }

    @Override
    public void disconnect() throws IOException {
        if (fs != null) {
            fs.close();
        }
    }

    @Override
    public boolean isConnected() {
        return connected;
    }
}