FileTollDataStore.java

/*
 * #!
 * %
 * Copyright (C) 2014 - 2016 Humboldt-Universität zu Berlin
 * %
 * 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 de.hub.cs.dbis.lrb.toll;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.LinkedList;
import java.util.Queue;

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

import storm.lrb.model.TollEntry;





/**
 * A {@link TollDataStore} that uses a file for storage including all disadvantages. Use only in a very simple topology
 * as the file I/O can easily produce a performance bottleneck.
 * 
 * @author richter
 */
public class FileTollDataStore implements TollDataStore {
	private static final long serialVersionUID = 1L;
	private static final Logger LOG = LoggerFactory.getLogger(FileTollDataStore.class);
	private final File histFile;
	
	private boolean firstWriteDone = false;
	
	/**
	 * Creates a {@code FileTollDataStore} using a temporary file
	 * 
	 * @throws java.io.IOException
	 *             if the creation of the temporary file fails
	 */
	public FileTollDataStore() throws IOException {
		this.histFile = File.createTempFile("aeolus-lrb", null);
	}
	
	/**
	 * Creates a {@code FileTollDataStore} reading from {@code histFile}.
	 * 
	 * @param histFile
	 */
	public FileTollDataStore(File histFile) {
		this.histFile = histFile;
	}
	
	/**
	 * 
	 * @param histFilePath
	 * @throws FileNotFoundException
	 *             if the file denoted by {@code histFilePath} doesn't exist
	 * @throws IllegalArgumentException
	 *             if {@code histFilePath} is {@code null} or empty.
	 */
	public FileTollDataStore(String histFilePath) throws FileNotFoundException {
		if(histFilePath == null) {
			throw new IllegalArgumentException("histFilePath mustn't be null.");
		}
		if(histFilePath.isEmpty()) {
			throw new IllegalArgumentException("no filename for historic data given.");
		}
		this.histFile = new File(histFilePath);
	}
	
	@Override
	public Integer retrieveToll(int xWay, int day, int vehicleIdentifier) {
		ObjectInputStream objectInputStream = null;
		try {
			FileInputStream is = new FileInputStream(this.histFile);
			objectInputStream = new ObjectInputStream(is);
			Object nextObject = objectInputStream.readObject();
			while(nextObject != null) {
				TollEntry next = (TollEntry)nextObject;
				if(next.getxWay() == xWay && next.getADay() == day && next.getVehicleIdentifier() == vehicleIdentifier) {
					return next.getToll();
				}
			}
			objectInputStream.close();
			is.close();
		} catch(IOException ex) {
			throw new RuntimeException(ex);
		} catch(ClassNotFoundException ex) {
			throw new RuntimeException(ex);
		} finally {
			if(objectInputStream != null) {
				try {
					objectInputStream.close();
				} catch(IOException e) {
					LOG.error("Could not close file input stream of " + this.histFile, e);
				}
			}
		}
		return null;
	}
	
	@Override
	public void storeToll(int xWay, int day, int vehicleIdentifier, int toll) {
		try {
			if(!this.firstWriteDone) {
				FileOutputStream os = new FileOutputStream(this.histFile, true // append
				);
				ObjectOutputStream objectOutputStream = new ObjectOutputStream(os);
				objectOutputStream.writeObject(null);
				objectOutputStream.flush();
				objectOutputStream.close();
				os.flush();
				os.close();
				this.firstWriteDone = true;
			}
			FileInputStream is = new FileInputStream(this.histFile);
			ObjectInputStream objectInputStream = new ObjectInputStream(is);
			File tmpStoreFile = File.createTempFile("aeolus-lrb", null);
			FileOutputStream os = new FileOutputStream(tmpStoreFile);
			ObjectOutputStream objectOutputStream = new ObjectOutputStream(os);
			Object nextObject = objectInputStream.readObject();
			Queue<Object> tmpStore = new LinkedList<Object>();
			while(nextObject != null) {
				tmpStore.add(nextObject);
				if(tmpStore.size() > 1000) {
					while(!tmpStore.isEmpty()) {
						objectOutputStream.writeObject(tmpStore.poll());
					}
				}
				nextObject = objectInputStream.readObject();
			}
			TollEntry newTollEntry = new TollEntry(vehicleIdentifier, xWay, day, toll);
			
			objectOutputStream.writeObject(newTollEntry);
			objectOutputStream.writeObject(null);
			objectInputStream.close();
			objectOutputStream.close();
			is.close();
			os.close();
			this.histFile.delete();
			tmpStoreFile.renameTo(this.histFile);
		} catch(IOException ex) {
			throw new RuntimeException(ex);
		} catch(ClassNotFoundException ex) {
			throw new RuntimeException(ex);
		}
	}
	
	@Override
	public Integer removeEntry(int xWay, int day, int vehicleIdentifier) {
		Integer retValue = null;
		try {
			FileInputStream is = new FileInputStream(this.histFile);
			ObjectInputStream objectInputStream = new ObjectInputStream(is);
			File tmpStoreFile = File.createTempFile("aeolus-lrb", null);
			FileOutputStream os = new FileOutputStream(tmpStoreFile);
			ObjectOutputStream objectOutputStream = new ObjectOutputStream(os);
			Object nextObject = objectInputStream.readObject();
			Queue<Object> tmpStore = new LinkedList<Object>();
			while(nextObject != null) {
				TollEntry next = (TollEntry)nextObject;
				if(!(next.getxWay() == xWay && next.getADay() == day && next.getVehicleIdentifier() == vehicleIdentifier)) {
					tmpStore.add(nextObject);
					if(tmpStore.size() > 1000) {
						while(!tmpStore.isEmpty()) {
							objectOutputStream.writeObject(tmpStore.poll());
						}
					}
				} else {
					retValue = next.getToll();
				}
				nextObject = objectInputStream.readObject();
			}
			objectOutputStream.writeObject(null);
			objectInputStream.close();
			objectOutputStream.close();
			is.close();
			os.close();
			this.histFile.delete();
			tmpStoreFile.renameTo(this.histFile);
		} catch(IOException ex) {
			throw new RuntimeException(ex);
		} catch(ClassNotFoundException ex) {
			throw new RuntimeException(ex);
		}
		return retValue;
	}
	
}