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/**
*
*/
package de.fhswf.in.inf.java1.aufgabe10;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/**
* A class, that counts words in files.
*
* @author $Author: $
* @version $Revision: $, $Date: $ UTC
*/
public class ParallelWordCount
{
private static final Integer NEWVALUE = new Integer(1);
/**
* Counts words in one line.
*
* @author $Author: $
* @version $Revision: $, $Date: $ UTC
*/
private class LineWordCount implements Runnable
{
private String[] lineArray;
/**
* Creates the object which will be threaded.
*
* @param wordMap
* The wordMap into which the counts should be added.
* @param line
* The line to be counted.
*/
public LineWordCount(String line)
{
if (line == null)
{
throw new IllegalArgumentException("Line can't be null.");
}
if (line.isEmpty())
{
throw new IllegalArgumentException("Line can't be empty.");
}
lineArray = line.split("[^\\p{IsAlphabetic}\\p{Digit}]+");
}
/*
* (non-Javadoc)
*
* @see java.lang.Runnable#run()
*/
@Override
public final void run()
{
for (String word : lineArray)
{
// Split creates empty String, if first char is a split char.
if (!word.isEmpty())
{
word = word.toLowerCase();
boolean success;
do
{
success = true;
Integer tmp = wordMap.putIfAbsent(word, NEWVALUE);
if (tmp != null)
{
success = wordMap.replace(word, tmp, tmp + 1);
}
}
while (!success);
}
}
}
}
private static final int TIMEOUT = 30;
private ConcurrentSkipListMap<String, Integer> wordMap;
/**
* Empty constructor.
*
*/
public ParallelWordCount()
{
}
/**
* Reads a file and counts the words.
*
* @param file
* The file to be read.
*/
public final void readFile(File file)
{
try (BufferedReader f = new BufferedReader(new FileReader(file)))
{
if (wordMap == null)
{
wordMap = new ConcurrentSkipListMap<>();
}
wordMap.clear();
String line = null;
ExecutorService executer = Executors.newFixedThreadPool(Runtime
.getRuntime().availableProcessors());
while ((line = f.readLine()) != null)
{
Runnable worker = new LineWordCount(line);
executer.execute(worker);
}
executer.shutdown();
boolean success = false;
try
{
success = executer.awaitTermination(TIMEOUT, TimeUnit.SECONDS);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
if (!success)
{
wordMap = null;
throw new IllegalStateException(
"Waiting for threads has timed out.");
}
}
catch (IOException e)
{
e.printStackTrace(System.err);
}
}
/**
* Returns all words from the file.
*
* @return An unmodifiable Set of the words from the file.
*/
public final Set<String> getWords()
{
if (wordMap == null)
{
throw new IllegalStateException("First a file must be read.");
}
return Collections.unmodifiableSet(wordMap.keySet());
}
/**
* Returns the count of a word in a file.
*
* @param word
* The file to be counted.
* @return Returns the count of findings in the file.
*/
public final int getCount(String word)
{
if (wordMap == null)
{
throw new IllegalStateException("First a file must be read.");
}
if (word == null)
{
throw new IllegalArgumentException("Word must be a valid referece.");
}
if (word.isEmpty())
{
throw new IllegalArgumentException("The word can't be empty.");
}
Integer tmp = wordMap.get(word);
if (tmp == null)
{
return 0;
}
return tmp;
}
}
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