[jira] [Created] (LUCENE-8476) Bug fix and optimizations in UserDictionary(KoreanAnalyzer)

["Namgyu Kim (JIRA)" <ji...@apache.org>]

Namgyu Kim created LUCENE-8476:
----------------------------------

             Summary:  Bug fix and optimizations in UserDictionary(KoreanAnalyzer)
                 Key: LUCENE-8476
                 URL: https://issues.apache.org/jira/browse/LUCENE-8476
             Project: Lucene - Core
          Issue Type: Bug
          Components: modules/analysis
            Reporter: Namgyu Kim


 

■ Bug fix

1) BufferedReader's close method is not called.

 
{code:java}
// Line 57 method
public static UserDictionary open(Reader reader) throws IOException {

  BufferedReader br = new BufferedReader(reader);
  String line = null;
  List<String> entries = new ArrayList<>();

  // text + optional segmentations
  while ((line = br.readLine()) != null) {
    ...
  }

  if (entries.isEmpty()) {
    return null;
  } else {
    return new UserDictionary(entries);
  }
}{code}
If you look at the code above, there is no close() method for the "br" variable.
As I know, BufferedReader can cause a +memory leak+ if the close method is not called.
So I changed the code below.
{code:java}
// Line 57 method
public static UserDictionary open(Reader reader) throws IOException {

  String line = null;
  List<String> entries = new ArrayList<>();

  // text + optional segmentations
  try (BufferedReader br = new BufferedReader(reader)) {
    while ((line = br.readLine()) != null) {
      ...
    }
  }

  if (entries.isEmpty()) {
    return null;
  } else {
    return new UserDictionary(entries);
  }
}
{code}
I solved this problem with "[try-with-resources|https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html]" method available since Java 7.

 

■ Optimizations

1) Change from Collections.sort to List.sort (UserDictionary constructor)
{code:java}
// Line 82 method
private UserDictionary(List<String> entries) throws IOException {
  final CharacterDefinition charDef = CharacterDefinition.getInstance();
  Collections.sort(entries,
      Comparator.comparing(e -> e.split("\\s+")[0]));

  PositiveIntOutputs fstOutput = PositiveIntOutputs.getSingleton();
  ...
}{code}
List.sort in Java 8 is known to be faster than existing Collections.sort. (http://ankitsambyal.blogspot.com/2014/03/difference-between-listsort-and.html) So I changed the code below.

 
{code:java}
// Line 82 method
private UserDictionary(List<String> entries) throws IOException {
  final CharacterDefinition charDef = CharacterDefinition.getInstance();
  entries.sort(Comparator.comparing(e -> e.split("\\s+")[0]));

  PositiveIntOutputs fstOutput = PositiveIntOutputs.getSingleton();
  ...
}{code}
 

 

2) Remove unnecessary null check (UserDictionary constructor)

 
{code:java}
// Line 82 method
private UserDictionary(List<String> entries) throws IOException {
  ...
  String lastToken = null;
  ...
  for (String entry : entries) {
    String[] splits = entry.split("\\s+");
    String token = splits[0];
    if (lastToken != null && token.equals(lastToken)) {
      continue;
    }
    char lastChar = entry.charAt(entry.length()-1);
  ...
}{code}
Looking at this part of the code,
{code:java}
if (lastToken != null && token.equals(lastToken)) {
  continue;
}{code}
A null check for lastToken is unnecessary.
Because the equals method of the String class internally performs a null check.
So I changed the code as below.
{code:java}
// Line 82 method
private UserDictionary(List<String> entries) throws IOException {
  ...
  String lastToken = null;
  ...
  for (String entry : entries) {
    String[] splits = entry.split("\\s+");
    String token = splits[0];
    if (token.equals(lastToken)) {
      continue;
    }
    char lastChar = entry.charAt(entry.length()-1);
  ...
}{code}
 

 

 



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