130614 sebastiano panichella - mining source code descriptions from developers communications

Mining Source Code Descriptions from Developer Communications

Sebastiano Jairo Massimiliano Andrian Gerardo Panichella Aponte Di Penta Marcus Canfora

Context: Software Project

Documentation

Source Code

Developer

Class diagram

Sequence diagram Program

Comprehension

Maintenance Tasks


Documentation

Source Code

Developer

understanding

Class diagram


Comprehension

Difficult

Maintenance Tasks


Documentation

Source Code

Developer

understanding

describes

Class diagram


Comprehension

understanding Difficult

Maintenance Tasks

Source Code

Developer

Coming back to the reality...


Program Comprehension

Maintenance Tasks

understanding Difficult

We argue that messages exchanged among contributors/developers are a useful source of information to help understanding source code.

Idea

In such situations developers need to infer knowledge from,

the source code itself source code descriptions in external artifacts.

Developer

We argue that messages exchanged among contributors/developers are a useful source of information to help understanding source code.

Idea

In such situations developers need to infer knowledge from,

the source code itself source code descriptions in external artifacts.

Developer

..................................................

When call the method IndexSplitter.split(File

destDir, String[] segs) from the Lucene cotrib

directory(contrib/misc/src/java/org/apache/luc

ene/index) it creates an index with segments

descriptor file with wrong data. Namely wrong

is the number representing the name of segment

that would be created next in this index.

..................................................

CLASS: IndexSplitter METHOD: split

A Five Step-Approach for Mining Method Descriptions

Developer

Step 1: Downloading emails/bugs reports and tracing them onto classes

Two heuristics

The discussion contains a fully-qualified class name (e.g., org.apache.lucene.analysis.MappingCharFilter); or the email contains a file name (e.g., MappingCharFilter.java)

For bug reports, we complement the above heuristic by matching the bug ID of each closed bug to the commit notes, therefore tracing the bug report to the files changed in that commit

Developer Discussion

When call the method .split(File destDir, String[] segs) from the

Lucene cotrib directory (contrib/misc/src/java/org/apache/lucene/index) it creates

an index with segments descriptor file with wrong data. Namely wrong is the number

representing the name of segment that would be created next in this index.

public void split(File destDir, String[] segs) throws IOException {

destDir.mkdirs();

FSDirectory destFSDir = FSDirectory.open(destDir);

SegmentInfos destInfos = new SegmentInfos }

If some of the segments of the index already has this name this results either to

impossibility to create new segment or in crating of an corrupted segment.

IndexSplitter

Step 1: Downloading emails/bugs reports and tracing them onto classes

Two heuristics

The discussion contains a fully-qualified class name (e.g., org.apache.lucene.analysis.MappingCharFilter); or the email contains a file name (e.g., MappingCharFilter.java)

For bug reports, we complement the above heuristic by matching the bug ID of each closed bug to the commit notes, therefore tracing the bug report to the files changed in that commit


When call the method .split(File destDir, String[] segs) from the





destDir.mkdirs();





CLASS: IndexSplitter

IndexSplitter

Step 2: Extracting paragraphs

Two heuristics

We consider as paragraphs, text section separated by one or more white lines

We prune out paragraph description from source code fragments and/or stack Traces "by using an approach inspired by the work of Bacchelli et al.


When call the method IndexSplitter.split(File destDir, String[] segs) from the





destDir.mkdirs();





PAR2

PAR3

PAR1

When call the method IndexSplitter.split(File destDir, String[] segs) from the Lucene cotrib directory it creates an index with segments

descriptor file with wrong data. Namely wrong is the number

representing the name of segment that would be created next in this

index.

......................................................................................

......................................................................................

......................................................................................

......................................................................................

Step 3: Tracing paragraphs onto methods

These paragraphs must

respect the following

two conditions:

A) A valid paragraph must contain the keyword “method”

B) and the method name must be followed by a open parenthesis— i.e., we match “foo(”


PAR1

CLASS: IndexSplitter

METHOD: split(

A) B)

Step 4: Heuristic based Filtering

We defined a set of heuristics to further filter the paragraphs associated with

methods that assign each paragraph a score:

..........................

Problem seems to come from

MainMethodeSearchEngine in org.eclipse.jdt.internal.ui.launcher

The Method

searchMainMethods

,there's

a call to addSubTypes(List,

IProgressMonitor, IJavaSearchScope)

Method if includesSubtypes flag is

ON. This method add all types sub-

types as soon as the given scope

encloses them without testing if

sub-types have a main! After return

IType[] before the excecution

..........................

CLASS: MainMethodSearchEngine

(IProgressMonitor,

IJavaSearchScope, boolean)

METHOD: serachMainMethods

SCORE




a) Method parameters: % of parameters s1= mentioned in the paragraphs. Value between 0 and 1

1 if the method does not

have parameters

..........................



The Method

searchMainMethods

,there's







sub-types have a main! After return


..........................


(IProgressMonitor,


METHOD: serachMainMethods % parameter = 100% -> s1= 1

SCORE

a) Method parameters: % of parameters s1= mentioned in the paragraphs. Value between 0 and 1 b) Syntactic descriptions (mentioning return values): check whether the paragraph contains the s2= keyword “return”. If YES Value equal 1, 0 otherwise


have parameters

Equal to one if the method is

void.

..........................



The Method

searchMainMethods

,there's







sub-types have a main! After


..........................



SCORE

(IProgressMonitor,


return

1+

% parameter = 100% -> s1= 1

=






have parameters


void.

c) Overriding/Overloading: 1 if any of the “overload” or s3=“override” keywords appears in the paragraph, 0 otherwise

d) Method invocations: 1 if any of the “call” or s4=“excecute” keywords appears in the paragraph, 0 otherwise

..........................



The Method

searchMainMethods

,there's

a to addSubTypes(List,






sub-types have a main! After

IType[] before the

..........................



SCORE =

return

1+

(IProgressMonitor,


excecution

call

0+ 1

% parameter = 100% -> s1= 1

= 2




We selected paragraphs that have: 1. s1 ≥ thP = 0.5

2. s2 + s3 + s4 ≥ thH = 1

SCORE = 1+ 0+ 1

% parameter = 100% -> s1= 1 ≥ 0.5

= 2 ≥ 1



have parameters


void.

c) Overriding/Overloading: 1 if any of the “overload” or s3=“override” keywords appears in the paragraph, 0 otherwise

d) Method invocations: 1 if any of the “call” or s4=“execute” keywords appears in the paragraph, 0 otherwise




OK

Step 5: Similarity based Filtering

We rank filtered paragraphs through their textual similarity with the method they are likely describing.

Removing: - English stop words; - Programming language keywords Using: - Camel Case splitting the on remaining words - Vector Space Model

METHOD PARAGRAPH SCORE Similarity

Method_3 Paragraph_4 2.5 96.1%











Step 5: Similarity based Filtering

We rank filtered paragraphs through their textual similarity with the method they are likely describing.

Removing: - English stop words; - Programming language keywords Using: - Camel Case splitting the on remaining words - Vector Space Model

METHOD PARAGRAPH SCORE Similarity












th>=0.80

Empirical Study • Goal: analyze source code descriptions in developer

discussions

• Purpose: investigating how developer discussions describe methods of Java Source Code

• Quality focus: find good method description in messages exchanged among contributors/developers

• Context: Bug-report and mailing lists of two Java Project Apache Lucene and Eclipse

Context

Research Questions RQ1 (method coverage): How many methods from

the analyzed software systems are described by the paragraphs identified by the proposed approach?

RQ2 (precision): How precise is the proposed approach

in identifying method descriptions?

RQ3 (missing descriptions): How many potentially

good method descriptions are missed by the approach?

RQ1: How many methods from the analyzed software systems are described by the paragraphs identified by the proposed approach?

RQ2: How precise is the proposed approach in identifying method descriptions?

We sampled 250 descriptions from each project

RQ3: How many potentially good method descriptions are missed by the approach?

TABLE III The analysis of a sample of 100 paragraphs traced to methods,

but not satisfying the Step 4 heuristic

System True Negatives False Negatives

Eclipse 78 22

Apache Lucene 67 33

We sampled 100 descriptions from each project

Conclusion

130614 sebastiano panichella - mining source code descriptions from developers communications

Technology

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