cross-application fan-in analysis for finding application-specific concerns

Software Engineering Laboratory, Department of Computer Science, Graduate School of Information Science and Technology, Osaka University

Cross-application Fan-in Analysis for Finding Application-specific Concerns

Makoto IchiiTakashi Ishio

Katsuro Inoue

Osaka University

1AOAsia 42008/12/2


Coding pattern detection Automatic detection of crosscutting concerns helps

Finding refactoring opportunities Understanding application-specific coding rules

Fung: Coding pattern detection tool [Ishio, 2008][Miyake, 2007]

Detects coding patterns including crosscutting concerns from an application using a data mining technique

Basic idea: “a crosscutting concern code frequently appears across an application”

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[Ishio, 2008] T. Ishio. H. Date, T. Miyake and K. Inoue, "Mining Coding Pattern to Detect Crosscutting Concerns in Java Programs", Proc. WCRE2008, 2008

[Miyake, 2007] T. Miyake, T. Ishio, K. Taniguchi, K. Inoue, "Towards Maintenance Support for Idiom-based Code Using Sequential Pattern Mining", Proc. AOASIA3, 2007


Example of coding pattern Coding pattern

An ordered sequence of method calls and control statements that frequently appears in source code.

Process of coding pattern detection

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…if (log.isDebugEnabled()){ log.debug(getMessage());}… …String status = getStatus();if (log.isDebugEnabled()){ log.debug(status);}… …if (log.isDebugEnabled()){ log.debug("QBK");}…

…isDebugEnabled()IFgetMessage()debug()END_IF……getStatus()isDebugEnabled()IFdebug()END_IF……isDebugEnabled()IFdebug()END_IF…

1: isDebugEnabled()2: IF3: debug()4: END_IF

Source code Method call sequence Coding patternparse & normalizeSequentialpattern mining


Needs for application-specific concerns Detected coding patterns include generic idioms

Idioms also frequently appear across code base Less interesting to developers who need application-

specific knowledge

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1: iterator()2: hasNext()3: LOOP4: next()5: hasNext()6: END_LOOP

Logging

Target application Detected patterns

Iterator idiom


Filtering approach:cross-application fan-in analysis Key Idea

Generic idioms appear in various applications Application-specific patterns appear in a few applications

Measure how widely a class/pattern is used across applications

– “Universality” metric

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Logging

Iterator idiom

Appears in only two applications

Appears in almost all applications


Approach overview Collect various applications

Including target application Analyze the use-relation between the classes in the applications Measure universality metric for each classes Filter out the patterns comprising only universally-used classes.

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1. …………………………2. …………………………3. …………………………4. …………………………5. …………………………………



1: activate2: IF3: deactivate4: END_IF

1: indexOf2: lastIndexOf3: substring

1: contains2: IF3: get4: END_IF



1: activate2: IF3: deactivate4: END_IF

1: indexOf2: lastIndexOf3: substring

1: contains2: IF3: get4: END_IF

Target application

Application collection Use-relation between classes List of universally-used classes

Detected patterns Filtered patterns


Cross-application use-relation An extension of ordinal static use-relation analysis between classes in an

application. Build a use-relation graph

Node: class Edge: static use-relation between classes

Kinds of use-relation Inheritance, Method call, Field access, Instantiation and Variable/Parameter

declaration

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Source code Use-relation graph

Warehouse

Liquor

WarehouseApp

WarehouseApp

class Liquor { long price; String name; …}

class Warehouse { … Liquor liq = new Liquor(); …}


Cross-application use-relation Analyze use-relation between classes across application

borders Analyze intra-application use-relation

in the same way with the case of single application If there are several copies of “used class” in different applications,

create edges to all of them

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Warehouse

Liquor

WarehouseApp

Store

Liquor

StoreApp

Paper

Shelf

A copy of Liquor in WarehouseApp


Class fan-in and application fan-in

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Warehouse

Liquor

WarehouseApp

Store

Liquor

StoreApp

Paper

Shelf

Class fan-in of a class c The number of classes using c

Application fan-in of a class c The number of applications using c

App Class CFI AFI

WA Warehouse 0 0

Liquor 3 2

SA Store 0 0

Shelf 1 1

Liquor 3 2

Paper 2 1


The Class Universality Metric Class universality of a class c

Represents how widely a class is used From many classes / applications

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App Class CFI AFI

WA Warehouse 0 0

Liquor 3 2

SA Store 0 0

Shelf 1 1

Liquor (copy) 3 2

Paper 2 1

Univ.

0

1.2

0

0.39

1.2

0.61

|)log(|

)1log(

|)log(|

)1log()(tyuniversali

A

a

C

ic cc

Frequently-used universally

Frequently-used locally

ic: class fan-in of c; ac: application fan-in of c;

|C|: total number of classes; |A|: total number of applications


The Pattern Universality Metric Pattern universality of a pattern p

The minimum universality value of the classes whose methods are invoked in p

A universal pattern comprises only universal classes

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Coding pattern

Class Univ.

Collection 0.72

Iterator 0.77

Involved classes


Pattern universality = 0.72


Case studiesCase Study 1

Measure class universality value of actual classes

Case Study 2 Measure pattern universality value of coding patterns

detected by Fung

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Case Study 1 – OverviewQuestions

Q.1 What kind of classes have high universality?Q.2 Can universality distinguish classes widely used and classes simply

frequently used?Q.3 What threshold value is good for filtering?

Process Measure class universality of classes in application collection Investigate the result to answer the questions

The top-20 classes in the universality [Q.1] Difference between the universality and the fan-in [Q.2] Distribution of the universality [Q.3]

Target 39 application packages (131,328 classes)

Java SE 1.5 Various OSS packages covering a broad range of domains

– Eclipse (IDE), Azureus (Network client), Apache Tomcat (Network server), Freemind (Drawing tool), …

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Case Study 1 –Top 20 classes in the class universality

Q.1 What kind of classes have high universality?

Fundamental / Utility classes

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Class name Univ. CFI

1 java.lang.String 0.933 69,324

2 java.lang.Object 0.915 55,628

3 java.util.List 0.793 12,9814 java.lang.System 0.780 11,191

5 java.lang.Class 0.776 10,590

6 java.lang.Throwable 0.775 10,467

7 java.util.Iterator 0.773 10,191

8 java.util.ArrayList 0.772 10,135

9 java.lang.Exception 0.761 8,840

10 java.util.Map 0.757 8,47611 java.lang.Integer 0.748 7,568

12 java.util.Set 0.741 6,954

13 java.io.File 0.736 6,554

14 java.lang.StringBuffer 0.735 6,907

15 java.io.PrintStream 0.730 6,132

16 java.util.HashMap 0.730 6,129

17 java.io.IOException 0.725 6,115

18 java.util.Collection 0.724 5,690

19 java.lang.IllegalArgumentException

0.714 5,057

20 java.lang.Runnable 0.699 6,790


Case Study 1 –Universality and fan-in

High universality / Low fan-in Classes with fundamental /

utility role

Low universality / High fan-in Classes implementing

crosscutting concerns in a large application

Q.2 Can universality distinguish classes widely used and classes simply frequently used?

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Class NameRank

[Univ.]Rank [CFI]

java.lang.Character 39 104

java.util.LinkedList 41 105

java.io.FileOutputStream 56 177

java.lang.Comparable 78 240

java.util.Stack 95 354

Class NameRank

[Univ.]Rank [CFI]

org.eclipse.swt...Control

213 25

org.eclipse.swt.SWT 221 34

org.eclipse.core…IResource

564 69

org.openide.util.NbBundle

1,398 24

org.openide.ErrorManager 1,496 54

High universality / Low fan-in

Low universality / High fan-in

Yes.


Case Study 1 –Distribution 1.0-0.5: general-purpose classes

Primitive/fundamental classes, collection utilities, … 0.5-0.2: domain-specific classes

Logging utility, networking, GUI, … 0.2-0: application-local classes

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Univ. #of Classes Package

1.0 – 0.9 2 java.lang

0.9 – 0.8 0 -

0.8 – 0.7 17 java.util, java.lang, java.io

0.7 – 0.6 18 java.lang, java.util, java.io, java.net, java.awt

0.6 – 0.5 49 java.util, java.lang, java.io, javax.swing, java.awt,...

0.5 – 0.4 80 java.io, java.lang, javax.swing, javax.swing, java.awt,...

0.4 – 0.3 196 org.eclipse.swt.widgets, javax.swing, java.util, java.awt.event, java.lang, ...

0.3 – 0.2 348 org.eclipse.swt.widgets, org.eclipse.swt.graphics, javax.swing, javax.management, java.awt, ...

0.2 – 0.1 1,385 org.eclipse.swt.widgets, org.eclipse.swt.dnd, javax.management,org.gudy.azureus2.core3.util, org.bouncycastle.asn1, ...

0.1 – 0.0 129,233 soot.jimple.parser.node, org.apache.poi.....functions, test, soot.coffi, ...

Q.3 What threshold value is good for filtering?0.2 for finding application-specific concerns0.5 for filtering out generic concerns


Case Study 2 – Overview Question

Can the pattern universality distinguish among generic, domain-specific and application-specific patterns?

Process Categorize coding patterns according to pattern universality

1.0 – 0.5: Generic pattern 0.5 – 0.2: Domain-specific pattern 0.2 – 0.0: Application-specific pattern

Target Coding patterns

Azureus (presented in [Ishio, 2008]) Application collection

Same as Case Study 12008/12/2 AOAsia 4 17


Case Study 2 – Result Generic patterns (2290 patterns)

String manipulation String.lastIndexOf() / IF / String.substring() / END_IF

Collection manipulation List.get() / IF / List.remove() / END_IF

Domain-specific patterns (79 patterns) Collection manipulation

Map.size() / Iterator.remove() / LinkedHashMap.get() / LinkedHashMap.remove()

Domain-specific?

Application-specific patterns (2293 patterns) Logging

LOOP / Thread.sleep() / Debug.printStackTrace() / END_LOOP Synchronization

IF / AEMonitor.enter() / ArrayList.remove() / AEMonitor.exit() / END_IF

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Q. Can the pattern universality distinguish generic / domain-specific / application-specific patterns?Almost yes.


Discussion Universality metric can distinguish universally-used

classes Resource management classes in Eclipse/NetBeans are

distinguished as application-specific although they have large fan-in

Universality metric value may depend on a set of applications

Case studies in different target are needed E.g. industrial software systems.

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Discussion Some domain-specific classes

have higher class universality than general-purpose classes

- Ideas to improve the metric Propagate fan-in through

important use-relation E.g. inheritance

Combining other metric

+Less popular generic concerns may be more interesting than famous domain-specific ones

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Class name Univ.

…

33 java.awt.Component 0.63

…

113 java.util.ListIterator 0.46

…

230 java.util.LinkedHashMap

0.36

…


Summary and future works Cross-application fan-in analysis for filtering coding

patterns Measures universality, or a metric that represents how

widely a class/pattern is used

Future work Case studies with different applications Refinement of the universality metric

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cross-application fan-in analysis for finding application-specific concerns

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