2006/09/19 AOAsia 2 1

Towards Locating a Functional Concern Based on a Program Slicing Technique

Takashi Ishio1,2, Ryusuke Niitani2 and Katsuro Inoue2

1University of British Columbia2Osaka University

2006/09/19 AOAsia 2 2

Abstract

Software includes many functional concerns. A functional concern is often implemented by

collaborative software modules. To understand a functional concern, you need to …

Identify clue program elements Find related modules Understand how the modules collaborate

We propose a heuristic approach to automatically extract and show the modules and their collaboration.

costly

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Program Slicing

An automatic technique to extract relevant statements and relations

1. A program P is converted to a program dependence graph. vertices: statements in P edges: control/data dependence relations

2. You specify a slicing criterion <s,v> in P. s: a statement v: a variable defined or used at s

3. You get statements that affect or depend on v by graph traversal.

1 i = 3;2 if (a > 0) {3 print i;4 }

data dependence

<3,i>

controldependence

use

definition

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Issue of Using Program Slicing

Slicing often results too many statements. main(), crosscutting concerns, …

If you calculate a program slice for , slicing extracts .

Main.main(args)App.run()Menu.onClick(buttonID)

FileDialog.getPath()Document.open(path)File.read(path)MDI.add(document)Log.debug(message)

App.quit()FileDialog.getPath()Document.save(path)File.write(path)

dependencecontrol flowconcern (open document)slicing result

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Our Method (1/2)

To extract closely related statements, we terminate the graph traversal at the appropriate vertices.

A barrier [1] is a vertex that terminates the traversal. The original barrier is set manually.

Main.main(args)App.run()Menu.onClick(buttonID)

FileDialog.getPath()Document.open(path)File.read(path)MDI.add(document)Log.debug(message)

App.quit()FileDialog.getPath()Document.save(path)File.write(path)

dependencecontrol flowconcern (open document)slicing resultbarrier

[1] Krinke, J.: Slicing, Chopping, and Path Conditions with Barriers.Software Quality Journal, Vol.12, No.4, pp.339-360,December 2004.

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Our Method (2/2)

Automatically identify appropriate barriers use heuristics

Extract a small subset of conservative slice Closely related to criteria

Conservative Slicing Our Method

dependencespecified criterionconcern relatedresultbarrier

automatically foundBarriers

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Extracting a Functional Concernwith Slicing1. Convert source code to a program dependence

graph

2. Specify one or more methods or fields of interest to you

Inputs are converted to vertices

3. Extract related statements

i. Identify primary vertices

ii. Identify barriers with heuristics

iii. Slice using the result of i. and ii.

4. Visualize the result of 3.

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3.i.Identifying “primary vertices”

Specified vertices= Your inputs

dominator

post-dominator

primary vertices

The vertices in which a barrier is not set to avoid terminating important traversals

The vertices in the paths from dominator to post-dominator dominator: the nearest common ancestor reachable

to all specified vertices post-dominator: the nearest common successor

reachable from all specified vertices

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3.ii.Identifying Barriers with Heuristics A field access

pass data from one concern to another A method entry point with no arguments

Its behavior is independent of the caller method.

An abstract method entry point Its behavior is defined at the interface level.

Library e.g. classes in java and javax package

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3.iii.Slicing A backward/forward traversal from criteria

The traversal is terminated at barriers.

dominator / post-dominatorspecified criterionbarrieradded by slicing

primary vertices slicing result

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Preliminary Case Study

Aim: estimate the effectiveness of our approach Target Program: Duplicated File Checker

Java / 1331 LOC / 14 files Overview

main() → read arguments → begin file checking → notify → output → (end file checking)

Target Concern: “notify” Input: 3 methods

notifyProgressValue, notifyErrorFile, notifyFinished

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Results: size

Small subset (less than 1/4 about LOC)

Heuristic slice:

Checker, FileList, FileMD5 and CheckerListener classes

(Non-heuristic slice) – (Heuristic slice):

Main, MainWindow and classes for GUI

Size of slices

Extracted classes

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Result: extracted slice(as a concern graph) “Notify” concern is

extracted appropriately. No weakly related

method (e.g. main())

Extracted slice (as a concern graph)

criterion

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Summary and Future Work

We proposed an approach to extract the collaborative modules implementing a functional concern. We introduced heuristics into slicing.

Future Work Develop a fully automated analysis tool Apply various heuristics

e.g. a high fan-in method Apply to large-scale software