Development By The Numbers We Are Going To Measure Complexity Why - - PowerPoint PPT Presentation

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Development By The Numbers We Are Going To Measure Complexity Why - - PowerPoint PPT Presentation

Apr 06, 2023 5 likes •1.33k views

Development By The Numbers We Are Going To Measure Complexity Why Should We Care About Complexity? "The Central Enemy Of Reliability is Complexity" - Geer et al. Complexity And Quality Are Strongly Related Basic Metrics

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Development By The Numbers

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We Are Going To Measure Complexity

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Why Should We Care About Complexity?

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  • Geer et al.

"The Central Enemy Of Reliability is Complexity"

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Complexity And Quality Are Strongly Related

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Basic Metrics

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Cyclomatic Complexity

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Cyclomatic Complexity

Number Of "Decision Points" In A Routine

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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Simple Right?

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Cyclomatic Complexity (Single Method)

1 - 4: Low Complexity 5 - 7: Moderate Complexity 8 - 10: High Complexity 11+: Very High Complexity

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Cyclomatic Complexity (Average Per Method)

1 - 2: Low Complexity 2 - 4: Moderate Complexity 4 - 6: High Complexity 6+: Very High Complexity

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Compare:

Average CC per Method Wordpress: 6.28 Drupal 7: 3.02 Drupal 8: 2.10 Symfony 2: 1.81 Zend Framework 2: 2.62 Laravel: 1.79

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Cyclomatic Complexity (Average Per Line Of Code)

.01 - .05: Low Complexity .05 - .10: Moderate Complexity .10 - .15: High Complexity .15+: Very High Complexity

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Compare:

Average CC per LOC Wordpress: 0.20 Drupal 7: 0.04 Drupal 8: 0.07 Symfony 2: 0.06 Zend Framework 2: 0.10 Laravel: 0.07

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N-Path Complexity

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N-Path Complexity

Number Of "Unique Paths" In A Routine

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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function foo($a, $b) { $c = 0; if ($a) { $c = $a; } elseif ($b) { $c = $b; } if ($a && $b) { $c = $a + $b; } return $c; }

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They Are The Same?

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Not Generally!

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath:

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath: 8

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function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; } if ($b) { $d += $b; } if ($c) { $d += $c; } return $d; }

CC: 4 NPath: 8 2^(CC-1)

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N-Path Complexity

<16: Low Complexity 17-128: Moderate Complexity 129-1024: High Complexity 1025+: Very High Complexity

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N-Path Complexity

Minimum Number Of Tests Required To Completely Test A Routine

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N-Path Complexity

entity_load() CC: N-Path:

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N-Path Complexity

entity_load() CC: 2 N-Path:

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Cyclomatic Complexity

1 - 4: Low Complexity 5 - 7: Moderate Complexity 8 - 10: High Complexity 11+: Very High Complexity

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N-Path Complexity

entity_load() CC: 2 N-Path: 2

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N-Path Complexity

drupal_http_request() CC: N-Path:

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N-Path Complexity

drupal_http_request() CC: 41 N-Path:

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Cyclomatic Complexity

1 - 4: Low Complexity 5 - 7: Moderate Complexity 8 - 10: High Complexity 11+: Very High Complexity

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N-Path Complexity

drupal_http_request() CC: 41 N-Path: 25,303,344,960

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To Completely Test

drupal_http_request() At 1 Line Of Code Per Test

Would Require

2 Terabytes

Worth Of Tests

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To Completely Test

drupal_http_request() At 1 Line Of Code Per Test

Would Require

412 DVD's

Worth Of Tests

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To Completely Test

drupal_http_request() At 1 Line Of Code Per Test

Would Require

670k Drupals

Worth Of Tests

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And That's Not The Worst One!

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N-Path Complexity _date_repeat_rrule_process()

CC: N-Path:

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N-Path Complexity _date_repeat_rrule_process()

CC: 81 N-Path:

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N-Path Complexity _date_repeat_rrule_process()

CC: 81 N-Path: 19,781,719,256

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N-Path Complexity _date_repeat_rrule_process()

CC: 81 N-Path: 19,781,719,256 ,250,000,000,000

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N-Path Complexity _date_repeat_rrule_process()

CC: 81 N-Path: 19,781,719,256 ,250,000,000,000 ,000,000,000

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To Completely Test

_date_repeat_rrule_process() At 1 Line Of Code Per Test

Would Require

336T 2009's

Worth Of Tests

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To Completely Test

_date_repeat_rrule_process() At 1 Line Of Code Per Test

Would Require

1 Greenland Ice Cap of microSD cards

Worth Of Tests

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CRAP

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CRAP

(Change Risk Analysis Predictions)

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CC = Cyclomatic Complexity (method)

COV = Test Coverage (percent) CRAP = CC + (CC^2 * (1 - COV)^3)

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CRAP

Relates Complexity And Test Coverage

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CRAP

Increasing Test Coverage Lowers CRAP Decreasing Complexity Lowers CRAP

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CRAP

A Low Complexity Method With No Tests

Is Good

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CRAP

A Low Complexity Method With Good Tests

Is Great

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CRAP

A Moderate Complexity Method With Good Tests

Is OK

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CRAP

A Moderate Complexity Method With No Tests

Is CRAP

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CRAP < 5: GREAT Code 5 - 15: Acceptable Code 15-30: Eih... Code 30+: CRAPpy Code

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How Do We Apply These Metrics?

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Sebastian Bergmann

PHPUnit DbUnit PHPLOC PHPCPD PHPCOV hphpa

www.phpqatools.org www.jenkins-php.org

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PHPLOC

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PHPLOC

By Sebastian Bergmann

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PHPLOC

By Sebastian Bergmann Command Line Tool

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PHPLOC

By Sebastian Bergmann Command Line Tool Summarizes An Entire Codebase

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$ phploc path/to/Drupal7/ Directories: 73 Files: 180 Lines of Code (LOC): 63347 Cyclomatic Complexity / Lines of Code: 0.04 Comment Lines of Code (CLOC): 19321 Non-Comment Lines of Code (NCLOC): 44026

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Namespaces: 0 Interfaces: 1 Traits: 0 Classes: 38 Abstract: 2 (5.26%) Concrete: 36 (94.74%) Average Class Length (NCLOC): 197

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Methods: 433 Scope: Non-Static: 378 (87.30%) Static: 55 (12.70%) Visibility: Public: 255 (58.89%) Non-Public: 178 (41.11%) Average Method Length (NCLOC): 17 Cyclomatic Complexity / Number of Methods: 3.02 Anonymous Functions: 0 Functions: 521 Constants: 22 Global constants: 15 Class constants: 7

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PDepend

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PDepend

By Manuel Pichler (Also German)

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PDepend

By Manuel Pichler (Also German) Like PHPLOC, But Granular

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PDepend

By Manuel Pichler (Also German) Like PHPLOC, But Granular Lower Level Analysis

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Fanout: Describes Outward Dependencies

  • Describes Dependence on Other Classes

ANDC: Average Num of Derived Classes

  • Describes How Much Inheritance Is Used

AHH: Average Hiearchy Height

  • Describes How Deep Of Inheritance Is Used
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PHPMD (Mess Detector)

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PHPMD

By Manuel Pichler (German)

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PHPMD

By Manuel Pichler (German) Finds "Messy" Parts Of Code

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PHPMD

By Manuel Pichler (German) Finds "Messy" Parts Of Code Finds Rule Violations

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PHPMD Rules

CodeSize

  • (CC, NPath, Number of Methods, Size of Methods, etc)

Design

  • (Eval, Goto, Exit(), Inheritance Depth)

Naming

  • (Short names, Inconsistent Names)

Unused Code Controversial

  • (Superglobal Access, Naming Conventions)
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Prevent Complex Code From Even Getting In!

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By Themselves Useful

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Over Time

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Over Time Invaluable

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Drupal 8.x Branch Non-Comment Lines Of Code

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Drupal 8.x Branch Number Of Classes

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Drupal 8.x Branch

Cyclomatic Complexity Per Method

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Drupal 8.x Branch Cyclomatic Complexity Per Line

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Drupal 8.x Branch

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One More Thing To Keep In Mind

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Anthony Ferrara @ircmaxell

ircmaxell@php.net

anthony.ferrara@nbcuni.com

blog.ircmaxell.com github.com/ircmaxell youtube.com/ircmaxell