PHP Code Review

PHP Code Review Sebastian Bergmann June 12th 2010

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Code Review What is the Return on Investment?

Code Review Direct Benefits  Improved code quality  Fewer defects in code  Improved communication about code  Education of junior programmers This slide contains material by Eric Brown

Code Review Indirect Benefits  Shorter development / test cycles  Reduced impact on technical support  More customer satisfaction  More maintainable code This slide contains material by Eric Brown

Code Review

Code Review Internal Can be problematic  Routine Blindness  ”Finger Pointing”

Code Review External

Five Types of Code Review

Five Types of Code Review Formal Inspection

Five Types of Code Review Formal Inspection  3-6 participants  Moderator  Reader (comprehension not critique)  Reviewer (critical analysis)  Observer (domain-specific advice) This slide contains material by Jason Cohen

Five Types of Code Review OvertheShoulder

Five Types of Code Review OvertheShoulder  Author  drives the code review  walks the reviewer through a set of code changes  Informal and simple  Not an enforcable process  It is easy to miss changes This slide contains material by Jason Cohen

Five Types of Code Review EMail PassAround

Five Types of Code Review EMail PassAround  Author sends changes to reviewers by email  Popular in Open Source projects  Sending of mail can be automated with triggers for the version control system This slide contains material by Jason Cohen

Five Types of Code Review Pair Programming

Five Types of Code Review Pair Programming  Part of eXtreme Programming  Can also be used standalone  Continuous Code Review This slide contains material by Jason Cohen

Five Types of Code Review ToolAssisted

Five Types of Code Review ToolAssisted  Automated Metrics Collection  Review Enforcement  Code Review Tools  Review Board  Atlassian Crucible  Continuous Integration  Static Code Analysis This slide contains material by Jason Cohen

Five Types of Code Review Summary  Formal inspections and pair programming are proven techniques but require large amounts of developer time.  Over-the-Shoulder reviews are easiest to implement but are not enforcable.  E-Mail pass-around and tool-assisted reviews strike a balance between time invested and ease of implementation. This slide contains material by Jason Cohen

Code Review of Wordpress 3.0 Beta 2 Where do we start?

Code Review of Wordpress 3.0 Beta 2 Where do we start?  How much code is there?  How is the code structured?  Can we find ”interesting” code using a tool?  Which parts of the code are executed during a normal page request?  Start reading the code.

Code Review of Wordpress 3.0 Beta 2 How much code is there? sb@thinkpad htdocs % phploc wordpress phploc 1.5.1 by Sebastian Bergmann. Directories: 23 Files: 303 Lines of Code (LOC): 161794 Cyclomatic Complexity / Lines of Code: 0.25 Executable Lines of Code (ELOC): 86802 Comment Lines of Code (CLOC): 49170 Non-Comment Lines of Code (NCLOC): 112624 Namespaces: 0 Interfaces: 0 Classes: 182 Abstract: 0 (0.00%) Concrete: 182 (100.00%) Average Class Length (NCLOC): 266 Methods: 1953 Scope: Non-Static: 1953 (100.00%) Static: 0 (0.00%) Visibility: Public: 1953 (100.00%) Non-Public: 0 (0.00%) Average Method Length (NCLOC): 24 Cyclomatic Complexity / Number of Methods: 5.35 Anonymous Functions: 0 Functions: 2159 Constants: 326 Global constants: 326 Class constants: 0

Code Review of Wordpress 3.0 Beta 2 How is the code structured? sb@thinkpad htdocs % phploc wordpress phploc 1.5.1 by Sebastian Bergmann. Directories: 23 Files: 303 Lines of Code (LOC): 161794 Cyclomatic Complexity / Lines of Code: 0.25 Executable Lines of Code (ELOC): 86802 Comment Lines of Code (CLOC): 49170 Non-Comment Lines of Code (NCLOC): 112624 Namespaces: 0 Interfaces: 0 Classes: 182 Abstract: 0 (0.00%) Concrete: 182 (100.00%) Average Class Length (NCLOC): 266 Methods: 1953 Scope: Non-Static: 1953 (100.00%) Static: 0 (0.00%) Visibility: Public: 1953 (100.00%) Non-Public: 0 (0.00%) Average Method Length (NCLOC): 24 Cyclomatic Complexity / Number of Methods: 5.35 Anonymous Functions: 0 Functions: 2159 Constants: 326 Global constants: 326 Class constants: 0

Code Review of Wordpress 3.0 Beta 2 How is the code structured? sb@thinkpad htdocs % pdepend --overview-pyramid=pyramid.svg wordpress ANDC Average Number of Derived Classes AHH Average Hierarchy Height NOP Number of Packages NOC Number of Classes NOM Number of Methods LOC Lines of Code (non-comment, non-whitespace) CYCLO Cyclomatic Complexity CALLS Number of Operation Calls FANOUT Number of Called Classes

Code Review of Wordpress 3.0 Beta 2 Can we find ”interesting” code using a tool? sb@thinkpad htdocs % phpcs --standard=CodeReview --extensions=php --report=source wordpress PHP CODE SNIFFER VIOLATION SOURCE SUMMARY -------------------------------------------------------------------------------- STANDARD CATEGORY SNIFF COUNT -------------------------------------------------------------------------------- Generic PHP No silenced errors 548 Generic Metrics Cyclomatic complexity 347 Generic Code analysis Unused function parameter 278 Generic Code analysis For loop with test function call 63 Generic Code analysis Empty statement 35 Generic Metrics Nesting level 30 Generic Code analysis Unconditional if statement 1 -------------------------------------------------------------------------------- A TOTAL OF 1302 SNIFF VIOLATION(S) WERE FOUND IN 7 SOURCE(S) --------------------------------------------------------------------------------

Code Review of Wordpress 3.0 Beta 2 Can we find ”interesting” code using a tool? sb@thinkpad htdocs % phpcs --standard=CodeReview --extensions=php wordpress FILE: /home/sb/wordpress/wp-admin/admin-ajax.php -------------------------------------------------------------------------------- FOUND 0 ERROR(S) AND 6 WARNING(S) AFFECTING 6 LINE(S) -------------------------------------------------------------------------------- 23 | WARNING | Silencing errors is discouraged 166 | WARNING | Silencing errors is discouraged 167 | WARNING | Silencing errors is discouraged 168 | WARNING | Silencing errors is discouraged 169 | WARNING | Silencing errors is discouraged 218 | WARNING | Function's cyclomatic complexity (11) exceeds 10; consider | | refactoring the function -------------------------------------------------------------------------------- FILE: /home/sb/wordpress/wp-admin/admin-header.php -------------------------------------------------------------------------------- FOUND 0 ERROR(S) AND 1 WARNING(S) AFFECTING 1 LINE(S) -------------------------------------------------------------------------------- 9 | WARNING | Silencing errors is discouraged -------------------------------------------------------------------------------- . . .

Code Review of Wordpress 3.0 Beta 2 Can we find ”interesting” code using a tool? wp-admin/admin-ajax.php 166 $total = (int) @$_POST['_total']; 167 $per_page = (int) @$_POST['_per_page']; 168 $page = (int) @$_POST['_page']; 169 $url = esc_url_raw( @$_POST['_url'] );

Code Review of Wordpress 3.0 Beta 2 Can we find ”interesting” code using a tool? wp-admin/admin-ajax.php 166 $total = (int) @$_POST['_total']; 167 $per_page = (int) @$_POST['_per_page']; 168 $page = (int) @$_POST['_page']; 169 $url = esc_url_raw( @$_POST['_url'] ); wp-includes/formatting.php 2251 function esc_url_raw( $url, $protocols = null ) { 2252 return esc_url( $url, $protocols, 'db' ); 2253 }

Code Review of Wordpress 3.0 Beta 2 Can we find ”interesting” code using a tool? wp-admin/admin-ajax.php 166 $total = (int) @$_POST['_total']; 167 $per_page = (int) @$_POST['_per_page']; 168 $page = (int) @$_POST['_page']; 169 $url = esc_url_raw( @$_POST['_url'] ); wp-includes/formatting.php 2210 function esc_url( $url, $protocols = null, $_context = 'display' ) { 2239 } 2251 function esc_url_raw( $url, $protocols = null ) { 2252 return esc_url( $url, $protocols, 'db' ); 2253 }

Code Review of Wordpress 3.0 Beta 2 Do we have duplicated code? sb@thinkpad htdocs % phpcpd wordpress phpcpd 1.3.2 by Sebastian Bergmann. Found 26 exact clones with 466 duplicated lines in 5 files: - wp-content/plugins/akismet/akismet.php:806-820 wp-content/plugins/akismet/akismet.php:873-887 . . . 0.29% duplicated lines out of 161794 total lines of code. Time: 17 seconds, Memory: 327.75Mb

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PHP Code Review

by Sebastian Bergmann on Jun 13, 2010

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PHP Code Review — Presentation Transcript