DEBUGGINGR U L E S A N D T O O L Sian barber - http://phpir.com - @ianbarber

I did XI wanted YInstead I got Z

http://www.debuggingrules.com

UNDERSTAND THE SYSTEM

RULE 1

RTFM

Framework

Wiki

PHPDoc

php.net

BugTracker

$field = $document->getField($fieldName);

if ($field->storeTermVector) { /** * @todo term vector storing support */ require_once 'Zend/Search/Lucene/Exception.php'; throw new Zend_Search_Lucene_Exception ('Store term vector functionality is not supported yet.');}

TOOLS

Komodo

Eclipse Zend Studio

NetBeans

PHPStorm Text

Mate

MAKE IT FAIL

RULE 2

Recreate And AutomatePHP UnitSimpleTestSeleniumPHP SlimJMeterAb

CONTROL VARIABLES

LoadTime

DBStateSession

Request

ServerEnv

User

Client

Timing

class Test_User extends PHPUnit_Framework_TestCase {

public function testUpdate() { $r = ("a", "b"); try { $u = User::fetch($this->newName); $result = $u->update($r); } catch (Id_Exception $e) { $this->fail($e->getMessage()); } $this->assertEquals($r, $u->getRoles()); } }

[root@localhost ~]# pear channel-discover pear.phpunit.de[root@localhost ~]# pear install phpunit/PHPUnit

http://seleniumhq.org/

class Example extends PHPUnit_Extensions_SeleniumTestCase { protected function setUp() { $this->setBrowser("*chrome"); $this->setBrowserUrl("http://general.dev/"); }

public function testMyTestCase() { $this->open("/"); $this->select("locale", "label=de"); $this->waitForPageToLoad("30000"); $this->assertTrue($this->isTextPresent( "Datenbank-Einrichtung")); }}

http://jakarta.apache.org/jmeter/

QUIT THINKINGAND LOOK

RULE 3

if($this->hasRoles) { $this->deleteRoles(); }

try { foreach($submittedRoles as $role) { $this->addRole($role); } } catch(Identity_Exception $e) { $this->log->warn('Role add failed.'); throw new Service_Exception_BadRequest( 'Cannot add user role'); }

Instrumentation:Inspect or Report

Xdebughttp://www.xdebug.org

[root@localhost ~]# pecl install xdebug

zend_extension=/usr/lib64/php/modules/xdebug.so

xdebug.profiler_enable=1 xdebug.profiler_output_dir=/tmp

Debugging Commands

Web Server

PHP Script

XDebugDebugging Client

xdebug.remote_enable=1 xdebug.remote_port=9000 xdebug.remote_mode=req xdebug.remote_host=192.168.192.1 # xdebug.remote_connect_back=1

[root@localhost ~]# lsof -p 4365 COMMAND USER FD TYPE DEVICE NAME httpd apache mem REG 253,0 /lib64/libssl.so.0.9.8e httpd apache mem REG 253,0 /usr/lib64/php/modules/xdebug.so httpd apache mem REG 253,0 /usr/lib64/libsqlite3.so.0.8.6

[root@localhost ~]# strace -cp 4365 Process 6910 attached - interrupt to quit Process 6910 detached % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ------------- 36.91 0.037307 466 80 getdents 30.07 0.030393 950 32 7 access 17.04 0.017224 154 112 10 open 5.08 0.005136 12 444 9 lstat 3.87 0.003910 18 213 1 read 3.04 0.003071 29 107 close 2.57 0.002598 1299 2 writev 0.78 0.000785 1 631 stat

[root@localhost ~]# strace -Tp 4365 Process 6910 attached - interrupt to quit epoll_wait(16, {{EPOLLIN, {u32=31389672, u64=47128707528680}}}, 2, 10000) = 1 <6.926140> accept(4, {sa_family=AF_INET6, sin6_port=htons(64930), inet_pton (AF_INET6, "::ffff:192.168.192.1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [47128676139036]) = 17 <0.000094> fcntl(17, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000035> read(17, "POST / HTTP/1.1\r\nHost: general.d"..., 8000) = 522 <0.000044> stat("/mnt/hgfs/habari/htdocs/", {st_mode=S_IFDIR|0755, st_size=408, ...}) = 0 <0.000527> open("/mnt/hgfs/habari/htdocs/.htaccess", O_RDONLY) = 18 <0.000457> fcntl(17, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000037>

[root@localhost ~]# strace -Tp 4365 Process 6910 attached - interrupt to quit epoll_wait(16, {{EPOLLIN, {u32=31389672, u64=47128707528680}}}, 2, 10000) = 1 <6.926140> accept(4, {sa_family=AF_INET6, sin6_port=htons(64930), inet_pton (AF_INET6, "::ffff:192.168.192.1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [47128676139036]) = 17 <0.000094> fcntl(17, F_SETFL, O_RDWR|O_NONBLOCK) = 0 <0.000035>

read(17, "POST / HTTP/1.1\r\nHost: general.d"..., 8000) = 522 <0.000044> stat("/mnt/hgfs/habari/htdocs/", {st_mode=S_IFDIR|0755, st_size=408, ...}) = 0 <0.000527>

open("/mnt/hgfs/habari/htdocs/.htaccess", O_RDONLY) = 18 <0.000457>

error_log("Message for the PHP log") error_log("Log to email", 1, "me@foo.com"); error_log("Log to a file",3, "/tmp/m.log"); error_log("Message for the SAPI log", 4);

ZendLog

sfLogger

Drupalsyslog

KohanaLog

LOGGING SYSTEM

SyslogMQ File

Database PipeGearman

FirePHP

[root@localhost ~]# pear channel-discover pear.firephp.org [root@localhost ~]# pear install firephp/FirePHPCore

require_once('FirePHPCore/FirePHP.class.php'); ob_start(); $firephp = FirePHP::getInstance(true); doStuff($firephp); $firephp->warn('Done Stuff'); $firephp->error('An error!'); $firephp->log($_GET); ob_end_flush();

function doStuff($firephp) { $firephp->trace('Stuff Backtrace'); echo "This page intentionally blank"; }

DIVIDE ANDCONQUER

RULE 4

<?xml version="1.0" encoding="UTF-8"?><phpunit bootstrap="./TestHelper.php" colors="true"> <testsuite name="Commonlib Tests"> <directory>./library/Cl/</directory> <directory>./library/Sso/</directory> </testsuite><filter> <whitelist> <directory suffix=".php">../Sso/</directory> <directory suffix=".php">../Cl/</directory></whitelist></filter></phpunit>

Folder Root

SSOCL

Model UserAuth Client

PluginAdapter Exception Abstract

GearmanSFDCSSO

<?php

$worker = new GearmanWorker(); $worker->addServer(); $worker->addFunction( "allow_access", "allowAccess"); $worker->addFunction( "deny_access", "denyAccess");

while ($worker->work());

git bisect start git bisect bad git bisect good <known good rev>

git bisect ?

git bisect reset

Git Bisect

Request

Front Controller

InputFilter

Controller

Model

Plugin

View1

2

3

good bad

Firewall

Cache

Web Server

Database

Firewall

Cache

Web Server

Database

Wireshark

Curl

Netcat

MySQLProxy

Tamper Data

Xdebug

Tamper Datahttps://addons.mozilla.org/firefox/addon/966

Wiresharkhttp://www.wireshark.org/

[root@localhost ~]# { echo -ne "HTTP/1.0 200 OK\r\n \r\n"; cat test.html; } | nc -l 8080 GET / HTTP/1.1 User-Agent: curl/7.19.7 (i386-apple-darwin10.0.0) libcurl/7.19.7 OpenSSL/0.9.8l zlib/1.2.3 Host: general.dev:8080 Accept: */*

[root@localhost ~]# curl http://general.dev:8080 -v * About to connect() to general.dev port 8080 (#0) * Trying 192.168.192.129... connected * Connected to general.dev (192.168.192.129) port 8080 (#0) > GET / HTTP/1.1 > User-Agent: curl/7.19.7 (i386-apple-darwin10.0.0) libcurl/7.19.7 OpenSSL/0.9.8l zlib/1.2.3 > Host: general.dev:8080

MySQL Proxy

local log_file = 'mysql.log' local fh = io.open(log_file, "a+")

function read_query( packet ) if string.byte(packet) == proxy.COM_QUERY then local query = string.sub(packet, 2) fh:write( string.format("%s\n",query)) fh:flush() end end

CHANGE ONETHING ATA TIME

RULE 5

Source Control

[root@localhost ~]#: svn stM index.php

[root@localhost ~]#: git stash saveSaved working directory and index state WIP on master: 0e22fdd Initial checkinHEAD is now at 0e22fdd Initial checkin

[root@localhost ~]#: git status# On branch masternothing to commit (working directory clean)

Source Control

[root@localhost ~]#: svn log . ------------------------------------------- r4341 | rickc | 2010-09-24 03:01 | 3 lines

Don't test if Post::tags is empty before getting tags. There may be a performance hit for this. It can be dealt with if it is noticable. Fixes ticket #1235. Props to ilo for the patch.

Note that Post still needs to be updated to use real Tags, not an array of slug/label pairs as the tags member.--------------------------------------------

Known Good

[root@localhost ~]# diff -yw web.conf web2.conf <VirtualHost *:80> <VirtualHost *:80> ServerAdmin root@e.com ServerAdmin root@e.com DocumentRoot /www/htdocs | DocumentRoot /www/hdocs ServerName general.dev ServerName general.dev ErrorLog logs/error_log ErrorLog logs/error_log</VirtualHost> </VirtualHost>

KEEP ANAUDIT TRAIL

RULE 6

Hot Key Loghttp://www.blacktree.com/

http://simplenoteapp.com/https://launchpad.net/mbhttp://do.davebsd.com/

Backpack Journalhttp://backpackit.com/

[root@localhost htdocs]# history 20 365 ls /mnt/hgfs/habari/ 366 ls 367 vi /etc/httpd/conf.d/web.conf 368 setenforce 0 369 /etc/init.d/httpd restart 370 vi /var/log/httpd/error_log 371 cd /mnt/hgfs/habari/ 372 ls 373 cd htdocs/ 374 ls 375 cd scripts/ 376 ls 377 cd .. 378 ls 379 vi /etc/php.ini

CHECK THE PLUG

RULE 7

[root@localhost ~]# apachectl -M Loaded Modules: core_module (static) mpm_prefork_module (static) http_module (static) so_module (static) auth_basic_module (shared) auth_digest_module (shared) authn_file_module (shared) authn_alias_module (shared) authn_anon_module (shared) authn_dbm_module (shared) authn_default_module (shared) authz_host_module (shared) authz_user_module (shared)

Sources of Plugs

[root@localhost ~]# whoami root [root@localhost ~]# ifconfig eth0 Link encap:Ethernet HWaddr 00:0C:29:E8:03:F1 inet addr:192.168.192.129 Bcast:192.168.192.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fee8:3f1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:189820 errors:0 dropped:0 overruns:0 frame:0 TX packets:117261 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:83583857 (79.7 MiB) TX bytes:24261778 (23.1 MiB)

GET A FRESHVIEW

RULE 8

“Grovelling is not a substitute for doing your homework” - ESR

http://www.catb.org/esr/faqs/smart-questions.html

IF YOU DIDN’T FIX IT -IT AIN’T FIXED

RULE 9

Five Whys

The page is blank: Why?There is a fatal error : Why?

No mb_check_encoding(): Why?mbstring is not installed: Why?It isn’t part of the build: Why?

It was setup for another project.

The Rules1. Understand The System2. Make It Fail3. Quit Thinking And Look4. Divide And Conquer5. Change One Thing At A Time6. Keep An Audit Trail7. Check The Plug8. Get A Fresh View9. If You Didn’t Fix It, It Ain’t Fixed

?Questions

When men were men and wore white coats - by Jitzehttp://www.flickr.com/photos/jitze1942/4292084185/Vacuum Tube Etch-A-Sketch - by Jurvetsonhttp://www.flickr.com/photos/jurvetson/197768962/Classic - by Oskayhttp://www.flickr.com/photos/oskay/1364147095Firmware Bug - by Oskayhttp://www.flickr.com/photos/oskay/1364148351Ready to hop - by Oskayhttp://www.flickr.com/photos/oskay/1364153441/Albino - by Oskayhttp://www.flickr.com/photos/oskay/1364143833Coming Through! - by Oskayhttp://www.flickr.com/photos/oskay/1364147807Tux the Pinguin - by Patrick van der VeldenFrom the photographer’s private collection

Image Credits

THANK YOUDEBUGGING: RULES AND TOOLS

http://joind.in/3393