Escaping Dependency Hell v2

ESCAPINGDEPENDENCY HELL

Michael Haeuslmann - PHP UG Munich 2016Source: Escape from Hell Constantine by Rommeu

ESCAPING GERMANWINTER?

Michael Haeuslmann - PHP UG Munich 2016Source: Escape from Hell Constantine by Rommeu

PART I: DISCUSSION

WHAT IS DEPENDENCY HELL?

WHAT IS A DEPENDENCY?

... a dependency signifies a supplier/clientrelationship between model elements

where the modification of a supplier mayimpact the client model elements

- UML Specification v2.5

WHY SHOULD WE CARE?

MICHAEL HAEUSLMANN (@MICHAELHAEU)FREELANCER (PHPRAGMATIC.COM)

married, love to travel, board games, ...developing in PHP for ~8 yearsprofessional work in PHP (mostly legacy apps)open source for all the exciting stuff

Buuuut ...

I don't want to be a freelancer anymore ...

... sooooo ...

WE KNOW WE'RE INDEPENDENCY HELL.

HOW DO WE ESCAPE?

COMPLEX VS. COMPLICATEDBubble Sort?

COMPLEX VS. COMPLICATEDBubble Sort?

COMPLEX VS. COMPLICATEDCache Invalidation?

COMPLEX VS. COMPLICATEDCache Invalidation?

COMPLEX VS. COMPLICATEDCache Invalidation?

COMPLEX VS. COMPLICATEDCache Invalidation?

COMPLEX VS. COMPLICATEDCache Invalidation?

COMPLEX VS. COMPLICATEDWeb Applications?

COMPLEX VS. COMPLICATEDWeb Applications?

COMPLEX VS. COMPLICATEDIt doesn't have to be complicated

WHAT DO WE DO ABOUT IT?Read the code and take notes? We don't want to do everything ourselves

use a tool → Managing dependencies in the right way helps with: Complexity, maintenance and understandability

PART II: ANALYSE

WHAT SHOULD DEPENDENCY ANALYSIS TELLUS?

Where should we start refactoring? Why does [SomeClass] always break? What does our architecture actually look like? Is our architecture the way it should be?

TOOLSPHP DEPEND BY MANUEL PICHLER

many metrics many metrics hard to maintain too vague

TOOLSPHP DEPEND BY MANUEL PICHLER

TOOLS

detects even the sneakiest dependencies

generates dependency visualizations

hackable (grep, sed, awk, ...)

for the nerds: written using functional style

supports PHP 5.2 to 7.1

FEATURES Text For quick feedback, debugging, UNIX pipes etc. Visualisations (UML & DSM & dot) Detailed dependency & architectural analysis (Metrics)

DEPHPEND - TEXT OUTPUT$> wget http://phar.dephpend.com/dephpend.phar$> composer global require dephpend/dephpend:dev­master$> dephpend help text _ _____ _ _ _____ _ | | | __ \| | | | __ \ | | __| | ___| |__) | |__| | |__) |__ _ __ __| | / _` |/ _ \ ___/| __ | ___/ _ \ '_ \ / _` | | (_| | __/ | | | | | | | __/ | | | (_| | \__,_|\___|_| |_| |_|_| \___|_| |_|\__,_| version 0.1

Usage: text [options] [­­] ()...

$> dephpend text ~/workspace/dephpend/src

Mihaeu\PhpDependencies\Util\AbstractMap ­­> Mihaeu\PhpDependencies\Util\CollectionMihaeu\PhpDependencies\Util\DI ­­> Mihaeu\PhpDependencies\Analyser\Analyser...

(*) make sure XDebug is not enabled or use php -n

DEPHPEND - TEXT OUTPUT$> dephpend text ~/workspace/dephpend/src ­­no­classes | sort

Mihaeu\PhpDependencies\Analyser ­­> Mihaeu\PhpDependencies\DependenciesMihaeu\PhpDependencies\Analyser ­­> Mihaeu\PhpDependencies\OSMihaeu\PhpDependencies\Analyser ­­> Mihaeu\PhpDependencies\UtilMihaeu\PhpDependencies\Analyser ­­> PhpParserMihaeu\PhpDependencies\Analyser ­­> PhpParser\NodeMihaeu\PhpDependencies\Analyser ­­> PhpParser\Node\ExprMihaeu\PhpDependencies\Analyser ­­> PhpParser\Node\NameMihaeu\PhpDependencies\Analyser ­­> PhpParser\Node\StmtMihaeu\PhpDependencies\Analyser ­­> PhpParser\NodeVisitor...

$> dephpend text ~/workspace/dephpend/src ­­no­classes \ | grep ­e 'Analyser ­­> .*OS'

Mihaeu\PhpDependencies\Analyser ­­> Mihaeu\PhpDependencies\OS

DEPHPEND - TEXT OUTPUTMake it yours!

#!/usr/bin/env sh

php build/dephpend.phar text ~/workspace/dephpend/src ­­no­classes | grep \

­e 'Analyser ­­> .*OS' \

­e 'OS ­­> .*Analyser'

if [ "$?" ­eq 0 ]; then

echo 'Architecture violation!'

exit 1

fi

DEPHPEND - TEXT OUTPUT

<?php

$output = shell_exec('dephpend text ' .'~/workspace/myMVCFramework/src ­­no­classes');$constraints = [ 'Model.* ­­> .*View', 'View.* ­­> .*Model',];

if (preg_match('/('.implode(')|(', $constraints).')/x', $output)) echo 'Architecture violation'.PHP_EOL; exit(1);

DEPHPEND - UML (SORT OF)dePHPend packages

$> dephpend uml ~/workspace/dephpend/src ­­no­classes ­­output=uml.png

DEPHPEND - UML (SORT OF)Symfony components

$> php ­d memory_limit=512M dephpend.phar uml \

~/workspace/symfony/src/Symfony/Component \

­­no­classes \

­­depth 3 \ # Symfony\Component\HttpKernel\Controller\ArgumentResolver \ # → Symfony\Component\HttpKernel

­­exclude­regex='/Test/' \ # Symfony\Component\HttpFoundation\Tests

­­output=uml.png

DEPHPEND - UML (SORT OF)Symfony components

DEPHPEND - UML (SORT OF)Symfony HTTP Kernel

DEPENDENCY STRUCTURE MATRIX(DSM)

large graphs are unreadable same data as graph diagrams (e.g. UML class diagram) quick overview for large apps

DEPHPEND DSM

NDEPEND EXAMPLE

PART III: FIX

WHAT DO WE WANT?

We want code which is ... ... easier to understand ... easier to maintain ... easier to test

OBSCURE/NASTY DEPENDENCIES

Some dependencies cannot be detected by any tool (or developer):

Fake collections (array) Overuse of scalar values (int, string, ...) Temporal dependencies, etc.

BE EXPLICIT!

Implicit dependencies are hard to understand/manage!function sendNewsletter( array $customers, string $message);

function sendNewsletter( CustomerCollection $customers, Message $message);

WHICH ALLOCATES MORE RAM?ARRAY

$customer = [ 'id' => 123, 'name' => 'John Doe', 'city' => 'Example City',];

CUSTOM CLASSclass Customer /** @var int */ private $id;

/** @var string */ private $name;

/** @var string */ private $city;

Winner (less RAM): custom classProof: http://www.slideshare.net/patrick.allaert/php-data-structures-and-the-impact-of-php-7-on-

them-php-days-2015

DON'T MAKE ME LOOK IT UP/** * @param mixed $email * @param string|Email|array $email */function addEmail($email) if (is_array($email)) // pray everything inside the array actually is an email foreach ($email as $singleEmail) addEmail($singleEmail); else if (is_string($email)) addEmail(new Email($email)); else if ($email instanceof Email) this­>emails[] = email; else throw new InvalidArgumentException('Bad argument type');

DON'T MAKE ME LOOK IT UPfunction addEmail(Email $email) $this­>emails[] = $email;

function addEmailString(string $email) $this­>addEmail(new Email($email));

function addEmailArray(array $emails) foreach ($emails as $email) /** @var Email $email */ if (is_string($email)) $this­>addEmailstring($email); else if ($email instanceof Email) $this­>addEmail($email); else throw new InvalidArgumentException('Bad argument type');

function addEmailCollection(EmailCollection $emails) $emails­>each(function (Email $email) $this­>addEmail($email); );

DON'T MAKE ME LOOK IT UPfunction addEmail(Email $email) $this­>emails[] = $email;

function addEmailCollection(EmailCollection $emails) $emails­>each(function (Email $email) $this­>addEmail($email); );

function addEmailString(string $email) $this­>addEmail(new Email($email));

function addEmailArray(array $emails) foreach ($emails as $email) /** @var Email $email */ if (is_string($email)) $this­>addEmailstring($email); else if ($email instanceof Email) $this­>addEmail($email); else throw new InvalidArgumentException('Bad argument type');

PRINCIPLES OF OO: SOLID

Single responsibility principle Open/closed principle Liskov substitution principle Interface segregation principle Dependency inversion principle

DEPENDENCY INVERSIONBAD:

class CustomerRepository public function __construct() $this­>db = new MySQLDatabase(new DefaultConfig());

BETTER:class CustomerRepository public function __construct(MySQLDatabase $db) $this­>db = $db;

GOOD:class CustomerRepository public function __construct(Database $db) $this­>db = $db;

Easier to understand and test, less likely to break

DEPENDENCY INJECTIONCONTAINERS

$container = new Pimple\Container();

$container['cstmrrepo'] = function ($database) return new CustomerRepository($database);;

$cstmrRepo = $container['cstmrrepo'];

Too easy? obscure dependencies using YAMLadd another 3rd party libraryadd overhead by parsing meta format/sarcasm

AVOID IMPLICIT DEPENDENCIES IN FAVOR OFEXPLICIT ONES

// why not do it yourselves?class DependencyInjectionContainer

// eager load public function getCustomerRepository() : CustomerRepository return new CustomerRepository($this­>otherDeps);

// OR: lazy load public function getCustomerRepository() : CustomerRepository if (null === $this­>customerRepository) $this­>customerRepository = new CustomerRepository($this­>otherDeps); return $this­>customerRepository;

$dependencyInjectionContainer­>getCustomerRepository();

SERVICE LOCATORclass CustomerRepository public function __construct(ServiceLocator $serviceLocator) $this­>db = $serviceLocator­>getDb();

new CustomerRepository($serviceLocator);

Same or similar implementation, but different usage:

CHOOSE DEPENDENCY INJECTIONCONTAINERS OVER SERVICE LOCATORS

Service Locator provides access to everythingMight as well use globals...(but not really)Target class knows more than it should= more reasons to change (=break)Always choose REAL Dependency Injection

'MEMBER SYMONFY HTTPKERNEL?

WHERE TO GO FROM HERE?improve visualizations command for constraint checks caching better Test & CI integration

Contributions, ideas, feedback, bug reports are welcome!

QUESTIONS

???LINKS

http://www.slideshare.net/michael-haeuslmann/escaping-dependency-hell

https://dephpend.comhttps://github.com/mihaeu/dephpend

HOW DOES IT WORK?

STATIC ANALYSIS

Transform the code to make parsing easierInfer direct types (require, new, type hints, ...)Infer indirect types (DICs, ...)

DYNAMIC ANALYSIS

profile the applicationtrack function tracescollect all possible input values

STATIC ANALYSISEasy right?

use SomeNamespace\SomeClass;

class MyClass extends MyParent implements MyInterface

/**

* @return AnotherClass

*/

public function someFunction(SomeClass $someClass) : AnotherClass

StaticClass::staticFunction();

return new AnotherClass();

STATIC ANALYSISOr is it?

class MyClass

public function someMethod($dependency)

return call_user_func('globalFunction', $dependency);

or:

DYNAMIC ANALYSISXDebug to the rescue!

; php.ini

zend_extension=/path/to/xdebug.so

[xdebug]xdebug.profiler_enable = 1xdebug.auto_trace=1xdebug.collect_params=1xdebug.collect_return=3xdebug.collect_assignments=1xdebug.trace_format=1xdebug.trace_options=1

# https://github.com/mihaeu/dephpend/blob/develop/bin/dephpendphp­trace ­­dynamic=/path/to/trace­file.xt ­S localhost:8080

DYNAMIC ANALYSISTRACE START [2016­10­19 16:59:03]1 0 0 0.000189 363984 main 1 /home/mike/workspace/dephpend/bin/dephpend 0 0

2 1 0 0.000209 363984 get_declared_classes 0 /home/mike/workspace/dephpend/bin/dephpend 80

...

11 211058 0 3.503452 4856528 strpos 0 /home/mike/workspace/dephpend/vendor/symfony/console/Formatter/OutputFormatter.php 177 2 string(15111) string(2)

...3 200813 R long 3.504303 238672TRACE END [2016­10­19 16:59:07]

DYNAMIC ANALYSIS

Parse the trace file and merge with static results

$> dephpend text src \ ­­dynamic=/path/to/trace­file.xt \ ­­filter­from=YourNamespace \ ­­exclude­regex='(Test)|(Mock)'

There are no secrets at runtime!

@ m i c h a e l h a e u - PHP UG Munich 2016 - h t t p s : / / d e p h p e n d . c o m

CREDITSNDepend

Slide Coder Deviant Art

PDepend Artifacts scaled DSM

http://www.ndepend.com/docs/dependency-structure-matrix-dsm

http://rommeu.deviantart.com/art/Escape-from-Hell-Constantine-204115701

pdepend.org

https://erik.doernenburg.com/2010/04/dependency-structure-matrix/