In the first part of the presentation we see how Symfony2 implements HTTP cache. In the second one there's an explanation of why application cache layers suck, why nerly every php application does caching in the less productive way and how you benefit from HTTP cache from this point of view.

1. HTTP caching and Symfony2
Be lazy, be ESI
Alessandro Nadalin
May, 13 2011

2. Symfony2 sucks
at caching

3. because it doesn't have an application caching layer

4. high five, that's great

5. Sf2 embraces the HTTP caching specification
and that's not because

6. Fabien is
lazy

7. that's because

8. Fabien kicks asses

9. HTTP cache
is a
King
in Symfony2

10. Caching in Symfony2

11. Caching is, obviously, a matter of the response

12. since the response is an object,
we have some basic OO stuff
to handle HTTP cache

13. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

14. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

15. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

16. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

17. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

18. Creating a response
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
return $res;
}

19. Expiration

20. Expiration
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$date = new DateTime();
$date->modify('+600 seconds');
$res->setExpires($date);
return $res;
}

21. Expiration
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$date = new DateTime();
$date->modify('+600 seconds');
$res->setExpires($date);
return $res;
}

22. Expiration
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$date = new DateTime();
$date->modify('+600 seconds');
$res->setExpires($date);
return $res;
}

23. Expiration through Cache-Control
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$res->setMaxAge(600);
$res->setSharedMaxAge(600);
return $res;
}

24. Expiration through Cache-Control
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$res->setMaxAge(600);
$res->setSharedMaxAge(600);
return $res;
}

25. Expiration through Cache-Control
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$res->setMaxAge(600);
$res->setSharedMaxAge(600);
return $res;
}

26. Expiration through Cache-Control
public function indexAction()
{
$res = $this->render('MyBundle:Default:home.html.twig', array(
'title' => 'My blog',
));
$res->setMaxAge(600);
$res->setSharedMaxAge(600);
return $res;
}
Shared caches, like Symfony2 reverse proxy

27. Validation

28. Validation
public function articleAction($id)
{
$article = $this->get('entity_manager')->query($id)...
$res = $this->render('MyBundle:Default:article.html.twig', array(
'article' => '$article',
));
$etag = "article:{$article->getId()}:{$article->getVersion()}";
$res->setETag($etag);
$res->setLastModified($article->getModifiedAt());
return $res;

29. Validation
public function articleAction($id)
{
$article = $this->get('entity_manager')->query($id)...
$res = $this->render('MyBundle:Default:article.html.twig', array(
'article' => '$article',
));
$etag = "article:{$article->getId()}:{$article->getVersion()}";
$res->setETag($etag);
$res->setLastModified($article->getModifiedAt());
return $res;

30. Validation
public function articleAction($id)
{
$article = $this->get('entity_manager')->query($id)...
$res = $this->render('MyBundle:Default:article.html.twig', array(
'article' => '$article',
));
$etag = "article:{$article->getId()}:{$article->getVersion()}";
$res->setETag($etag);
$res->setLastModified($article->getModifiedAt());
return $res;

31. Validation
public function articleAction($id)
{
$article = $this->get('entity_manager')->query($id)...
$res = $this->render('MyBundle:Default:article.html.twig', array(
'article' => '$article',
));
$etag = "article:{$article->getId()}:{$article->getVersion()}";
$res->setETag($etag);
$res->setLastModified($article->getModifiedAt());
return $res;

32. Validation
public function articleAction($id)
{
$article = $this->get('entity_manager')->query($id)...
$res = $this->render('MyBundle:Default:article.html.twig', array(
'article' => '$article',
));
$etag = "article:{$article->getId()}:{$article->getVersion()}";
Datetime object
$res->setETag($etag);
$res->setLastModified($article->getModifiedAt());
return $res;

33. Automagically get a Datetime from Doctrine2
namespace AcmeBlogBundleEntity;
/**
* @orm:Entity
* @orm:Table(name="article")
*/
class Article
{
/**
* @orm:Column(type="datetime", name="modified_at")
*/
protected $modifiedAt;

34. Automagically get a Datetime from Doctrine2
namespace AcmeBlogBundleEntity;
/**
* @orm:Entity
* @orm:Table(name="article")
*/
class Article
{
/**
* @orm:Column(type="datetime", name="modified_at")
*/
protected $modifiedAt;

35. but hey, you say

36. what's the advatage of using validation if we always hit
the DB and create a new Response?

37. Validation, the right way
public function articleAction($id)
{
$res = new Response()
$etag = Memcache::get("Article:{$id}:etag");
$lastModified = Memcache::get("Article:{$id}:last_modified");
$res->setETag($etag);
$res->setLastModified($lastModified);
if ($res->isNotModified($this->get('request'))) {
return $res;
}
$article = $this->get('entity_manager')->query($id)...
...

38. Validation, the right way
public function articleAction($id)
{
$res = new Response()
$etag = Memcache::get("Article:{$id}:etag");
$lastModified = Memcache::get("Article:{$id}:last_modified");
$res->setETag($etag);
$res->setLastModified($lastModified);
if ($res->isNotModified($this->get('request'))) {
return $res;
}
$article = $this->get('entity_manager')->query($id)...
...

39. Validation, the right way
public function articleAction($id)
{
$res = new Response()
$etag = Memcache::get("Article:{$id}:etag");
$lastModified = Memcache::get("Article:{$id}:last_modified");
$res->setETag($etag);
$res->setLastModified($lastModified);
if ($res->isNotModified($this->get('request'))) {
return $res;
}
$article = $this->get('entity_manager')->query($id)...
...

40. Validation, the right way
public function articleAction($id)
{
$res = new Response()
$etag = Memcache::get("Article:{$id}:etag");
$lastModified = Memcache::get("Article:{$id}:last_modified");
$res->setETag($etag);
$res->setLastModified($lastModified);
if ($res->isNotModified($this->get('request'))) {
return $res;
}
$article = $this->get('entity_manager')->query($id)...
...

41. relax

42. Calculating an Etag, or a date, is cheaper
than generating a full MVC response

43. Control your power

44. Additional management
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPublic();
$res->setNotModified();
...

45. Varying the response
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPublic();
$res->setNotModified();
...

46. Cacheable by all caches
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPublic();
$res->setNotModified();
...

47. or by local only
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPrivate();
$res->setNotModified();
...

48. Good old 304
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPrivate();
$res->setNotModified();
...

49. Stale
public function articleAction($id)
{
$res = new Response()
$res->setVary(array(
'Accept-Encoding',
));
$res->setPrivate();
$res->expire();
...

50. but hey, you say

51. HTTP's cache fails when dealing with really dynamic pages,
because consumers will always have to hit the origin server,
although a part of the page would be cacheable ( header and
footer, for example )

52. no bueno, you say

53. NOPE

54. ESI was built for that
http://www.w3.org/TR/esi-lang
<esi:include src="http://mysite.com/twitterfeeds.html" />

55. ESI and Symfony2
# controller
$response->setSharedMaxAge(3600);
# app/config/config.yml
framework:
esi: { enabled: true }
# template
{% render '...:twitterFeeds' with {}, {'standalone': true} %}
# fragment controller
$response->setSharedMaxAge(15);

56. ESI and Symfony2
# controller
$response->setSharedMaxAge(3600);
# app/config/config.yml
framework:
esi: { enabled: true }
# template
{% render '...:twitterFeeds' with {}, {'standalone': true} %}
# fragment controller
$response->setSharedMaxAge(15);

57. ESI and Symfony2
# controller
$response->setSharedMaxAge(3600);
# app/config/config.yml
framework:
esi: { enabled: true }
# template
{% render '...:twitterFeeds' with {}, {'standalone': true} %}
# fragment controller
$response->setSharedMaxAge(15);

58. ESI and Symfony2
# controller
$response->setSharedMaxAge(3600);
# app/config/config.yml
framework:
esi: { enabled: true }
# template
{% render '...:twitterFeeds' with {}, {'standalone': true} %}
# fragment controller
$response->setSharedMaxAge(15);

59. ESI and Symfony2
# controller
$response->setSharedMaxAge(3600);
# app/config/config.yml
framework:
esi: { enabled: true }
# template
{% render '...:twitterFeeds' with {}, {'standalone': true} %}
# fragment controller
$response->setSharedMaxAge(15);

60. Use Symfony2 reverse proxy

61. Use Symfony2 reverse proxy
(slower)

62. or Varnish
http://www.varnish-cache.org/

63. Varnish configuration
backend apache {
.host = "127.0.0.1";
.port = "8080";
}
sub vcl_recv {
unset req.http.Accept-Encoding;
unset req.http.Vary;
set req.http.Surrogate-Capability = "abc=ESI/1.0";
}
sub vcl_fetch {
esi;
...

64. Varnish configuration
backend apache {
.host = "127.0.0.1";
tell Symfony2
.port = "8080"; you're behind a reverse proxy
}
able to handle the ESI specification
sub vcl_recv {
unset req.http.Accept-Encoding;
unset req.http.Vary;
set req.http.Surrogate-Capability = "abc=ESI/1.0";
}
sub vcl_fetch {
esi;
...
}

65. Why HTTP caching
is so
important?

66. Ask yourself:
as a developer, what do I want
on my application?

67. Evolve
Loose coupling
Work less

68. Evolve
Because you want your platform to extensible
Loose coupling
Work less

69. Evolve
Because you want your platform to extensible
Loose coupling
Because you want it to be easy to integrate with, evolve, plug
and mantain
Work less

70. Evolve
Because you want your platform to extensible
Loose coupling
Because you want it to be easy to integrate with, evolve, plug
and mantain
Work less
Because every LoC is bug-prone and our man-day is a hard-to-
scale cost

71. enters our Hero #1

74. enters our Hero #2

76. http://www.lullabot.com/articles/a-beginners-guide-to-caching-data

77. 2007

78. 2011?

79. it supports
HTTP caching!
http://drupal.org/node/147310

80. it supports
HTTP caching!
http://drupal.org/node/147310
( people is supposed to clap their hands here )

81. but

82. wait.... how?

83. Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],

84. Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],

85. Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],

86. Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],

87. is that even legal?

88. "but you can redefine them!"

89. drupal_add_http_header()

90. function drupal_add_http_header()
{
...
...
drupal_send_headers($headers);
}

91. so, what
drupal_send_headers()
can do so evil?

92. header() ,
of course

93. which means

94. drupal_add_http_header('Dumb-Header', 'I'm batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', 'I'm not');
var_dump(headers_list());

95. drupal_add_http_header('Dumb-Header', 'I'm batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', 'I'm not');
var_dump(headers_list());
array
0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7'
1 => string 'Cache: I'm not'

96. drupal_add_http_header('Dumb-Header', 'I-m batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', false);
var_dump(headers_list());

97. drupal_add_http_header('Dumb-Header', 'I-m batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', false);
var_dump(headers_list());
array
0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7'
1 => string 'Cache: I'm batman'

98. drupal_add_http_header('Dumb-Header', 'I-m batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', ' ');
var_dump(headers_list());

99. drupal_add_http_header('Dumb-Header', 'I-m batman!');
...
// other logic
...
drupal_add_http_header('Dumb-Header', ' ');
var_dump(headers_list());
array
0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7'
1 => string 'Cache:'

100. or

101. you can use header_remove()
( PHP 5.3 )

102. and create a new class to
manage/keep track of
headers and caching directives

103. but we're lazy
and
we don't want to reinvent the wheel

104. Goals
Work less
evolve
loose coupling

105. Goals
Work less
evolve
loose coupling

106. everything is done for us!
:)
but....

107. tmp files, cache tables, procedural code...
mmmmh....
gotta be something better

108. Frameworks

110. symfony ONE

111. Cache is used for compiling routes, autoloading, ...

112. Cache is used for compiling routes, autoloading, ...
...but also for storing the view

113. Goals
Work less
evolve
loose coupling

114. Goals
Work less
evolve
loose coupling

115. at least because we use a framework

116. HTTP

117. Goals
Work less
evolve
loose coupling

118. Less work

119. because the hard work is delegated to the browser/proxy

120. Evolve

121. because cache is abstracted from the application

122. Loose coupling

123. because caching is bound to the protocol, HTTP, not
to your implementation ( Sf, RoR, Django )

124. Alessandro Nadalin

125. Alessandro Nadalin

126. Alessandro Nadalin
odino.org

127. Alessandro Nadalin
odino.org
@_odino_

128. Alessandro Nadalin
odino.org
@_odino_
http://joind.in/talk/view/2988

129. Alessandro Nadalin
odino.org
@_odino_
http://joind.in/talk/view/2988
Thanks!

130. Credits
http://www.flickr.com/photos/snakphotography/5004775320/sizes/o/in/photostream/
http://www.flickr.com/photos/ashatenbroeke/4367373081/sizes/z/in/photostream/
http://www.flickr.com/photos/juanpg/3333385784/sizes/z/in/photostream/
http://www.flickr.com/photos/congvo/301678287/sizes/l/in/photostream/
http://www.flickr.com/photos/adamrice/280300202/sizes/l/in/photostream/
http://www.flickr.com/photos/tomer_a/541411897/sizes/o/in/photostream/
http://www.flickr.com/photos/subpra/4514008262/sizes/l/in/photostream/
http://www.flickr.com/photos/lippincott/2539720043/sizes/l/in/photostream/
http://www.flickr.com/photos/rawryder/5086090931/sizes/l/in/photostream/
http://www.flickr.com/photos/robboudon/5312731161/sizes/l/in/photostream/
http://www.flickr.com/photos/bc-burnslibrary/4158243488/sizes/o/in/photostream/
http://www.flickr.com/photos/13606325@N08/2416993706/sizes/o/in/photostream/
http://www.flickr.com/photos/neothezion/5135841069/sizes/l/in/photostream/
http://www.flickr.com/photos/planetschwa/2494067809/
http://www.flickr.com/photos/thomasthomas/258931782/
http://www.flickr.com/photos/jungle_boy/220181177/sizes/l/in/photostream/
http://www.flickr.com/photos/ramduk/3708039504/sizes/z/in/photostream/
http://www.flickr.com/photos/sashawolff/3228711025/sizes/l/in/photostream/