This PR was squashed before being merged into the 3.3-dev branch (closes#21478).
Discussion
----------
[Asset] Add support for preloading with links and HTTP/2 push
| Q | A
| ------------- | ---
| Branch? | master
| Bug fix? | no
| New feature? | yes
| BC breaks? | no
| Deprecations? | no
| Tests pass? | yes
| Fixed tickets | n/a
| License | MIT
| Doc PR | todo
Allows compatible clients to preload mandatory assets like scripts, stylesheets or images according to [the "preload" working draft of the W3C](https://www.w3.org/TR/preload/).
Thanks to this PR, Symfony will automatically adds `Link` HTTP headers with a `preload` relation for mandatory assets. If an intermediate proxy supports HTTP/2 push, it will convert preload headers. For instance [Cloudflare supports this feature](https://blog.cloudflare.com/using-http-2-server-push-with-php/).
It dramatically increases pages speed and make the web greener because only one TCP connection is used to fetch all mandatory assets (decrease servers and devices loads, improve battery lives).
Usage:
Updated version:
```html
<html>
<body>
Hello
<script src="{{ preload(asset('/scripts/foo.js'), 'script') }}"></script>
</body>
</html>
```
~~First proposal:~~
```html
<html>
<body>
Hello
<script src="{{ preloaded_asset('/scripts/foo.js', 'script') }}"></script>
</body>
</html>
```
- [x] Add tests
Commits
-------
7bab21700d [Asset] Add support for preloading with links and HTTP/2 push
* 3.2:
Fix typo in process error message
Update to PHPUnit namespaces
Minor typo fix messsagesData -> messagesData
remove translation data collector when not usable
* 3.2: (40 commits)
fixed CS
fixed CS
fixed CS fixer config
fixed typo
Revert "fixed typo"
fixed typo
fixed CS
Avoid setting request attributes from signature arguments in AnnotationClassLoader
[DependencyInjection] Add some missing typehints in YamlFileLoader
[DependencyInjection] minor: Fix a DocBlock
[HttpKernel] Give higher priority to adding request formats
[Cache] Fix tags expiration
[PhpUnit] Blacklist DeprecationErrorHandler in stack traces
[PropertyInfo] Don't try to access a property thru a static method
[PropertyInfo] Exclude static methods form properties guessing
[Workflow] Added new validator to make sure each place has unique translation names
[Cache] [PdoAdapter] Fix MySQL 1170 error (blob as primary key)
[FrameworkBundle] Fix third level headers for MarkdownDescriptor
[Ldap] Using Ldap stored username instead of form submitted one
[Ldap] load users with the good username case
...
* 3.1: (31 commits)
fixed CS
fixed CS
fixed CS fixer config
fixed typo
Revert "fixed typo"
fixed typo
fixed CS
Avoid setting request attributes from signature arguments in AnnotationClassLoader
[DependencyInjection] Add some missing typehints in YamlFileLoader
[DependencyInjection] minor: Fix a DocBlock
[HttpKernel] Give higher priority to adding request formats
[PropertyInfo] Don't try to access a property thru a static method
[PropertyInfo] Exclude static methods form properties guessing
[FrameworkBundle] Fix third level headers for MarkdownDescriptor
[Ldap] Using Ldap stored username instead of form submitted one
[Ldap] load users with the good username case
[DoctrineBridge] Fixed invalid unique value as composite key
[Doctrine Bridge] fix UniqueEntityValidator for composite object primary keys
[TwigBundle] do not lose already set method calls
#20411 fix Yaml parsing for very long quoted strings
...
* 2.8: (26 commits)
fixed CS
fixed CS
fixed CS fixer config
fixed typo
Revert "fixed typo"
fixed typo
fixed CS
Avoid setting request attributes from signature arguments in AnnotationClassLoader
[DependencyInjection] Add some missing typehints in YamlFileLoader
[DependencyInjection] minor: Fix a DocBlock
[HttpKernel] Give higher priority to adding request formats
[PropertyInfo] Don't try to access a property thru a static method
[PropertyInfo] Exclude static methods form properties guessing
[FrameworkBundle] Fix third level headers for MarkdownDescriptor
[TwigBundle] do not lose already set method calls
#20411 fix Yaml parsing for very long quoted strings
CS: apply is_null
DX: remove invalid inheritdoc
bumped Symfony version to 2.8.17
updated VERSION for 2.8.16
...
* 2.7:
fixed typo
Revert "fixed typo"
fixed typo
fixed CS
Avoid setting request attributes from signature arguments in AnnotationClassLoader
[DependencyInjection] Add some missing typehints in YamlFileLoader
[DependencyInjection] minor: Fix a DocBlock
[HttpKernel] Give higher priority to adding request formats
[FrameworkBundle] Fix third level headers for MarkdownDescriptor
[TwigBundle] do not lose already set method calls
#20411 fix Yaml parsing for very long quoted strings
CS: apply is_null
DX: remove invalid inheritdoc
bumped Symfony version to 2.7.24
updated VERSION for 2.7.23
update CONTRIBUTORS for 2.7.23
updated CHANGELOG for 2.7.23
[FrameworkBundle] Skip test if xdebug.file_link_format is defined.
* 3.1:
use HHVM 3.15 to run tests
[TwigBridge] fix Twig 2.x compatibility
removed some PHP CS Fixer rules
Improve language
[Console] SymfonyStyle: Escape trailing backslashes in user texts
Mention the community review guide
[Form] fix group sequence based validation
[Console] Fix question formatting using SymfonyStyle::ask()
* 2.8:
use HHVM 3.15 to run tests
[TwigBridge] fix Twig 2.x compatibility
removed some PHP CS Fixer rules
Improve language
[Console] SymfonyStyle: Escape trailing backslashes in user texts
Mention the community review guide
[Form] fix group sequence based validation
[Console] Fix question formatting using SymfonyStyle::ask()
* 2.7:
use HHVM 3.15 to run tests
[TwigBridge] fix Twig 2.x compatibility
removed some PHP CS Fixer rules
Improve language
[Console] SymfonyStyle: Escape trailing backslashes in user texts
Mention the community review guide
[Form] fix group sequence based validation
[Console] Fix question formatting using SymfonyStyle::ask()
* 3.1:
fixed obsolete getMock() usage
fixed obsolete getMock() usage
fixed obsolete getMock() usage
[WebProfilerBundle] Display multiple HTTP headers in WDT
do not remove the Twig ExceptionController service
removed obsolete condition
do not try to register incomplete definitions
* 2.8:
fixed obsolete getMock() usage
fixed obsolete getMock() usage
[WebProfilerBundle] Display multiple HTTP headers in WDT
do not remove the Twig ExceptionController service
removed obsolete condition
do not try to register incomplete definitions
* 3.1: (28 commits)
Fix merge
[Validator] add class name to the cache key
[Serializer] Remove AbstractObjectNormalizer::isAttributeToNormalize
Throw less misleading exception when property access not found
[Twig] Fix deprecations with Twig 1.29
Fixed typo
[FrameworkBundle] Removed the kernel.debug parameter from the cache pool namespace seed
Fix email address
fix the docblock in regard to the role argument
Don't use the "app" global variable in the profiler
[VarDumper] fix tests when xdebug is enabled
Fix merge
FIXED NON EXISTING TYPE DECLARATION
[Cache] Fix dumping SplDoublyLinkedList iter mode
[Console] fixed PHP7 Errors when not using Dispatcher
Regression test for missing controller arguments (3.1)
Regression test for missing controller arguments
fix a test checking for a value
[Form][DX] FileType "multiple" fixes
fixed CS
...
* 2.8:
[Twig] Fix deprecations with Twig 1.29
Fixed typo
Fix email address
fix the docblock in regard to the role argument
[VarDumper] fix tests when xdebug is enabled
Fix merge
[Cache] Fix dumping SplDoublyLinkedList iter mode
[Console] fixed PHP7 Errors when not using Dispatcher
Regression test for missing controller arguments
fix a test checking for a value
[Form][DX] FileType "multiple" fixes
fixed CS
[TwigBundle] Fix twig loader registered twice
[WebProfilerBundle] Fix dump block is unfairly restrained
[Console] Fix wrong handling of multiline arg/opt descriptions
[DependencyInjection] PhpDumper.php: hasReference() should not search references in lazy service arguments.
[Form] fixed "empty_value" option deprecation
Cast result to int before adding to it
* 3.1:
[TwigBridge] fix tests
Tag the FormFieldRegistry as being internal
[Form] Fix Date\TimeType marked as invalid on request with single_text and zero seconds
[FrameworkBundle] Register the ArrayDenormalizer
[Serializer] Fix DataUriNormalizer's regex
[Validator] Added missing swedish translation
[TranslationDebug] workaround for getFallbackLocales.
[Translation] fixed nested fallback catalogue using multiple locales.
fixed phpdoc
[Command] Fixed method comments as phpDoc syntax
Added single quotes for upgrade guides.
* 2.8:
[TwigBridge] fix tests
Tag the FormFieldRegistry as being internal
[Form] Fix Date\TimeType marked as invalid on request with single_text and zero seconds
[Validator] Added missing swedish translation
[TranslationDebug] workaround for getFallbackLocales.
[Translation] fixed nested fallback catalogue using multiple locales.
fixed phpdoc
[Command] Fixed method comments as phpDoc syntax
Added single quotes for upgrade guides.
* 2.7:
[TwigBridge] fix tests
Tag the FormFieldRegistry as being internal
[Form] Fix Date\TimeType marked as invalid on request with single_text and zero seconds
[Validator] Added missing swedish translation
[TranslationDebug] workaround for getFallbackLocales.
[Translation] fixed nested fallback catalogue using multiple locales.
fixed phpdoc
[Command] Fixed method comments as phpDoc syntax
* 3.1:
[TwigBundle] fixed usage of getSource in tests
Trim constant values in XmlFileLoader
move test to the HttpKernel component
[TwigBridge] fixed Twig_Source required argument
[HttpKernel] Fix a regression in the RequestDataCollector
[HttpKernel] Refactor a RequestDataCollector test case to use a data provider
* 2.8:
[TwigBundle] fixed usage of getSource in tests
Trim constant values in XmlFileLoader
move test to the HttpKernel component
[TwigBridge] fixed Twig_Source required argument
* 2.7:
[TwigBundle] fixed usage of getSource in tests
Trim constant values in XmlFileLoader
move test to the HttpKernel component
[TwigBridge] fixed Twig_Source required argument
* 3.1:
[TwigBridge] removed deprecations added in Twig 1.27
PHP CS Fixer: use php_unit_dedicate_assert
3.0 Upgrade Guide: Added details describing how to pass data to a form through the options resolver
fixed Filesystem:makePathRelative and added 2 more testcases
no 304 response if method is not cacheable
move tags from decorated to decorating service
* 2.8:
[TwigBridge] removed deprecations added in Twig 1.27
PHP CS Fixer: use php_unit_dedicate_assert
3.0 Upgrade Guide: Added details describing how to pass data to a form through the options resolver
fixed Filesystem:makePathRelative and added 2 more testcases
no 304 response if method is not cacheable
move tags from decorated to decorating service