Manifests#

Purpose#

Manifests help to cache information which is too expensive to generate on each request. Some manifests generate maps, e.g. class names to filesystem locations. Others store aggregate information like nested configuration graphs.

Storage#

By default, manifests are stored on the local filesystem through PHP's serialize() method. Combined with PHP opcode caching this provides fast access. In order to share manifests between servers, or centralise cache management, other storage adapters are available. These can be configured by a SS_MANIFESTCACHE constant, placed in your _ss_environment.php.

  • ManifestCache_File: The default adapter using PHP's serialize()
  • ManifestCache_File_PHP: Using var_export(), which is faster when a PHP opcode cache is installed
  • ManifestCache_APC: Use PHP's APC object cache

You can write your own adapters by implementing the ManifestCache interface.

Traversing the Filesystem#

Since manifests usually extract their information from files in the webroot, they require a powerful traversal tool: SS_FileFinder. The class provides filtering abilities for files and folders, as well as callbacks for recursive traversal. Each manifest has its own implementation, for example ManifestFileFinder, adding more domain specific filtering like including themes, or excluding tests.

PHP Class Manifest#

The ClassManifest builds a manifest of all classes, interfaces and some additional items present in a directory, and caches it.

It finds the following information:

  • Class and interface names and paths
  • All direct and indirect descendants of a class
  • All implementors of an interface
  • All module configuration files

The gathered information can be accessed through SS_ClassLoader::instance(), as well as ClassInfo. Some useful commands of the ClassInfo API:

  • ClassInfo::subclassesFor($class): Returns a list of classes that inherit from the given class
  • ClassInfo::ancestry($class): Returns the passed class name along with all its parent class names
  • ClassInfo::implementorsOf($interfaceName): Returns all classes implementing the passed in interface

In the absence of a generic module API, it is also the primary way to identify which modules are installed, through ClassManifest::getModules(). A module is defined as a toplevel folder in the webroot which contains either a _config.php file, or a _config/ folder. Modules can be specifically excluded from manifests by creating a blank _manifest_exclude file in the module folder.

By default, the finder implementation will exclude any classes stored in files within a tests/ folder, unless tests are executed.

Template Manifest#

The SS_TemplateManifest class builds a manifest of all templates present in a directory, in both modules and themes. Templates in tests/ folders are automatically excluded. The chapter on template inheritance provides more details on its operation.

Config Manifest#

The SS_ConfigManifest loads builds a manifest of configuration items, for both PHP and YAML. It also takes care of ordering and merging configuration fragments. The chapter on configuration has more details.

Flushing#

If a ?flush=1 query parameter is added to a URL, a call to flush() will be triggered on any classes that implement the Flushable interface. This enables developers to clear manifest caches, for example when adding new templates or PHP classes. Note that you need to be in dev mode or logged-in as an administrator for flushing to take effect.