Registry

Object Hierarchy:

Description:

[ CCode ( type_id = "gst_registry_get_type ()" ) ]
public class Registry : Object

One registry holds the metadata of a set of plugins.

Design:

The Registry object is a list of plugins and some functions for dealing with them. Each Plugin is matched 1-1 with a file on disk, and may or may not be loaded at a given time.

The primary source, at all times, of plugin information is each plugin file itself. Thus, if an application wants information about a particular plugin, or wants to search for a feature that satisfies given criteria, the primary means of doing so is to load every plugin and look at the resulting information that is gathered in the default registry. Clearly, this is a time consuming process, so we cache information in the registry file. The format and location of the cache file is internal to gstreamer.

On startup, plugins are searched for in the plugin search path. The following locations are checked in this order:

* location from --gst-plugin-path commandline option. * the GST_PLUGIN_PATH environment variable. * the GST_PLUGIN_SYSTEM_PATH environment variable. * default locations (if GST_PLUGIN_SYSTEM_PATH is not set). Those default locations are: `$XDG_DATA_HOME/gstreamer-$GST_API_VERSION/plugins/` and `$prefix/libs/gstreamer-$GST_API_VERSION/`. [$XDG_DATA_HOME](http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html) defaults to `$HOME/.local/share`.

The registry cache file is loaded from `$XDG_CACHE_HOME/gstreamer-$GST_API_VERSION/registry-$ARCH.bin` (where $XDG_CACHE_HOME defaults to `$HOME/.cache`) or the file listed in the `GST_REGISTRY` env var. One reason to change the registry location is for testing.

For each plugin that is found in the plugin search path, there could be 3 possibilities for cached information:

* the cache may not contain information about a given file. * the cache may have stale information. * the cache may have current information.

In the first two cases, the plugin is loaded and the cache updated. In addition to these cases, the cache may have entries for plugins that are not relevant to the current process. These are marked as not available to the current process. If the cache is updated for whatever reason, it is marked dirty.

A dirty cache is written out at the end of initialization. Each entry is checked to make sure the information is minimally valid. If not, the entry is simply dropped.

typeof (unichar2)typeof (unichar2) Implementation notes:

The "cache" and "registry" are different concepts and can represent different sets of plugins. For various reasons, at init time, the cache is stored in the default registry, and plugins not relevant to the current process are marked with the CACHED bit. These plugins are removed at the end of initialization.

Namespace: Gst

Package: gstreamer-1.0

Content:

Static methods:

public static unowned Registry @get ()
Retrieves the singleton plugin registry.
public static bool fork_is_enabled ()
By default GStreamer will perform scanning and rebuilding of the registry file using a helper child process.
public static void fork_set_enabled (bool enabled)
Applications might want to disable/enable spawning of a child helper process when rebuilding the registry.

Creation methods:

protected Registry ()

Methods:

public bool add_feature (PluginFeature feature)
Add the feature to the registry.
public bool add_plugin (Plugin plugin)
Add the plugin to the registry.
public bool check_feature_version (string feature_name, uint min_major, uint min_minor, uint min_micro)
Checks whether a plugin feature by the given name exists in this and whether its version is at least the version required.
public List<PluginFeature> feature_filter (PluginFeatureFilter filter, bool first)
Runs a filter against all features of the plugins in the registry and returns a GList with the results.
public PluginFeature? find_feature (string name, Type type)
Find the pluginfeature with the given name and type in the registry.
public Plugin? find_plugin (string name)
Find the plugin with the given name in the registry.
public List<PluginFeature> get_feature_list (Type type)
Retrieves a List of PluginFeature of type.
public List<PluginFeature> get_feature_list_by_plugin (string name)
Retrieves a List of features of the plugin with name name.
public uint32 get_feature_list_cookie ()
Returns the registry's feature list cookie.
public List<Plugin> get_plugin_list ()
Get a copy of all plugins registered in the given registry.
public Plugin? lookup (string filename)
Look up a plugin in the given registry with the given filename.
public PluginFeature? lookup_feature (string name)
Find a PluginFeature with name in this.
public List<Plugin> plugin_filter (PluginFilter filter, bool first)
Runs a filter against all plugins in the registry and returns a List with the results.
public void remove_feature (PluginFeature feature)
Remove the feature from the registry.
public void remove_plugin (Plugin plugin)
Remove the plugin from the registry.
public bool scan_path (string path)
Scan the given path for plugins to add to the registry.

Signals:

public signal void feature_added (PluginFeature feature)
Signals that a feature has been added to the registry (possibly replacing a previously-added one by the same name)
public signal void plugin_added (Plugin plugin)
Signals that a plugin has been added to the registry (possibly replacing a previously-added one by the same name)

Inherited Members:

All known members inherited from class Gst.Object

All known members inherited from class GLib.Object