Class Registry

java.lang.Object

org.javagi.base.ProxyInstance

org.gnome.gobject.TypeInstance

org.gnome.gobject.GObject

org.gnome.gobject.InitiallyUnowned

org.freedesktop.gstreamer.gst.GstObject

org.freedesktop.gstreamer.gst.Registry

All Implemented Interfaces:

Proxy

@Generated("org.javagi.JavaGI")
public class Registry
extends GstObject

One registry holds the metadata of a set of plugins.

Design:

The GstRegistry object is a list of plugins and some functions for dealing with them. Each GstPlugin 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 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.

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 PluginFlags.CACHED bit. These plugins are removed at the end of initialization.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Registry.Builder<B extends Registry.Builder<B>>	Inner class implementing a builder pattern to construct a GObject with properties.
static interface	Registry.FeatureAddedCallback	Functional interface declaration of the FeatureAddedCallback callback.
static interface	Registry.PluginAddedCallback	Functional interface declaration of the PluginAddedCallback callback.
static class	Registry.RegistryClass

Nested classes/interfaces inherited from class GstObject

GstObject.DeepNotifyCallback, GstObject.Object$Impl, GstObject.ObjectClass

Nested classes/interfaces inherited from class InitiallyUnowned

InitiallyUnowned.InitiallyUnownedClass

Nested classes/interfaces inherited from class GObject

GObject.NotifyCallback

Constructor Summary

Constructors

Constructor	Description
Registry()	Create a new Registry.
Registry(MemorySegment address)	Create a Registry instance for the provided memory address.

Method Summary

Modifier and Type	Method	Description
boolean	addFeature(PluginFeature feature)	Add the feature to the registry.
boolean	addPlugin(Plugin plugin)	Add the plugin to the registry.
protected Registry	asParent()	Return this instance as if it were its parent type.
static Registry.Builder<? extends Registry.Builder>	builder()	A Registry.Builder object constructs a Registry with the specified properties.
boolean	checkFeatureVersion(String featureName, int minMajor, int minMinor, int minMicro)	Checks whether a plugin feature by the given name exists in this Registry and whether its version is at least the version required.
void	emitFeatureAdded(@Nullable PluginFeature feature)	Emits the "feature-added" signal.
void	emitPluginAdded(@Nullable Plugin plugin)	Emits the "plugin-added" signal.
List<PluginFeature>	featureFilter(@Nullable PluginFeatureFilter filter, boolean first)	Runs a filter against all features of the plugins in the registry and returns a GList with the results.
@Nullable PluginFeature	findFeature(String name, Type type)	Find the pluginfeature with the given name and type in the registry.
@Nullable Plugin	findPlugin(String name)	Find the plugin with the given name in the registry.
static boolean	forkIsEnabled()	By default GStreamer will perform scanning and rebuilding of the registry file using a helper child process.
static void	forkSetEnabled(boolean enabled)	Applications might want to disable/enable spawning of a child helper process when rebuilding the registry.
static Registry	get()	Retrieves the singleton plugin registry.
List<PluginFeature>	getFeatureList(Type type)	Retrieves a GList of GstPluginFeature of type.
List<PluginFeature>	getFeatureListByPlugin(String name)	Retrieves a GList of features of the plugin with name name.
int	getFeatureListCookie()	Returns the registry's feature list cookie.
static MemoryLayout	getMemoryLayout()	The memory layout of the native struct.
List<Plugin>	getPluginList()	Get a copy of all plugins registered in the given registry.
static @Nullable Type	getType()	Get the GType of the Registry class.
@Nullable Plugin	lookup(String filename)	Look up a plugin in the given registry with the given filename.
@Nullable PluginFeature	lookupFeature(String name)	Find a GstPluginFeature with name in registry.
SignalConnection<Registry.FeatureAddedCallback>	onFeatureAdded(Registry.FeatureAddedCallback handler)	Signals that a feature has been added to the registry (possibly replacing a previously-added one by the same name)
SignalConnection<Registry.PluginAddedCallback>	onPluginAdded(Registry.PluginAddedCallback handler)	Signals that a plugin has been added to the registry (possibly replacing a previously-added one by the same name)
List<Plugin>	pluginFilter(@Nullable PluginFilter filter, boolean first)	Runs a filter against all plugins in the registry and returns a GList with the results.
void	removeFeature(PluginFeature feature)	Remove the feature from the registry.
void	removePlugin(Plugin plugin)	Remove the plugin from the registry.
boolean	scanPath(String path)	Scan the given path for plugins to add to the registry.

Methods inherited from class GstObject

addControlBinding, checkUniqueness, deepNotify, defaultDeepNotify, defaultError, emitDeepNotify, getControlBinding, getControlRate, getGValueArray, getName, getParent, getPathString, getValue, getValueArray, hasActiveControlBindings, hasAncestor, hasAsAncestor, hasAsParent, onDeepNotify, ref, refSink, removeControlBinding, replace, setControlBindingDisabled, setControlBindingsDisabled, setControlRate, setName, setParent, suggestNextSync, syncValues, unparent, unref

Methods inherited from class GObject

addToggleRef, addWeakPointer, bindProperty, bindProperty, bindProperty, bindPropertyFull, bindPropertyFull, bindPropertyWithClosures, bindPropertyWithClosures, compatControl, connect, connect, connect, constructed, disconnect, dispatchPropertiesChanged, dispose, dupData, dupQdata, emit, emitNotify, finalize_, forceFloating, freezeNotify, get, getData, getProperty, getProperty, getProperty, getQdata, getv, interfaceFindProperty, interfaceInstallProperty, interfaceListProperties, isFloating, newInstance, newInstance, newv, notify, notify, notifyByPspec, onNotify, refSink, removeToggleRef, removeWeakPointer, replaceData, replaceQdata, runDispose, set, setData, setDataFull, setProperty, setProperty, setProperty, setQdata, setQdataFull, setv, stealData, stealQdata, takeRef, thawNotify, watchClosure, weakRef, weakUnref, withProperties

Methods inherited from class TypeInstance

callParent, callParent, cast, getPrivate, readGClass, writeGClass

Methods inherited from class ProxyInstance

equals, handle, hashCode

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Registry

public Registry(MemorySegment address)

Create a Registry instance for the provided memory address.

Parameters:

address - the memory address of the native object

Registry

public Registry()

Create a new Registry.

Method Details

getType

public static @Nullable Type getType()

Get the GType of the Registry class.

Returns:

the GType

getMemoryLayout

public static MemoryLayout getMemoryLayout()

The memory layout of the native struct.

Returns:

the memory layout

asParent

protected Registry asParent()

Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.

Overrides:

asParent in class GstObject

Returns:

the instance as if it were its parent type

forkIsEnabled

public static boolean forkIsEnabled()

By default GStreamer will perform scanning and rebuilding of the registry file using a helper child process.

Applications might want to disable this behaviour with the gst_registry_fork_set_enabled() function, in which case new plugins are scanned (and loaded) into the application process.

Returns:

true if GStreamer will use the child helper process when rebuilding the registry.

forkSetEnabled

public static void forkSetEnabled(boolean enabled)

Applications might want to disable/enable spawning of a child helper process when rebuilding the registry. See gst_registry_fork_is_enabled() for more information.

Parameters:

enabled - whether rebuilding the registry can use a temporary child helper process.

get

public static Registry get()

Retrieves the singleton plugin registry. The caller does not own a reference on the registry, as it is alive as long as GStreamer is initialized.

Returns:

the GstRegistry.

addFeature

public boolean addFeature(PluginFeature feature)

Add the feature to the registry. The feature-added signal will be emitted.

feature's reference count will be incremented, and any floating reference will be removed (see gst_object_ref_sink())

Parameters:

feature - the feature to add

Returns:

true on success.

MT safe.

addPlugin

public boolean addPlugin(Plugin plugin)

Add the plugin to the registry. The plugin-added signal will be emitted.

plugin's reference count will be incremented, and any floating reference will be removed (see gst_object_ref_sink())

Parameters:

plugin - the plugin to add

Returns:

true on success.

MT safe.

checkFeatureVersion

public boolean checkFeatureVersion(String featureName,
 int minMajor,
 int minMinor,
 int minMicro)

Checks whether a plugin feature by the given name exists in this Registry and whether its version is at least the version required.

Parameters:

featureName - the name of the feature (e.g. "oggdemux")

minMajor - the minimum major version number

minMinor - the minimum minor version number

minMicro - the minimum micro version number

Returns:

true if the feature could be found and the version is the same as the required version or newer, and false otherwise.

featureFilter

public List<PluginFeature> featureFilter(@Nullable PluginFeatureFilter filter,
 boolean first)

Runs a filter against all features of the plugins in the registry and returns a GList with the results. If the first flag is set, only the first match is returned (as a list with a single object).

Parameters:

filter - the filter to use

first - only return first match

Returns:

a GList of GstPluginFeature. Use gst_plugin_feature_list_free() after usage.

MT safe.

findFeature

public @Nullable PluginFeature findFeature(String name,
 Type type)

Find the pluginfeature with the given name and type in the registry.

Parameters:

name - the pluginfeature name to find

type - the pluginfeature type to find

Returns:

the pluginfeature with the given name and type or null if the plugin was not found. gst_object_unref() after usage.

MT safe.

findPlugin

public @Nullable Plugin findPlugin(String name)

Find the plugin with the given name in the registry. The plugin will be reffed; caller is responsible for unreffing.

Parameters:

name - the plugin name to find

Returns:

the plugin with the given name or null if the plugin was not found. gst_object_unref() after usage.

MT safe.

getFeatureList

public List<PluginFeature> getFeatureList(Type type)

Retrieves a GList of GstPluginFeature of type.

Parameters:

type - a GType.

Returns:

a GList of GstPluginFeature of type. Use gst_plugin_feature_list_free() after use

MT safe.

getFeatureListByPlugin

public List<PluginFeature> getFeatureListByPlugin(String name)

Retrieves a GList of features of the plugin with name name.

Parameters:

name - a plugin name.

Returns:

a GList of GstPluginFeature. Use gst_plugin_feature_list_free() after usage.

getFeatureListCookie

public int getFeatureListCookie()

Returns the registry's feature list cookie. This changes every time a feature is added or removed from the registry.

Returns:

the feature list cookie.

getPluginList

public List<Plugin> getPluginList()

Get a copy of all plugins registered in the given registry. The refcount of each element in the list in incremented.

Returns:

a GList of GstPlugin. Use gst_plugin_list_free() after usage.

MT safe.

lookup

public @Nullable Plugin lookup(String filename)

Look up a plugin in the given registry with the given filename. If found, plugin is reffed.

Parameters:

filename - the name of the file to look up

Returns:

the GstPlugin if found, or null if not. gst_object_unref() after usage.

lookupFeature

public @Nullable PluginFeature lookupFeature(String name)

Find a GstPluginFeature with name in registry.

Parameters:

name - a GstPluginFeature name

Returns:

a GstPluginFeature with its refcount incremented, use gst_object_unref() after usage.

MT safe.

pluginFilter

public List<Plugin> pluginFilter(@Nullable PluginFilter filter,
 boolean first)

Runs a filter against all plugins in the registry and returns a GList with the results. If the first flag is set, only the first match is returned (as a list with a single object). Every plugin is reffed; use gst_plugin_list_free() after use, which will unref again.

Parameters:

filter - the filter to use

first - only return first match

Returns:

a GList of GstPlugin. Use gst_plugin_list_free() after usage.

MT safe.

removeFeature

public void removeFeature(PluginFeature feature)

Remove the feature from the registry.

MT safe.

Parameters:

feature - the feature to remove

removePlugin

public void removePlugin(Plugin plugin)

Remove the plugin from the registry.

MT safe.

Parameters:

plugin - the plugin to remove

scanPath

public boolean scanPath(String path)

Scan the given path for plugins to add to the registry. The syntax of the path is specific to the registry.

Parameters:

path - the path to scan

Returns:

true if registry changed

onFeatureAdded

public SignalConnection<Registry.FeatureAddedCallback> onFeatureAdded(Registry.FeatureAddedCallback handler)

Signals that a feature has been added to the registry (possibly replacing a previously-added one by the same name)

Parameters:

handler - the signal handler

Returns:

a signal handler ID to keep track of the signal connection

See Also:

• Registry.FeatureAddedCallback.run(PluginFeature)

emitFeatureAdded

public void emitFeatureAdded(@Nullable PluginFeature feature)

Emits the "feature-added" signal. See onFeatureAdded(Registry.FeatureAddedCallback).

onPluginAdded

public SignalConnection<Registry.PluginAddedCallback> onPluginAdded(Registry.PluginAddedCallback handler)

Signals that a plugin has been added to the registry (possibly replacing a previously-added one by the same name)

Parameters:

handler - the signal handler

Returns:

a signal handler ID to keep track of the signal connection

See Also:

• Registry.PluginAddedCallback.run(Plugin)

emitPluginAdded

public void emitPluginAdded(@Nullable Plugin plugin)

Emits the "plugin-added" signal. See onPluginAdded(Registry.PluginAddedCallback).

builder

public static Registry.Builder<? extends Registry.Builder> builder()

A Registry.Builder object constructs a Registry with the specified properties. Use the various set...() methods to set properties, and finish construction with Registry.Builder.build().

Returns:

the builder object