This module contains plugin interface for plainbox. Plugins are based on pkg_resources entry points feature. Any python package can advertise the existence of entry points associated with a given namespace. Any other package can query a given namespace and enumerate a sequence of entry points.
Each entry point has a name and importable identifier. The identifier can be imported using the load() method. A loaded entry point is exposed as an instance of PlugIn. A high-level collection of plugins (that may eventually also query alternate backends) is offered by PlugInCollection.
Using PlugInCollection.load() one can load all plugins from a particular namespace and work with them using provided utility methods such as PlugInCollection.get_by_name() or PlugInCollection.get_all_names()
The set of loaded plugins can be overridden by mock/patching PlugInCollection._get_entry_points(). This is especially useful for testing in isolation from whatever entry points may exist in the system.
Bases: plainbox.impl.secure.plugins.PlugInCollectionBase
Collection of plug-ins based on filesystem entries
Instantiate with dir_list and ext, call load() and then access any of the loaded plug-ins using the API offered. All loaded plugin information files are wrapped by a plug-in container. By default that is PlugIn but it may be adjusted if required.
The name of each plugin is the base name of the plugin file, the object of each plugin is the text read from the plugin file.
Time, in fractional seconds, that was required to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Context manager for using fake list of plugins
Parameters: |
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The provided list of plugins overrides any previously loaded plugins and prevent loading any other, real, plugins. After the context manager exits the previous state is restored.
Get a list of all the pairs of plugin name and plugin
Returns: | a list of tuples (plugin.plugin_name, plugin) |
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Get a list of all the plug-in names
Returns: | a list of plugin names |
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Get an list of plug-in objects
Get a list of all the plug-ins
Returns: | a list of plugin objects |
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Get the specified plug-in (by name)
Parameters: | name – name of the plugin to locate |
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Returns: | PlugIn like object associated with the name |
Raises KeyError: | |
if the specified name cannot be found |
Get the sum of load and wrap time of each plugin object
Returns: | The total number of fractional seconds of wall-clock time spent by loading this collection. This value doesn’t include some small overhead of this class but is representative of the load times of pluggable code. |
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Load all plug-ins.
This method loads all plug-ins from the search directories (as defined by the path attribute). Missing directories are silently ignored.
List of problems encountered while loading plugins
Internal method of PlugInCollectionBase.
Parameters: |
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This method prepares a wrapper (PlugIn subclass instance) for the specified plugin name/object by attempting to instantiate the wrapper class. If a PlugInError exception is raised then it is added to the problem_list and the corresponding plugin is not added to the collection of plugins.
Bases: builtins.object
Piece of code loaded at runtime, one of many for a given extension point
Bases: builtins.object
A collection of IPlugIn objects.
Time, in fractional seconds, that was used to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Context manager for using fake list of plugins
Parameters: |
|
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The provided list of plugins and exceptions overrides any previously loaded plugins and prevent loading any other, real, plugins. After the context manager exits the previous state is restored.
Get an list of plug-in objects
This is a shortcut that gives fastest access to a list of IPlugIn.plugin_object of each loaded plugin.
Get the cost to prepare everything required by this collection
Returns: | The total number of fractional seconds of wall-clock time spent on discovering, loading and wrapping each object now contained in this collection. |
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Bases: builtins.object
Support class for FsPlugInCollection’s subclasses that behaves like a string of text loaded from a file. The actual text is loaded on demand, the first time it is needed.
The actual methods implemented here are just enough to work for loading a provider. Since __getattr__() is implemented the class should be pretty versatile but your millage may vary.
Bases: plainbox.impl.secure.plugins.FsPlugInCollection
Collection of plug-ins based on filesystem entries
Instantiate with dir_list and ext, call load() and then access any of the loaded plug-ins using the API offered. All loaded plugin information files are wrapped by a plug-in container. By default that is PlugIn but it may be adjusted if required.
The name of each plugin is the base name of the plugin file, the object of each plugin is a handle that can be used to optionally load the content of the file.
Time, in fractional seconds, that was required to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Context manager for using fake list of plugins
Parameters: |
|
---|
The provided list of plugins overrides any previously loaded plugins and prevent loading any other, real, plugins. After the context manager exits the previous state is restored.
Get a list of all the pairs of plugin name and plugin
Returns: | a list of tuples (plugin.plugin_name, plugin) |
---|
Get a list of all the plug-in names
Returns: | a list of plugin names |
---|
Get an list of plug-in objects
Get a list of all the plug-ins
Returns: | a list of plugin objects |
---|
Get the specified plug-in (by name)
Parameters: | name – name of the plugin to locate |
---|---|
Returns: | PlugIn like object associated with the name |
Raises KeyError: | |
if the specified name cannot be found |
Get the sum of load and wrap time of each plugin object
Returns: | The total number of fractional seconds of wall-clock time spent by loading this collection. This value doesn’t include some small overhead of this class but is representative of the load times of pluggable code. |
---|
Load all plug-ins.
This method loads all plug-ins from the search directories (as defined by the path attribute). Missing directories are silently ignored.
List of problems encountered while loading plugins
Internal method of PlugInCollectionBase.
Parameters: |
|
---|
This method prepares a wrapper (PlugIn subclass instance) for the specified plugin name/object by attempting to instantiate the wrapper class. If a PlugInError exception is raised then it is added to the problem_list and the corresponding plugin is not added to the collection of plugins.
Bases: plainbox.impl.secure.plugins.PlugInCollectionBase
Collection of plug-ins based on a mapping of imported objects
All loaded plugin information files are wrapped by a plug-in container. By default that is PlugIn but it may be adjusted if required.
Time, in fractional seconds, that was required to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Note
This overridden version can be called at any time, unlike the base class implementation. Before all discovery is done, it simply returns zero.
Get a list of all the pairs of plugin name and plugin
Returns: | a list of tuples (plugin.plugin_name, plugin) |
---|
Get an list of plug-in objects
Get a list of all the plug-ins
Returns: | a list of plugin objects |
---|
Get the specified plug-in (by name)
Parameters: | name – name of the plugin to locate |
---|---|
Returns: | PlugIn like object associated with the name |
Raises KeyError: | |
if the specified name cannot be found |
Get the sum of load and wrap time of each plugin object
Returns: | The total number of fractional seconds of wall-clock time spent by loading this collection. This value doesn’t include some small overhead of this class but is representative of the load times of pluggable code. |
---|
List of problems encountered while loading plugins
Internal method of PlugInCollectionBase.
Parameters: |
|
---|
This method prepares a wrapper (PlugIn subclass instance) for the specified plugin name/object by attempting to instantiate the wrapper class. If a PlugInError exception is raised then it is added to the problem_list and the corresponding plugin is not added to the collection of plugins.
Bases: plainbox.impl.secure.plugins.PlugInCollectionBase
Collection of plug-ins based on pkg_resources
Instantiate with namespace, call load() and then access any of the loaded plug-ins using the API offered. All loaded objects are wrapped by a plug-in container. By default that is PlugIn but it may be adjusted if required.
Time, in fractional seconds, that was required to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Context manager for using fake list of plugins
Parameters: |
|
---|
The provided list of plugins overrides any previously loaded plugins and prevent loading any other, real, plugins. After the context manager exits the previous state is restored.
Get a list of all the pairs of plugin name and plugin
Returns: | a list of tuples (plugin.plugin_name, plugin) |
---|
Get a list of all the plug-in names
Returns: | a list of plugin names |
---|
Get an list of plug-in objects
Get a list of all the plug-ins
Returns: | a list of plugin objects |
---|
Get the specified plug-in (by name)
Parameters: | name – name of the plugin to locate |
---|---|
Returns: | PlugIn like object associated with the name |
Raises KeyError: | |
if the specified name cannot be found |
Get the sum of load and wrap time of each plugin object
Returns: | The total number of fractional seconds of wall-clock time spent by loading this collection. This value doesn’t include some small overhead of this class but is representative of the load times of pluggable code. |
---|
Load all plug-ins.
This method loads all plug-ins from the specified name-space. It may perform a lot of IO so it’s somewhat slow / expensive on a cold disk cache.
Note
this method queries pkg-resources only once.
List of problems encountered while loading plugins
Internal method of PlugInCollectionBase.
Parameters: |
|
---|
This method prepares a wrapper (PlugIn subclass instance) for the specified plugin name/object by attempting to instantiate the wrapper class. If a PlugInError exception is raised then it is added to the problem_list and the corresponding plugin is not added to the collection of plugins.
Bases: plainbox.impl.secure.plugins.IPlugIn
Simple plug-in that does not offer any guarantees beyond knowing it’s name and some arbitrary external object.
Bases: plainbox.impl.secure.plugins.IPlugInCollection
Base class that shares some of the implementation with the other PlugInCollection implemenetations.
Time, in fractional seconds, that was required to discover all objects.
This time is separate from the load and wrap time of all each individual plug-in. Typically this is either a fixed cost or a predictable cost related to traversing the file system.
Context manager for using fake list of plugins
Parameters: |
|
---|
The provided list of plugins overrides any previously loaded plugins and prevent loading any other, real, plugins. After the context manager exits the previous state is restored.
Get a list of all the pairs of plugin name and plugin
Returns: | a list of tuples (plugin.plugin_name, plugin) |
---|
Get the specified plug-in (by name)
Parameters: | name – name of the plugin to locate |
---|---|
Returns: | PlugIn like object associated with the name |
Raises KeyError: | |
if the specified name cannot be found |
Get the sum of load and wrap time of each plugin object
Returns: | The total number of fractional seconds of wall-clock time spent by loading this collection. This value doesn’t include some small overhead of this class but is representative of the load times of pluggable code. |
---|
Load all plug-ins.
This method loads all plug-ins from the specified name-space. It may perform a lot of IO so it’s somewhat slow / expensive on a cold disk cache.
Internal method of PlugInCollectionBase.
Parameters: |
|
---|
This method prepares a wrapper (PlugIn subclass instance) for the specified plugin name/object by attempting to instantiate the wrapper class. If a PlugInError exception is raised then it is added to the problem_list and the corresponding plugin is not added to the collection of plugins.
Bases: builtins.Exception
Exception that may be raised by PlugIn.__init__() to signal it cannot be fully loaded and should not be added to any collection.
Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.
Get the current “time”.
Returns: | A fractional number of seconds since some undefined base event. |
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This methods returns the current “time” that is useful for measuring plug-in loading time. The return value is meaningless but delta between two values is a fractional number of seconds between the two corresponding events.