io.cdap.wrangler.registry

Class SystemDirectiveRegistry

java.lang.Object

io.cdap.wrangler.registry.SystemDirectiveRegistry

All Implemented Interfaces:

DirectiveRegistry, Closeable, AutoCloseable

public final class SystemDirectiveRegistry
extends Object
implements DirectiveRegistry

This class is implementation of DirectiveRegistry for maintaining a registry of system provided directives. The directives maintained within this registry and present and loaded by the Classloader that is responsible for loading this class.

In order to load the directives, this class scans through all classes that implement the interface Directive. Instead of scanning entire JAR, it uses the package name a starting point for scanning the classes that implement the Directive interface.

For every class found, this scan will create a instance of DirectiveInfo object and store it in the registry.

See Also:

UserDirectiveRegistry, CompositeDirectiveRegistry, DirectiveInfo

Constructor Summary

Constructors

Constructor and Description
SystemDirectiveRegistry()
SystemDirectiveRegistry(List<String> namespaces) This constructor uses the user provided namespace as starting pointing for scanning classes that implement the interface Directive.

Method Summary

Modifier and Type	Method and Description
void	close() Closes any resources acquired during initialization or otherwise.
DirectiveInfo	get(String namespace, String name) Given the name of the directive, returns the information related to the directive.
Iterable<DirectiveInfo>	list(String namespace) List the directives in the specified namespace
void	reload(String namespace) This method reloads the directives from the artifacts into the registry.

Methods inherited from class java.lang.Object

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

Constructor Detail

SystemDirectiveRegistry

public SystemDirectiveRegistry()
                        throws DirectiveLoadException

Throws:

DirectiveLoadException

SystemDirectiveRegistry

public SystemDirectiveRegistry(List<String> namespaces)
                        throws DirectiveLoadException

This constructor uses the user provided namespace as starting pointing for scanning classes that implement the interface Directive.

Parameters:

namespaces - that is used as starting point for scanning classes.

Throws:

DirectiveLoadException - thrown if there are any issue loading the directive.

Method Detail

get

public DirectiveInfo get(String namespace,
                         String name)

Given the name of the directive, returns the information related to the directive.

Specified by:

get in interface DirectiveRegistry

Parameters:

name - of the directive to be retrieved from the registry.

namespace - the namespace of the directive

Returns:

an instance of DirectiveInfo if found, else null.

reload

public void reload(String namespace)

Description copied from interface: DirectiveRegistry

This method reloads the directives from the artifacts into the registry. Any implementation of this method should provide support for deletes, updates and additions.

Specified by:

reload in interface DirectiveRegistry

Parameters:

namespace - the namespace to reload directives in

list

public Iterable<DirectiveInfo> list(String namespace)

Description copied from interface: DirectiveRegistry

List the directives in the specified namespace

Specified by:

list in interface DirectiveRegistry

Parameters:

namespace - the namespace to list from

Returns:

Returns an iterator to iterate through all the DirectiveInfo objects maintained within the registry.

close

public void close()

Closes any resources acquired during initialization or otherwise.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable