Package com.yahoo.component.provider

Class ComponentRegistry<COMPONENT>

java.lang.Object
com.yahoo.component.provider.ComponentRegistry<COMPONENT>
public class ComponentRegistry<COMPONENT> extends Object
A generic superclass for component registries. Supports registration and lookup of components by id. The registry resolves id requests to the newest matching component version registered.

This registry supports the freeze pattern - changes can be made to this registry until freeze() is called. Subsequent change attempts will cause an exception. Freezing a registry after building makes it possible to avoid locking and memory synchronization on lookups.

Author:
bratseth

  • Constructor Details

    • ComponentRegistry

      public ComponentRegistry()

  • Method Details

    • freeze

      public void freeze()
      Freezes this registry to prevent further changes. Override this to freeze internal data structures and dependent objects. Overrides must call super. Calling freeze on an already frozen registry must have no effect.

    • isFrozen

      public final boolean isFrozen()
      returns whether this is currently frozen

    • register

      public void register(ComponentId id, COMPONENT component)
      Registers a component unless this registry is frozen. This will succeed even if this component name and version is already registered.
      Throws:
      IllegalStateException - if this chain is frozen

    • unregister

      public COMPONENT unregister(ComponentId id)
      Unregisters a component unless this registry is frozen. Note that the component is not deconstructed or otherwise modified in any way, this is the responsiblity of the caller.
      Parameters:
      id - the id of the component to be unregistered
      Returns:
      the component that was unregistered, or null if no such component was already registered

    • getComponent

      public COMPONENT getComponent(String componentSpecification)
      See getComponent(ComponentSpecification)
      Parameters:
      componentSpecification - a component specification string, see Version
      Returns:
      the component or null if no component of this name (and version, if specified) is registered here

    • getComponent

      public COMPONENT getComponent(ComponentId id)

    • getComponent

      public COMPONENT getComponent(ComponentSpecification id)
      Returns a component. If the id does not specify an (exact) version, the newest (matching) version is returned. For example, if version 3.1 is specified and we have 3.1.0, 3.1.1 and 3.1.3 registered, 3.1.3 is returned.
      Parameters:
      id - the id of the component to return. May not include a version, or include an underspecified version, in which case the highest (matching) version which does not contain a qualifier is returned
      Returns:
      the search chain or null if no component of this name (and matching version, if specified) is registered

    • findBestMatch

      protected static Version findBestMatch(VersionSpecification versionSpec, Set<Version> versions)
      Finds the best (highest) matching version among a set.
      Returns:
      the matching version, or null if there are no matches

    • allComponents

      public List<COMPONENT> allComponents()
      Returns an unmodifiable snapshot of all components present in this registry.

    • allComponentsById

      public Map<ComponentId,COMPONENT> allComponentsById()
      Returns an unmodifiable snapshot of all components present in this registry, by id.

    • getComponentCount

      public int getComponentCount()
      Returns the number of components in this

    • singleton

      public static <COMPONENT> ComponentRegistry<COMPONENT> singleton(ComponentId id, COMPONENT component)
      Returns a frozen registry with a single component, for convenience