Package au.csiro.pathling.utilities

Interface ObjectHolder<C extends Serializable,V>

Type Parameters:
C - the type of the configuration
V - the type of the instance
All Known Implementing Classes:
ObjectHolder.KeyedHolder, ObjectHolder.SingletonHolder
public interface ObjectHolder<C extends Serializable,V>
Represents a scoped storage for instances of type V that can be created from configuration of type C. The concrete implementations can use various strategies for storing the instances. For example a singleton can manage a single instance per process.
Author:
Piotr Szul, John Grimes

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static class 
    ObjectHolder.KeyedHolder<C extends Serializable,V>
    An implementation of ObjectHolder that memoises one instance per distinct configuration within the process.
    static class 
    ObjectHolder.SingletonHolder<C extends Serializable,V>
    A singleton implementation of ObjectHolder that holds a single instance of something.

  • Method Summary

    Modifier and Type
    Method
    Description
    V
    getOrCreate(C config)
    Retrieves the instance associated with given configuration and if necessary creates ones.
    static <C extends Serializable, V>
    ObjectHolder<C,V>
    perConfiguration(Function<C,V> constructor)
    Creates the holder memoising one instance per distinct configuration within the process.
    static <C extends Serializable, V>
    ObjectHolder<C,V>
    perConfiguration(Function<C,V> constructor, boolean closeOnShutdown, int shutdownHookPriority)
    Creates the holder memoising one instance per distinct configuration within the process.
    void
    reset()
    Destroys all the instances stored the underlying scope.
    static <C extends Serializable, V>
    ObjectHolder<C,V>
    singleton(Function<C,V> constructor)
    Creates the holder allowing a single instance to be created per process.
    static <C extends Serializable, V>
    ObjectHolder<C,V>
    singleton(Function<C,V> constructor, boolean closeOnShutdown, int shutdownHookPriority)
    Creates the holder allowing a single instance to be created per process.

  • Method Details

    • getOrCreate

      V getOrCreate(@Nonnull C config)
      Retrieves the instance associated with given configuration and if necessary creates ones.
      Parameters:
      config - the configuration for the instance.
      Returns:
      the instance associated with the holder.

    • reset

      void reset()
      Destroys all the instances stored the underlying scope.

    • singleton

      static <C extends Serializable, V> ObjectHolder<C,V> singleton(@Nonnull Function<C,V> constructor, boolean closeOnShutdown, int shutdownHookPriority)
      Creates the holder allowing a single instance to be created per process. Attempts to create another instance with different configuration will fail.
      Type Parameters:
      C - the type of the configuration.
      V - the type of the instance.
      Parameters:
      constructor - the function that creates new instance from the configuration.
      closeOnShutdown - whether to close the instance on JVM shutdown.
      shutdownHookPriority - the priority of the shutdown hook.
      Returns:
      the singleton holder.

    • singleton

      static <C extends Serializable, V> ObjectHolder<C,V> singleton(@Nonnull Function<C,V> constructor)
      Creates the holder allowing a single instance to be created per process. Attempts to create another instance with different configuration will fail. The instance will be closed on JVM shutdown.
      Type Parameters:
      C - the type of the configuration.
      V - the type of the instance.
      Parameters:
      constructor - the function that creates new instance from the configuration.
      Returns:
      the singleton holder.

    • perConfiguration

      static <C extends Serializable, V> ObjectHolder<C,V> perConfiguration(@Nonnull Function<C,V> constructor, boolean closeOnShutdown, int shutdownHookPriority)
      Creates the holder memoising one instance per distinct configuration within the process. Several configurations may coexist, so lookups with different configurations each receive their own instance rather than failing.
      Type Parameters:
      C - the type of the configuration.
      V - the type of the instance.
      Parameters:
      constructor - the function that creates a new instance from the configuration.
      closeOnShutdown - whether to close the held instances on JVM shutdown.
      shutdownHookPriority - the priority of the shutdown hook.
      Returns:
      the keyed holder.

    • perConfiguration

      static <C extends Serializable, V> ObjectHolder<C,V> perConfiguration(@Nonnull Function<C,V> constructor)
      Creates the holder memoising one instance per distinct configuration within the process. Several configurations may coexist, so lookups with different configurations each receive their own instance rather than failing. The held instances will be closed on JVM shutdown.
      Type Parameters:
      C - the type of the configuration.
      V - the type of the instance.
      Parameters:
      constructor - the function that creates a new instance from the configuration.
      Returns:
      the keyed holder.