io.grpc.internal

Class SharedResourceHolder

java.lang.Object

io.grpc.internal.SharedResourceHolder

@ThreadSafe
public final class SharedResourceHolder
extends Object

A holder for shared resource singletons.

Components like client channels and servers need certain resources, e.g. a thread pool, to run. If the user has not provided such resources, these components will use a default one, which is shared as a static resource. This class holds these default resources and manages their life-cycles.

A resource is identified by the reference of a SharedResourceHolder.Resource object, which is typically a singleton, provided to the get() and release() methods. Each Resource object (not its class) maps to an object cached in the holder.

Resources are ref-counted and shut down after a delay when the ref-count reaches zero.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SharedResourceHolder.Resource<T> Defines a resource, and the way to create and destroy instances of it.

Method Summary

Modifier and Type	Method and Description
static <T> T	get(SharedResourceHolder.Resource<T> resource) Try to get an existing instance of the given resource.
static <T> T	release(SharedResourceHolder.Resource<T> resource, T instance) Releases an instance of the given resource.

Methods inherited from class java.lang.Object

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

Method Detail

get

public static <T> T get(SharedResourceHolder.Resource<T> resource)

Try to get an existing instance of the given resource. If an instance does not exist, create a new one with the given factory.

Parameters:

resource - the singleton object that identifies the requested static resource

release

public static <T> T release(SharedResourceHolder.Resource<T> resource,
                            T instance)

Releases an instance of the given resource.

The instance must have been obtained from get(Resource). Otherwise will throw IllegalArgumentException.

Caller must not release a reference more than once. It's advisory that you clear the reference to the instance with the null returned by this method.

Parameters:

resource - the singleton Resource object that identifies the released static resource

instance - the released static resource

Returns:

a null which the caller can use to clear the reference to that instance.