org.apache.brooklyn.camp.brooklyn.spi.dsl

Class BrooklynDslDeferredSupplier<T>

java.lang.Object

org.apache.brooklyn.camp.brooklyn.spi.dsl.BrooklynDslDeferredSupplier<T>

All Implemented Interfaces:

java.io.Serializable, TaskFactory<Task<T>>, DeferredSupplier<T>, ImmediateSupplier<T>

Direct Known Subclasses:

BrooklynDslCommon.DslBrooklynObjectConfigSupplier, DslComponent, DslDeferredFunctionCall

public abstract class BrooklynDslDeferredSupplier<T>
extends java.lang.Object
implements DeferredSupplier<T>, ImmediateSupplier<T>, TaskFactory<Task<T>>, java.io.Serializable

Provide an object suitable to resolve chained invocations in a parsed YAML / Deployment Plan DSL, which also implements DeferredSupplier so that they can be resolved when needed (e.g. when entity-lookup and execution contexts are available).

Implementations of this abstract class are expected to be immutable and thread safe, as instances must support usage in multiple Assembly instances created from a single AssemblyTemplate. The object can be used in parallel from multiple threads and no locking is done as all extending objects are assumed to be stateless.

Subclasses which return a deferred value are typically only resolvable in the context of a Task on an Entity; these should be only used as the value of a ConfigKey set in the YAML, and should not accessed until after the components / entities are created and are being started. (TODO the precise semantics of this are under development.)

The threading model is that only one thread can call get() at a time. An interruptible lock is obtained using #lock for the duration of that method. It is important to not use synchronized because that is not interruptible - if someone tries to get the value and interrupts after a short wait, then we must release the lock immediately and return.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.brooklyn.util.core.task.ImmediateSupplier

ImmediateSupplier.ImmediateUnsupportedException, ImmediateSupplier.ImmediateValueNotAvailableException

Constructor Summary

Constructors

Constructor and Description
BrooklynDslDeferredSupplier()

Method Summary

Modifier and Type	Method and Description
T	get()
abstract Task<T>	newTask()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.brooklyn.util.core.task.ImmediateSupplier

getImmediately

Constructor Detail

BrooklynDslDeferredSupplier

public BrooklynDslDeferredSupplier()

Method Detail

get

public final T get()

Specified by:

get in interface DeferredSupplier<T>

newTask

public abstract Task<T> newTask()

Specified by:

newTask in interface TaskFactory<Task<T>>