- Enclosing class:
ScopedValue<T>
A Carrier is used to accumlate mappings so that an operation (a
Runnable or Callable) can be executed with all scoped values in the
mapping bound to values. The following example runs an operation with k1
bound (or rebound) to v1, and k2 bound (or rebound) to v2.
A Carrier is immutable and thread-safe. The where method returns a new Carrier object,
it does not mutate an existing mapping.
Unless otherwise specified, passing a null argument to a method in
this class will cause a NullPointerException to be thrown.
- Since:
- 20
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Method Summary
Modifier and TypeMethodDescription<R> RCalls a value-returning operation with each scoped value in this mapping bound to its value in the current thread.<T> Tget(ScopedValue<T> key) Returns the value of aScopedValuein this mapping.voidRuns an operation with each scoped value in this mapping bound to its value in the current thread.where(ScopedValue<T> key, T value) Returns a newCarrierwith the mappings from this carrier plus a new mapping fromkeytovalue.
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Method Details
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where
Returns a newCarrierwith the mappings from this carrier plus a new mapping fromkeytovalue. If this carrier already has a mapping for the scoped valuekeythen it will map to the newvalue. The current carrier is immutable, so it is not changed by this method.- Type Parameters:
T- the type of the value- Parameters:
key- theScopedValuekeyvalue- the value, can benull- Returns:
- a new
Carrierwith the mappings from this carrier plus the new mapping
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get
Returns the value of aScopedValuein this mapping.- Type Parameters:
T- the type of the value- Parameters:
key- theScopedValuekey- Returns:
- the value
- Throws:
NoSuchElementException- if the key is not present in this mapping
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call
Calls a value-returning operation with each scoped value in this mapping bound to its value in the current thread. When the operation completes (normally or with an exception), each scoped value in the mapping will revert to being unbound, or revert to its previous value when previously bound, in the current thread.Scoped values are intended to be used in a structured manner. If
opcreates aStructuredTaskScopebut does not close it, then exitingopcauses the underlying construct of eachStructuredTaskScopecreated in the dynamic scope to be closed. This may require blocking until all child threads have completed their sub-tasks. The closing is done in the reverse order that they were created. Once closed,StructureViolationExceptionis thrown.- Type Parameters:
R- the type of the result of the operation- Parameters:
op- the operation to run- Returns:
- the result
- Throws:
Exception- ifopcompletes with an exception- See Also:
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run
Runs an operation with each scoped value in this mapping bound to its value in the current thread. When the operation completes (normally or with an exception), each scoped value in the mapping will revert to being unbound, or revert to its previous value when previously bound, in the current thread.Scoped values are intended to be used in a structured manner. If
opcreates aStructuredTaskScopebut does not close it, then exitingopcauses the underlying construct of eachStructuredTaskScopecreated in the dynamic scope to be closed. This may require blocking until all child threads have completed their sub-tasks. The closing is done in the reverse order that they were created. Once closed,StructureViolationExceptionis thrown.- Parameters:
op- the operation to run- See Also:
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