Class ScopedValue.Carrier

java.lang.Object
java.lang.ScopedValue.Carrier
Enclosing class:
ScopedValue<T>
public static final class ScopedValue.Carrier extends Object
A mapping of scoped values, as keys, to values.

A Carrier is used to accumulate mappings so that an operation (a Runnable or ScopedValue.CallableOp) 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. 

    ScopedValue.where(k1, v1).where(k2, v2).run(() -> ... );

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:
25

  • Method Summary

    Modifier and Type
    Method
    Description
    <R, X extends Throwable>
    R
    call(ScopedValue.CallableOp<? extends R, X> op)
    Calls a value-returning operation with each scoped value in this mapping bound to its value in the current thread.
    <T> T
    get(ScopedValue<T> key)
    Returns the value of a ScopedValue in this mapping.
    void
    run(Runnable op)
    Runs an operation with each scoped value in this mapping bound to its value in the current thread.
    <T> ScopedValue.Carrier
    where(ScopedValue<T> key, T value)
    Returns a new Carrier with the mappings from this carrier plus a new mapping from key to value.

    Methods declared in class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
    boolean
    equals(Object o)
    Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    May cause performance issues, deadlocks and hangs.
    final Class<? extends Object>
    getClass()
    Answers the unique instance of java.lang.Class which represents the class of the receiver.
    int
    hashCode()
    Answers an integer hash code for the receiver.
    final void
    notify()
    Causes one thread which is waiting on the receiver to be made ready to run.
    final void
    notifyAll()
    Causes all threads which are waiting on the receiver to be made ready to run.
    String
    toString()
    Answers a string containing a concise, human-readable description of the receiver.
    final void
    wait()
    Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
    final void
    wait(long time)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
    final void
    wait(long time, int frac)
    Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

  • Method Details

    • where

      public <T> ScopedValue.Carrier where(ScopedValue<T> key, T value)
      Returns a new Carrier with the mappings from this carrier plus a new mapping from key to value. If this carrier already has a mapping for the scoped value key then it will map to the new value. The current carrier is immutable, so it is not changed by this method.
      Type Parameters:
      T - the type of the value
      Parameters:
      key - the ScopedValue key
      value - the value, can be null
      Returns:
      a new Carrier with the mappings from this carrier plus the new mapping

    • get

      public <T> T get(ScopedValue<T> key)
      Returns the value of a ScopedValue in this mapping.
      Type Parameters:
      T - the type of the value
      Parameters:
      key - the ScopedValue key
      Returns:
      the value
      Throws:
      NoSuchElementException - if the key is not present in this mapping

    • call

      public <R, X extends Throwable> R call(ScopedValue.CallableOp<? extends R, X> op) throws X
      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. If op completes with an exception then it propagated by this method.

      Scoped values are intended to be used in a structured manner. If code invoked directly or indirectly by the operation creates a StructuredTaskScopePREVIEW but does not closePREVIEW it, then it is detected as a structure violation when the operation completes (normally or with an exception). In that case, the underlying construct of the StructuredTaskScope is closed and StructureViolationExceptionPREVIEW is thrown.

      Type Parameters:
      R - the type of the result of the operation
      X - type of the exception thrown by the operation
      Parameters:
      op - the operation to run
      Returns:
      the result
      Throws:
      StructureViolationExceptionPREVIEW - if a structure violation is detected
      X - if op completes with an exception

    • run

      public void run(Runnable op)
      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. If op completes with an exception then it propagated by this method.

      Scoped values are intended to be used in a structured manner. If code invoked directly or indirectly by the operation creates a StructuredTaskScopePREVIEW but does not closePREVIEW it, then it is detected as a structure violation when the operation completes (normally or with an exception). In that case, the underlying construct of the StructuredTaskScope is closed and StructureViolationExceptionPREVIEW is thrown.

      Parameters:
      op - the operation to run
      Throws:
      StructureViolationExceptionPREVIEW - if a structure violation is detected