scala.concurrent.stm

TxnLocal

trait TxnLocal[A] extends RefLike[A, InTxnEnd]

TxnLocal[A] holds an instance of A that is local to an atomic block. See the factory method in the companion object for information about the life-cycle.

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Abstract Value Members

  1. abstract def get(implicit txn: InTxnEnd): A

    Performs a transactional read and checks that it is consistent with all reads already made by txn.

    Performs a transactional read and checks that it is consistent with all reads already made by txn. Equivalent to apply(), which is more concise in many situations.

    txn

    an active transaction.

    returns

    the value of the Ref as observed by txn.

    Definition Classes
    SourceLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  2. abstract def getWith[Z](f: (A) ⇒ Z)(implicit txn: InTxnEnd): Z

    Returns f(get), possibly reevaluating f to avoid rollback if a conflicting change is made but the old and new values are equal after application of f.

    Returns f(get), possibly reevaluating f to avoid rollback if a conflicting change is made but the old and new values are equal after application of f. Requires that f(x) == f(y) if x == y.

    getWith(f) is equivalent to f(relaxedGet({ f(_) == f(_) })), although perhaps more efficient.

    f

    an idempotent function.

    returns

    the result of applying f to the value contained in this Ref.

    Definition Classes
    SourceLike
  3. abstract def isInitialized(implicit txn: InTxn): Boolean

    Returns true if a value is already associated with this TxnLocal in the current transactional context, false otherwise.

  4. abstract def relaxedGet(equiv: (A, A) ⇒ Boolean)(implicit txn: InTxnEnd): A

    Returns the same value as get, but allows the caller to determine whether txn should be rolled back if another thread changes the value of this Ref before txn is committed.

    Returns the same value as get, but allows the caller to determine whether txn should be rolled back if another thread changes the value of this Ref before txn is committed. If ref.relaxedGet(equiv) returns v0 in txn, another context changes ref to v1, and equiv(v0, v1) == true, then txn won't be required to roll back (at least not due to this read). If additional changes are made to ref additional calls to the equivalence function will be made, always with v0 as the first parameter.

    equiv will always be invoked on the current thread. Extreme care should be taken if the equivalence function accesses any Refs.

    As an example, to perform a read that will not be validated during commit you can use the maximally permissive equivalence function:

    val unvalidatedValue = ref.relaxedGet({ (_, _) => true })

    To check view serializability rather than conflict serializability for a read:

    val viewSerializableValue = ref.relaxedGet({ _ == _ })

    The getWith method provides related functionality.

    equiv

    an equivalence function that returns true if a transaction that observed the first argument will still complete correctly, where the second argument is the actual value that should have been observed.

    returns

    a value of the Ref, not necessary consistent with the rest of the reads performed by txn.

    Definition Classes
    SourceLike
  5. abstract def set(v: A)(implicit txn: InTxnEnd): Unit

    Performs a transactional write.

    Performs a transactional write. The new value will not be visible by any other threads until (and unless) txn successfully commits. Equivalent to update(v).

    v

    a value to store in the Ref.

    Definition Classes
    SinkLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  6. abstract def swap(v: A)(implicit txn: InTxnEnd): A

    Works like set(v), but returns the old value.

    Works like set(v), but returns the old value.

    returns

    the previous value of this Ref, as observed by txn.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  7. abstract def transform(f: (A) ⇒ A)(implicit txn: InTxnEnd): Unit

    Transforms the value referenced by this Ref by applying the function f.

    Transforms the value referenced by this Ref by applying the function f. Acts like ref.set(f(ref.get)), but the execution of f may be deferred or repeated by the STM to reduce transaction conflicts.

    f

    a function that is safe to call multiple times, and safe to call later during the transaction.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  8. abstract def transformIfDefined(pf: PartialFunction[A, A])(implicit txn: InTxnEnd): Boolean

    Transforms the value v referenced by this Ref by to pf.apply(v), but only if pf.isDefinedAt(v).

    Transforms the value v referenced by this Ref by to pf.apply(v), but only if pf.isDefinedAt(v). Returns true if a transformation was performed, false otherwise. pf.apply and pf.isDefinedAt may be deferred or repeated by the STM to reduce transaction conflicts.

    pf

    a partial function that is safe to call multiple times, and safe to call later in the transaction.

    returns

    pf.isDefinedAt(v), where v was the value of this Ref before transformation (if any).

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  9. abstract def trySet(v: A)(implicit txn: InTxnEnd): Boolean

    Performs a transactional write and returns true, or returns false.

    Performs a transactional write and returns true, or returns false. The STM implementation may choose to return false to reduce (not necessarily avoid) blocking. If no other threads are performing any transactional or atomic accesses then this method will succeed.

    Definition Classes
    SinkLike

Concrete Value Members

  1. final def !=(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  2. final def ##(): Int

    Definition Classes
    AnyRef → Any
  3. def *=(rhs: A)(implicit txn: InTxnEnd, num: Numeric[A]): Unit

    Transforms the value stored in the Ref by multiplying it.

    Transforms the value stored in the Ref by multiplying it.

    Note: Implementations may choose to ignore the provided Numeric[A] instance if A is a primitive type.

    rhs

    the quantity by which to multiply the value of this Ref.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  4. def +=(rhs: A)(implicit txn: InTxnEnd, num: Numeric[A]): Unit

    Transforms the value stored in the Ref by incrementing it.

    Transforms the value stored in the Ref by incrementing it.

    Note: Implementations may choose to ignore the provided Numeric[A] instance if A is a primitive type.

    rhs

    the quantity by which to increment the value of this Ref.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  5. def -=(rhs: A)(implicit txn: InTxnEnd, num: Numeric[A]): Unit

    Transforms the value stored in the Ref by decrementing it.

    Transforms the value stored in the Ref by decrementing it.

    Note: Implementations may choose to ignore the provided Numeric[A] instance if A is a primitive type.

    rhs

    the quantity by which to decrement the value of this Ref.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  6. def /=(rhs: A)(implicit txn: InTxnEnd, num: Numeric[A]): Unit

    Transforms the value stored the Ref by performing a division on it, throwing away the remainder if division is not exact for instances of type A.

    Transforms the value stored the Ref by performing a division on it, throwing away the remainder if division is not exact for instances of type A. The careful reader will note that division is actually provided by Fractional[A] or Integral[A], it is not defined on Numeric[A]. To avoid compile-time ambiguity this method accepts a Numeric[A] and assumes that it can be converted at runtime into either a Fractional[A] or an Integral[A].

    Note: Implementations may choose to ignore the provided Numeric[A] instance if A is a primitive type.

    rhs

    the quantity by which to divide the value of this Ref.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  7. final def ==(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  8. def apply()(implicit txn: InTxnEnd): A

    Performs a transactional read and checks that it is consistent with all reads already made by txn.

    Performs a transactional read and checks that it is consistent with all reads already made by txn. Equivalent to get.

    Example:

    val x = Ref(0)
    atomic { implicit t =>
      ...
      val v = x() // perform a read inside a transaction
      ...
    }
    txn

    an active transaction.

    returns

    the value of the Ref as observed by txn.

    Definition Classes
    SourceLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  9. final def asInstanceOf[T0]: T0

    Definition Classes
    Any
  10. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  11. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  12. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  13. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  14. def getAndTransform(f: (A) ⇒ A)(implicit txn: InTxnEnd): A

    Transforms the value referenced by this Ref by applying the function f, and returns the previous value.

    Transforms the value referenced by this Ref by applying the function f, and returns the previous value.

    f

    a function that is safe to call multiple times.

    returns

    the previous value of this Ref (the value passed to f).

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  15. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any
  16. def hashCode(): Int

    Definition Classes
    AnyRef → Any
  17. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any
  18. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  19. final def notify(): Unit

    Definition Classes
    AnyRef
  20. final def notifyAll(): Unit

    Definition Classes
    AnyRef
  21. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef
  22. def toString(): String

    Definition Classes
    AnyRef → Any
  23. def transformAndExtract[B](f: (A) ⇒ (A, B))(implicit txn: InTxnEnd): B

    Transforms the value referenced by this Ref from v to f(v)._1, and returns f(v)._2.

    Transforms the value referenced by this Ref from v to f(v)._1, and returns f(v)._2.

    f

    a function that is safe to call multiple times.

    returns

    the second element of the pair returned by f.

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  24. def transformAndGet(f: (A) ⇒ A)(implicit txn: InTxnEnd): A

    Transforms the value referenced by this Ref by applying the function f, and returns the new value.

    Transforms the value referenced by this Ref by applying the function f, and returns the new value.

    f

    a function that is safe to call multiple times.

    returns

    the new value of this Ref (the value returned from f).

    Definition Classes
    RefLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  25. def update(v: A)(implicit txn: InTxnEnd): Unit

    Performs a transactional write.

    Performs a transactional write. The new value will not be visible by any other threads until (and unless) txn successfully commits. Equivalent to set(v).

    Example:

    val x = Ref(0)
    atomic { implicit t =>
      ...
      x() = 10 // perform a write inside a transaction
      ...
    }
    v

    a value to store in the Ref.

    Definition Classes
    SinkLike
    Exceptions thrown
    IllegalStateException

    if txn is not active.

  26. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  27. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  28. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

Inherited from RefLike[A, InTxnEnd]

Inherited from SinkLike[A, InTxnEnd]

Inherited from SourceLike[A, InTxnEnd]

Inherited from AnyRef

Inherited from Any

Ungrouped