Packages

class CCSTM extends CCSTMExecutor with STMImpl with Factory

The reference STM implementation for scala.concurrent.stm. CCSTM is a library-only STM based on the SwissTM algorithm, extended to reduce the overhead of non-transactional accesses, allow partial rollback, and include modular blocking and composition operators retry and orAtomic.

During construction the system property "ccstm.stats" is checked. If it is "true" or "1" (actually if it starts with any of the characters 't', 'T', 'y', 'Y', or '1') then statistics are recorded while the program runs and printed to Console during JVM shutdown.

Statistics are tracked separately for top-level transactions and true nested transactions. Many nested atomic blocks can be merged into the top-level transaction by CCSTM for efficiency; these are not reported as nested.

Reported statistics are either counts or exponential histograms. For histograms sum is the sum of the samples, count is the number of transactions for which the statistic was non-zero, avg is sum/count and the histogram reports in brackets the number of samples that had a value of 1, 2..3, 4..7, 8..15, and so on.

Counters:

  • commits -- committed transactions
  • alternatives -- alternatives provided to atomic, one sample per call to atomic
  • retrySet -- memory locations watched while performing modular blocking, one sample per top-level blocking event
  • retryWaitElapsed -- milliseconds elapsed during modular blocking, one sample per top-level blocking event
  • explicitRetries -- explicit retries using retry, retryFor, Ref.View.await or Ref.View.tryAwait
  • unrecordedTxns -- rollbacks that were to erase a successful use of atomic.unrecorded
  • optimisticRetries -- rollbacks that were automatically retried, one line per OptimisticFailureCause.category
  • failures -- rollbacks that were not retried, one line for each type of exception in UncaughtExceptionCause
  • blockingAcquires -- internal locks that could not be acquired immediately
  • commitReadSet -- optimistic Ref reads, one sample per committed top-level transaction
  • commitBargeSet -- locations read pessimistically, one sample per committed top-level transaction
  • commitWriteSet -- locations written, one sample per committed top-level transaction
  • rollbackReadSet -- optimistic Ref reads, one sample per transaction that was rolled back
  • rollbackBargeSet -- locations read pessimistically, one sample per transaction that was rolled back
  • rollbackWriteSet -- locations written pessimistically, one sample per transaction that was rolled back

Read and write set counts for a nested transaction are merged into its parent if it commits, they are not counted separately during the nested commit.

Linear Supertypes
Factory, STMImpl, TxnContext, RefFactory, CCSTMExecutor, Serializable, java.io.Serializable, Product, Equals, TxnExecutor, AnyRef, Any
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Inherited
  1. CCSTM
  2. Factory
  3. STMImpl
  4. TxnContext
  5. RefFactory
  6. CCSTMExecutor
  7. Serializable
  8. Serializable
  9. Product
  10. Equals
  11. TxnExecutor
  12. AnyRef
  13. Any
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Visibility
  1. Public
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Instance Constructors

  1. new CCSTM()

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def apply[Z](block: (InTxn) ⇒ Z)(implicit mt: MaybeTxn): Z

    Executes block one or more times until an atomic execution is achieved, buffering and/or locking writes so they are not visible until success.

    Executes block one or more times until an atomic execution is achieved, buffering and/or locking writes so they are not visible until success.

    Z

    the return type of the atomic block

    block

    code to execute atomically

    returns

    the value returned from block after a successful optimistic concurrency attempt

    Definition Classes
    CCSTMExecutor → TxnExecutor
  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  7. def compareAndSet[A, B](a: Ref[A], a0: A, a1: A, b: Ref[B], b0: B, b1: B): Boolean

    Atomically compares and sets two Refs, probably more efficiently then the corresponding transaction.

    Atomically compares and sets two Refs, probably more efficiently then the corresponding transaction. Equivalent to 

    atomic { implicit t =>
  a() == a0 && b() == b0 && { a() = a1 ; b() = b1 ; true }
}
    Definition Classes
    CCSTMExecutor → TxnExecutor
  8. def compareAndSetIdentity[A <: AnyRef, B <: AnyRef](a: Ref[A], a0: A, a1: A, b: Ref[B], b0: B, b1: B): Boolean

    Atomically compares and sets two Refs using identity comparison, probably more efficiently then the corresponding transaction.

    Atomically compares and sets two Refs using identity comparison, probably more efficiently then the corresponding transaction. Equivalent to 

    atomic { implicit t =>
  val f = (a() eq a0) && (b() eq b0)
  if (f && (a0 ne a1))
    a() = a1
  if (f && (b0 ne b1))
    b() = b1
  f
}
    Definition Classes
    CCSTMExecutor → TxnExecutor
  9. val controlFlowTest: (Throwable) ⇒ Boolean
    Definition Classes
    CCSTMExecutor
  10. def dynCurrentOrNull: InTxn

    Returns the current InTxn instance if it is active or in the process of committing on the current thread, null otherwise.

    Returns the current InTxn instance if it is active or in the process of committing on the current thread, null otherwise. Always performs a dynamic lookup.

    Definition Classes
    CCSTM → TxnContext
  11. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  12. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  13. def findCurrent(implicit mt: MaybeTxn): Option[InTxn]

    Returns Some(txn) if txn is the InTxn active or in the process of committing on the current thread, None otherwise.

    Returns Some(txn) if txn is the InTxn active or in the process of committing on the current thread, None otherwise.

    Definition Classes
    CCSTM → TxnContext
  14. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
  15. def isControlFlow(x: Throwable): Boolean

    Returns true if x should be treated as a transfer of control, rather than an error.

    Returns true if x should be treated as a transfer of control, rather than an error. Atomic blocks that end with an uncaught control flow exception are committed, while atomic blocks that end with an uncaught error exception are rolled back.

    All implementations of this method must return true for instances that implement scala.util.control.ControlThrowable.

    Definition Classes
    CCSTMExecutor → TxnExecutor
  16. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  17. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  18. def newCommitBarrier(timeout: Long, unit: TimeUnit): CommitBarrier

    Returns a new commit barrier suitable for coordinating commits by this STM implementation.

    Returns a new commit barrier suitable for coordinating commits by this STM implementation.

    Definition Classes
    CCSTM → STMImpl
  19. def newRef[T](v0: T)(implicit arg0: ClassManifest[T]): Ref[T]

    T will not be one of the primitive types (for which a newRef specialization exists).

    T will not be one of the primitive types (for which a newRef specialization exists).

    Definition Classes
    Factory → RefFactory
  20. def newRef(v0: Unit): Ref[Unit]
    Definition Classes
    Factory → RefFactory
  21. def newRef(v0: Double): Ref[Double]
    Definition Classes
    Factory → RefFactory
  22. def newRef(v0: Long): Ref[Long]
    Definition Classes
    Factory → RefFactory
  23. def newRef(v0: Float): Ref[Float]
    Definition Classes
    Factory → RefFactory
  24. def newRef(v0: Int): Ref[Int]
    Definition Classes
    Factory → RefFactory
  25. def newRef(v0: Char): Ref[Char]
    Definition Classes
    Factory → RefFactory
  26. def newRef(v0: Short): Ref[Short]
    Definition Classes
    Factory → RefFactory
  27. def newRef(v0: Byte): Ref[Byte]
    Definition Classes
    Factory → RefFactory
  28. def newRef(v0: Boolean): Ref[Boolean]
    Definition Classes
    Factory → RefFactory
  29. def newTArray[A](xs: TraversableOnce[A])(implicit arg0: ClassManifest[A]): TArray[A]
    Definition Classes
    Factory → RefFactory
  30. def newTArray[A](length: Int)(implicit arg0: ClassManifest[A]): TArray[A]
    Definition Classes
    Factory → RefFactory
  31. def newTMap[A, B]: TMap[A, B]
    Definition Classes
    Factory → RefFactory
  32. def newTMapBuilder[A, B]: Builder[(A, B), TMap[A, B]] { ... /* 2 definitions in type refinement */ }
    Definition Classes
    Factory → RefFactory
  33. def newTSet[A]: TSet[A]
    Definition Classes
    Factory → RefFactory
  34. def newTSetBuilder[A]: Builder[A, TSet[A]] { ... /* 2 definitions in type refinement */ }
    Definition Classes
    Factory → RefFactory
  35. def newTxnLocal[A](init: ⇒ A, initialValue: (InTxn) ⇒ A, beforeCommit: (InTxn) ⇒ Unit, whilePreparing: (InTxnEnd) ⇒ Unit, whileCommitting: (InTxnEnd) ⇒ Unit, afterCommit: (A) ⇒ Unit, afterRollback: (Status) ⇒ Unit, afterCompletion: (Status) ⇒ Unit): TxnLocal[A]
    Definition Classes
    Factory → RefFactory
  36. final def notify(): Unit
    Definition Classes
    AnyRef
  37. final def notifyAll(): Unit
    Definition Classes
    AnyRef
  38. def oneOf[Z](blocks: (InTxn) ⇒ Z*)(implicit mt: MaybeTxn): Z

    Atomically executes a transaction that is composed from blocks by joining with a left-biased orAtomic operator.

    Atomically executes a transaction that is composed from blocks by joining with a left-biased orAtomic operator. The following two examples are equivalent. Using orAtomic:

    atomic { implicit t =>
  // body A
} orAtomic { implicit t =>
  // body B
} ...

    Using oneOf:

    atomic.oneOf( { implicit t: InTxn =>
  // body A
}, { implicit t: InTxn =>
  // body B
} )

    The first block will be attempted in an optimistic transaction until it either succeeds, fails with no retry possible (in which case the causing exception will be rethrown), or performs a call to retry. If a retry is requested, then the next block will be attempted in the same fashion. If all blocks are explicitly retried then execution resumes at the first block, but only after another context has changed some value read by one of the attempts.

    The left-biasing of the orAtomic composition guarantees that if the first block does not call retry, no other blocks will be executed.

    Definition Classes
    CCSTMExecutor → TxnExecutor
  39. val postDecisionFailureHandler: (Status, Throwable) ⇒ Unit
    Definition Classes
    CCSTMExecutor → TxnExecutor
  40. def pushAlternative[Z](mt: MaybeTxn, block: (InTxn) ⇒ Z): Boolean

    (rare) Associates an alternative atomic block with the current thread.

    (rare) Associates an alternative atomic block with the current thread. The next call to apply will consider block to be an alternative. Multiple alternatives may be associated before calling apply. Returns true if this is the first pushed alternative, false otherwise. This method is not usually called directly. Alternative atomic blocks are only attempted if the previous alternatives call retry.

    Note that it is not required that pushAlternative be called on the same instance of TxnExecutor as apply, just that they have been derived from the same original executor.

    Definition Classes
    CCSTMExecutor → TxnExecutor
  41. val retryTimeoutNanos: Option[Long]
    Definition Classes
    CCSTMExecutor → TxnExecutor
  42. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  43. def toString(): String
    Definition Classes
    CCSTMExecutor → AnyRef → Any
  44. def unrecorded[Z](block: (InTxn) ⇒ Z, outerFailure: (RollbackCause) ⇒ Z)(implicit mt: MaybeTxn): Z

    Performs a computation in a transaction and returns the result, but always rolls back the transaction.

    Performs a computation in a transaction and returns the result, but always rolls back the transaction. No writes performed by block will be committed or exposed to other threads. This may be useful for heuristic decisions or for debugging, as for the various dbgStr implementations.

    The caller is responsible for correctness: It is a code smell if Z is a type that is constructed from Ref, TMap, TSet, .....

    If this method is executed inside an outer transaction that has status Txn.RolledBack then block can't complete. The default behavior (if outerFailure is null) in that case is to immediately roll back the outer transaction. If a non-null outerFailure handler has been provided, however, it allow this method to return. This is useful when the unrecorded transaction is being used for debugging or logging.

    atomic.unrecorded { implicit txn => code } is roughly equivalent to the following, except that the rollback cause used will be Txn.UnrecordedTxnCause: 

    case class Tunnel(z: Z) extends Exception {}
try {
  atomic.withControlFlowRecognizer({
    case Tunnel(_) => false
  }) { implicit txn =>
    throw Tunnel(code)
  }
} catch {
  case Tunnel(z) => z
}
    Definition Classes
    CCSTMExecutor → TxnExecutor
  45. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  46. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  47. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  48. def withControlFlowRecognizer(pf: PartialFunction[Throwable, Boolean]): TxnExecutor

    Returns a TxnExecutor e that is identical to this one, except that e.isControlFlow(x) will return pf(x) if pf.isDefined(x).

    Returns a TxnExecutor e that is identical to this one, except that e.isControlFlow(x) will return pf(x) if pf.isDefined(x). For exceptions for which pf is not defined the decision will be deferred to the previous implementation.

    This function may be combined with TxnExecutor.transformDefault to add system-wide recognition of a control-transfer exception that does not extend scala.util.control.ControlThrowable. For example, to modify the default behavior of all TxnExecutor.isControlFlow calls to accept DSLNonLocalControlTransferException: 

    TxnExecutor.transformDefault { e =>
  e.withControlFlowRecognizer {
    case _: DSLNonLocalControlTransferException => true
  }
}
    Definition Classes
    CCSTMExecutor → TxnExecutor
  49. def withPostDecisionFailureHandler(handler: (Status, Throwable) ⇒ Unit): TxnExecutor

    Returns a TxnExecutor e that is identical to this one, except that e.postDecisionFailureHandler will return handler.

    Returns a TxnExecutor e that is identical to this one, except that e.postDecisionFailureHandler will return handler. This function may be called from inside a function passed to TxnExecutor.transformDefault to change the system-wide post-decision failure handler.

    Definition Classes
    CCSTMExecutor → TxnExecutor
  50. def withRetryTimeout(timeout: Long, unit: TimeUnit = TimeUnit.MILLISECONDS): TxnExecutor

    Returns a TxnExecutor that is identical to this one except that it has the specified retry timeout.

    Returns a TxnExecutor that is identical to this one except that it has the specified retry timeout. The default time unit is milliseconds. If the retry timeout expires the retry will be cancelled with an InterruptedException.

    Definition Classes
    TxnExecutor
  51. def withRetryTimeoutNanos(timeout: Option[Long]): TxnExecutor

    Returns a TxnExecutor that is identical to this one, except that it has a retryTimeout of timeoutNanos.

    Returns a TxnExecutor that is identical to this one, except that it has a retryTimeout of timeoutNanos.

    Definition Classes
    CCSTMExecutor → TxnExecutor

Inherited from Factory

Inherited from STMImpl

Inherited from TxnContext

Inherited from RefFactory

Inherited from CCSTMExecutor

Inherited from Serializable

Inherited from java.io.Serializable

Inherited from Product

Inherited from Equals

Inherited from TxnExecutor

Inherited from AnyRef

Inherited from Any

Ungrouped