package fusing
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Type Members
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class
ActorGraphInterpreter
extends Actor with ActorLogging
INTERNAL API
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final
case class
Batch
[In, Out](max: Long, costFn: (In) ⇒ Long, seed: (In) ⇒ Out, aggregate: (Out, In) ⇒ Out) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
Buffer
[T](size: Int, overflowStrategy: OverflowStrategy) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
Collect
[In, Out](pf: PartialFunction[In, Out]) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
- final class Delay [T] extends SimpleLinearGraphStage[T]
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final
case class
Drop
[T](count: Long) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
DropWhile
[T](p: (T) ⇒ Boolean) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
- final class DropWithin [T] extends SimpleLinearGraphStage[T]
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final
class
Expand
[In, Out] extends GraphStage[FlowShape[In, Out]]
INTERNAL API
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final
case class
Filter
[T](p: (T) ⇒ Boolean) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
class
FlattenMerge
[T, M] extends GraphStage[FlowShape[Graph[SourceShape[T], M], T]]
INTERNAL API
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final
case class
Fold
[In, Out](zero: Out, f: (Out, In) ⇒ Out) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
class
FoldAsync
[In, Out] extends GraphStage[FlowShape[In, Out]]
INTERNAL API
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final
class
GraphInterpreter
extends AnyRef
INTERNAL API
INTERNAL API
From an external viewpoint, the GraphInterpreter takes an assembly of graph processing stages encoded as a GraphInterpreter#GraphAssembly object and provides facilities to execute and interact with this assembly. The lifecycle of the Interpreter is roughly the following:
- Boundary logics are attached via attachDownstreamBoundary() and attachUpstreamBoundary()
- init() is called
- execute() is called whenever there is need for execution, providing an upper limit on the processed events
- finish() is called before the interpreter is disposed, preferably after isCompleted returned true, although in abort cases this is not strictly necessary
The execute() method of the interpreter accepts an upper bound on the events it will process. After this limit is reached or there are no more pending events to be processed, the call returns. It is possible to inspect if there are unprocessed events left via the isSuspended method. isCompleted returns true once all stages reported completion inside the interpreter.
The internal architecture of the interpreter is based on the usage of arrays and optimized for reducing allocations on the hot paths.
One of the basic abstractions inside the interpreter is the akka.stream.impl.fusing.GraphInterpreter.Connection. A connection represents an output-input port pair (an analogue for a connected RS Publisher-Subscriber pair). The Connection object contains all the necessary data for the interpreter to pass elements, demand, completion or errors across the Connection. In particular
- portStates contains a bitfield that tracks the states of the ports (output-input) corresponding to this connection. This bitfield is used to decode the event that is in-flight.
- connectionSlot contains a potential element or exception that accompanies the event encoded in the portStates bitfield
- inHandler contains the InHandler instance that handles the events corresponding to the input port of the connection
- outHandler contains the OutHandler instance that handles the events corresponding to the output port of the connection
On top of the Connection table there is an eventQueue, represented as a circular buffer of Connections. The queue contains the Connections that have pending events to be processed. The pending event itself is encoded in the portState bitfield of the Connection. This implies that there can be only one event in flight for a given Connection, which is true in almost all cases, except a complete-after-push or fail-after-push which has to be decoded accordingly.
The layout of the portState bitfield is the following:
|- state machn.-| Only one bit is hot among these bits 64 32 16 | 8 4 2 1 | +---+---+---|---+---+---+---| | | | | | | | | | | | | | | From the following flags only one is active in any given time. These bits encode | | | | | | | state machine states, and they are "moved" around using XOR masks to keep other bits | | | | | | | intact. | | | | | | | | | | | | | +- InReady: The input port is ready to be pulled | | | | | +----- Pulling: A pull is active, but have not arrived yet (queued) | | | | +--------- Pushing: A push is active, but have not arrived yet (queued) | | | +------------- OutReady: The output port is ready to be pushed | | | | | +----------------- InClosed: The input port is closed and will not receive any events. | | A push might be still in flight which will be then processed first. | +--------------------- OutClosed: The output port is closed and will not receive any events. +------------------------- InFailed: Always set in conjunction with InClosed. Indicates that the close event is a failure
Sending an event is usually the following sequence:
- An action is requested by a stage logic (push, pull, complete, etc.)
- the state machine in portStates is transitioned from a ready state to a pending event
- the affected Connection is enqueued
Receiving an event is usually the following sequence:
- the Connection to be processed is dequeued
- the type of the event is determined from the bits set on portStates
- the state machine in portStates is transitioned to a ready state
- using the inHandlers/outHandlers table the corresponding callback is called on the stage logic.
Because of the FIFO construction of the queue the interpreter is fair, i.e. a pending event is always executed after a bounded number of other events. This property, together with suspendability means that even infinite cycles can be modeled, or even dissolved (if preempted and a "stealing" external event is injected; for example the non-cycle edge of a balance is pulled, dissolving the original cycle).
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final
class
GraphInterpreterShell
extends AnyRef
INTERNAL API
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final
case class
GraphModule
(assembly: GraphAssembly, shape: Shape, attributes: Attributes, matValIDs: Array[Module]) extends AtomicModule with Product with Serializable
INTERNAL API
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final
case class
GraphStageModule
(shape: Shape, attributes: Attributes, stage: GraphStageWithMaterializedValue[Shape, Any]) extends AtomicModule with Product with Serializable
INTERNAL API
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final
class
GroupBy
[T, K] extends GraphStage[FlowShape[T, Source[T, NotUsed]]]
INTERNAL API
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final
case class
Grouped
[T](n: Int) extends GraphStage[FlowShape[T, Seq[T]]] with Product with Serializable
INTERNAL API
- final class GroupedWithin [T] extends GraphStage[FlowShape[T, Seq[T]]]
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final
case class
Intersperse
[T](start: Option[T], inject: T, end: Option[T]) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
LimitWeighted
[T](n: Long, costFn: (T) ⇒ Long) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
Log
[T](name: String, extract: (T) ⇒ Any, logAdapter: Option[LoggingAdapter]) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
Map
[In, Out](f: (In) ⇒ Out) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
MapAsync
[In, Out](parallelism: Int, f: (In) ⇒ Future[Out]) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
MapAsyncUnordered
[In, Out](parallelism: Int, f: (In) ⇒ Future[Out]) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
MapError
[T](f: PartialFunction[Throwable, Throwable]) extends SimpleLinearGraphStage[T] with Product with Serializable
Maps error with the provided function if it is defined for an error or, otherwise, passes it on unchanged.
Maps error with the provided function if it is defined for an error or, otherwise, passes it on unchanged.
While similar to Recover this stage can be used to transform an error signal to a different one *without* logging it as an error in the process. So in that sense it is NOT exactly equivalent to
recover(t => throw t2)
since recover would log thet2
error. -
final
class
PrefixAndTail
[T] extends GraphStage[FlowShape[T, (Seq[T], Source[T, NotUsed])]]
INTERNAL API
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final
case class
Recover
[T](pf: PartialFunction[Throwable, T]) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
- final class RecoverWith [T, M] extends SimpleLinearGraphStage[T]
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final
class
Reduce
[T] extends SimpleLinearGraphStage[T]
INTERNAL API
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final
case class
Scan
[In, Out](zero: Out, f: (Out, In) ⇒ Out) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
ScanAsync
[In, Out](zero: Out, f: (Out, In) ⇒ Future[Out]) extends GraphStage[FlowShape[In, Out]] with Product with Serializable
INTERNAL API
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final
case class
Sliding
[T](n: Int, step: Int) extends GraphStage[FlowShape[T, Seq[T]]] with Product with Serializable
INTERNAL API
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final
class
Split
[T] extends GraphStage[FlowShape[T, Source[T, NotUsed]]]
INTERNAL API
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final
class
StatefulMapConcat
[In, Out] extends GraphStage[FlowShape[In, Out]]
INTERNAL API
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final
class
SubSource
[T] extends GraphStage[SourceShape[T]]
INTERNAL API
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abstract
class
SupervisedGraphStageLogic
extends GraphStageLogic
INTERNAL API
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final
case class
Take
[T](count: Long) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
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final
case class
TakeWhile
[T](p: (T) ⇒ Boolean, inclusive: Boolean = false) extends SimpleLinearGraphStage[T] with Product with Serializable
INTERNAL API
- final class TakeWithin [T] extends SimpleLinearGraphStage[T]
Value Members
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object
ActorGraphInterpreter
INTERNAL API
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object
GraphInterpreter
INTERNAL API
INTERNAL API
(See the class for the documentation of the internals)
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object
GraphStages
INTERNAL API
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object
Split
INTERNAL API
- object SubSource