object Task extends TaskInstances with Serializable
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- Task.scala
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final
case class
Context
(scheduler: Scheduler, connection: StackedCancelable, frameRef: FrameIndexRef, options: Options) extends Product with Serializable
The
Context
under which Task is supposed to be executed.The
Context
under which Task is supposed to be executed.This definition is of interest only when creating tasks with Task.unsafeCreate, which exposes internals and is considered unsafe to use.
- scheduler
is the Scheduler in charge of evaluation on
runAsync
.- connection
is the StackedCancelable that handles the cancellation on
runAsync
- frameRef
is a thread-local counter that keeps track of the current frame index of the run-loop. The run-loop is supposed to force an asynchronous boundary upon reaching a certain threshold, when the task is evaluated with monix.execution.ExecutionModel.BatchedExecution. And this
frameIndexRef
should be reset whenever a real asynchronous boundary happens. See the description of FrameIndexRef.- options
is a set of options for customizing the task's behavior upon evaluation.
-
type
FrameIndex = Int
A run-loop frame index is a number representing the current run-loop cycle, being incremented whenever a
flatMap
evaluation happens.A run-loop frame index is a number representing the current run-loop cycle, being incremented whenever a
flatMap
evaluation happens.It gets used for automatically forcing asynchronous boundaries, according to the ExecutionModel injected by the Scheduler when the task gets evaluated with
runAsync
.- See also
-
sealed abstract
class
FrameIndexRef
extends AnyRef
A reference that boxes a FrameIndex possibly using a thread-local.
A reference that boxes a FrameIndex possibly using a thread-local.
This definition is of interest only when creating tasks with Task.unsafeCreate, which exposes internals and is considered unsafe to use.
In case the Task is executed with BatchedExecution, this class boxes a FrameIndex in order to transport it over light async boundaries, possibly using a ThreadLocal, since this index is not supposed to survive when threads get forked.
The FrameIndex is a counter that increments whenever a
flatMap
operation is evaluated. And withBatchedExecution
, whenever that counter exceeds the specified threshold, an asynchronous boundary is automatically inserted. However this capability doesn't blend well with light asynchronous boundaries, for exampleAsync
tasks that never fork logical threads or TrampolinedRunnable instances executed by capable schedulers. This is why FrameIndexRef is part of the Context of execution for Task, available for asynchronous tasks that get created with Task.unsafeCreate.Note that in case the execution model is not BatchedExecution then this reference is just a dummy, since there's no point in keeping a counter around, plus setting and fetching from a
ThreadLocal
can be quite expensive. -
type
OnFinish[+A] = (Context, Callback[A]) ⇒ Unit
Type alias representing callbacks for asynchronous tasks.
-
final
case class
Options
(autoCancelableRunLoops: Boolean) extends Product with Serializable
Set of options for customizing the task's behavior.
Set of options for customizing the task's behavior.
- autoCancelableRunLoops
should be set to
true
in case you wantflatMap
driven loops to be auto-cancelable. Defaults tofalse
.
-
class
TypeClassInstances extends Instance[Task] with Instance[Task, Throwable] with Instance[Task] with Instance[Task]
Groups the implementation for the type-classes defined in monix.types.
Groups the implementation for the type-classes defined in monix.types.
- Definition Classes
- TaskInstances
Value Members
-
final
def
!=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
- Definition Classes
- AnyRef → Any
-
final
def
==(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
apply[A](f: ⇒ A): Task[A]
Returns a new task that, when executed, will emit the result of the given function, executed asynchronously.
Returns a new task that, when executed, will emit the result of the given function, executed asynchronously.
- f
is the callback to execute asynchronously
-
final
def
asInstanceOf[T0]: T0
- Definition Classes
- Any
-
def
async[A](register: (Scheduler, Callback[A]) ⇒ Cancelable): Task[A]
Create a
Task
from an asynchronous computation.Create a
Task
from an asynchronous computation.Alias for create.
-
def
chooseFirstOf[A, B](fa: Task[A], fb: Task[B]): Task[Either[(A, CancelableFuture[B]), (CancelableFuture[A], B)]]
Creates a
Task
that upon execution will execute both given tasks (possibly in parallel in case the tasks are asynchronous) and will return the result of the task that manages to complete first, along with a cancelable future of the other task.Creates a
Task
that upon execution will execute both given tasks (possibly in parallel in case the tasks are asynchronous) and will return the result of the task that manages to complete first, along with a cancelable future of the other task.If the first task that completes
-
def
chooseFirstOfList[A](tasks: TraversableOnce[Task[A]]): Task[A]
Creates a
Task
that upon execution will return the result of the first completed task in the given list and then cancel the rest. -
def
clone(): AnyRef
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- def coeval[A](a: Coeval[A]): Task[A]
-
def
create[A](register: (Scheduler, Callback[A]) ⇒ Cancelable): Task[A]
Create a
Task
from an asynchronous computation, which takes the form of a function with which we can register a callback.Create a
Task
from an asynchronous computation, which takes the form of a function with which we can register a callback.This can be used to translate from a callback-based API to a straightforward monadic version.
- register
is a function that will be called when this
Task
is executed, receiving a callback as a parameter, a callback that the user is supposed to call in order to signal the desired outcome of thisTask
.
- val defaultOptions: Options
-
def
defer[A](fa: ⇒ Task[A]): Task[A]
Promote a non-strict value representing a Task to a Task of the same type.
-
def
deferFuture[A](fa: ⇒ Future[A]): Task[A]
Promote a non-strict Scala
Future
to aTask
of the same type.Promote a non-strict Scala
Future
to aTask
of the same type.The equivalent of doing:
Task.defer(Task.fromFuture(fa))
-
def
deferFutureAction[A](f: (Scheduler) ⇒ Future[A]): Task[A]
Wraps calls that generate
Future
results into Task, provided a callback with an injected Scheduler to act as the necessaryExecutionContext
.Wraps calls that generate
Future
results into Task, provided a callback with an injected Scheduler to act as the necessaryExecutionContext
.This builder helps with wrapping
Future
-enabled APIs that need an implicitExecutionContext
to work. Consider this example:import scala.concurrent.{ExecutionContext, Future} def sumFuture(list: Seq[Int])(implicit ec: ExecutionContext): Future[Int] = Future(list.sum)
We'd like to wrap this function into one that returns a lazy
Task
that evaluates this sum every time it is called, because that's how tasks work best. However in order to invoke this function anExecutionContext
is needed:def sumTask(list: Seq[Int])(implicit ec: ExecutionContext): Task[Int] = Task.deferFuture(sumFuture(list))
But this is not only superfluous, but against the best practices of using
Task
. The difference is thatTask
takes a Scheduler (inheriting fromExecutionContext
) only when runAsync happens. But withdeferFutureAction
we get to have an injectedScheduler
in the passed callback:def sumTask(list: Seq[Int]): Task[Int] = Task.deferFutureAction { implicit scheduler => sumFuture(list) }
- f
is the function that's going to be executed when the task gets evaluated, generating the wrapped
Future
-
def
delay[A](a: ⇒ A): Task[A]
Alias for eval.
-
final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
def
equals(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
eval[A](a: ⇒ A): Task[A]
Promote a non-strict value to a Task, catching exceptions in the process.
Promote a non-strict value to a Task, catching exceptions in the process.
Note that since
Task
is not memoized, this will recompute the value each time theTask
is executed. -
def
evalOnce[A](a: ⇒ A): Task[A]
Promote a non-strict value to a Task that is memoized on the first evaluation, the result being then available on subsequent evaluations.
-
def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
-
def
fork[A](fa: Task[A], scheduler: Scheduler): Task[A]
Mirrors the given source
Task
, but upon execution ensure that evaluation forks into a separate (logical) thread.Mirrors the given source
Task
, but upon execution ensure that evaluation forks into a separate (logical) thread.The given Scheduler will be used for execution of the Task, effectively overriding the
Scheduler
that's passed inrunAsync
. Thus you can execute a wholeTask
on a separate thread-pool, useful for example in case of doing I/O.- fa
is the task that will get executed asynchronously
- scheduler
is the scheduler to use for execution
-
def
fork[A](fa: Task[A]): Task[A]
Mirrors the given source
Task
, but upon execution ensure that evaluation forks into a separate (logical) thread.Mirrors the given source
Task
, but upon execution ensure that evaluation forks into a separate (logical) thread.The Scheduler used will be the one that is used to start the run-loop in
runAsync
.- fa
is the task that will get executed asynchronously
-
def
fromFuture[A](f: Future[A]): Task[A]
Converts the given Scala
Future
into aTask
.Converts the given Scala
Future
into aTask
.NOTE: if you want to defer the creation of the future, use in combination with defer.
-
def
fromTry[A](a: Try[A]): Task[A]
Builds a Task instance out of a Scala
Try
. -
def
gather[A, M[X] <: TraversableOnce[X]](in: M[Task[A]])(implicit cbf: CanBuildFrom[M[Task[A]], A, M[A]]): Task[M[A]]
Nondeterministically gather results from the given collection of tasks, returning a task that will signal the same type of collection of results once all tasks are finished.
Nondeterministically gather results from the given collection of tasks, returning a task that will signal the same type of collection of results once all tasks are finished.
This function is the nondeterministic analogue of
sequence
and should behave identically tosequence
so long as there is no interaction between the effects being gathered. However, unlikesequence
, which decides on a total order of effects, the effects in agather
are unordered with respect to each other.Although the effects are unordered, we ensure the order of results matches the order of the input sequence. Also see gatherUnordered for the more efficient alternative.
-
def
gatherUnordered[A](in: TraversableOnce[Task[A]]): Task[List[A]]
Nondeterministically gather results from the given collection of tasks, without keeping the original ordering of results.
Nondeterministically gather results from the given collection of tasks, without keeping the original ordering of results.
If the tasks in the list are set to execute asynchronously, forking logical threads, then the tasks will execute in parallel.
This function is similar to gather, but neither the effects nor the results will be ordered. Useful when you don't need ordering because:
- it has non-blocking behavior (but not wait-free)
- it can be more efficient (compared with gather), but not necessarily (if you care about performance, then test)
- in
is a list of tasks to execute
-
final
def
getClass(): Class[_]
- Definition Classes
- AnyRef → Any
-
def
hashCode(): Int
- Definition Classes
- AnyRef → Any
-
final
def
isInstanceOf[T0]: Boolean
- Definition Classes
- Any
-
def
mapBoth[A1, A2, R](fa1: Task[A1], fa2: Task[A2])(f: (A1, A2) ⇒ R): Task[R]
Apply a mapping functions to the results of two tasks, nondeterministically ordering their effects.
Apply a mapping functions to the results of two tasks, nondeterministically ordering their effects.
If the two tasks are synchronous, they'll get executed one after the other, with the result being available asynchronously. If the two tasks are asynchronous, they'll get scheduled for execution at the same time and in a multi-threading environment they'll execute in parallel and have their results synchronized.
-
final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
def
never[A]: Task[A]
A Task instance that upon evaluation will never complete.
-
implicit
val
nondeterminism: TypeClassInstances
Type-class instances for Task that have nondeterministic effects for Applicative.
Type-class instances for Task that have nondeterministic effects for Applicative.
It can be optionally imported in scope to make
map2
andap
to potentially run tasks in parallel.- Definition Classes
- TaskInstances
-
final
def
notify(): Unit
- Definition Classes
- AnyRef
-
final
def
notifyAll(): Unit
- Definition Classes
- AnyRef
-
def
now[A](a: A): Task[A]
Returns a
Task
that on execution is always successful, emitting the given strict value. -
def
pure[A](a: A): Task[A]
Lifts a value into the task context.
Lifts a value into the task context. Alias for now.
-
def
raiseError[A](ex: Throwable): Task[A]
Returns a task that on execution is always finishing in error emitting the specified exception.
-
def
sequence[A, M[X] <: TraversableOnce[X]](in: M[Task[A]])(implicit cbf: CanBuildFrom[M[Task[A]], A, M[A]]): Task[M[A]]
Given a
TraversableOnce
of tasks, transforms it to a task signaling the collection, executing the tasks one by one and gathering their results in the same collection.Given a
TraversableOnce
of tasks, transforms it to a task signaling the collection, executing the tasks one by one and gathering their results in the same collection.This operation will execute the tasks one by one, in order, which means that both effects and results will be ordered. See gather and gatherUnordered for unordered results or effects, and thus potential of running in parallel.
It's a simple version of traverse.
-
def
suspend[A](fa: ⇒ Task[A]): Task[A]
Alias for defer.
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
tailRecM[A, B](a: A)(f: (A) ⇒ Task[Either[A, B]]): Task[B]
Keeps calling
f
until it returns aRight
result.Keeps calling
f
until it returns aRight
result.Based on Phil Freeman's Stack Safety for Free.
-
def
toString(): String
- Definition Classes
- AnyRef → Any
-
def
traverse[A, B, M[X] <: TraversableOnce[X]](in: M[A])(f: (A) ⇒ Task[B])(implicit cbf: CanBuildFrom[M[A], B, M[B]]): Task[M[B]]
Given a
TraversableOnce[A]
and a functionA => Task[B]
, sequentially apply the function to each element of the collection and gather their results in the same collection.Given a
TraversableOnce[A]
and a functionA => Task[B]
, sequentially apply the function to each element of the collection and gather their results in the same collection.It's a generalized version of sequence.
-
implicit
val
typeClassInstances: TypeClassInstances
Type-class instances for Task.
-
final
val
unit: Task[Unit]
A
Task[Unit]
provided for convenience. -
def
unsafeCreate[A](onFinish: OnFinish[A]): Task[A]
Constructs a lazy Task instance whose result will be computed asynchronously.
Constructs a lazy Task instance whose result will be computed asynchronously.
**WARNING:** Unsafe to use directly, only use if you know what you're doing. For building
Task
instances safely see Task.create.Rules of usage:
- the received
StackedCancelable
can be used to store cancelable references that will be executed upon cancel; everypush
must happen at the beginning, before any execution happens andpop
must happen afterwards when the processing is finished, before signaling the result - the received
FrameRef
indicates the current frame index and must be reset on real asynchronous boundaries (which avoids doing extra async boundaries in batched execution mode) - before execution, an asynchronous boundary is recommended, to avoid stack overflow errors, but can happen using the scheduler's facilities for trampolined execution
- on signaling the result (
onSuccess
,onError
), another async boundary is necessary, but can also happen with the scheduler's facilities for trampolined execution (e.g.asyncOnSuccess
andasyncOnError
)
**WARNING:** note that not only is this builder unsafe, but also unstable, as the OnFinish callback type is exposing volatile internal implementation details. This builder is meant to create optimized asynchronous tasks, but for normal usage prefer Task.create.
- the received
-
def
unsafeStartAsync[A](source: Task[A], context: Context, cb: Callback[A]): Unit
Unsafe utility - starts the execution of a Task with a guaranteed asynchronous boundary, by providing the needed Scheduler, StackedCancelable and Callback.
Unsafe utility - starts the execution of a Task with a guaranteed asynchronous boundary, by providing the needed Scheduler, StackedCancelable and Callback.
DO NOT use directly, as it is UNSAFE to use, unless you know what you're doing. Prefer Task.runAsync and
Task.fork
. -
def
unsafeStartNow[A](source: Task[A], context: Context, cb: Callback[A]): Unit
Unsafe utility - starts the execution of a Task, by providing the needed Scheduler, StackedCancelable and Callback.
Unsafe utility - starts the execution of a Task, by providing the needed Scheduler, StackedCancelable and Callback.
DO NOT use directly, as it is UNSAFE to use, unless you know what you're doing. Prefer Task.runAsync.
-
def
unsafeStartTrampolined[A](source: Task[A], context: Context, cb: Callback[A]): Unit
Unsafe utility - starts the execution of a Task with a guaranteed trampolined asynchronous boundary, by providing the needed Scheduler, StackedCancelable and Callback.
Unsafe utility - starts the execution of a Task with a guaranteed trampolined asynchronous boundary, by providing the needed Scheduler, StackedCancelable and Callback.
DO NOT use directly, as it is UNSAFE to use, unless you know what you're doing. Prefer Task.runAsync and
Task.fork
. -
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
def
wander[A, B, M[X] <: TraversableOnce[X]](in: M[A])(f: (A) ⇒ Task[B])(implicit cbf: CanBuildFrom[M[A], B, M[B]]): Task[M[B]]
Given a
TraversableOnce[A]
and a functionA => Task[B]
, nondeterministically apply the function to each element of the collection and return a task that will signal a collection of the results once all tasks are finished.Given a
TraversableOnce[A]
and a functionA => Task[B]
, nondeterministically apply the function to each element of the collection and return a task that will signal a collection of the results once all tasks are finished.This function is the nondeterministic analogue of
traverse
and should behave identically totraverse
so long as there is no interaction between the effects being gathered. However, unliketraverse
, which decides on a total order of effects, the effects in awander
are unordered with respect to each other.Although the effects are unordered, we ensure the order of results matches the order of the input sequence. Also see wanderUnordered for the more efficient alternative.
It's a generalized version of gather.
-
def
wanderUnordered[A, B, M[X] <: TraversableOnce[X]](in: M[A])(f: (A) ⇒ Task[B]): Task[List[B]]
Given a
TraversableOnce[A]
and a functionA => Task[B]
, nondeterministically apply the function to each element of the collection without keeping the original ordering of the results.Given a
TraversableOnce[A]
and a functionA => Task[B]
, nondeterministically apply the function to each element of the collection without keeping the original ordering of the results.This function is similar to wander, but neither the effects nor the results will be ordered. Useful when you don't need ordering because:
- it has non-blocking behavior (but not wait-free)
- it can be more efficient (compared with wander), but not necessarily (if you care about performance, then test)
It's a generalized version of gatherUnordered.
-
def
zip2[A1, A2, R](fa1: Task[A1], fa2: Task[A2]): Task[(A1, A2)]
Pairs two Task instances.
-
def
zip3[A1, A2, A3](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3]): Task[(A1, A2, A3)]
Pairs three Task instances.
-
def
zip4[A1, A2, A3, A4](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4]): Task[(A1, A2, A3, A4)]
Pairs four Task instances.
-
def
zip5[A1, A2, A3, A4, A5](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4], fa5: Task[A5]): Task[(A1, A2, A3, A4, A5)]
Pairs five Task instances.
-
def
zip6[A1, A2, A3, A4, A5, A6](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4], fa5: Task[A5], fa6: Task[A6]): Task[(A1, A2, A3, A4, A5, A6)]
Pairs six Task instances.
-
def
zipList[A](sources: Task[A]*): Task[List[A]]
Gathers the results from a sequence of tasks into a single list.
Gathers the results from a sequence of tasks into a single list. The effects are not ordered, but the results are.
-
def
zipMap2[A1, A2, R](fa1: Task[A1], fa2: Task[A2])(f: (A1, A2) ⇒ R): Task[R]
Pairs two Task instances, creating a new instance that will apply the given mapping function to the resulting pair.
-
def
zipMap3[A1, A2, A3, R](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3])(f: (A1, A2, A3) ⇒ R): Task[R]
Pairs three Task instances, applying the given mapping function to the result.
-
def
zipMap4[A1, A2, A3, A4, R](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4])(f: (A1, A2, A3, A4) ⇒ R): Task[R]
Pairs four Task instances, applying the given mapping function to the result.
-
def
zipMap5[A1, A2, A3, A4, A5, R](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4], fa5: Task[A5])(f: (A1, A2, A3, A4, A5) ⇒ R): Task[R]
Pairs five Task instances, applying the given mapping function to the result.
-
def
zipMap6[A1, A2, A3, A4, A5, A6, R](fa1: Task[A1], fa2: Task[A2], fa3: Task[A3], fa4: Task[A4], fa5: Task[A5], fa6: Task[A6])(f: (A1, A2, A3, A4, A5, A6) ⇒ R): Task[R]
Pairs six Task instances, applying the given mapping function to the result.
- object FrameIndexRef
This is the API documentation for the Monix library.
Package Overview
monix.execution exposes lower level primitives for dealing with asynchronous execution:
Atomic
types, as alternative tojava.util.concurrent.atomic
monix.eval is for dealing with evaluation of results, thus exposing Task and Coeval.
monix.reactive exposes the
Observable
pattern:Observable
implementationsmonix.types implements type-class shims, to be translated to type-classes provided by libraries such as Cats or Scalaz.
monix.cats is the optional integration with the Cats library, providing translations for the types described in
monix.types
.monix.scalaz is the optional integration with the Scalaz library, providing translations for the types described in
monix.types
.