Introduce Task monad #1802
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Introduce Task monad #1802
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pjfanning
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Mar 18, 2025
pjfanning
reviewed
Mar 19, 2025
pjfanning
reviewed
Mar 19, 2025
| } | ||
| future.onComplete { res => | ||
| childFiber.complete(res) | ||
| }(scala.concurrent.ExecutionContext.global) |
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- we need to avoid hardcoding the global context
- even if comes to setting up a config in the reference.conf that defines an executioncontext created specifically for this
- might be nicer if it was controlled by an implicit param though
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Sure thing, this one was temporary, that's why it's explicit :) I'll replace it with executor. The intent is to make the executor pluggable (probably by picking a dispatcher from the Materializer), I just haven't decided for the API on that yet.
This commit introduces Task, a data structure that represents a recipe, or program, for producing a value of type T (or failing with an exception). It is similar in semantics to RunnableGraph[T], but intended as first-class building block. It has the following properties: - A task can have resources associated to it, which are guaranteed to be released if the task is cancelled or fails - Tasks can be forked so multiple ones can run concurrently - Such forked tasks can be cancelled A Task can be created from a RunnableGraph which has a KillSwitch, by connecting a Source and a Sink through a KillSwitch, or by direct lambda functions.
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This commit introduces Task, a data structure that represents a recipe, or program, for producing a value of type T (or failing with an exception). It is similar in semantics to RunnableGraph[T], but intended as first-class building block.
It has the following properties:
A Task can be created from a RunnableGraph which has a KillSwitch, by connecting a Source and a Sink through a KillSwitch, or by direct lambda functions.
Open discussion points and TODOs (in order of highest architectural impact):
KillSwitchdoesn't communicate back a trigger when the graph is actually done cancelling. It would be very nice to have that, but this might need deeper changes in pekko.streammodule, but it should probably have its own.TaskDef:case class FinallyDef[T](base: TaskDef[T], cleanup: TaskDef[_]), which can then guarantee cleanup even under cancellation signals.zip,race, ...).delay()and general scheduling by hooking in the scheduling features ofMaterializerFixes #1801 .