7c79f05cd4
This PR improves the `Promise` API by considering how dropped promises can lead to never-finished tasks.
25 lines
1.1 KiB
Text
25 lines
1.1 KiB
Text
def assertBEq [BEq α] [ToString α] (caption : String) (actual expected : α) : IO Unit := do
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unless actual == expected do
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throw <| IO.userError <|
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s!"{caption}: expected '{expected}', got '{actual}'"
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def test : IO Unit := do
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let p1 : IO.Promise Unit ← IO.Promise.new -- resolving queues the task
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let p2 : IO.Promise Unit ← IO.Promise.new -- resolved once task is running
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let p3 : IO.Promise Unit ← IO.Promise.new -- resolving finishes the task
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let t ← BaseIO.mapTask (fun _ => do p2.resolve (); IO.wait p3.result?) p1.result?
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assertBEq "p1" (← IO.getTaskState p1.result?) .running
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assertBEq "p2" (← IO.getTaskState p2.result?) .running
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assertBEq "p3" (← IO.getTaskState p3.result?) .running
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assertBEq "t" (← IO.getTaskState t) .waiting
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p1.resolve ()
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assertBEq "p1" (← IO.getTaskState p1.result?) .finished
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let _ ← IO.wait p2.result?
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assertBEq "p2" (← IO.getTaskState p2.result?) .finished
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assertBEq "t" (← IO.getTaskState t) .running
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p3.resolve ()
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assertBEq "p3" (← IO.getTaskState p3.result?) .finished
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let _ ← IO.wait t
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assertBEq "t" (← IO.getTaskState t) .finished
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#eval test
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