Avoid unbounded stack consumption for synchronous control flow #96
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Previously, as sequence of state transitions that did not pass through an asynchrous boundary incurred stack frames. The trivial loop in the enclosed test case would then overflow the stack. This commit merges the `resume` and `apply(tr: Try[Any])` methods into a `apply`. It changes the body of this method to be an infinite loop with returns at the terminal points in the state machine (or at a terminal failure.) To allow merging of these previously separate matches, states that contain an await are now allocated two state ids: one for the setup code that calls `onComplete`, and one for the code in the continuation that records the result and advances the state machine. Fixes scala#93
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| @@ -49,6 +49,7 @@ private[async] trait TransformUtils { | |||
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| private def isByName(fun: Tree): ((Int, Int) => Boolean) = { | |||
| if (Boolean_ShortCircuits contains fun.symbol) (i, j) => true | |||
| else if (fun.tpe == null) (x, y) => false | |||
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Candidate for hoisting? (or it is already hoisted by the compiler?)
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The compiler will hoist these in 2.12, but it isn't done today.
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See also #98 |
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Previously, as sequence of state transitions that did not pass through an
asynchrous boundary incurred stack frames. The trivial loop in the enclosed
test case would then overflow the stack.
This commit merges the
resumeandapply(tr: Try[Any])methods into aapply. It changes the body of this method to be an infinite loop withreturns at the terminal points in the state machine (or at a terminal
failure.)
To allow merging of these previously separate matches, states that contain
an await are now allocated two state ids: one for the setup code that calls
onComplete, and one for the code in the continuation that records theresult and advances the state machine.
Review by @phaller / @danarmak