Fix racy promises in SpecTestRunner #2693
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thebrianchen
changed the title
wilhuff
reviewed
Mar 3, 2020
This multi-tab limbo documents test test fails if we don't make the exception. If we fully drain the queue after |
thebrianchen
requested review from
schmidt-sebastian
and removed request for
schmidt-sebastian
| @@ -219,6 +222,11 @@ export class AsyncQueue { | |||
| return this._isShuttingDown; | |||
| } | |||
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| // Visible for testing | |||
| isEmpty(): boolean { | |||
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We should be able to make this private or remove it entirely.
| // It should still be possible to drain the queue after it is shutting down. | ||
| return this.enqueueEvenAfterShutdown(() => Promise.resolve()); | ||
| async drain(): Promise<void> { | ||
| // Operations in the queue prior to draining may have enqueued additional |
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I don't know if this works, but if it does you could get rid of all size accounting:
let currentTail : Promise<void>;
do (
currentTail = this.tail;
await currentTail;
} while (currentTail !== this.tail);
thebrianchen
commented
Mar 5, 2020
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Context: An update to
tslib(link) changed the promise resolution order. We previously had multiple race conditions in the SpecTestRunner that happened to resolve in the correct order, but now break. Although we drain the AsyncQueue after each step, operations scheduled onto the AQ as part of the step run after thedrain()call with thetslibupdate, as opposed to running beforedrain()previously.This PR makes the
SpecTestRunnerdrain until the AQ is empty, which ensures that theSpecTestRunneris in a consistent state before moving onto the next step.