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Fix race condition that causes task cancellation to be missed in TaskScheduler #2152

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Merged
merged 1 commit into from
May 14, 2025
Merged

Fix race condition that causes task cancellation to be missed in TaskScheduler #2152

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4 changes: 1 addition & 3 deletions Sources/SemanticIndex/PreparationTaskDescription.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -105,9 +105,7 @@ package struct PreparationTaskDescription: IndexTaskDescription {
do {
try await buildSystemManager.prepare(targets: Set(targetsToPrepare))
} catch {
logger.error(
"Preparation failed: \(error.forLogging)"
)
logger.error("Preparation failed: \(error.forLogging)")
}
await hooks.preparationTaskDidFinish?(self)
if !Task.isCancelled {
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8 changes: 8 additions & 0 deletions Sources/SemanticIndex/TaskScheduler.swift
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Expand Up @@ -249,6 +249,14 @@ package actor QueuedTask<TaskDescription: TaskDescriptionProtocol> {
_isExecuting.value = true
executionTask = task
executionTaskCreatedContinuation.yield(task)
if self.resultTaskCancelled.value {
// The queued task might have been cancelled after the execution ask was started but before the task was yielded
// to `executionTaskCreatedContinuation`. In that case the result task will simply cancel the await on the
// `executionTaskCreatedStream` and hence not call `valuePropagatingCancellation` on the execution task. This
// means that the queued task cancellation wouldn't be propagated to the execution task. To address this, check if
// `resultTaskCancelled` was set and, if so, explicitly cancel the execution task here.
task.cancel()
}
await executionStateChangedCallback?(self, .executing)
return await task.value
}
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