Add patch activation callback#2193
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| // ts-prune-ignore-next (used by the workflow Worker thread entry point) | ||
| export function waitForPatchActivationCallbackResult(resultBuffer: SharedArrayBuffer): boolean { | ||
| const header = getHeader(resultBuffer); | ||
| Atomics.wait(header, 0, PatchActivationCallbackStatus.Pending); |
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This is waiting on user-supplied logic right? So what happens if it hangs and never returns? I'm guessing the workflow times out but does that cause other things running on this worker to stall as well? Might be fine but worth checking.
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Good point can add a test
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July 16, 2026 23:17
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What was changed
Added an experimental
WorkerOptions.patchActivationCallbackthat lets a worker decide whether the first newly encountered, non-replaypatchedcall activates a patch.The callback receives frozen workflow information and the patch ID. Its strict boolean decision is memoized for the workflow run. Declined patches return
falsewithout recording a marker, while replay, existing history markers, and deprecated patches retain their existing behavior.Because Workflow code normally executes in worker threads while
patchedis synchronous, the implementation uses a scoped synchronous worker-thread bridge based onSharedArrayBufferandAtomics. The callback closure stays on the Worker side and is never serialized or evaluated from source.This ports the behavior introduced by temporalio/sdk-ruby#481.
Why?
This allows workflow changes using
patchedto roll out gradually without every new-code worker immediately recording a marker that older workers cannot replay.Testing