Add epoch deadline callback binding to Store - #373
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martindevans merged 1 commit intoAug 16, 2026
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Wasmtime's `wasmtime_store_epoch_deadline_callback` was unbound, so the only way to bound wasm execution was a single `SetEpochDeadline` fixed at call start. Stopping a running guest early meant incrementing the engine-wide epoch, which traps every other in-flight store sharing the engine. `Store.SetEpochDeadlineCallback` binds it: the callback runs on the executing thread when the deadline is reached, and either returns a new relative deadline to resume with, or throws to terminate the execution. A throwing callback surfaces to the caller as the inner exception of a `WasmtimeException`, using the same `CallbackErrorCause` mechanism as host function callbacks, so a host can renew a short deadline per tick and stop the guest on cancellation. Yielding (`WASMTIME_UPDATE_DEADLINE_YIELD`) is not exposed, as it requires async support this binding does not enable. Covered by tests for deadline renewal, callback replacement and null arguments.
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Looks good, thanks for working on this
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Wasmtime's
wasmtime_store_epoch_deadline_callbackwas unbound, so the only way to bound wasm execution was a singleSetEpochDeadlinefixed at call start. Stopping a running guest early meant incrementing the engine-wide epoch, which traps every other in-flight store sharing the engine.Store.SetEpochDeadlineCallbackbinds it: the callback runs on the executing thread when the deadline is reached, and either returns a new relative deadline to resume with, or throws to terminate the execution. A throwing callback surfaces to the caller as the inner exception of aWasmtimeException, using the sameCallbackErrorCausemechanism as host function callbacks, so a host can renew a short deadline per tick and stop the guest on cancellation.Yielding (
WASMTIME_UPDATE_DEADLINE_YIELD) is not exposed, as it requires async support this binding does not enable.Covered by tests for deadline renewal, callback replacement and null arguments.