fix/host response double clone#219
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get_host_response() cloned the response Vec once for __host_response_len and again for __host_response, on every host callback. Add host_response_len()/with_host_response() to ModuleState/ModuleStateAsync for clone-free access, and use them in wasmtime-provider and wasm3-provider callbacks, cutting copies per callback from 3 to 1. Deprecate get_host_response() in favor of the new accessors, keeping it for backward compatibility. Add rstest-parameterized unit tests covering both. Signed-off-by: Flavio Castelli <fcastelli@suse.com> Assisted-by: Claude Sonnet 5.0
Prepare a minor release of wapc and wasmtime-provider to include the performance fix. Signed-off-by: Flavio Castelli <fcastelli@suse.com>
pkedy
approved these changes
Jul 11, 2026
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While assessing a review comment on a project making use of waPC, I realised we could do a minor optimization when dealing with the host response.
The
get_host_response()cloned the response Vec once for__host_response_lenand again for__host_response, on every host callback.This PR adds
host_response_len()andwith_host_response()methods toModuleState/ModuleStateAsync(inside ofwapccrate) for clone-free access.The it uses them in
wasmtime-providerandwasm3-provider(which I know, is currently disabled but it was a cheap edit) callbacks, cutting copies per callback from 3 to 1. This can be significant when the host response is a big.This PR deprecates
get_host_response()in favor of the new accessors, keeping it for backward compatibility. We can remove this legacy API in a future major release of thewapccreate.This PR also does a minor bump of the
wapcandwasmtime-providercrates. I'll take care of that once this gets merged.