I introduced the call_hook machinery when I was working on Fastly's embedding of wasmtime. I'm noodling what some design changes there might look like and I'm curious if any other embedders are actually using that feature with components, and if so, what are you using it for?
@Dan Gohman is Fastly still using the call hook in roughly the same way as before with the component embedding?
pinging some other folks who have maintained major embeddings: @Joel Dice @Bailey Hayes @Yosh Wuyts @Saúl Cabrera
@Pat Hickey We're still using it, or rather, we're using call_hook_async now, but for effectively the same purpose, iiuc.
we're not currently using it
cc/ @Dan Chiarlone (danbugs) @Lucy Menon
cc/ @Jeff Charles
I believe that Spin is using the synchronous version for tracking time-in and time-out for requests
Last updated: Jan 29 2026 at 13:25 UTC