Stream: git-wasmtime

Topic: wasmtime / issue #5403 How to use StoreLimits with WasiCtx?

Wasmtime GitHub notifications bot (Dec 09 2022 at 13:54):

TheWaWaR opened issue #5403:

wasmtime version: 3.0.1

Currently, we can use wasmtime_wasi::WasiCtx as follow:

let mut linker: Linker<WasiCtx> = Linker::new(&engine);
wasmtime_wasi::add_to_linker(&mut linker, |s| s)?;
let wasi = WasiCtxBuilder::new().build();
let mut store = Store::new(engine, wasi);

The problem here is the WasiCtx can only be used as concrete store state and can't compose with other fields.

From the example we can use like this:

store.limiter(move |state| &mut state.limits);

But now wasit have no limits field, so how can we StoreLimits to limit the resource usage?

Wasmtime GitHub notifications bot (Dec 09 2022 at 14:22):

bjorn3 commented on issue #5403:

I believe you can do

struct State {
    limits: MyResourceLimiter,
    wasi: WasiCtx,
}

let mut linker: Linker<WasiCtx> = Linker::new(&engine);
wasmtime_wasi::add_to_linker(&mut linker, |state| &mut state.wasi)?;
let wasi = WasiCtxBuilder::new().build();
let limits = todo!();
let mut store = Store::new(engine, State { limits, wasi });
store.limiter(move |state| &mut state.limits);

Wasmtime GitHub notifications bot (Dec 09 2022 at 14:29):

TheWaWaR commented on issue #5403:

Oh, there it is.

Thanks very much!

Wasmtime GitHub notifications bot (Dec 09 2022 at 14:29):

TheWaWaR closed issue #5403:

wasmtime version: 3.0.1

Currently, we can use wasmtime_wasi::WasiCtx as follow:

let mut linker: Linker<WasiCtx> = Linker::new(&engine);
wasmtime_wasi::add_to_linker(&mut linker, |s| s)?;
let wasi = WasiCtxBuilder::new().build();
let mut store = Store::new(engine, wasi);

The problem here is the WasiCtx can only be used as concrete store state and can't compose with other fields.

From the example we can use like this:

store.limiter(move |state| &mut state.limits);

But now wasit have no limits field, so how can we StoreLimits to limit the resource usage?

Last updated: Dec 06 2025 at 06:05 UTC