Method make_call

crates/wasmtime/src/runtime/component/concurrent.rs:2368–2413

Return a closure which will call the specified function in the scope of the specified task. This will use `GuestTask::lower_params` to lower the parameters, but will not lift the result; instead, it returns a `[MaybeUninit ; MAX_FLAT_PARAMS]` from which the result, if any, may be lifted. Note that an async-lifted export will have returned its result using the `task.return` intrinsic (or n

(
            store: StoreContextMut<T>,
            guest_thread: QualifiedThreadId,
            callee: SendSyncPtr<VMFuncRef>,
            param_count: usize,
            result_count: usize,
     

        /// SAFETY: `callee` must be a valid `*mut VMFuncRef` at the time when
        /// the returned closure is called.
        unsafe fn make_call<T: 'static>(
            store: StoreContextMut<T>,
            guest_thread: QualifiedThreadId,
            callee: SendSyncPtr<VMFuncRef>,
            param_count: usize,
            result_count: usize,
        ) -> impl FnOnce(&mut dyn VMStore) -> Result<[MaybeUninit<ValRaw>; MAX_FLAT_PARAMS]>
        + Send
        + Sync
        + 'static
        + use<T> {
            let token = StoreToken::new(store);
            move |store: &mut dyn VMStore| {
                let mut storage = [MaybeUninit::uninit(); MAX_FLAT_PARAMS];

                store
                    .concurrent_state_mut()
                    .get_mut(guest_thread.thread)?
                    .state = GuestThreadState::Running;
                let task = store.concurrent_state_mut().get_mut(guest_thread.task)?;
                let lower = match task.lower_params.take() {
                    Some(l) => l,
                    None => bail_bug!("lower_params missing"),
                };

                lower(store, &mut storage[..param_count])?;

                let mut store = token.as_context_mut(store);

                // SAFETY: Per the contract documented in `make_call's`
                // documentation, `callee` must be a valid pointer.
                unsafe {
                    crate::Func::call_unchecked_raw(
                        &mut store,
                        callee.as_non_null(),
                        NonNull::new(
                            &mut storage[..param_count.max(result_count)]
                                as *mut [MaybeUninit<ValRaw>] as _,
                        )
                        .unwrap(),
                    )?;
                }

                Ok(storage)
            }
        }

        // SAFETY: Per the contract described in this function documentation,
        // the `callee` pointer which `call` closes over must be valid when