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use crate::component::func::HostFunc;
use crate::component::matching::InstanceType;
use crate::component::{
Component, ComponentExportIndex, ComponentNamedList, Func, Lift, Lower, ResourceType, TypedFunc,
};
use crate::instance::OwnedImports;
use crate::linker::DefinitionType;
use crate::prelude::*;
use crate::runtime::vm::component::{ComponentInstance, OwnedComponentInstance};
use crate::runtime::vm::{CompiledModuleId, VMFuncRef};
use crate::store::{StoreOpaque, Stored};
use crate::{AsContextMut, Engine, Module, StoreContextMut};
use alloc::sync::Arc;
use core::marker;
use core::ptr::{self, NonNull};
use wasmtime_environ::{component::*, EngineOrModuleTypeIndex};
use wasmtime_environ::{EntityIndex, EntityType, Global, PrimaryMap, WasmValType};
/// An instantiated component.
///
/// This type represents an instantiated [`Component`](super::Component).
/// Instances have exports which can be accessed through functions such as
/// [`Instance::get_func`] or [`Instance::get_export`]. Instances are owned by a
/// [`Store`](crate::Store) and all methods require a handle to the store.
///
/// Component instances are created through
/// [`Linker::instantiate`](super::Linker::instantiate) and its family of
/// methods.
///
/// This type is similar to the core wasm version
/// [`wasmtime::Instance`](crate::Instance) except that it represents an
/// instantiated component instead of an instantiated module.
#[derive(Copy, Clone)]
pub struct Instance(pub(crate) Stored<Option<Box<InstanceData>>>);
pub(crate) struct InstanceData {
instances: PrimaryMap<RuntimeInstanceIndex, crate::Instance>,
// NB: in the future if necessary it would be possible to avoid storing an
// entire `Component` here and instead storing only information such as:
//
// * Some reference to `Arc<ComponentTypes>`
// * Necessary references to closed-over modules which are exported from the
// component itself.
//
// Otherwise the full guts of this component should only ever be used during
// the instantiation of this instance, meaning that after instantiation much
// of the component can be thrown away (theoretically).
component: Component,
state: OwnedComponentInstance,
/// Arguments that this instance used to be instantiated.
///
/// Strong references are stored to these arguments since pointers are saved
/// into the structures such as functions within the
/// `OwnedComponentInstance` but it's our job to keep them alive.
///
/// One purpose of this storage is to enable embedders to drop a `Linker`,
/// for example, after a component is instantiated. In that situation if the
/// arguments weren't held here then they might be dropped, and structures
/// such as `.lowering()` which point back into the original function would
/// become stale and use-after-free conditions when used. By preserving the
/// entire list here though we're guaranteed that nothing is lost for the
/// duration of the lifetime of this instance.
imports: Arc<PrimaryMap<RuntimeImportIndex, RuntimeImport>>,
}
impl Instance {
/// Looks up an exported function by name within this [`Instance`].
///
/// The `store` argument provided must be the store that this instance
/// lives within and the `name` argument is the lookup key by which to find
/// the exported function. If the function is found then `Some` is returned
/// and otherwise `None` is returned.
///
/// The `name` here can be a string such as `&str` or it can be a
/// [`ComponentExportIndex`] which is loaded prior from a [`Component`].
///
/// # Panics
///
/// Panics if `store` does not own this instance.
///
/// # Examples
///
/// Looking up a function which is exported from the root of a component:
///
/// ```
/// use wasmtime::{Engine, Store};
/// use wasmtime::component::{Component, Linker};
///
/// # fn main() -> wasmtime::Result<()> {
/// let engine = Engine::default();
/// let component = Component::new(
/// &engine,
/// r#"
/// (component
/// (core module $m
/// (func (export "f"))
/// )
/// (core instance $i (instantiate $m))
/// (func (export "f")
/// (canon lift (core func $i "f")))
/// )
/// "#,
/// )?;
///
/// // Look up the function by name
/// let mut store = Store::new(&engine, ());
/// let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
/// let func = instance.get_func(&mut store, "f").unwrap();
///
/// // The function can also be looked up by an index via a precomputed index.
/// let (_, export) = component.export_index(None, "f").unwrap();
/// let func = instance.get_func(&mut store, &export).unwrap();
/// # Ok(())
/// # }
/// ```
///
/// Looking up a function which is exported from a nested instance:
///
/// ```
/// use wasmtime::{Engine, Store};
/// use wasmtime::component::{Component, Linker};
///
/// # fn main() -> wasmtime::Result<()> {
/// let engine = Engine::default();
/// let component = Component::new(
/// &engine,
/// r#"
/// (component
/// (core module $m
/// (func (export "f"))
/// )
/// (core instance $i (instantiate $m))
/// (func $f
/// (canon lift (core func $i "f")))
///
/// (instance $i
/// (export "f" (func $f)))
/// (export "i" (instance $i))
/// )
/// "#,
/// )?;
///
/// // First look up the exported instance, then use that to lookup the
/// // exported function.
/// let (_, instance_index) = component.export_index(None, "i").unwrap();
/// let (_, func_index) = component.export_index(Some(&instance_index), "f").unwrap();
///
/// // Then use `func_index` at runtime.
/// let mut store = Store::new(&engine, ());
/// let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
/// let func = instance.get_func(&mut store, &func_index).unwrap();
///
/// // Alternatively the `instance` can be used directly in conjunction with
/// // the `get_export` method.
/// let instance_index = instance.get_export(&mut store, None, "i").unwrap();
/// let func_index = instance.get_export(&mut store, Some(&instance_index), "f").unwrap();
/// let func = instance.get_func(&mut store, &func_index).unwrap();
/// # Ok(())
/// # }
/// ```
pub fn get_func(
&self,
mut store: impl AsContextMut,
name: impl InstanceExportLookup,
) -> Option<Func> {
let store = store.as_context_mut().0;
let data = store[self.0].take().unwrap();
let ret = name.lookup(&data.component).and_then(|index| {
match &data.component.env_component().export_items[index] {
Export::LiftedFunction { ty, func, options } => Some(Func::from_lifted_func(
store, self, &data, *ty, func, options,
)),
_ => None,
}
});
store[self.0] = Some(data);
ret
}
/// Looks up an exported [`Func`] value by name and with its type.
///
/// This function is a convenience wrapper over [`Instance::get_func`] and
/// [`Func::typed`]. For more information see the linked documentation.
///
/// Returns an error if `name` isn't a function export or if the export's
/// type did not match `Params` or `Results`
///
/// # Panics
///
/// Panics if `store` does not own this instance.
pub fn get_typed_func<Params, Results>(
&self,
mut store: impl AsContextMut,
name: impl InstanceExportLookup,
) -> Result<TypedFunc<Params, Results>>
where
Params: ComponentNamedList + Lower,
Results: ComponentNamedList + Lift,
{
let f = self
.get_func(store.as_context_mut(), name)
.ok_or_else(|| anyhow!("failed to find function export"))?;
Ok(f.typed::<Params, Results>(store)
.with_context(|| format!("failed to convert function to given type"))?)
}
/// Looks up an exported module by name within this [`Instance`].
///
/// The `store` argument provided must be the store that this instance
/// lives within and the `name` argument is the lookup key by which to find
/// the exported module. If the module is found then `Some` is returned
/// and otherwise `None` is returned.
///
/// The `name` here can be a string such as `&str` or it can be a
/// [`ComponentExportIndex`] which is loaded prior from a [`Component`].
///
/// For some examples see [`Instance::get_func`] for loading values from a
/// component.
///
/// # Panics
///
/// Panics if `store` does not own this instance.
pub fn get_module(
&self,
mut store: impl AsContextMut,
name: impl InstanceExportLookup,
) -> Option<Module> {
let store = store.as_context_mut().0;
let (data, export, _) = self.lookup_export(store, name)?;
match export {
Export::ModuleStatic { index, .. } => {
Some(data.component.static_module(*index).clone())
}
Export::ModuleImport { import, .. } => match &data.imports[*import] {
RuntimeImport::Module(m) => Some(m.clone()),
_ => unreachable!(),
},
_ => None,
}
}
/// Looks up an exported resource type by name within this [`Instance`].
///
/// The `store` argument provided must be the store that this instance
/// lives within and the `name` argument is the lookup key by which to find
/// the exported resource. If the resource is found then `Some` is returned
/// and otherwise `None` is returned.
///
/// The `name` here can be a string such as `&str` or it can be a
/// [`ComponentExportIndex`] which is loaded prior from a [`Component`].
///
/// For some examples see [`Instance::get_func`] for loading values from a
/// component.
///
/// # Panics
///
/// Panics if `store` does not own this instance.
pub fn get_resource(
&self,
mut store: impl AsContextMut,
name: impl InstanceExportLookup,
) -> Option<ResourceType> {
let store = store.as_context_mut().0;
let (data, export, _) = self.lookup_export(store, name)?;
match export {
Export::Type(TypeDef::Resource(id)) => Some(data.ty().resource_type(*id)),
Export::Type(_)
| Export::LiftedFunction { .. }
| Export::ModuleStatic { .. }
| Export::ModuleImport { .. }
| Export::Instance { .. } => None,
}
}
/// A methods similar to [`Component::export_index`] except for this
/// instance.
///
/// This method will lookup the `name` provided within the `instance`
/// provided and return a [`ComponentExportIndex`] which can be used to
/// pass to other `get_*` functions like [`Instance::get_func`].
///
/// # Panics
///
/// Panics if `store` does not own this instance.
pub fn get_export(
&self,
mut store: impl AsContextMut,
instance: Option<&ComponentExportIndex>,
name: &str,
) -> Option<ComponentExportIndex> {
self._get_export(store.as_context_mut().0, instance, name)
}
fn _get_export(
&self,
store: &StoreOpaque,
instance: Option<&ComponentExportIndex>,
name: &str,
) -> Option<ComponentExportIndex> {
let data = store[self.0].as_ref().unwrap();
let index = data.component.lookup_export_index(instance, name)?;
Some(ComponentExportIndex {
id: data.component_id(),
index,
})
}
fn lookup_export<'a>(
&self,
store: &'a StoreOpaque,
name: impl InstanceExportLookup,
) -> Option<(&'a InstanceData, &'a Export, ExportIndex)> {
let data = store[self.0].as_ref().unwrap();
let index = name.lookup(&data.component)?;
Some((
data,
&data.component.env_component().export_items[index],
index,
))
}
}
/// Trait used to lookup the export of a component instance.
///
/// This trait is used as an implementation detail of [`Instance::get_func`]
/// and related `get_*` methods. Notable implementors of this trait are:
///
/// * `str`
/// * `String`
/// * [`ComponentExportIndex`]
///
/// Note that this is intended to be a `wasmtime`-sealed trait so it shouldn't
/// need to be implemented externally.
pub trait InstanceExportLookup {
#[doc(hidden)]
fn lookup(&self, component: &Component) -> Option<ExportIndex>;
}
impl<T> InstanceExportLookup for &T
where
T: InstanceExportLookup + ?Sized,
{
fn lookup(&self, component: &Component) -> Option<ExportIndex> {
T::lookup(self, component)
}
}
impl InstanceExportLookup for str {
fn lookup(&self, component: &Component) -> Option<ExportIndex> {
component
.env_component()
.exports
.get(self, &NameMapNoIntern)
.copied()
}
}
impl InstanceExportLookup for String {
fn lookup(&self, component: &Component) -> Option<ExportIndex> {
str::lookup(self, component)
}
}
impl InstanceData {
pub fn lookup_def(&self, store: &mut StoreOpaque, def: &CoreDef) -> crate::runtime::vm::Export {
match def {
CoreDef::Export(e) => self.lookup_export(store, e),
CoreDef::Trampoline(idx) => {
crate::runtime::vm::Export::Function(crate::runtime::vm::ExportFunction {
func_ref: self.state.trampoline_func_ref(*idx),
})
}
CoreDef::InstanceFlags(idx) => {
crate::runtime::vm::Export::Global(crate::runtime::vm::ExportGlobal {
definition: self.state.instance_flags(*idx).as_raw(),
vmctx: ptr::null_mut(),
global: Global {
wasm_ty: WasmValType::I32,
mutability: true,
},
})
}
}
}
pub fn lookup_export<T>(
&self,
store: &mut StoreOpaque,
item: &CoreExport<T>,
) -> crate::runtime::vm::Export
where
T: Copy + Into<EntityIndex>,
{
let instance = &self.instances[item.instance];
let id = instance.id(store);
let instance = store.instance_mut(id);
let idx = match &item.item {
ExportItem::Index(idx) => (*idx).into(),
// FIXME: ideally at runtime we don't actually do any name lookups
// here. This will only happen when the host supplies an imported
// module so while the structure can't be known at compile time we
// do know at `InstancePre` time, for example, what all the host
// imports are. In theory we should be able to, as part of
// `InstancePre` construction, perform all name=>index mappings
// during that phase so the actual instantiation of an `InstancePre`
// skips all string lookups. This should probably only be
// investigated if this becomes a performance issue though.
ExportItem::Name(name) => instance.module().exports[name],
};
instance.get_export_by_index(idx)
}
#[inline]
pub fn instance(&self) -> &ComponentInstance {
&self.state
}
#[inline]
pub fn instance_ptr(&self) -> *mut ComponentInstance {
self.state.instance_ptr()
}
#[inline]
pub fn component_types(&self) -> &Arc<ComponentTypes> {
self.component.types()
}
#[inline]
pub fn component_id(&self) -> CompiledModuleId {
self.component.id()
}
#[inline]
pub fn ty(&self) -> InstanceType<'_> {
InstanceType::new(self.instance())
}
// NB: This method is only intended to be called during the instantiation
// process because the `Arc::get_mut` here is fallible and won't generally
// succeed once the instance has been handed to the embedder. Before that
// though it should be guaranteed that the single owning reference currently
// lives within the `ComponentInstance` that's being built.
fn resource_types_mut(&mut self) -> &mut ImportedResources {
Arc::get_mut(self.state.resource_types_mut())
.unwrap()
.downcast_mut()
.unwrap()
}
}
struct Instantiator<'a> {
component: &'a Component,
data: InstanceData,
core_imports: OwnedImports,
imports: &'a PrimaryMap<RuntimeImportIndex, RuntimeImport>,
}
pub(crate) enum RuntimeImport {
Func(Arc<HostFunc>),
Module(Module),
Resource {
ty: ResourceType,
// A strong reference to the host function that represents the
// destructor for this resource. At this time all resources here are
// host-defined resources. Note that this is itself never read because
// the funcref below points to it.
//
// Also note that the `Arc` here is used to support the same host
// function being used across multiple instances simultaneously. Or
// otherwise this makes `InstancePre::instantiate` possible to create
// separate instances all sharing the same host function.
_dtor: Arc<crate::func::HostFunc>,
// A raw function which is filled out (including `wasm_call`) which
// points to the internals of the `_dtor` field. This is read and
// possibly executed by wasm.
dtor_funcref: VMFuncRef,
},
}
pub type ImportedResources = PrimaryMap<ResourceIndex, ResourceType>;
impl<'a> Instantiator<'a> {
fn new(
component: &'a Component,
store: &mut StoreOpaque,
imports: &'a Arc<PrimaryMap<RuntimeImportIndex, RuntimeImport>>,
) -> Instantiator<'a> {
let env_component = component.env_component();
store.modules_mut().register_component(component);
let imported_resources: ImportedResources =
PrimaryMap::with_capacity(env_component.imported_resources.len());
Instantiator {
component,
imports,
core_imports: OwnedImports::empty(),
data: InstanceData {
instances: PrimaryMap::with_capacity(env_component.num_runtime_instances as usize),
component: component.clone(),
state: OwnedComponentInstance::new(
component.runtime_info(),
Arc::new(imported_resources),
store.traitobj(),
),
imports: imports.clone(),
},
}
}
fn run<T>(&mut self, store: &mut StoreContextMut<'_, T>) -> Result<()> {
let env_component = self.component.env_component();
// Before all initializers are processed configure all destructors for
// host-defined resources. No initializer will correspond to these and
// it's required to happen before they're needed, so execute this first.
for (idx, import) in env_component.imported_resources.iter() {
let (ty, func_ref) = match &self.imports[*import] {
RuntimeImport::Resource {
ty, dtor_funcref, ..
} => (*ty, NonNull::from(dtor_funcref)),
_ => unreachable!(),
};
let i = self.data.resource_types_mut().push(ty);
assert_eq!(i, idx);
self.data.state.set_resource_destructor(idx, Some(func_ref));
}
// Next configure all `VMFuncRef`s for trampolines that this component
// will require. These functions won't actually get used until their
// associated state has been initialized through the global initializers
// below, but the funcrefs can all be configured here.
for (idx, sig) in env_component.trampolines.iter() {
let ptrs = self.component.trampoline_ptrs(idx);
let signature = match self.component.signatures().shared_type(*sig) {
Some(s) => s,
None => panic!("found unregistered signature: {sig:?}"),
};
self.data
.state
.set_trampoline(idx, ptrs.wasm_call, ptrs.array_call, signature);
}
for initializer in env_component.initializers.iter() {
match initializer {
GlobalInitializer::InstantiateModule(m) => {
let module;
let imports = match m {
// Since upvars are statically know we know that the
// `args` list is already in the right order.
InstantiateModule::Static(idx, args) => {
module = self.component.static_module(*idx);
self.build_imports(store.0, module, args.iter())
}
// With imports, unlike upvars, we need to do runtime
// lookups with strings to determine the order of the
// imports since it's whatever the actual module
// requires.
//
// FIXME: see the note in `ExportItem::Name` handling
// above for how we ideally shouldn't do string lookup
// here.
InstantiateModule::Import(idx, args) => {
module = match &self.imports[*idx] {
RuntimeImport::Module(m) => m,
_ => unreachable!(),
};
let args = module
.imports()
.map(|import| &args[import.module()][import.name()]);
self.build_imports(store.0, module, args)
}
};
// Note that the unsafety here should be ok because the
// validity of the component means that type-checks have
// already been performed. This means that the unsafety due
// to imports having the wrong type should not happen here.
//
// Also note we are calling new_started_impl because we have
// already checked for asyncness and are running on a fiber
// if required.
let i = unsafe {
crate::Instance::new_started_impl(store, module, imports.as_ref())?
};
self.data.instances.push(i);
}
GlobalInitializer::LowerImport { import, index } => {
let func = match &self.imports[*import] {
RuntimeImport::Func(func) => func,
_ => unreachable!(),
};
self.data.state.set_lowering(*index, func.lowering());
}
GlobalInitializer::ExtractMemory(mem) => self.extract_memory(store.0, mem),
GlobalInitializer::ExtractRealloc(realloc) => {
self.extract_realloc(store.0, realloc)
}
GlobalInitializer::ExtractPostReturn(post_return) => {
self.extract_post_return(store.0, post_return)
}
GlobalInitializer::Resource(r) => self.resource(store.0, r),
}
}
Ok(())
}
fn resource(&mut self, store: &mut StoreOpaque, resource: &Resource) {
let dtor = resource
.dtor
.as_ref()
.map(|dtor| self.data.lookup_def(store, dtor));
let dtor = dtor.map(|export| match export {
crate::runtime::vm::Export::Function(f) => f.func_ref,
_ => unreachable!(),
});
let index = self
.component
.env_component()
.resource_index(resource.index);
self.data.state.set_resource_destructor(index, dtor);
let ty = ResourceType::guest(store.id(), &self.data.state, resource.index);
let i = self.data.resource_types_mut().push(ty);
debug_assert_eq!(i, index);
}
fn extract_memory(&mut self, store: &mut StoreOpaque, memory: &ExtractMemory) {
let mem = match self.data.lookup_export(store, &memory.export) {
crate::runtime::vm::Export::Memory(m) => m,
_ => unreachable!(),
};
self.data
.state
.set_runtime_memory(memory.index, mem.definition);
}
fn extract_realloc(&mut self, store: &mut StoreOpaque, realloc: &ExtractRealloc) {
let func_ref = match self.data.lookup_def(store, &realloc.def) {
crate::runtime::vm::Export::Function(f) => f.func_ref,
_ => unreachable!(),
};
self.data.state.set_runtime_realloc(realloc.index, func_ref);
}
fn extract_post_return(&mut self, store: &mut StoreOpaque, post_return: &ExtractPostReturn) {
let func_ref = match self.data.lookup_def(store, &post_return.def) {
crate::runtime::vm::Export::Function(f) => f.func_ref,
_ => unreachable!(),
};
self.data
.state
.set_runtime_post_return(post_return.index, func_ref);
}
fn build_imports<'b>(
&mut self,
store: &mut StoreOpaque,
module: &Module,
args: impl Iterator<Item = &'b CoreDef>,
) -> &OwnedImports {
self.core_imports.clear();
self.core_imports.reserve(module);
let mut imports = module.compiled_module().module().imports();
for arg in args {
// The general idea of Wasmtime is that at runtime type-checks for
// core wasm instantiations internally within a component are
// unnecessary and superfluous. Naturally though mistakes may be
// made, so double-check this property of wasmtime in debug mode.
if cfg!(debug_assertions) {
let (imp_module, imp_name, expected) = imports.next().unwrap();
self.assert_type_matches(store, module, arg, imp_module, imp_name, expected);
}
// The unsafety here should be ok since the `export` is loaded
// directly from an instance which should only give us valid export
// items.
let export = self.data.lookup_def(store, arg);
unsafe {
self.core_imports.push_export(&export);
}
}
debug_assert!(imports.next().is_none());
&self.core_imports
}
fn assert_type_matches(
&self,
store: &mut StoreOpaque,
module: &Module,
arg: &CoreDef,
imp_module: &str,
imp_name: &str,
expected: EntityType,
) {
let export = self.data.lookup_def(store, arg);
// If this value is a core wasm function then the type check is inlined
// here. This can otherwise fail `Extern::from_wasmtime_export` because
// there's no guarantee that there exists a trampoline for `f` so this
// can't fall through to the case below
if let crate::runtime::vm::Export::Function(f) = &export {
let expected = match expected.unwrap_func() {
EngineOrModuleTypeIndex::Engine(e) => Some(e),
EngineOrModuleTypeIndex::Module(m) => module.signatures().shared_type(m),
EngineOrModuleTypeIndex::RecGroup(_) => unreachable!(),
};
let actual = unsafe { f.func_ref.as_ref().type_index };
assert_eq!(
expected,
Some(actual),
"type mismatch for import {imp_module:?} {imp_name:?}!!!\n\n\
expected {:#?}\n\n\
found {:#?}",
expected.and_then(|e| store.engine().signatures().borrow(e)),
store.engine().signatures().borrow(actual)
);
return;
}
let val = unsafe { crate::Extern::from_wasmtime_export(export, store) };
let ty = DefinitionType::from(store, &val);
crate::types::matching::MatchCx::new(module.engine())
.definition(&expected, &ty)
.expect("unexpected typecheck failure");
}
}
/// A "pre-instantiated" [`Instance`] which has all of its arguments already
/// supplied and is ready to instantiate.
///
/// This structure represents an efficient form of instantiation where import
/// type-checking and import lookup has all been resolved by the time that this
/// type is created. This type is primarily created through the
/// [`Linker::instantiate_pre`](crate::component::Linker::instantiate_pre)
/// method.
pub struct InstancePre<T> {
component: Component,
imports: Arc<PrimaryMap<RuntimeImportIndex, RuntimeImport>>,
_marker: marker::PhantomData<fn() -> T>,
}
// `InstancePre`'s clone does not require `T: Clone`
impl<T> Clone for InstancePre<T> {
fn clone(&self) -> Self {
Self {
component: self.component.clone(),
imports: self.imports.clone(),
_marker: self._marker,
}
}
}
impl<T> InstancePre<T> {
/// This function is `unsafe` since there's no guarantee that the
/// `RuntimeImport` items provided are guaranteed to work with the `T` of
/// the store.
///
/// Additionally there is no static guarantee that the `imports` provided
/// satisfy the imports of the `component` provided.
pub(crate) unsafe fn new_unchecked(
component: Component,
imports: PrimaryMap<RuntimeImportIndex, RuntimeImport>,
) -> InstancePre<T> {
InstancePre {
component,
imports: Arc::new(imports),
_marker: marker::PhantomData,
}
}
/// Returns the underlying component that will be instantiated.
pub fn component(&self) -> &Component {
&self.component
}
/// Returns the underlying engine.
pub fn engine(&self) -> &Engine {
self.component.engine()
}
/// Performs the instantiation process into the store specified.
//
// TODO: needs more docs
pub fn instantiate(&self, store: impl AsContextMut<Data = T>) -> Result<Instance> {
assert!(
!store.as_context().async_support(),
"must use async instantiation when async support is enabled"
);
self.instantiate_impl(store)
}
/// Performs the instantiation process into the store specified.
///
/// Exactly like [`Self::instantiate`] except for use on async stores.
//
// TODO: needs more docs
#[cfg(feature = "async")]
pub async fn instantiate_async(
&self,
mut store: impl AsContextMut<Data = T>,
) -> Result<Instance>
where
T: Send,
{
let mut store = store.as_context_mut();
assert!(
store.0.async_support(),
"must use sync instantiation when async support is disabled"
);
store.on_fiber(|store| self.instantiate_impl(store)).await?
}
fn instantiate_impl(&self, mut store: impl AsContextMut<Data = T>) -> Result<Instance> {
let mut store = store.as_context_mut();
store
.engine()
.allocator()
.increment_component_instance_count()?;
let mut instantiator = Instantiator::new(&self.component, store.0, &self.imports);
instantiator.run(&mut store).map_err(|e| {
store
.engine()
.allocator()
.decrement_component_instance_count();
e
})?;
let data = Box::new(instantiator.data);
let instance = Instance(store.0.store_data_mut().insert(Some(data)));
store.0.push_component_instance(instance);
Ok(instance)
}
}