wasmtime/runtime/component/component.rs
1use crate::component::InstanceExportLookup;
2use crate::component::matching::InstanceType;
3use crate::component::types;
4use crate::prelude::*;
5#[cfg(feature = "std")]
6use crate::runtime::vm::open_file_for_mmap;
7use crate::runtime::vm::{CompiledModuleId, VMArrayCallFunction, VMFuncRef, VMWasmCallFunction};
8use crate::{
9 Engine, Module, ResourcesRequired, code::EngineCode, code_memory::CodeMemory,
10 type_registry::TypeCollection,
11};
12use crate::{FuncType, ValType};
13use alloc::sync::Arc;
14use core::ops::Range;
15use core::ptr::NonNull;
16#[cfg(feature = "std")]
17use std::path::Path;
18use wasmtime_environ::component::{
19 CompiledComponentInfo, ComponentArtifacts, ComponentTypes, CoreDef, Export, ExportIndex,
20 GlobalInitializer, InstantiateModule, NameMapNoIntern, OptionsIndex, StaticModuleIndex,
21 TrampolineIndex, TypeComponentIndex, TypeFuncIndex, UnsafeIntrinsic, VMComponentOffsets,
22};
23use wasmtime_environ::{Abi, CompiledFunctionsTable, FuncKey, TypeTrace, WasmChecksum};
24use wasmtime_environ::{FunctionLoc, HostPtr, ObjectKind, PrimaryMap};
25
26/// A compiled WebAssembly Component.
27///
28/// This structure represents a compiled component that is ready to be
29/// instantiated. This owns a region of virtual memory which contains executable
30/// code compiled from a WebAssembly binary originally. This is the analog of
31/// [`Module`](crate::Module) in the component embedding API.
32///
33/// A [`Component`] can be turned into an
34/// [`Instance`](crate::component::Instance) through a
35/// [`Linker`](crate::component::Linker). [`Component`]s are safe to share
36/// across threads. The compilation model of a component is the same as that of
37/// [a module](crate::Module) which is to say:
38///
39/// * Compilation happens synchronously during [`Component::new`].
40/// * The result of compilation can be saved into storage with
41/// [`Component::serialize`].
42/// * A previously compiled artifact can be parsed with
43/// [`Component::deserialize`].
44/// * No compilation happens at runtime for a component — everything is done
45/// by the time [`Component::new`] returns.
46///
47/// ## Components and `Clone`
48///
49/// Using `clone` on a `Component` is a cheap operation. It will not create an
50/// entirely new component, but rather just a new reference to the existing
51/// component. In other words it's a shallow copy, not a deep copy.
52///
53/// ## Examples
54///
55/// For example usage see the documentation of [`Module`](crate::Module) as
56/// [`Component`] has the same high-level API.
57#[derive(Clone)]
58pub struct Component {
59 inner: Arc<ComponentInner>,
60}
61
62struct ComponentInner {
63 /// Unique id for this component within this process.
64 ///
65 /// Note that this is repurposing ids for modules intentionally as there
66 /// shouldn't be an issue overlapping them.
67 id: CompiledModuleId,
68
69 /// The engine that this component belongs to.
70 engine: Engine,
71
72 /// Component type index
73 ty: TypeComponentIndex,
74
75 /// Core wasm modules that the component defined internally, indexed by the
76 /// compile-time-assigned `ModuleUpvarIndex`.
77 static_modules: PrimaryMap<StaticModuleIndex, Module>,
78
79 /// Code-related information such as the compiled artifact, type
80 /// information, etc.
81 ///
82 /// Note that the `Arc` here is used to share this allocation with internal
83 /// modules.
84 code: Arc<EngineCode>,
85
86 /// Metadata produced during compilation.
87 info: CompiledComponentInfo,
88
89 /// The index of compiled functions and their locations in the text section
90 /// for this component.
91 index: Arc<CompiledFunctionsTable>,
92
93 /// A cached handle to the `wasmtime::FuncType` for the canonical ABI's
94 /// `realloc`, to avoid the need to look up types in the registry and take
95 /// locks when calling `realloc` via `TypedFunc::call_raw`.
96 realloc_func_type: Arc<FuncType>,
97
98 /// The checksum of the source binary from which the module was compiled.
99 checksum: WasmChecksum,
100}
101
102pub(crate) struct AllCallFuncPointers {
103 pub wasm_call: NonNull<VMWasmCallFunction>,
104 pub array_call: NonNull<VMArrayCallFunction>,
105}
106
107impl Component {
108 /// Compiles a new WebAssembly component from the in-memory list of bytes
109 /// provided.
110 ///
111 /// The `bytes` provided can either be the binary or text format of a
112 /// [WebAssembly component]. Note that the text format requires the `wat`
113 /// feature of this crate to be enabled. This API does not support
114 /// streaming compilation.
115 ///
116 /// This function will synchronously validate the entire component,
117 /// including all core modules, and then compile all components, modules,
118 /// etc., found within the provided bytes.
119 ///
120 /// [WebAssembly component]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Binary.md
121 ///
122 /// # Errors
123 ///
124 /// This function may fail and return an error. Errors may include
125 /// situations such as:
126 ///
127 /// * The binary provided could not be decoded because it's not a valid
128 /// WebAssembly binary
129 /// * The WebAssembly binary may not validate (e.g. contains type errors)
130 /// * Implementation-specific limits were exceeded with a valid binary (for
131 /// example too many locals)
132 /// * The wasm binary may use features that are not enabled in the
133 /// configuration of `engine`
134 /// * If the `wat` feature is enabled and the input is text, then it may be
135 /// rejected if it fails to parse.
136 ///
137 /// The error returned should contain full information about why compilation
138 /// failed.
139 ///
140 /// # Examples
141 ///
142 /// The `new` function can be invoked with a in-memory array of bytes:
143 ///
144 /// ```no_run
145 /// # use wasmtime::*;
146 /// # use wasmtime::component::Component;
147 /// # fn main() -> Result<()> {
148 /// # let engine = Engine::default();
149 /// # let wasm_bytes: Vec<u8> = Vec::new();
150 /// let component = Component::new(&engine, &wasm_bytes)?;
151 /// # Ok(())
152 /// # }
153 /// ```
154 ///
155 /// Or you can also pass in a string to be parsed as the wasm text
156 /// format:
157 ///
158 /// ```
159 /// # use wasmtime::*;
160 /// # use wasmtime::component::Component;
161 /// # fn main() -> Result<()> {
162 /// # let engine = Engine::default();
163 /// let component = Component::new(&engine, "(component (core module))")?;
164 /// # Ok(())
165 /// # }
166 #[cfg(any(feature = "cranelift", feature = "winch"))]
167 pub fn new(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Component> {
168 crate::CodeBuilder::new(engine)
169 .wasm_binary_or_text(bytes.as_ref(), None)?
170 .compile_component()
171 }
172
173 /// Compiles a new WebAssembly component from a wasm file on disk pointed
174 /// to by `file`.
175 ///
176 /// This is a convenience function for reading the contents of `file` on
177 /// disk and then calling [`Component::new`].
178 #[cfg(all(feature = "std", any(feature = "cranelift", feature = "winch")))]
179 pub fn from_file(engine: &Engine, file: impl AsRef<Path>) -> Result<Component> {
180 crate::CodeBuilder::new(engine)
181 .wasm_binary_or_text_file(file.as_ref())?
182 .compile_component()
183 }
184
185 /// Compiles a new WebAssembly component from the in-memory wasm image
186 /// provided.
187 ///
188 /// This function is the same as [`Component::new`] except that it does not
189 /// accept the text format of WebAssembly. Even if the `wat` feature
190 /// is enabled an error will be returned here if `binary` is the text
191 /// format.
192 ///
193 /// For more information on semantics and errors see [`Component::new`].
194 #[cfg(any(feature = "cranelift", feature = "winch"))]
195 pub fn from_binary(engine: &Engine, binary: &[u8]) -> Result<Component> {
196 crate::CodeBuilder::new(engine)
197 .wasm_binary(binary, None)?
198 .compile_component()
199 }
200
201 /// Same as [`Module::deserialize`], but for components.
202 ///
203 /// Note that the bytes referenced here must contain contents previously
204 /// produced by [`Engine::precompile_component`] or
205 /// [`Component::serialize`].
206 ///
207 /// For more information see the [`Module::deserialize`] method.
208 ///
209 /// # Unsafety
210 ///
211 /// The unsafety of this method is the same as that of the
212 /// [`Module::deserialize`] method.
213 ///
214 /// [`Module::deserialize`]: crate::Module::deserialize
215 pub unsafe fn deserialize(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Component> {
216 let code = engine.load_code_bytes(bytes.as_ref(), ObjectKind::Component)?;
217 Component::from_parts(engine, code, None)
218 }
219
220 /// Same as [`Module::deserialize_raw`], but for components.
221 ///
222 /// See [`Component::deserialize`] for additional information; this method
223 /// works identically except that it will not create a copy of the provided
224 /// memory but will use it directly.
225 ///
226 /// # Unsafety
227 ///
228 /// All of the safety notes from [`Component::deserialize`] apply here as well
229 /// with the additional constraint that the code memory provide by `memory`
230 /// lives for as long as the module and is nevery externally modified for
231 /// the lifetime of the deserialized module.
232 pub unsafe fn deserialize_raw(engine: &Engine, memory: NonNull<[u8]>) -> Result<Component> {
233 // SAFETY: the contract required by `load_code_raw` is the same as this
234 // function.
235 let code = unsafe { engine.load_code_raw(memory, ObjectKind::Component)? };
236 Component::from_parts(engine, code, None)
237 }
238
239 /// Same as [`Module::deserialize_file`], but for components.
240 ///
241 /// Note that the file referenced here must contain contents previously
242 /// produced by [`Engine::precompile_component`] or
243 /// [`Component::serialize`].
244 ///
245 /// For more information see the [`Module::deserialize_file`] method.
246 ///
247 /// # Unsafety
248 ///
249 /// The unsafety of this method is the same as that of the
250 /// [`Module::deserialize_file`] method.
251 ///
252 /// [`Module::deserialize_file`]: crate::Module::deserialize_file
253 #[cfg(feature = "std")]
254 pub unsafe fn deserialize_file(engine: &Engine, path: impl AsRef<Path>) -> Result<Component> {
255 let file = open_file_for_mmap(path.as_ref())?;
256 let code = engine
257 .load_code_file(file, ObjectKind::Component)
258 .with_context(|| format!("failed to load code for: {}", path.as_ref().display()))?;
259 Component::from_parts(engine, code, None)
260 }
261
262 /// Returns the type of this component as a [`types::Component`].
263 ///
264 /// This method enables runtime introspection of the type of a component
265 /// before instantiation, if necessary.
266 ///
267 /// ## Component types and Resources
268 ///
269 /// An important point to note here is that the precise type of imports and
270 /// exports of a component change when it is instantiated with respect to
271 /// resources. For example a [`Component`] represents an un-instantiated
272 /// component meaning that its imported resources are represented as abstract
273 /// resource types. These abstract types are not equal to any other
274 /// component's types.
275 ///
276 /// For example:
277 ///
278 /// ```
279 /// # use wasmtime::Engine;
280 /// # use wasmtime::component::Component;
281 /// # use wasmtime::component::types::ComponentItem;
282 /// # fn main() -> wasmtime::Result<()> {
283 /// # let engine = Engine::default();
284 /// let a = Component::new(&engine, r#"
285 /// (component (import "x" (type (sub resource))))
286 /// "#)?;
287 /// let b = Component::new(&engine, r#"
288 /// (component (import "x" (type (sub resource))))
289 /// "#)?;
290 ///
291 /// let (_, a_ty) = a.component_type().imports(&engine).next().unwrap();
292 /// let (_, b_ty) = b.component_type().imports(&engine).next().unwrap();
293 ///
294 /// let a_ty = match a_ty {
295 /// ComponentItem::Resource(ty) => ty,
296 /// _ => unreachable!(),
297 /// };
298 /// let b_ty = match b_ty {
299 /// ComponentItem::Resource(ty) => ty,
300 /// _ => unreachable!(),
301 /// };
302 /// assert!(a_ty != b_ty);
303 /// # Ok(())
304 /// # }
305 /// ```
306 ///
307 /// Additionally, however, these abstract types are "substituted" during
308 /// instantiation meaning that a component type will appear to have changed
309 /// once it is instantiated.
310 ///
311 /// ```
312 /// # use wasmtime::{Engine, Store};
313 /// # use wasmtime::component::{Component, Linker, ResourceType};
314 /// # use wasmtime::component::types::ComponentItem;
315 /// # fn main() -> wasmtime::Result<()> {
316 /// # let engine = Engine::default();
317 /// // Here this component imports a resource and then exports it as-is
318 /// // which means that the export is equal to the import.
319 /// let a = Component::new(&engine, r#"
320 /// (component
321 /// (import "x" (type $x (sub resource)))
322 /// (export "x" (type $x))
323 /// )
324 /// "#)?;
325 ///
326 /// let (_, import) = a.component_type().imports(&engine).next().unwrap();
327 /// let (_, export) = a.component_type().exports(&engine).next().unwrap();
328 ///
329 /// let import = match import {
330 /// ComponentItem::Resource(ty) => ty,
331 /// _ => unreachable!(),
332 /// };
333 /// let export = match export {
334 /// ComponentItem::Resource(ty) => ty,
335 /// _ => unreachable!(),
336 /// };
337 /// assert_eq!(import, export);
338 ///
339 /// // However after instantiation the resource type "changes"
340 /// let mut store = Store::new(&engine, ());
341 /// let mut linker = Linker::new(&engine);
342 /// linker.root().resource("x", ResourceType::host::<()>(), |_, _| Ok(()))?;
343 /// let instance = linker.instantiate(&mut store, &a)?;
344 /// let instance_ty = instance.get_resource(&mut store, "x").unwrap();
345 ///
346 /// // Here `instance_ty` is not the same as either `import` or `export`,
347 /// // but it is equal to what we provided as an import.
348 /// assert!(instance_ty != import);
349 /// assert!(instance_ty != export);
350 /// assert!(instance_ty == ResourceType::host::<()>());
351 /// # Ok(())
352 /// # }
353 /// ```
354 ///
355 /// Finally, each instantiation of an exported resource from a component is
356 /// considered "fresh" for all instantiations meaning that different
357 /// instantiations will have different exported resource types:
358 ///
359 /// ```
360 /// # use wasmtime::{Engine, Store};
361 /// # use wasmtime::component::{Component, Linker};
362 /// # fn main() -> wasmtime::Result<()> {
363 /// # let engine = Engine::default();
364 /// let a = Component::new(&engine, r#"
365 /// (component
366 /// (type $x (resource (rep i32)))
367 /// (export "x" (type $x))
368 /// )
369 /// "#)?;
370 ///
371 /// let mut store = Store::new(&engine, ());
372 /// let linker = Linker::new(&engine);
373 /// let instance1 = linker.instantiate(&mut store, &a)?;
374 /// let instance2 = linker.instantiate(&mut store, &a)?;
375 ///
376 /// let x1 = instance1.get_resource(&mut store, "x").unwrap();
377 /// let x2 = instance2.get_resource(&mut store, "x").unwrap();
378 ///
379 /// // Despite these two resources being the same export of the same
380 /// // component they come from two different instances meaning that their
381 /// // types will be unique.
382 /// assert!(x1 != x2);
383 /// # Ok(())
384 /// # }
385 /// ```
386 pub fn component_type(&self) -> types::Component {
387 self.with_uninstantiated_instance_type(|ty| types::Component::from(self.inner.ty, ty))
388 }
389
390 fn with_uninstantiated_instance_type<R>(&self, f: impl FnOnce(&InstanceType<'_>) -> R) -> R {
391 f(&InstanceType {
392 types: self.types(),
393 resources: None,
394 })
395 }
396
397 /// Final assembly step for a component from its in-memory representation.
398 ///
399 /// If the `artifacts` are specified as `None` here then they will be
400 /// deserialized from `code_memory`.
401 pub(crate) fn from_parts(
402 engine: &Engine,
403 code_memory: Arc<CodeMemory>,
404 artifacts: Option<ComponentArtifacts>,
405 ) -> Result<Component> {
406 let ComponentArtifacts {
407 ty,
408 info,
409 table: index,
410 mut types,
411 mut static_modules,
412 checksum,
413 } = match artifacts {
414 Some(artifacts) => artifacts,
415 None => postcard::from_bytes(code_memory.wasmtime_info())?,
416 };
417 let index = Arc::new(index);
418
419 // Validate that the component can be used with the current instance
420 // allocator.
421 engine.allocator().validate_component(
422 &info.component,
423 &VMComponentOffsets::new(HostPtr, &info.component),
424 &|module_index| &static_modules[module_index].module,
425 )?;
426
427 // Create a signature registration with the `Engine` for all trampolines
428 // and core wasm types found within this component, both for the
429 // component and for all included core wasm modules.
430 let signatures = engine.register_and_canonicalize_types(
431 types.module_types_mut(),
432 static_modules.iter_mut().map(|(_, m)| &mut m.module),
433 )?;
434 types.canonicalize_for_runtime_usage(&mut |idx| signatures.shared_type(idx).unwrap());
435
436 // Assemble the `EngineCode` artifact which is shared by all core wasm
437 // modules as well as the final component.
438 let types = Arc::new(types);
439 let code = Arc::new(EngineCode::new(code_memory, signatures, types.into())?);
440
441 // Convert all information about static core wasm modules into actual
442 // `Module` instances by converting each `CompiledModuleInfo`, the
443 // `types` type information, and the code memory to a runtime object.
444 let static_modules = static_modules
445 .into_iter()
446 .map(|(_, info)| {
447 Module::from_parts_raw(engine, code.clone(), info, index.clone(), false)
448 })
449 .collect::<Result<_>>()?;
450
451 let realloc_func_type = Arc::new(FuncType::new(
452 engine,
453 [ValType::I32, ValType::I32, ValType::I32, ValType::I32],
454 [ValType::I32],
455 ));
456
457 Ok(Component {
458 inner: Arc::new(ComponentInner {
459 id: CompiledModuleId::new(),
460 engine: engine.clone(),
461 ty,
462 static_modules,
463 code,
464 info,
465 index,
466 realloc_func_type,
467 checksum,
468 }),
469 })
470 }
471
472 pub(crate) fn ty(&self) -> TypeComponentIndex {
473 self.inner.ty
474 }
475
476 pub(crate) fn env_component(&self) -> &wasmtime_environ::component::Component {
477 &self.inner.info.component
478 }
479
480 pub(crate) fn static_module(&self, idx: StaticModuleIndex) -> &Module {
481 &self.inner.static_modules[idx]
482 }
483
484 #[cfg(any(feature = "profiling", feature = "debug"))]
485 pub(crate) fn static_modules(&self) -> impl Iterator<Item = &Module> {
486 self.inner.static_modules.values()
487 }
488
489 #[inline]
490 pub(crate) fn types(&self) -> &Arc<ComponentTypes> {
491 match self.inner.code.types() {
492 crate::code::Types::Component(types) => types,
493 // The only creator of a `Component` is itself which uses the other
494 // variant, so this shouldn't be possible.
495 crate::code::Types::Module(_) => unreachable!(),
496 }
497 }
498
499 pub(crate) fn signatures(&self) -> &TypeCollection {
500 self.inner.code.signatures()
501 }
502
503 pub(crate) fn trampoline_ptrs(&self, index: TrampolineIndex) -> AllCallFuncPointers {
504 let wasm_call = self
505 .store_invariant_func(FuncKey::ComponentTrampoline(Abi::Wasm, index))
506 .unwrap()
507 .cast();
508 let array_call = self
509 .store_invariant_func(FuncKey::ComponentTrampoline(Abi::Array, index))
510 .unwrap()
511 .cast();
512 AllCallFuncPointers {
513 wasm_call,
514 array_call,
515 }
516 }
517
518 pub(crate) fn unsafe_intrinsic_ptrs(
519 &self,
520 intrinsic: UnsafeIntrinsic,
521 ) -> Option<AllCallFuncPointers> {
522 let wasm_call = self
523 .store_invariant_func(FuncKey::UnsafeIntrinsic(Abi::Wasm, intrinsic))?
524 .cast();
525 let array_call = self
526 .store_invariant_func(FuncKey::UnsafeIntrinsic(Abi::Array, intrinsic))?
527 .cast();
528 Some(AllCallFuncPointers {
529 wasm_call,
530 array_call,
531 })
532 }
533
534 /// Look up a function in this component's text section by `FuncKey`.
535 ///
536 /// This supports only `FuncKey`s that do not invoke Wasm code,
537 /// i.e., code that is potentially Store-specific.
538 fn store_invariant_func(&self, key: FuncKey) -> Option<NonNull<u8>> {
539 assert!(key.is_store_invariant());
540 let loc = self.inner.index.func_loc(key)?;
541 Some(self.func_loc_to_pointer(loc))
542 }
543
544 /// Given a function location within this component's text section, get a
545 /// pointer to the function.
546 ///
547 /// This works only for Store-invariant functions.
548 ///
549 /// Panics on out-of-bounds function locations.
550 fn func_loc_to_pointer(&self, loc: &FunctionLoc) -> NonNull<u8> {
551 let text = self.engine_code().text();
552 let trampoline = &text[loc.start as usize..][..loc.length as usize];
553 NonNull::from(trampoline).cast()
554 }
555
556 pub(crate) fn engine_code(&self) -> &Arc<EngineCode> {
557 &self.inner.code
558 }
559
560 /// Get this component's code object's `.text` section, containing its
561 /// compiled executable code.
562 pub fn text(&self) -> &[u8] {
563 self.engine_code().text()
564 }
565
566 /// Get information about functions in this component's `.text` section:
567 /// their module index, function index, name, and offset+length.
568 pub fn functions(&self) -> impl Iterator<Item = crate::ModuleFunction> + '_ {
569 self.inner
570 .static_modules
571 .values()
572 .flat_map(|m| m.functions())
573 }
574
575 /// Get the address map for this component's `.text` section.
576 ///
577 /// See [`Module::address_map`] for more details.
578 pub fn address_map(&self) -> Option<impl Iterator<Item = (usize, Option<u32>)> + '_> {
579 Some(
580 wasmtime_environ::iterate_address_map(self.engine_code().address_map_data())?
581 .map(|(offset, file_pos)| (offset as usize, file_pos.file_offset())),
582 )
583 }
584
585 /// Same as [`Module::serialize`], except for a component.
586 ///
587 /// Note that the artifact produced here must be passed to
588 /// [`Component::deserialize`] and is not compatible for use with
589 /// [`Module`].
590 ///
591 /// [`Module::serialize`]: crate::Module::serialize
592 /// [`Module`]: crate::Module
593 pub fn serialize(&self) -> Result<Vec<u8>> {
594 let image = self.engine_code().image();
595 let mut v = TryVec::new();
596 v.reserve(image.len())?;
597 v.try_extend(image.iter().copied())?;
598 Ok(v.into())
599 }
600
601 /// Creates a new `VMFuncRef` with all fields filled out for the destructor
602 /// specified.
603 ///
604 /// The `dtor`'s own `VMFuncRef` won't have `wasm_call` filled out but this
605 /// component may have `resource_drop_wasm_to_native_trampoline` filled out
606 /// if necessary in which case it's filled in here.
607 pub(crate) fn resource_drop_func_ref(&self, dtor: &crate::func::HostFunc) -> VMFuncRef {
608 // Host functions never have their `wasm_call` filled in at this time.
609 assert!(dtor.func_ref().wasm_call.is_none());
610
611 // Note that if `resource_drop_wasm_to_native_trampoline` is not present
612 // then this can't be called by the component, so it's ok to leave it
613 // blank.
614 let wasm_call = self
615 .store_invariant_func(FuncKey::ResourceDropTrampoline)
616 .map(|f| f.cast().into());
617
618 VMFuncRef {
619 wasm_call,
620 ..*dtor.func_ref()
621 }
622 }
623
624 /// Returns a summary of the resources required to instantiate this
625 /// [`Component`][crate::component::Component].
626 ///
627 /// Note that when a component imports and instantiates another component or
628 /// core module, we cannot determine ahead of time how many resources
629 /// instantiating this component will require, and therefore this method
630 /// will return `None` in these scenarios.
631 ///
632 /// Potential uses of the returned information:
633 ///
634 /// * Determining whether your pooling allocator configuration supports
635 /// instantiating this component.
636 ///
637 /// * Deciding how many of which `Component` you want to instantiate within
638 /// a fixed amount of resources, e.g. determining whether to create 5
639 /// instances of component X or 10 instances of component Y.
640 ///
641 /// # Example
642 ///
643 /// ```
644 /// # fn main() -> wasmtime::Result<()> {
645 /// use wasmtime::{Config, Engine, component::Component};
646 ///
647 /// let mut config = Config::new();
648 /// config.wasm_multi_memory(true);
649 /// config.wasm_component_model(true);
650 /// let engine = Engine::new(&config)?;
651 ///
652 /// let component = Component::new(&engine, &r#"
653 /// (component
654 /// ;; Define a core module that uses two memories.
655 /// (core module $m
656 /// (memory 1)
657 /// (memory 6)
658 /// )
659 ///
660 /// ;; Instantiate that core module three times.
661 /// (core instance $i1 (instantiate (module $m)))
662 /// (core instance $i2 (instantiate (module $m)))
663 /// (core instance $i3 (instantiate (module $m)))
664 /// )
665 /// "#)?;
666 ///
667 /// let resources = component.resources_required()
668 /// .expect("this component does not import any core modules or instances");
669 ///
670 /// // Instantiating the component will require allocating two memories per
671 /// // core instance, and there are three instances, so six total memories.
672 /// assert_eq!(resources.num_memories, 6);
673 /// assert_eq!(resources.max_initial_memory_size, Some(6));
674 ///
675 /// // The component doesn't need any tables.
676 /// assert_eq!(resources.num_tables, 0);
677 /// assert_eq!(resources.max_initial_table_size, None);
678 /// # Ok(()) }
679 /// ```
680 pub fn resources_required(&self) -> Option<ResourcesRequired> {
681 let mut resources = ResourcesRequired {
682 num_memories: 0,
683 max_initial_memory_size: None,
684 num_tables: 0,
685 max_initial_table_size: None,
686 };
687 for init in &self.env_component().initializers {
688 match init {
689 GlobalInitializer::InstantiateModule(inst, _) => match inst {
690 InstantiateModule::Static(index, _) => {
691 let module = self.static_module(*index);
692 resources.add(&module.resources_required());
693 }
694 InstantiateModule::Import(_, _) => {
695 // We can't statically determine the resources required
696 // to instantiate this component.
697 return None;
698 }
699 },
700 GlobalInitializer::LowerImport { .. }
701 | GlobalInitializer::ExtractMemory(_)
702 | GlobalInitializer::ExtractTable(_)
703 | GlobalInitializer::ExtractRealloc(_)
704 | GlobalInitializer::ExtractCallback(_)
705 | GlobalInitializer::ExtractPostReturn(_)
706 | GlobalInitializer::Resource(_) => {}
707 }
708 }
709 Some(resources)
710 }
711
712 /// Returns the range, in the host's address space, that this module's
713 /// compiled code resides at.
714 ///
715 /// For more information see
716 /// [`Module::image_range`](crate::Module::image_range).
717 pub fn image_range(&self) -> Range<*const u8> {
718 self.inner.code.image().as_ptr_range()
719 }
720
721 /// Force initialization of copy-on-write images to happen here-and-now
722 /// instead of when they're requested during first instantiation.
723 ///
724 /// When [copy-on-write memory
725 /// initialization](crate::Config::memory_init_cow) is enabled then Wasmtime
726 /// will lazily create the initialization image for a component. This method
727 /// can be used to explicitly dictate when this initialization happens.
728 ///
729 /// Note that this largely only matters on Linux when memfd is used.
730 /// Otherwise the copy-on-write image typically comes from disk and in that
731 /// situation the creation of the image is trivial as the image is always
732 /// sourced from disk. On Linux, though, when memfd is used a memfd is
733 /// created and the initialization image is written to it.
734 ///
735 /// Also note that this method is not required to be called, it's available
736 /// as a performance optimization if required but is otherwise handled
737 /// automatically.
738 pub fn initialize_copy_on_write_image(&self) -> Result<()> {
739 for (_, module) in self.inner.static_modules.iter() {
740 module.initialize_copy_on_write_image()?;
741 }
742 Ok(())
743 }
744
745 /// Looks up a specific export of this component by `name` optionally nested
746 /// within the `instance` provided.
747 ///
748 /// See related method [`Self::get_export`] for additional docs and
749 /// examples.
750 ///
751 /// This method is primarily used to acquire a [`ComponentExportIndex`]
752 /// which can be used with [`Instance`](crate::component::Instance) when
753 /// looking up exports. Export lookup with [`ComponentExportIndex`] can
754 /// skip string lookups at runtime and instead use a more efficient
755 /// index-based lookup.
756 ///
757 /// This method only returns the [`ComponentExportIndex`]. If you need the
758 /// corresponding [`types::ComponentItem`], use the related function
759 /// [`Self::get_export`].
760 ///
761 ///
762 /// [`Instance`](crate::component::Instance) has a corresponding method
763 /// [`Instance::get_export_index`](crate::component::Instance::get_export_index).
764 pub fn get_export_index(
765 &self,
766 instance: Option<&ComponentExportIndex>,
767 name: &str,
768 ) -> Option<ComponentExportIndex> {
769 let index = self.lookup_export_index(instance, name)?;
770 Some(ComponentExportIndex {
771 id: self.inner.id,
772 index,
773 })
774 }
775
776 /// Looks up a specific export of this component by `name` optionally nested
777 /// within the `instance` provided.
778 ///
779 /// This method is primarily used to acquire a [`ComponentExportIndex`]
780 /// which can be used with [`Instance`](crate::component::Instance) when
781 /// looking up exports. Export lookup with [`ComponentExportIndex`] can
782 /// skip string lookups at runtime and instead use a more efficient
783 /// index-based lookup.
784 ///
785 /// This method takes a few arguments:
786 ///
787 /// * `engine` - the engine that was used to compile this component.
788 /// * `instance` - an optional "parent instance" for the export being looked
789 /// up. If this is `None` then the export is looked up on the root of the
790 /// component itself, and otherwise the export is looked up on the
791 /// `instance` specified. Note that `instance` must have come from a
792 /// previous invocation of this method.
793 /// * `name` - the name of the export that's being looked up.
794 ///
795 /// If the export is located then two values are returned: a
796 /// [`types::ComponentItem`] which enables introspection about the type of
797 /// the export and a [`ComponentExportIndex`]. The index returned notably
798 /// implements the [`InstanceExportLookup`] trait which enables using it
799 /// with [`Instance::get_func`](crate::component::Instance::get_func) for
800 /// example.
801 ///
802 /// The returned [`types::ComponentItem`] is more expensive to calculate
803 /// than the [`ComponentExportIndex`]. If you only consume the
804 /// [`ComponentExportIndex`], use the related method
805 /// [`Self::get_export_index`] instead.
806 ///
807 /// [`Instance`](crate::component::Instance) has a corresponding method
808 /// [`Instance::get_export`](crate::component::Instance::get_export).
809 ///
810 /// # Examples
811 ///
812 /// ```
813 /// use wasmtime::{Engine, Store};
814 /// use wasmtime::component::{Component, Linker};
815 /// use wasmtime::component::types::ComponentItem;
816 ///
817 /// # fn main() -> wasmtime::Result<()> {
818 /// let engine = Engine::default();
819 /// let component = Component::new(
820 /// &engine,
821 /// r#"
822 /// (component
823 /// (core module $m
824 /// (func (export "f"))
825 /// )
826 /// (core instance $i (instantiate $m))
827 /// (func (export "f")
828 /// (canon lift (core func $i "f")))
829 /// )
830 /// "#,
831 /// )?;
832 ///
833 /// // Perform a lookup of the function "f" before instantiaton.
834 /// let (ty, export) = component.get_export(None, "f").unwrap();
835 /// assert!(matches!(ty, ComponentItem::ComponentFunc(_)));
836 ///
837 /// // After instantiation use `export` to lookup the function in question
838 /// // which notably does not do a string lookup at runtime.
839 /// let mut store = Store::new(&engine, ());
840 /// let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
841 /// let func = instance.get_typed_func::<(), ()>(&mut store, &export)?;
842 /// // ...
843 /// # Ok(())
844 /// # }
845 /// ```
846 pub fn get_export(
847 &self,
848 instance: Option<&ComponentExportIndex>,
849 name: &str,
850 ) -> Option<(types::ComponentItem, ComponentExportIndex)> {
851 let info = self.env_component();
852 let index = self.lookup_export_index(instance, name)?;
853 let item = self.with_uninstantiated_instance_type(|instance| {
854 types::ComponentItem::from_export(
855 &self.inner.engine,
856 &info.export_items[index],
857 instance,
858 )
859 });
860 Some((
861 item,
862 ComponentExportIndex {
863 id: self.inner.id,
864 index,
865 },
866 ))
867 }
868
869 pub(crate) fn lookup_export_index(
870 &self,
871 instance: Option<&ComponentExportIndex>,
872 name: &str,
873 ) -> Option<ExportIndex> {
874 let info = self.env_component();
875 let exports = match instance {
876 Some(idx) => {
877 if idx.id != self.inner.id {
878 return None;
879 }
880 match &info.export_items[idx.index] {
881 Export::Instance { exports, .. } => exports,
882 _ => return None,
883 }
884 }
885 None => &info.exports,
886 };
887 exports.get(name, &NameMapNoIntern).copied()
888 }
889
890 pub(crate) fn id(&self) -> CompiledModuleId {
891 self.inner.id
892 }
893
894 /// Returns the [`Engine`] that this [`Component`] was compiled by.
895 pub fn engine(&self) -> &Engine {
896 &self.inner.engine
897 }
898
899 pub(crate) fn realloc_func_ty(&self) -> &Arc<FuncType> {
900 &self.inner.realloc_func_type
901 }
902
903 #[allow(
904 unused,
905 reason = "used only for verification with wasmtime `rr` feature \
906 and requires a lot of unnecessary gating across crates"
907 )]
908 pub(crate) fn checksum(&self) -> &WasmChecksum {
909 &self.inner.checksum
910 }
911
912 /// Returns the `Export::LiftedFunction` metadata associated with `export`.
913 ///
914 /// # Panics
915 ///
916 /// Panics if `export` is out of bounds or if it isn't a `LiftedFunction`.
917 pub(crate) fn export_lifted_function(
918 &self,
919 export: ExportIndex,
920 ) -> (TypeFuncIndex, &CoreDef, OptionsIndex) {
921 let component = self.env_component();
922 match &component.export_items[export] {
923 Export::LiftedFunction { ty, func, options } => (*ty, func, *options),
924 _ => unreachable!(),
925 }
926 }
927}
928
929/// A value which represents a known export of a component.
930///
931/// This is the return value of [`Component::get_export`] and implements the
932/// [`InstanceExportLookup`] trait to work with lookups like
933/// [`Instance::get_func`](crate::component::Instance::get_func).
934#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
935pub struct ComponentExportIndex {
936 pub(crate) id: CompiledModuleId,
937 pub(crate) index: ExportIndex,
938}
939
940impl InstanceExportLookup for ComponentExportIndex {
941 fn lookup(&self, component: &Component) -> Option<ExportIndex> {
942 if component.inner.id == self.id {
943 Some(self.index)
944 } else {
945 None
946 }
947 }
948}
949
950#[cfg(test)]
951mod tests {
952 use crate::component::Component;
953 use crate::{CodeBuilder, Config, Engine};
954 use wasmtime_environ::MemoryInitialization;
955
956 #[test]
957 fn cow_on_by_default() {
958 let mut config = Config::new();
959 config.wasm_component_model(true);
960 let engine = Engine::new(&config).unwrap();
961 let component = Component::new(
962 &engine,
963 r#"
964 (component
965 (core module
966 (memory 1)
967 (data (i32.const 100) "abcd")
968 )
969 )
970 "#,
971 )
972 .unwrap();
973
974 for (_, module) in component.inner.static_modules.iter() {
975 let init = &module.env_module().memory_initialization;
976 assert!(matches!(init, MemoryInitialization::Static { .. }));
977 }
978 }
979
980 #[test]
981 #[cfg_attr(miri, ignore)]
982 fn image_range_is_whole_image() {
983 let wat = r#"
984 (component
985 (core module
986 (memory 1)
987 (data (i32.const 0) "1234")
988 (func (export "f") (param i32) (result i32)
989 local.get 0)))
990 "#;
991 let engine = Engine::default();
992 let mut builder = CodeBuilder::new(&engine);
993 builder.wasm_binary_or_text(wat.as_bytes(), None).unwrap();
994 let bytes = builder.compile_component_serialized().unwrap();
995
996 let comp = unsafe { Component::deserialize(&engine, &bytes).unwrap() };
997 let image_range = comp.image_range();
998 let len = image_range.end.addr() - image_range.start.addr();
999 // Length may be strictly greater if it becomes page-aligned.
1000 assert!(len >= bytes.len());
1001 }
1002}