Module component

Support for the component model in Wasmtime.

This module contains all of the internal type definitions used by Wasmtime to process the component model. Despite everything being pub here this is not the public interface of Wasmtime to the component model. Instead this is the internal support to mirror the core wasm support that Wasmtime already implements.

Some main items contained within here are:

• Type hierarchy information for the component model
• Translation of a component into Wasmtime’s representation
• Type information about a component used at runtime

This module also contains a lot of Serialize/Deserialize types which are encoded in the final compiled image for a component.

Note that this entire module is gated behind the component-model Cargo feature.

Warning: In-progress

As-of the time of this writing this module is incomplete and under development. It will be added to incrementally over time as more features are implemented. Current design decisions are also susceptible to change at any time. Some comments may reflect historical rather than current state as well (sorry).

Re-exports

• pub use crate::StaticModuleIndex;
• pub use crate::FuncIndex;
• pub use crate::GlobalIndex;
• pub use crate::MemoryIndex;
• pub use crate::TableIndex;

Modules

• dfg
  A dataflow-graph-like intermediate representation of a component

Structs

• Adapter
  Metadata information about a fused adapter.
• AdapterOptions
  Configuration options which can be specified as part of the canonical ABI in the component model.
• AllCallFunc
  A triple of related functions/trampolines variants with differing calling conventions: {wasm,array}_call.
• CanonicalAbiInfo
  Bye information about a type in the canonical ABI, with metadata for both memory32 and memory64-based types.
• CanonicalOptions
  Canonical ABI options associated with a lifted or lowered function.
• CompiledComponentInfo
  Runtime state that a component retains to support its operation.
• Component
  Run-time-type-information about a Component, its structure, and how to instantiate it.
• ComponentArtifacts
  Serializable state that’s stored in a compilation artifact.
• ComponentFuncIndex
  Index within a component’s component function index space.
• ComponentIndex
  Index within a component’s component index space.
• ComponentInstanceIndex
  Index within a component’s component instance index space.
• ComponentTranslation
  Metadata as a result of compiling a component.
• ComponentTypeIndex
  Index within a component’s component type index space.
• ComponentTypes
  Runtime information about the type information contained within a component.
• ComponentTypesBuilder
  Structured used to build a ComponentTypes during translation.
• ComponentUpvarIndex
  Same as ModuleUpvarIndex but for components.
• CoreExport
  Identifier of an exported item from a core WebAssembly module instance.
• DefinedResourceIndex
  Index pointing to a local resource defined within a component.
• ExportIndex
  An index into Component::export_items at the end of compilation.
• ExtractMemory
  Metadata for extraction of a memory of what’s being extracted and where it’s going.
• ExtractPostReturn
  Same as ExtractMemory but for the post-return canonical option.
• ExtractRealloc
  Same as ExtractMemory but for the realloc canonical option.
• FlatTypes
  Flat representation of a type in just core wasm types.
• ImportIndex
  Used to index imports into a Component
• LoweredIndex
  Index that represents a lowered host function and is used to represent host function lowerings with options and such.
• ModuleIndex
  Index within a component’s module index space.
• ModuleInstanceIndex
  Index within a component’s module instance index space.
• ModuleUpvarIndex
  Index into a “closed over variables” list for components used to implement outer aliases. For more information on this see the documentation for the LexicalScope structure.
• NameMap
  A semver-aware map for imports/exports of a component.
• NameMapNoIntern
  For use with NameMap when no interning should happen and instead string keys are copied as-is.
• RecordField
  One field within a record.
• Resource
  Description of a new resource declared in a GlobalInitializer::Resource variant.
• ResourceIndex
  Index pointing to a resource within a component.
• ResourcesBuilder
  Builder state used to translate wasmparser’s ResourceId types to Wasmtime’s TypeResourceTableIndex type.
• RuntimeComponentInstanceIndex
  Same as RuntimeInstanceIndex but tracks component instances instead.
• RuntimeImportIndex
  Index that represents a leaf item imported into a component where a “leaf” means “not an instance”.
• RuntimeInstanceIndex
  Index that represents a core wasm instance created at runtime.
• RuntimeMemoryIndex
  Index representing a linear memory extracted from a wasm instance which is stored in a VMComponentContext. This is used to deduplicate references to the same linear memory where it’s only stored once in a VMComponentContext.
• RuntimePostReturnIndex
  Same as RuntimeMemoryIndex except for the post-return function.
• RuntimeReallocIndex
  Same as RuntimeMemoryIndex except for the realloc function.
• StaticComponentIndex
  Same as StaticModuleIndex but for components.
• TrampolineIndex
  Index for all trampolines that are compiled in Cranelift for a component.
• Translator
  Structure used to translate a component and parse it.
• TypeComponent
  The type of a component in the component model.
• TypeComponentIndex
  Index pointing to a component’s type (exports/imports with component-model types)
• TypeComponentInstance
  The type of a component instance in the component model, or an instantiated component.
• TypeComponentInstanceIndex
  Index pointing to a component instance’s type (exports with component-model types, no imports)
• TypeEnum
  Shape of an “enum” type in interface types, not to be confused with a Rust enum type.
• TypeEnumIndex
  Index pointing to an enum type in the component model.
• TypeFlags
  Shape of a “flags” type in interface types.
• TypeFlagsIndex
  Index pointing to a flags type in the component model.
• TypeFunc
  A component function type in the component model.
• TypeFuncIndex
  Index pointing to a component model function type with arguments/result as interface types.
• TypeList
  Shape of a “list” interface type.
• TypeListIndex
  Index pointing to a list type in the component model.
• TypeModule
  The type of a module in the component model.
• TypeModuleIndex
  Index pointing to a core wasm module’s type (exports/imports with core wasm types)
• TypeOption
  Shape of an “option” interface type.
• TypeOptionIndex
  Index pointing to an option type in the component model (aka a Option<T, E>)
• TypeRecord
  Shape of a “record” type in interface types.
• TypeRecordIndex
  Index pointing to a record type in the component model (aka a struct).
• TypeResourceTable
  Metadata about a resource table added to a component.
• TypeResourceTableIndex
  Index pointing to a resource table within a component.
• TypeResult
  Shape of a “result” interface type.
• TypeResultIndex
  Index pointing to an result type in the component model (aka a Result<T, E>)
• TypeTuple
  Shape of a “tuple” type in interface types.
• TypeTupleIndex
  Index pointing to a tuple type in the component model.
• TypeVariant
  Shape of a “variant” type in interface types.
• TypeVariantIndex
  Index pointing to a variant type in the component model (aka an enum).
• VMComponentOffsets
  Runtime offsets within a VMComponentContext for a specific component.
• VariantInfo
  ABI information about the representation of a variant.

Enums

• ComponentItem
  Equivalent of EntityIndex but for the component model instead of core wasm.
• CoreDef
  Definition of a core wasm item and where it can come from within a component.
• Export
  Possible exports from a component.
• ExportItem
  An index at which to find an item within a runtime instance.
• FixedEncoding
• FlatType
• GlobalInitializer
  GlobalInitializer instructions to get processed when instantiating a component
• InstantiateModule
  Different methods of instantiating a core wasm module.
• InterfaceType
  All possible interface types that values can have.
• StringEncoding
  Possible encodings of strings within the component model.
• Trampoline
  A list of all possible trampolines that may be required to compile a component completely.
• Transcode
  Possible transcoding operations that must be provided by the host.
• TypeDef
  Types of imports and exports in the component model.

Constants

• FLAG_MAY_ENTER
  Flag for the VMComponentContext::flags field which corresponds to the canonical ABI flag may_enter
• FLAG_MAY_LEAVE
  Flag for the VMComponentContext::flags field which corresponds to the canonical ABI flag may_leave
• FLAG_NEEDS_POST_RETURN
  Flag for the VMComponentContext::flags field which is set whenever a function is called to indicate that post_return must be called next.
• MAX_FLAT_PARAMS
  Canonical ABI-defined constant for the maximum number of “flat” parameters to a wasm function, or the maximum number of parameters a core wasm function will take for just the parameters used. Over this number the heap is used for transferring parameters.
• MAX_FLAT_RESULTS
  Canonical ABI-defined constant for the maximum number of “flat” results. This number of results are returned directly from wasm and otherwise results are transferred through memory.
• MAX_FLAT_TYPES
  Maximum number of flat types, for either params or results.
• VMCOMPONENT_MAGIC
  Equivalent of VMCONTEXT_MAGIC except for components.

Traits

• ComponentCompiler
  Compilation support necessary for components.
• NameMapIntern
  A helper trait used in conjunction with NameMap to optionally intern keys to non-strings.