* Add resource limiting to the Wasmtime API.
This commit adds a `ResourceLimiter` trait to the Wasmtime API.
When used in conjunction with `Store::new_with_limiter`, this can be used to
monitor and prevent WebAssembly code from growing linear memories and tables.
This is particularly useful when hosts need to take into account host resource
usage to determine if WebAssembly code can consume more resources.
A simple `StaticResourceLimiter` is also included with these changes that will
simply limit the size of linear memories or tables for all instances created in
the store based on static values.
* Code review feedback.
* Implemented `StoreLimits` and `StoreLimitsBuilder`.
* Moved `max_instances`, `max_memories`, `max_tables` out of `Config` and into
`StoreLimits`.
* Moved storage of the limiter in the runtime into `Memory` and `Table`.
* Made `InstanceAllocationRequest` use a reference to the limiter.
* Updated docs.
* Made `ResourceLimiterProxy` generic to remove a level of indirection.
* Fixed the limiter not being used for `wasmtime::Memory` and
`wasmtime::Table`.
* Code review feedback and bug fix.
* `Memory::new` now returns `Result<Self>` so that an error can be returned if
the initial requested memory exceeds any limits placed on the store.
* Changed an `Arc` to `Rc` as the `Arc` wasn't necessary.
* Removed `Store` from the `ResourceLimiter` callbacks. Custom resource limiter
implementations are free to capture any context they want, so no need to
unnecessarily store a weak reference to `Store` from the proxy type.
* Fixed a bug in the pooling instance allocator where an instance would be
leaked from the pool. Previously, this would only have happened if the OS was
unable to make the necessary linear memory available for the instance. With
these changes, however, the instance might not be created due to limits
placed on the store. We now properly deallocate the instance on error.
* Added more tests, including one that covers the fix mentioned above.
* Code review feedback.
* Add another memory to `test_pooling_allocator_initial_limits_exceeded` to
ensure a partially created instance is successfully deallocated.
* Update some doc comments for better documentation of `Store` and
`ResourceLimiter`.
This commit removes `HostRef<T>` from the C API which only served the
purpose now of converting each type to a `wasm_ref_t*`. Our
implementation, however, does not guarantee that you'll get the same
`wasm_ref_t*` for each actual underlying item (e.g. if you put a func in
a table and then get the func as an export and from the table then
`same` will report `false`). Additionally the fate of `wasm_ref_t*`
seems somewhat unclear at this point.
The change here is to make the `same` and cast functions all abort
saying they're unimplemented. (similar to the host info functions). If
and when we get around to reimplementing these functions we can ensure
they're implemented uniformly and work well for all intended use cases.
Better to be loud that we don't support attaching arbitrary host info to
`externref`s than to limp along and pretend we do support it. Supporting it
properly won't reuse any of this code anyways.
It isn't used by anything except for the C API and all of our embedder-exposed
APIs are already internally `Rc`-based, so it doesn't make sense to use with
them.
This is enough to get an `externref -> externref` identity function
passing.
However, `externref`s that are dropped by compiled Wasm code are (safely)
leaked. Follow up work will leverage cranelift's stack maps to resolve this
issue.
* Compute instance exports on demand.
Instead having instances eagerly compute a Vec of Externs, and bumping
the refcount for each Extern, compute Externs on demand.
This also enables `Instance::get_export` to avoid doing a linear search.
This also means that the closure returned by `get0` and friends now
holds an `InstanceHandle` to dynamically hold the instance live rather
than being scoped to a lifetime.
* Compute module imports and exports on demand too.
And compute Extern::ty on demand too.
* Add a utility function for computing an ExternType.
* Add a utility function for looking up a function's signature.
* Add a utility function for computing the ValType of a Global.
* Rename wasmtime_environ::Export to EntityIndex.
This helps differentiate it from other Export types in the tree, and
describes what it is.
* Fix a typo in a comment.
* Simplify module imports and exports.
* Make `Instance::exports` return the export names.
This significantly simplifies the public API, as it's relatively common
to need the names, and this avoids the need to do a zip with
`Module::exports`.
This also changes `ImportType` and `ExportType` to have public members
instead of private members and accessors, as I find that simplifies the
usage particularly in cases where there are temporary instances.
* Remove `Instance::module`.
This doesn't quite remove `Instance`'s `module` member, it gets a step
closer.
* Use a InstanceHandle utility function.
* Don't consume self in the `Func::get*` methods.
Instead, just create a closure containing the instance handle and the
export for them to call.
* Use `ExactSizeIterator` to avoid needing separate `num_*` methods.
* Rename `Extern::func()` etc. to `into_func()` etc.
* Revise examples to avoid using `nth`.
* Add convenience methods to instance for getting specific extern types.
* Use the convenience functions in more tests and examples.
* Avoid cloning strings for `ImportType` and `ExportType`.
* Remove more obviated clone() calls.
* Simplify `Func`'s closure state.
* Make wasmtime::Export's fields private.
This makes them more consistent with ExportType.
* Fix compilation error.
* Make a lifetime parameter explicit, and use better lifetime names.
Instead of 'me, use 'instance and 'module to make it clear what the
lifetime is.
* More lifetime cleanups.
* Refactor and improve safety of C API
This commit is intended to be a relatively large refactoring of the C
API which is targeted at improving the safety of our C API definitions.
Not all of the APIs have been updated yet but this is intended to be the
start.
The goal here is to make as many functions safe as we can, expressing
inputs/outputs as native Rust types rather than raw pointers wherever
possible. For example instead of `*const wasm_foo_t` we'd take
`&wasm_foo_t`. Instead of returning `*mut wasm_foo_t` we'd return
`Box<wasm_foo_t>`. No ABI/API changes are intended from this commit,
it's supposed to only change how we define all these functions
internally.
This commit also additionally implements a few more API bindings for
exposed vector types by unifying everything into one macro.
Finally, this commit moves many internal caches in the C API to the
`OnceCell` type which provides a safe interface for one-time
initialization.
* Split apart monolithic C API `lib.rs`
This commit splits the monolithic `src/lib.rs` in the C API crate into
lots of smaller files. The goal here is to make this a bit more readable
and digestable. Each module now contains only API bindings for a
particular type, roughly organized around the grouping in the wasm.h
header file already.
A few more extensions were added, such as filling out `*_as_*`
conversions with both const and non-const versions. Additionally many
APIs were made safer in the same style as the previous commit, generally
preferring Rust types rather than raw pointer types.
Overall no functional change is intended here, it should be mostly just
code movement and minor refactorings!
* Make a few wasi C bindings safer
Use safe Rust types where we can and touch up a few APIs here and there.
* Implement `wasm_*type_as_externtype*` APIs
This commit restructures `wasm_externtype_t` to be similar to
`wasm_extern_t` so type conversion between the `*_extern_*` variants to
the concrete variants are all simple casts. (checked in the case of
general to concrete, of course).
* Consistently imlpement host info functions in the API
This commit adds a small macro crate which is then used to consistently
define the various host-info-related functions in the C API. The goal
here is to try to mirror what the `wasm.h` header provides to provide a
full implementation of the header.
