bcf3544924
* Optimize `Func::call` and its C API This commit is an alternative to #3298 which achieves effectively the same goal of optimizing the `Func::call` API as well as its C API sibling of `wasmtime_func_call`. The strategy taken here is different than #3298 though where a new API isn't created, rather a small tweak to an existing API is done. Specifically this commit handles the major sources of slowness with `Func::call` with: * Looking up the type of a function, to typecheck the arguments with and use to guide how the results should be loaded, no longer hits the rwlock in the `Engine` but instead each `Func` contains its own `FuncType`. This can be an unnecessary allocation for funcs not used with `Func::call`, so this is a downside of this implementation relative to #3298. A mitigating factor, though, is that instance exports are loaded lazily into the `Store` and in theory not too many funcs are active in the store as `Func` objects. * Temporary storage is amortized with a long-lived `Vec` in the `Store` rather than allocating a new vector on each call. This is basically the same strategy as #3294 only applied to different types in different places. Specifically `wasmtime::Store` now retains a `Vec<u128>` for `Func::call`, and the C API retains a `Vec<Val>` for calling `Func::call`. * Finally, an API breaking change is made to `Func::call` and its type signature (as well as `Func::call_async`). Instead of returning `Box<[Val]>` as it did before this function now takes a `results: &mut [Val]` parameter. This allows the caller to manage the allocation and we can amortize-remove it in `wasmtime_func_call` by using space after the parameters in the `Vec<Val>` we're passing in. This change is naturally a breaking change and we'll want to consider it carefully, but mitigating factors are that most embeddings are likely using `TypedFunc::call` instead and this signature taking a mutable slice better aligns with `Func::new` which receives a mutable slice for the results. Overall this change, in the benchmark of "call a nop function from the C API" is not quite as good as #3298. It's still a bit slower, on the order of 15ns, because there's lots of capacity checks around vectors and the type checks are slightly less optimized than before. Overall though this is still significantly better than today because allocations and the rwlock to acquire the type information are both avoided. I personally feel that this change is the best to do because it has less of an API impact than #3298. * Rebase issues
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS with a small install script:
$ curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
Features
-
Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.
-
Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
-
Configurable. Whether you need to precompile your wasm ahead of time, generate code blazingly fast with Lightbeam, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.
-
WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
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Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders or usewasmtimeConan package - [C++] - the
wasmtime-cpprepository or usewasmtime-cppConan package - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!
It's Wasmtime.