c73673559b
This commit improves the runtime support for wasm-to-host invocations for functions created with `Func::new` or `wasmtime_func_new` in the C API. Previously a `Vec` (sometimes a `SmallVec`) would be dynamically allocated on each host call to store the arguments that are coming from wasm and going to the host. In the case of the `wasmtime` crate we need to decode the `u128`-stored values, and in the case of the C API we need to decode the `Val` into the C API's `wasmtime_val_t`. The technique used in this commit is to store a singular `Vec<T>` inside the "store", be it the literal `Store<T>` or within the `T` in the case of the C API, which can be reused across wasm->host calls. This means that we're unlikely to actually perform dynamic memory allocation and instead we should hit a faster path where the `Vec` always has enough capacity. Note that this is just a mild improvement for `Func::new`-based functions. It's still the case that `Func::wrap` is much faster, but unfortunately the C API doesn't have access to `Func::wrap`, so the main motivation here is accelerating the C API.
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 - [C++] - the
wasmtime-cpprepository - 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.