54c07d8f16
* Implement defining host functions at the Config level. This commit introduces defining host functions at the `Config` rather than with `Func` tied to a `Store`. The intention here is to enable a host to define all of the functions once with a `Config` and then use a `Linker` (or directly with `Store::get_host_func`) to use the functions when instantiating a module. This should help improve the performance of use cases where a `Store` is short-lived and redefining the functions at every module instantiation is a noticeable performance hit. This commit adds `add_to_config` to the code generation for Wasmtime's `Wasi` type. The new method adds the WASI functions to the given config as host functions. This commit adds context functions to `Store`: `get` to get a context of a particular type and `set` to set the context on the store. For safety, `set` cannot replace an existing context value of the same type. `Wasi::set_context` was added to set the WASI context for a `Store` when using `Wasi::add_to_config`. * Add `Config::define_host_func_async`. * Make config "async" rather than store. This commit moves the concept of "async-ness" to `Config` rather than `Store`. Note: this is a breaking API change for anyone that's already adopted the new async support in Wasmtime. Now `Config::new_async` is used to create an "async" config and any `Store` associated with that config is inherently "async". This is needed for async shared host functions to have some sanity check during their execution (async host functions, like "async" `Func`, need to be called with the "async" variants). * Update async function tests to smoke async shared host functions. This commit updates the async function tests to also smoke the shared host functions, plus `Func::wrap0_async`. This also changes the "wrap async" method names on `Config` to `wrap$N_host_func_async` to slightly better match what is on `Func`. * Move the instance allocator into `Engine`. This commit moves the instantiated instance allocator from `Config` into `Engine`. This makes certain settings in `Config` no longer order-dependent, which is how `Config` should ideally be. This also removes the confusing concept of the "default" instance allocator, instead opting to construct the on-demand instance allocator when needed. This does alter the semantics of the instance allocator as now each `Engine` gets its own instance allocator rather than sharing a single one between all engines created from a configuration. * Make `Engine::new` return `Result`. This is a breaking API change for anyone using `Engine::new`. As creating the pooling instance allocator may fail (likely cause is not enough memory for the provided limits), instead of panicking when creating an `Engine`, `Engine::new` now returns a `Result`. * Remove `Config::new_async`. This commit removes `Config::new_async` in favor of treating "async support" as any other setting on `Config`. The setting is `Config::async_support`. * Remove order dependency when defining async host functions in `Config`. This commit removes the order dependency where async support must be enabled on the `Config` prior to defining async host functions. The check is now delayed to when an `Engine` is created from the config. * Update WASI example to use shared `Wasi::add_to_config`. This commit updates the WASI example to use `Wasi::add_to_config`. As only a single store and instance are used in the example, it has no semantic difference from the previous example, but the intention is to steer users towards defining WASI on the config and only using `Wasi::add_to_linker` when more explicit scoping of the WASI context is required.
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 - 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.