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* Instead of simply panicking, return an error when we attempt to resume on a dying fiber. This situation should never occur in the existing code base, but can be triggered if support for running outside async code in a call hook. * Shift `async_cx()` to return an `Option`, reflecting if the fiber is dying. This should never happen in the existing code base, but is a nice forward-looking guard. The current implementations simply lift the trap that would eventually be produced by such an operation into a `Trap` (or similar) at the invocation of `async_cx()`. * Add support for using `async` call hooks. This retains the ability to do non-async hooks. Hooks end up being implemented as an async trait with a handler call, to get around some issues passing around async closures. This change requires some of the prior changes to handle picking up blocked tasks during fiber shutdown, to avoid some panics during timeouts and other such events. * More fully specify a doc link, to avoid a doc-building error. * Revert the use of catchable traps on cancellation of a fiber; turn them into expect()/unwrap(). The justification for this revert is that (a) these events shouldn't happen, and (b) they wouldn't be catchable by wasm anyways. * Replace a duplicated check in `async` hook evaluation with a single check. This also moves the checks inside of their respective Async variants, meaning that if you're using an async-enabled version of wasmtime but using the synchronous versions of the callbacks, you won't pay any penalty for validating the async context. * Use `match &mut ...` insead of `ref mut`. * Add some documentation on why/when `async_cx` can return None. * Add two simple test cases for async call hooks. * Fix async_cx() to check both the box and the value for current_poll_cx. In the prior version, we only checked that the box had not been cleared, but had not ensured that there was an actual context for us to use. This updates the check to validate both, returning None if the inner context is missing. This allows us to skip a validation check inside `block_on`, since all callers will have run through the `async_cx` check prior to arrival. * Tweak the timeout test to address PR suggestions. * Add a test about dropping async hooks while suspended Should help exercise that the check for `None` is properly handled in a few more locations. Co-authored-by: Alex Crichton <alex@alexcrichton.com>
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, 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.
-
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.