Alex Crichton fcf6208750 Initial skeleton of some component model processing (#4005)
* Initial skeleton of some component model processing

This commit is the first of what will likely be many to implement the
component model proposal in Wasmtime. This will be structured as a
series of incremental commits, most of which haven't been written yet.
My hope is to make this incremental and over time to make this easier to
review and easier to test each step in isolation.

Here much of the skeleton of how components are going to work in
Wasmtime is sketched out. This is not a complete implementation of the
component model so it's not all that useful yet, but some things you can
do are:

* Process the type section into a representation amenable for working
  with in Wasmtime.
* Process the module section and register core wasm modules.
* Process the instance section for core wasm modules.
* Process core wasm module imports.
* Process core wasm instance aliasing.
* Ability to compile a component with core wasm embedded.
* Ability to instantiate a component with no imports.
* Ability to get functions from this component.

This is already starting to diverge from the previous module linking
representation where a `Component` will try to avoid unnecessary
metadata about the component and instead internally only have the bare
minimum necessary to instantiate the module. My hope is we can avoid
constructing most of the index spaces during instantiation only for it
to all ge thrown away. Additionally I'm predicting that we'll need to
see through processing where possible to know how to generate adapters
and where they are fused.

At this time you can't actually call a component's functions, and that's
the next PR that I would like to make.

* Add tests for the component model support

This commit uses the recently updated wasm-tools crates to add tests for
the component model added in the previous commit. This involved updating
the `wasmtime-wast` crate for component-model changes. Currently the
component support there is quite primitive, but enough to at least
instantiate components and verify the internals of Wasmtime are all
working correctly. Additionally some simple tests for the embedding API
have also been added.
2022-05-20 15:33:18 -05:00
2020-02-28 09:16:05 -08:00

wasmtime

A standalone runtime for WebAssembly

A Bytecode Alliance project

build status zulip chat supported rustc stable Documentation Status

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

  • Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code either at runtime or ahead-of-time. Wasmtime's runtime is also optimized for cases such as efficient instantiation, low-overhead transitions between the embedder and wasm, and scalability of concurrent instances.

  • Secure. Wasmtime's development is strongly focused on the correctness of its implementation with 24/7 fuzzing donated by Google's OSS Fuzz, leveraging Rust's API and runtime safety guarantees, careful design of features and APIs through an RFC process, a security policy in place for when things go wrong, and a release policy for patching older versions as well. We follow best practices for defense-in-depth and known protections and mitigations for issues like Spectre. Finally, we're working to push the state-of-the-art by collaborating with academic researchers to formally verify critical parts of Wasmtime and Cranelift.

  • Configurable. Wastime supports a rich set of APIs and build time configuration to provide many options such as further means of restricting WebAssembly beyond its basic guarantees such as its CPU and Memory consumption. Wasmtime also runs in tiny environments all the way up to massive servers with many concurrent instances.

  • 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:

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.

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