c0c368d151
* Skip memfd creation with precompiled modules This commit updates the memfd support internally to not actually use a memfd if a compiled module originally came from disk via the `wasmtime::Module::deserialize_file` API. In this situation we already have a file descriptor open and there's no need to copy a module's heap image to a new file descriptor. To facilitate a new source of `mmap` the currently-memfd-specific-logic of creating a heap image is generalized to a new form of `MemoryInitialization` which is attempted for all modules at module-compile-time. This means that the serialized artifact to disk will have the memory image in its entirety waiting for us. Furthermore the memory image is ensured to be padded and aligned carefully to the target system's page size, notably meaning that the data section in the final object file is page-aligned and the size of the data section is also page aligned. This means that when a precompiled module is mapped from disk we can reuse the underlying `File` to mmap all initial memory images. This means that the offset-within-the-memory-mapped-file can differ for memfd-vs-not, but that's just another piece of state to track in the memfd implementation. In the limit this waters down the term "memfd" for this technique of quickly initializing memory because we no longer use memfd unconditionally (only when the backing file isn't available). This does however open up an avenue in the future to porting this support to other OSes because while `memfd_create` is Linux-specific both macOS and Windows support mapping a file with copy-on-write. This porting isn't done in this PR and is left for a future refactoring. Closes #3758 * Enable "memfd" support on all unix systems Cordon off the Linux-specific bits and enable the memfd support to compile and run on platforms like macOS which have a Linux-like `mmap`. This only works if a module is mapped from a precompiled module file on disk, but that's better than not supporting it at all! * Fix linux compile * Use `Arc<File>` instead of `MmapVecFileBacking` * Use a named struct instead of mysterious tuples * Comment about unsafety in `Module::deserialize_file` * Fix tests * Fix uffd compile * Always align data segments No need to have conditional alignment since their sizes are all aligned anyway * Update comment in build.rs * Use rustix, not `region` * Fix some confusing logic/names around memory indexes These functions all work with memory indexes, not specifically defined memory indexes.
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.
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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.