761347db1e
We formerly introduced `MemorySizer` as a way to control capacity independently of size. This was the first and only feature in `CompileConfig`. While possibly used privately, `MemorySizer` has never been used in public GitHub code. These APIs interfere with how we do caching of compiled modules. Notably, they can change the min or max defined in wasm, which invalidates some constants. This has also had a bad experience, forcing everyone to boilerplate`wazero.NewCompileConfig()` despite that API never being used in open source. This addresses the use cases in a different way, by moving configuration to `RuntimeConfig` instead. This allows us to remove `MemorySizer` and `CompileConfig`, and the problems with them, yet still retaining functionality in case someone uses it. * `RuntimeConfig.WithMemoryLimitPages(uint32)`: Prevents memory from growing to 4GB (spec limit) per instance. * This works regardless of whether the wasm encodes max or not. If there is no max, it becomes effectively this value. * `RuntimeConfig.WithMemoryCapacityFromMax(bool)`: Prevents reallocations (when growing). * Wasm that never sets max will grow from min to the limit above. Note: Those who want to change their wasm (ex insert a max where there was none), have to do that externally, ex via compiler settings or post-build transformations such as [wabin](https://github.com/tetratelabs/wabin) Signed-off-by: Adrian Cole <adrian@tetrate.io>
Allocation examples
The examples in this directory deal with memory allocation concerns in WebAssembly, e.g. How to pass strings in and out of WebAssembly functions.
$ go run greet.go wazero
wasm >> Hello, wazero!
go >> Hello, wazero!
While the below examples use strings, they are written in a way that would work for binary serialization.
- Rust - Calls Wasm built with
cargo build --release --target wasm32-unknown-unknown - TinyGo - Calls Wasm built with
tinygo build -o X.wasm -scheduler=none --no-debug -target=wasi X.go - Zig - Calls Wasm built with
zig build
Note: Each of the above languages differ in both terms of exports and runtime behavior around allocation, because there is no WebAssembly specification for it. For example, TinyGo exports allocation functions while Rust and Zig don't. Also, Rust eagerly collects memory before returning from a Wasm function while TinyGo does not.
We still try to keep the examples as close to the same as possible, and highlight things to be aware of in the respective source and README files.