b63d4e6dcd
Formerly, we introduced `wazero.Namespace` to help avoid module name or import conflicts while still sharing the runtime's compilation cache. Now that we've introduced `CompilationCache` `wazero.Namespace` is no longer necessary. By removing it, we reduce the conceptual load on end users as well internal complexity. Since most users don't use namespace, the change isn't very impactful.
Users who are only trying to avoid module name conflict can generate a name like below instead of using multiple runtimes:
```go
moduleName := fmt.Sprintf("%d", atomic.AddUint64(&m.instanceCounter, 1))
module, err := runtime.InstantiateModule(ctx, compiled, config.WithName(moduleName))
```
For `HostModuleBuilder` users, we no longer take `Namespace` as the last parameter of `Instantiate` method:
```diff
// log to the console.
_, err := r.NewHostModuleBuilder("env").
NewFunctionBuilder().WithFunc(logString).Export("log").
- Instantiate(ctx, r)
+ Instantiate(ctx)
if err != nil {
log.Panicln(err)
}
```
The following is an example diff a use of namespace can use to keep compilation cache while also ensuring their modules don't conflict:
```diff
func useMultipleRuntimes(ctx context.Context, cache) {
- r := wazero.NewRuntime(ctx)
+ cache := wazero.NewCompilationCache()
for i := 0; i < N; i++ {
- // Create a new namespace to instantiate modules into.
- ns := r.NewNamespace(ctx) // Note: this is closed when the Runtime is
+ r := wazero.NewRuntimeWithConfig(ctx, wazero.NewRuntimeConfig().WithCompilationCache(cache))
// Instantiate a new "env" module which exports a stateful function.
_, err := r.NewHostModuleBuilder("env").
```
Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
Rust allocation example
This example shows how to pass strings in and out of a Wasm function defined
in Rust, built with cargo build --release --target wasm32-unknown-unknown
$ go run greet.go wazero
Hello, wazero!
Under the covers, lib.rs does a few things of interest:
- Uses a WebAssembly-tuned memory allocator: wee_alloc.
- Exports wrapper functions to allocate and deallocate memory.
- Uses
&strinstead of CString (NUL-terminated strings). - Uses
std::mem::forgetto prevent Rust from eagerly freeing pointers returned.
Note: We chose to not use CString because it keeps the example similar to how you would track memory for arbitrary blobs. We also watched function signatures carefully as Rust compiles different WebAssembly signatures depending on the input type.
See https://wazero.io/languages/rust/ for more tips.