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Simplifies API per feedback (#427)

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During #425, @neilalexander gave constructive feedback that the API is
both moving fast, and not good enough yet. This attempts to reduce the
incidental complexity at the cost of a little conflation.

### odd presence of `wasm` and `wasi` packages -> `api` package

We had public API packages in wasm and wasi, which helped us avoid
leaking too many internals as public. That these had names that look
like there should be implementations in them cause unnecessary
confusion. This squashes both into one package "api" which has no
package collission with anything.

We've long struggled with the poorly specified and non-uniformly
implemented WASI specification. Trying to bring visibility to its
constraints knowing they are routinely invalid taints our API for no
good reason. This removes all `WASI` commands for a default to invoke
the function `_start` if it exists. In doing so, there's only one path
to start a module.

Moreover, this puts all wasi code in a top-level package "wasi" as it
isn't re-imported by any internal types.

### Reuse of Module for pre and post instantiation to `Binary` -> `Module`

Module is defined by WebAssembly in many phases, from decoded to
instantiated. However, using the same noun in multiple packages is very
confusing. We at one point tried a name "DecodedModule" or
"InstantiatedModule", but this is a fools errand. By deviating slightly
from the spec we can make it unambiguous what a module is.

This make a result of compilation a `Binary`, retaining `Module` for an
instantiated one. In doing so, there's no longer any name conflicts
whatsoever.

### Confusion about config -> `ModuleConfig`

Also caused by splitting wasm into wasm+wasi is configuration. This
conflates both into the same type `ModuleConfig` as it is simpler than
trying to explain a "will never be finished" api of wasi snapshot-01 in
routine use of WebAssembly. In other words, this further moves WASI out
of the foreground as it has been nothing but burden.

```diff
--- a/README.md
+++ b/README.md
@@ -49,8 +49,8 @@ For example, here's how you can allow WebAssembly modules to read
-wm, err := r.InstantiateModule(wazero.WASISnapshotPreview1())
-defer wm.Close()
+wm, err := wasi.InstantiateSnapshotPreview1(r)
+defer wm.Close()

-sysConfig := wazero.NewSysConfig().WithFS(os.DirFS("/work/home"))
-module, err := wazero.StartWASICommandWithConfig(r, compiled, sysConfig)
+config := wazero.ModuleConfig().WithFS(os.DirFS("/work/home"))
+module, err := r.InstantiateModule(binary, config)
 defer module.Close()
 ...
```
This commit is contained in:
Crypt Keeper
2022-04-02 06:42:36 +08:00
committed by GitHub
parent 3c3df6b836
commit 2664b1eb62
127 changed files with 3153 additions and 3230 deletions
Download Patch File Download Diff File Expand all files Collapse all files

36
builder.go
View File

@@ -1,8 +1,8 @@
package wazero
import (
internalwasm "github.com/tetratelabs/wazero/internal/wasm"
"github.com/tetratelabs/wazero/wasm"
"github.com/tetratelabs/wazero/api"
"github.com/tetratelabs/wazero/internal/wasm"
)
// ModuleBuilder is a way to define a WebAssembly 1.0 (20191205) in Go.
@@ -25,7 +25,7 @@ import (
// Note: Insertion order is not retained. Anything defined by this builder is sorted lexicographically on Build.
type ModuleBuilder interface {
// ExportFunction adds a function written in Go, which a WebAssembly Module can import.
// ExportFunction adds a function written in Go, which a WebAssembly module can import.
//
// * name - the name to export. Ex "random_get"
// * goFunc - the `func` to export.
@@ -39,24 +39,24 @@ type ModuleBuilder interface {
// return x + y
// }
//
// Host functions may also have an initial parameter (param[0]) of type context.Context or wasm.Module.
// Host functions may also have an initial parameter (param[0]) of type context.Context or api.Module.
//
// Ex. This uses a Go Context:
//
// addInts := func(ctx context.Context, x uint32, uint32) uint32 {
// addInts := func(m context.Context, x uint32, uint32) uint32 {
// // add a little extra if we put some in the context!
// return x + y + ctx.Value(extraKey).(uint32)
// return x + y + m.Value(extraKey).(uint32)
// }
//
// The most sophisticated context is wasm.Module, which allows access to the Go context, but also
// The most sophisticated context is api.Module, which allows access to the Go context, but also
// allows writing to memory. This is important because there are only numeric types in Wasm. The only way to share other
// data is via writing memory and sharing offsets.
//
// Ex. This reads the parameters from!
//
// addInts := func(ctx wasm.Module, offset uint32) uint32 {
// x, _ := ctx.Memory().ReadUint32Le(offset)
// y, _ := ctx.Memory().ReadUint32Le(offset + 4) // 32 bits == 4 bytes!
// addInts := func(m api.Module, offset uint32) uint32 {
// x, _ := m.Memory().ReadUint32Le(offset)
// y, _ := m.Memory().ReadUint32Le(offset + 4) // 32 bits == 4 bytes!
// return x + y
// }
//
@@ -67,13 +67,13 @@ type ModuleBuilder interface {
// ExportFunctions is a convenience that calls ExportFunction for each key/value in the provided map.
ExportFunctions(nameToGoFunc map[string]interface{}) ModuleBuilder
// Build returns a Module to instantiate, or returns an error if any of the configuration is invalid.
Build() (*Module, error)
// Build returns a module to instantiate, or returns an error if any of the configuration is invalid.
Build() (*CompiledCode, error)
// Instantiate is a convenience that calls Build, then Runtime.InstantiateModule
//
// Note: Fields in the builder are copied during instantiation: Later changes do not affect the instantiated result.
Instantiate() (wasm.Module, error)
Instantiate() (api.Module, error)
}
// moduleBuilder implements ModuleBuilder
@@ -107,20 +107,20 @@ func (b *moduleBuilder) ExportFunctions(nameToGoFunc map[string]interface{}) Mod
}
// Build implements ModuleBuilder.Build
func (b *moduleBuilder) Build() (*Module, error) {
func (b *moduleBuilder) Build() (*CompiledCode, error) {
// TODO: we can use r.enabledFeatures to fail early on things like mutable globals
if module, err := internalwasm.NewHostModule(b.moduleName, b.nameToGoFunc); err != nil {
if module, err := wasm.NewHostModule(b.moduleName, b.nameToGoFunc); err != nil {
return nil, err
} else {
return &Module{name: b.moduleName, module: module}, nil
return &CompiledCode{module: module}, nil
}
}
// Instantiate implements ModuleBuilder.Instantiate
func (b *moduleBuilder) Instantiate() (wasm.Module, error) {
func (b *moduleBuilder) Instantiate() (api.Module, error) {
if module, err := b.Build(); err != nil {
return nil, err
} else {
return b.r.InstantiateModule(module)
return b.r.InstantiateModuleWithConfig(module, NewModuleConfig().WithName(b.moduleName))
}
}