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wasm_loader.go
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/
wasm_loader.go
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package caddy_wasm
import (
"context"
"fmt"
"math/rand"
"sync"
"github.com/tetratelabs/wazero"
"github.com/tetratelabs/wazero/api"
)
type ModuleInstance struct {
module api.Module
mut sync.Mutex
}
func (m *ModuleInstance) acquire() {
m.mut.Lock()
}
func (m *ModuleInstance) tryAcquire() bool {
return m.mut.TryLock()
}
func (m *ModuleInstance) Release() {
m.mut.Unlock()
}
func (m *ModuleInstance) Module() api.Module {
return m.module
}
type WebAssemblyLoader struct {
mut sync.RWMutex
instances []*ModuleInstance
maxInstances int
rt wazero.Runtime
module wazero.CompiledModule
moduleConfig wazero.ModuleConfig
}
func (w *WebAssemblyLoader) Get() *ModuleInstance {
w.mut.RLock()
defer w.mut.RUnlock()
if len(w.instances) == 0 {
return nil
}
// this starts iterating from a random point in the slide
// to avoid always using the first one
// this may be overkill
len := len(w.instances)
mod := rand.Int() % len
for ix := range w.instances {
if w.instances[(mod+ix)%len].tryAcquire() {
return w.instances[ix]
}
}
return nil
}
func (w *WebAssemblyLoader) GetOrLoad(ctx context.Context) (*ModuleInstance, error) {
// try to use the ones we have
if inst := w.Get(); inst != nil {
return inst, nil
}
if len(w.instances) >= w.maxInstances {
return nil, fmt.Errorf("max instances reached")
}
// ok we need to make a new one
mod, err := w.rt.InstantiateModule(ctx, w.module, w.moduleConfig)
if err != nil {
return nil, err
}
instance := &ModuleInstance{
module: mod,
mut: sync.Mutex{},
}
instance.acquire()
w.mut.Lock()
defer w.mut.Unlock()
w.instances = append(w.instances, instance)
return instance, nil
}
type VersionedLoader struct {
DefaultVersion string
Versions VersionCollection
Loaders map[string]*WebAssemblyLoader
rt wazero.Runtime
}
func MakeVersionedLoader(ctx context.Context, v VersionCollection, rt wazero.Runtime) (*VersionedLoader, error) {
versions, err := v.GetVersions()
if err != nil {
return nil, err
}
if len(versions) == 0 {
return nil, fmt.Errorf("no versions found")
}
defaultVersion := versions[0]
loader := &VersionedLoader{
DefaultVersion: defaultVersion,
Versions: v,
Loaders: make(map[string]*WebAssemblyLoader),
rt: rt,
}
for _, version := range versions {
// TODO: lazy load here?
if err := loader.loadVersion(ctx, version); err != nil {
return nil, err
}
}
return loader, nil
}
func (v *VersionedLoader) GetOrLoad(ctx context.Context, version string) (*ModuleInstance, error) {
loader, ok := v.Loaders[version]
if !ok {
return nil, fmt.Errorf("no such version: %s", version)
}
return loader.GetOrLoad(ctx)
}
func (v *VersionedLoader) loadVersion(ctx context.Context, version string) error {
var data []byte
data, err := v.Versions.GetWebAssembly(version)
if err != nil {
return err
}
var mod wazero.CompiledModule
mod, err = v.rt.CompileModule(ctx, data)
if err != nil {
return err
}
v.Loaders[version] = &WebAssemblyLoader{
rt: v.rt,
module: mod,
maxInstances: 10,
// TODO: fill out this config here
moduleConfig: wazero.NewModuleConfig(),
}
return nil
}