52 lines
924 B
Go
52 lines
924 B
Go
package singleton
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import (
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"fmt"
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"reflect"
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"github.com/navidrome/navidrome/log"
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)
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var (
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instances = make(map[string]any)
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getOrCreateC = make(chan entry)
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)
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type entry struct {
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f func() any
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object any
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resultC chan any
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}
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// GetInstance returns an existing instance of object. If it is not yet created, calls `constructor`, stores the
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// result for future calls and return it
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func GetInstance[T any](constructor func() T) T {
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var t T
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e := entry{
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object: t,
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f: func() any {
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return constructor()
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},
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resultC: make(chan any),
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}
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getOrCreateC <- e
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v := <-e.resultC
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return v.(T)
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}
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func init() {
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go func() {
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for {
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e := <-getOrCreateC
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name := reflect.TypeOf(e.object).String()
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v, created := instances[name]
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if !created {
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v = e.f()
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log.Trace("Created new singleton", "type", name, "instance", fmt.Sprintf("%+v", v))
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instances[name] = v
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}
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e.resultC <- v
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}
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}()
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}
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