45 lines
823 B
Go
45 lines
823 B
Go
package singleton
|
|
|
|
import (
|
|
"fmt"
|
|
"reflect"
|
|
"sync"
|
|
|
|
"github.com/navidrome/navidrome/log"
|
|
)
|
|
|
|
var (
|
|
instances = make(map[string]any)
|
|
lock sync.RWMutex
|
|
)
|
|
|
|
// GetInstance returns an existing instance of object. If it is not yet created, calls `constructor`, stores the
|
|
// result for future calls and returns it
|
|
func GetInstance[T any](constructor func() T) T {
|
|
var v T
|
|
name := reflect.TypeOf(v).String()
|
|
|
|
v, available := func() (T, bool) {
|
|
lock.RLock()
|
|
defer lock.RUnlock()
|
|
v, available := instances[name].(T)
|
|
return v, available
|
|
}()
|
|
|
|
if available {
|
|
return v
|
|
}
|
|
|
|
lock.Lock()
|
|
defer lock.Unlock()
|
|
v, available = instances[name].(T)
|
|
if available {
|
|
return v
|
|
}
|
|
|
|
v = constructor()
|
|
log.Trace("Created new singleton", "type", name, "instance", fmt.Sprintf("%+v", v))
|
|
instances[name] = v
|
|
return v
|
|
}
|