| 1 | package steward |
| 2 | |
| 3 | import ( |
| 4 | "reflect" |
| 5 | "sync" |
| 6 | |
| 7 | "github.com/soverenio/vanilla/throw" |
| 8 | ) |
| 9 | |
| 10 | var ( |
| 11 | singletonStorageLock sync.Mutex |
| 12 | singletonStorage = make(map[interface{}]Asset) |
| 13 | ) |
| 14 | |
| 15 | func RegisterSingleton(assetKey interface{}, asset Asset) (got Asset, isNew bool) { |
| 16 | if !isComparable(assetKey) { |
| 17 | panic(throw.IllegalValue()) |
| 18 | } |
| 19 | |
| 20 | singletonStorageLock.Lock() |
| 21 | defer singletonStorageLock.Unlock() |
| 22 | |
| 23 | if oldSingleton, ok := singletonStorage[assetKey]; ok { |
| 24 | return oldSingleton, false |
| 25 | } |
| 26 | |
| 27 | singletonStorage[assetKey] = asset |
| 28 | return asset, true |
| 29 | } |
| 30 | |
| 31 | type DummySingleton struct { |
| 32 | key interface{} |
| 33 | } |
| 34 | |
| 35 | func (d DummySingleton) asset() {} |
| 36 | |
| 37 | func ReserveSingleton(assetKey interface{}) { |
| 38 | if !isComparable(assetKey) { |
| 39 | panic(throw.IllegalValue()) |
| 40 | } |
| 41 | |
| 42 | singletonStorageLock.Lock() |
| 43 | defer singletonStorageLock.Unlock() |
| 44 | |
| 45 | if _, ok := singletonStorage[assetKey]; ok { |
| 46 | panic(throw.IllegalState()) // trying to assign dummy singleton to already assigned key |
| 47 | } |
| 48 | |
| 49 | singletonStorage[assetKey] = DummySingleton{} |
| 50 | } |
| 51 | |
| 52 | func (d DummySingleton) Name() string { |
| 53 | return reflect.TypeOf(d.key).Name() |
| 54 | } |
| 55 | |