gistfile1.swift

```swift
actor GiftCache {
  private(set) var cachedGifts: [GiftId: CachedGift] = [:]
  
  // this method would be caller by other parts
  func add(gift: CachedGift) {
    cachedGifts[gift.giftId] = gift
    //...
  }
  
  func cachedGift(of giftId: GiftId) throws -> CachedGift {
    if let gift = cachedGifts[giftId] {
      return gift
    } else {
      let gift = try load(giftId) // this is a synce operation
      cachedGifts[giftId] = gift
      return gift
    }
  }
}

public class GiftManager {
  let cache = GiftCache()
  private var unsafeCachedGifts: [GiftId: CachedGift] = [:]
  
  @MainActor
  public func refreshUnsafeCache() async {
    self.unsafeCachedGifts = await cache.cachedGifts
  }
  
  public func unsafeDurationForGift(giftId: GiftId) -> TimeInterval {
    dispatchPrecondition(condition: .onQueue(.main))
    Task {
      _ = try? await cache.cachedGift(of: giftId)
      await refreshUnsafeCache()
    }
    let gift = unsafeCachedGifts[giftId]
    return // ...
  }
}
```