sindresorhus / Defaults

💾 Swifty and modern UserDefaults
https://swiftpackageindex.com/sindresorhus/Defaults/documentation/defaults
MIT License
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Cache bridge deserialization #138

Open BeyondiOS opened 1 year ago

BeyondiOS commented 1 year ago
struct User3: Codable, Defaults.Serializable {
    let name: String
    let age: String
}

extension Defaults.Keys {
    static let user3 = Key<User3>("user3", default: .init(name: "Hello", age: "24"))
}
...
    func test2() {
        print(Defaults[.user3])
        print(Defaults[.user3])
    }
...

The above code will call bridge.deserialize twice. If user3 is an array and there are many attributes of the User3 type, will it affect performance?

Would it be better to cache the data after Defaults[.user3] is executed once?

extension Defaults.Serializable {
    ....
    static func toValue(_ anyObject: Any) -> Self? {
        // Return directly if `anyObject` can cast to Value, since it means `Value` is a natively supported type.
        if
            isNativelySupportedType,
            let anyObject = anyObject as? Self
        {
            return anyObject
        } else if let value = bridge.deserialize(anyObject as? Serializable) {
            return value as? Self
        }

        return nil
    }
        ....
sindresorhus commented 1 year ago

It can affect performance yes, if the data is large and you're calling it many times in a loop. But in common cases, it should not be a problem. You should not store huge amounts of data in UserDefaults anyway.

I do think we should look into caching the deserialized data using an LRU cache.

Actually, the first thing we could do is to simply cache all calls for 5 seconds. That way, we can make sure that we don't waste time on deserializing things that are called in a loop.