0x5a.live

for different kinds of informations and explorations.

GitHub - yysskk/MemoryCache: LRU, type-safe, thread-safe memory cache class in Swift

LRU, type-safe, thread-safe memory cache class in Swift - yysskk/MemoryCache

Visit Site

GitHub - yysskk/MemoryCache: LRU, type-safe, thread-safe memory cache class in Swift

LRU, type-safe, thread-safe memory cache class in Swift - yysskk/MemoryCache

MemoryCache

Overview

MemoryCache is a memory cache class in swift.

The MemoryCache class incorporates LRU policies, which ensure that a cache doesn’t use too much of the system’s memory. If memory is needed by other applications, it removes some items from the cache, minimizing its memory footprint.
You can add, remove, and query items with expiration in the cache from different threads without having to lock the cache yourself. ( thread-safe )
Unlike the NSCache class, the cache guarantees a type by its key. ( type-safe )

let memoryCache = MemoryCache.default // or initialize

// Defining a string (or hash) key for a dog value.
let dogKey = StringKey<Dog>("dog")

// Setting a dog value in memoryCache.
memoryCache.set(dog, for: dogKey)

// Getting a cached dog value in memoryCache.
let cachedDog = try? memoryCache.value(for: dogKey)

// Removing a cached dog value in memoryCache.
memoryCache.remove(for: dogKey)

Usage

Basic

Defining keys

let dogKey = StringKey<Dog>("dog")

Adding a Cached Value

memoryCache.set(dog, for: dogKey)

Getting a Cached Value

let dog = try? memoryCache.value(for: dogKey)

Removing Cached Values

Removes the cache of the specified key.

memoryCache.remove(for: dogKey)

Removes the cache of the specified key if it expired.

memoryCache.removeIfExpired(for: dogKey)

Removes All.

memoryCache.removeAll()

Others

Properties

/// The maximum total cost that the memoryCache can hold before it starts evicting caches.
var totalCostLimit: Int

/// The maximum number of caches the memoryCache should hold.
var countLimit: Int

/// The total cost of values in the memoryCache.
var totalCost: Int

/// The number of values in the memoryCache.
var count: Int

/// A Boolean value indicating whether the memoryCache has no values.
var isEmpty: Bool

Implement delegate

import MemoryCache

class SomeClass: NSObject, MemoryCacheDelegate {

    let memoryCache: MemoryCache
    
    init() {
        memoryCache = MemoryCache.default
        
        ...
        
        super.init()

        memoryCache.delegate = self
    }
    
    func memoryCache(_ memoryCache: MemoryCache, willEvict cache: Any) {
        // Called when an cache is about to be evicted or removed from the memoryCache.
    }
}

Expiration date

You can specify expiration date for cache. The default expiration is .never.

/// The expiration date is `.never`.
memoryCache.set(dog, for: dogKey, expiration: .never)

/// The expiration date is `.seconds("""10s""")`.
memoryCache.set(dog, for: dogKey, expiration: .seconds(10))

/// The expiration date is `.date("""TOMORROW""")`.
memoryCache.set(dog, for: dogKey, expiration: .date(Date().addingTimeInterval(60 * 60 * 24)))

/// Remove the cache of the specified key if it expired.
memoryCache.removeIfExpired(for: dogKey)