101 lines
2.5 KiB
Swift
101 lines
2.5 KiB
Swift
//
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// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
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//
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@objc
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public class AnyLRUCache: NSObject {
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private let backingCache: LRUCache<NSObject, NSObject>
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@objc
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public init(maxSize: Int) {
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backingCache = LRUCache(maxSize: maxSize)
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}
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@objc
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public func get(key: NSObject) -> NSObject? {
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return self.backingCache.get(key: key)
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}
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@objc
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public func set(key: NSObject, value: NSObject) {
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self.backingCache.set(key: key, value: value)
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}
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@objc
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public func clear() {
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self.backingCache.clear()
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}
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}
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// A simple LRU cache bounded by the number of entries.
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public class LRUCache<KeyType: Hashable & Equatable, ValueType> {
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private var cacheMap: [KeyType: ValueType] = [:]
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private var cacheOrder: [KeyType] = []
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private let maxSize: Int
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@objc
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public init(maxSize: Int) {
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self.maxSize = maxSize
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NotificationCenter.default.addObserver(self,
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selector: #selector(didReceiveMemoryWarning),
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name: UIApplication.didReceiveMemoryWarningNotification,
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object: nil)
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NotificationCenter.default.addObserver(self,
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selector: #selector(didEnterBackground),
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name: NSNotification.Name.OWSApplicationDidEnterBackground,
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object: nil)
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}
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deinit {
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NotificationCenter.default.removeObserver(self)
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}
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@objc func didEnterBackground() {
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clear()
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}
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@objc func didReceiveMemoryWarning() {
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clear()
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}
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private func updateCacheOrder(key: KeyType) {
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cacheOrder = cacheOrder.filter { $0 != key }
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cacheOrder.append(key)
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}
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public func get(key: KeyType) -> ValueType? {
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guard let value = cacheMap[key] else {
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// Miss
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return nil
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}
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// Hit
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updateCacheOrder(key: key)
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return value
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}
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public func set(key: KeyType, value: ValueType) {
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cacheMap[key] = value
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updateCacheOrder(key: key)
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while cacheOrder.count > maxSize {
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guard let staleKey = cacheOrder.first else {
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return
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}
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cacheOrder.removeFirst()
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cacheMap.removeValue(forKey: staleKey)
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}
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}
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@objc
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public func clear() {
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cacheMap.removeAll()
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cacheOrder.removeAll()
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}
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}
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