add auto clear object strategy

Author: tclyhaiqing-xu

Source/Shared/Configuration/DiskConfig.swift

@@ -6,6 +6,10 @@ public struct DiskConfig {
   /// Expiry date that will be applied by default for every added object
   /// if it's not overridden in the add(key: object: expiry: completion:) method
   public let expiry: Expiry
+
+  /// ExpirationMode that will be applied  for every added object
+  public let expirationMode: ExpirationMode
+
   /// Maximum size of the disk cache storage (in bytes)
   public let maxSize: UInt
   /// A folder to store the disk cache contents. Defaults to a prefixed directory in Caches if nil
@@ -15,11 +19,15 @@ public struct DiskConfig {
   /// Support only on iOS and tvOS.
   public let protectionType: FileProtectionType?
 
-  public init(name: String, expiry: Expiry = .never,
+  public init(name: String,
+              expiry: Expiry = .never,
+              expirationMode: ExpirationMode = .auto,
               maxSize: UInt = 0, directory: URL? = nil,
               protectionType: FileProtectionType? = nil) {
     self.name = name
     self.expiry = expiry
+    self.expirationMode  = expirationMode
+    
     self.maxSize = maxSize
     self.directory = directory
     self.protectionType = protectionType

Source/Shared/Configuration/MemoryConfig.swift

@@ -1,20 +1,27 @@
 import Foundation
 
 public struct MemoryConfig {
-  /// Expiry date that will be applied by default for every added object
-  /// if it's not overridden in the add(key: object: expiry: completion:) method
-  public let expiry: Expiry
-  /// The maximum number of objects in memory the cache should hold.
-  /// If 0, there is no count limit. The default value is 0.
-  public let countLimit: UInt
-
-  /// The maximum total cost that the cache can hold before it starts evicting objects.
-  /// If 0, there is no total cost limit. The default value is 0
-  public let totalCostLimit: UInt
-
-  public init(expiry: Expiry = .never, countLimit: UInt = 0, totalCostLimit: UInt = 0) {
-    self.expiry = expiry
-    self.countLimit = countLimit
-    self.totalCostLimit = totalCostLimit
-  }
+    /// Expiry date that will be applied by default for every added object
+    /// if it's not overridden in the add(key: object: expiry: completion:) method
+    public let expiry: Expiry
+    
+    /// ExpirationMode that will be applied  for every added object
+    public let expirationMode: ExpirationMode
+    
+    /// The maximum number of objects in memory the cache should hold.
+    /// If 0, there is no count limit. The default value is 0.
+    public let countLimit: UInt
+    
+    /// The maximum total cost that the cache can hold before it starts evicting objects.
+    /// If 0, there is no total cost limit. The default value is 0
+    public let totalCostLimit: UInt
+    
+    public init(expiry: Expiry = .never, expirationMode: ExpirationMode = .auto, countLimit: UInt = 0, totalCostLimit: UInt = 0) {
+        self.expiry = expiry
+        self.expirationMode = expirationMode
+            
+        self.countLimit = countLimit
+        self.totalCostLimit = totalCostLimit
+        
+    }
 }

Source/Shared/Storage/AsyncStorage.swift

@@ -127,3 +127,9 @@ public extension AsyncStorage {
     return storage
   }
 }
+
+public extension AsyncStorage {
+  func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    self.innerStorage.applyExpiratonMode(expirationMode)
+  }
+}

Source/Shared/Storage/DiskStorage.swift

@@ -1,4 +1,8 @@
-import Foundation
+#if canImport(UIKit)
+import UIKit
+#elseif canImport(AppKit) && !targetEnvironment(macCatalyst)
+import AppKit
+#endif
 
 /// Save objects to file on disk
 final public class DiskStorage<Key: Hashable, Value> {
@@ -17,6 +21,9 @@ final public class DiskStorage<Key: Hashable, Value> {
 
   private let transformer: Transformer<Value>
   private let hasher = Hasher.constantAccrossExecutions()
+    
+  private var didEnterBackgroundObserver: NSObjectProtocol?
+
 
   // MARK: - Initialization
   public convenience init(config: DiskConfig, fileManager: FileManager = FileManager.default, transformer: Transformer<Value>) throws {
@@ -54,6 +61,29 @@ final public class DiskStorage<Key: Hashable, Value> {
     self.fileManager = fileManager
     self.path = path
     self.transformer = transformer
+    applyExpiratonMode(self.config.expirationMode)
+  }
+    
+  public func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    if let didEnterBackgroundObserver = didEnterBackgroundObserver {
+      NotificationCenter.default.removeObserver(didEnterBackgroundObserver)
+    }
+      
+    if expirationMode == .auto {
+      didEnterBackgroundObserver =
+      NotificationCenter.default.addObserver(forName: UIApplication.didEnterBackgroundNotification,
+                                             object: nil,
+                                             queue: nil) { [weak self] _ in
+        guard let `self` = self else { return }
+        try? self.removeExpiredObjects()
+      }
+    }
+  }
+    
+  deinit {
+    if let didEnterBackgroundObserver = didEnterBackgroundObserver {
+      NotificationCenter.default.removeObserver(didEnterBackgroundObserver)
+    }
   }
 }
 

Source/Shared/Storage/HybridStorage.swift

@@ -180,3 +180,10 @@ public extension HybridStorage {
     return self.diskStorage.totalSize
   }
 }
+
+public extension HybridStorage {
+  func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    self.memoryStorage.applyExpiratonMode(expirationMode)
+    self.diskStorage.applyExpiratonMode(expirationMode)
+  }
+}

Source/Shared/Storage/MemoryStorage.swift

@@ -1,4 +1,8 @@
-import Foundation
+#if canImport(UIKit)
+import UIKit
+#elseif canImport(AppKit) && !targetEnvironment(macCatalyst)
+import AppKit
+#endif
 
 public class MemoryStorage<Key: Hashable, Value>: StorageAware {
   final class WrappedKey: NSObject {
@@ -22,11 +26,39 @@ public class MemoryStorage<Key: Hashable, Value>: StorageAware {
   fileprivate var keys = Set<Key>()
   /// Configuration
   fileprivate let config: MemoryConfig
+    
+  /// The closure to be called when the key has been removed
+  public var onRemove: ((Key) -> Void)?
+    
+  public var didEnterBackgroundObserver: NSObjectProtocol?
 
   public init(config: MemoryConfig) {
     self.config = config
     self.cache.countLimit = Int(config.countLimit)
     self.cache.totalCostLimit = Int(config.totalCostLimit)
+    applyExpiratonMode(self.config.expirationMode)
+  }
+
+  public func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    if let didEnterBackgroundObserver = didEnterBackgroundObserver {
+      NotificationCenter.default.removeObserver(didEnterBackgroundObserver)
+    }
+    if expirationMode == .auto {
+      didEnterBackgroundObserver =
+      NotificationCenter.default.addObserver(forName: UIApplication.didEnterBackgroundNotification,
+                                                       object: nil,
+                                                       queue: nil)
+      { [weak self] _ in
+        guard let `self` = self else { return }
+        self.removeExpiredObjects()
+      }
+    }
+  }
+    
+  deinit {
+    if let didEnterBackgroundObserver = didEnterBackgroundObserver {
+      NotificationCenter.default.removeObserver(didEnterBackgroundObserver)
+    }
   }
 }
 
@@ -41,8 +73,10 @@ extension MemoryStorage {
 
   public func setObject(_ object: Value, forKey key: Key, expiry: Expiry? = nil) {
     let capsule = MemoryCapsule(value: object, expiry: .date(expiry?.date ?? config.expiry.date))
-    let const = MemoryLayout.size(ofValue: capsule)
-    cache.setObject(capsule, forKey: WrappedKey(key), cost: const)
+    
+    /// MemoryLayout.size(ofValue:) return the contiguous memory footprint of the given instance , so cost is always MemoryCapsule size (8 bytes)
+    let cost = MemoryLayout.size(ofValue: capsule)
+    cache.setObject(capsule, forKey: WrappedKey(key), cost: cost)
     keys.insert(key)
   }
 
@@ -67,6 +101,7 @@ extension MemoryStorage {
   public func removeObject(forKey key: Key) {
     cache.removeObject(forKey: WrappedKey(key))
     keys.remove(key)
+    onRemove?(key)
   }
 
   public func entry(forKey key: Key) throws -> Entry<Value> {

Source/Shared/Storage/Storage.swift

@@ -123,3 +123,9 @@ public extension Storage {
     return self.hybridStorage.diskStorage.totalSize
   }
 }
+
+public extension Storage {
+  func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    self.hybridStorage.applyExpiratonMode(expirationMode)
+  }
+}

Source/Shared/Storage/SyncStorage.swift

@@ -73,3 +73,9 @@ public extension SyncStorage {
     return storage
   }
 }
+
+public extension SyncStorage {
+  func applyExpiratonMode(_ expirationMode: ExpirationMode) {
+    self.innerStorage.applyExpiratonMode(expirationMode)
+  }
+}

Tests/iOS/Tests/Storage/AsyncStorageTests.swift

@@ -62,4 +62,68 @@ final class AsyncStorageTests: XCTestCase {
 
     wait(for: [expectation], timeout: 1)
   }
+    
+    func testAutoClearAllExpiredObjectWhenApplicationEnterBackground() {
+        let expiry1: Expiry = .date(Date().addingTimeInterval(-10))
+        let expiry2: Expiry = .date(Date().addingTimeInterval(10))
+        let key1 = "item1"
+        let key2 = "item2"
+        var key1Removed = false
+        var key2Removed = false
+        storage.innerStorage.memoryStorage.onRemove = { key in
+          key1Removed = true
+          key2Removed = true
+          XCTAssertTrue(key1Removed)
+          XCTAssertTrue(key2Removed)
+        }
+            
+        storage.innerStorage.diskStorage.onRemove = { path in
+          key1Removed = true
+          key2Removed = true
+          XCTAssertTrue(key1Removed)
+          XCTAssertTrue(key2Removed)
+        }
+        
+        storage.setObject(user, forKey: key1, expiry: expiry1) { _ in
+            
+        }
+        storage.setObject(user, forKey: key2, expiry: expiry2) { _ in
+            
+        }
+        ///Device enters background
+        NotificationCenter.default.post(name: UIApplication.didEnterBackgroundNotification, object: nil)
+      }
+        
+    func testManualManageExpirationMode() {
+        storage.applyExpiratonMode(.manual)
+        let expiry1: Expiry = .date(Date().addingTimeInterval(-10))
+        let expiry2: Expiry = .date(Date().addingTimeInterval(60))
+        let key1 = "item1"
+        let key2 = "item2"
+          
+        var key1Removed = false
+        var key2Removed = false
+        storage.innerStorage.memoryStorage.onRemove = { key in
+          key1Removed = true
+          key2Removed = true
+          XCTAssertFalse(key1Removed)
+          XCTAssertFalse(key2Removed)
+        }
+          
+        storage.innerStorage.diskStorage.onRemove = { path in
+          key1Removed = true
+          key2Removed = true
+          XCTAssertFalse(key1Removed)
+          XCTAssertFalse(key2Removed)
+        }
+        
+        storage.setObject(user, forKey: key1, expiry: expiry1) { _ in
+            
+        }
+        storage.setObject(user, forKey: key2, expiry: expiry2) { _ in
+            
+        }
+        ///Device enters background
+        NotificationCenter.default.post(name: UIApplication.didEnterBackgroundNotification, object: nil)
+      }
 }

Tests/iOS/Tests/Storage/DiskStorageTests.swift

@@ -215,5 +215,37 @@ final class DiskStorageTests: XCTestCase {
     let filePath = "\(storage.path)/\(storage.makeFileName(for: key))"
     XCTAssertEqual(storage.makeFilePath(for: key), filePath)
   }
+    
+  func testAutoClearAllExpiredObjectWhenApplicationEnterBackground() {
+    let expiry1: Expiry = .date(Date().addingTimeInterval(-10))
+    let expiry2: Expiry = .date(Date().addingTimeInterval(10))
+    let key1 = "item1"
+    let key2 = "item2"
+    let filePathForKey1 = storage.makeFilePath(for: key1)
+    storage.onRemove = { key in
+      XCTAssertTrue(key == filePathForKey1)
+    }
+    try? storage.setObject(testObject, forKey: key1, expiry: expiry1)
+    try? storage.setObject(testObject, forKey: key2, expiry: expiry2)
+        ///Device enters background
+    NotificationCenter.default.post(name: UIApplication.didEnterBackgroundNotification, object: nil)
+    }
+    
+    func testManualManageExpirationMode() {
+        storage.applyExpiratonMode(.manual)
+        let expiry1: Expiry = .date(Date().addingTimeInterval(-10))
+        let expiry2: Expiry = .date(Date().addingTimeInterval(10))
+        let key1 = "item1"
+        let key2 = "item2"
+        var success = true
+        storage.onRemove = { key in
+            success = false
+            XCTAssertTrue(success)
+        }
+        try? storage.setObject(testObject, forKey: key1, expiry: expiry1)
+        try? storage.setObject(testObject, forKey: key2, expiry: expiry2)
+            ///Device enters background
+        NotificationCenter.default.post(name: UIApplication.didEnterBackgroundNotification, object: nil)
+    }
 }