Feature/resilience implementation

Package.resolved

@@ -1,6 +1,24 @@
 {
   "object": {
     "pins": [
+      {
+        "package": "CircuitBreaker",
+        "repositoryURL": "https://github.com/Kitura/CircuitBreaker.git",
+        "state": {
+          "branch": null,
+          "revision": "bd4255762e48cc3748a448d197f1297a4ba705f7",
+          "version": "5.1.0"
+        }
+      },
+      {
+        "package": "LoggerAPI",
+        "repositoryURL": "https://github.com/Kitura/LoggerAPI.git",
+        "state": {
+          "branch": null,
+          "revision": "e82d34eab3f0b05391082b11ea07d3b70d2f65bb",
+          "version": "1.9.200"
+        }
+      },
       {
         "package": "PromiseKit",
         "repositoryURL": "https://github.com/mxcl/PromiseKit.git",
@@ -10,6 +28,15 @@
           "version": "6.17.0"
         }
       },
+      {
+        "package": "SQLite.swift",
+        "repositoryURL": "https://github.com/stephencelis/SQLite.swift.git",
+        "state": {
+          "branch": null,
+          "revision": "7a2e3cd27de56f6d396e84f63beefd0267b55ccb",
+          "version": "0.14.1"
+        }
+      },
       {
         "package": "swift-atomics",
         "repositoryURL": "https://github.com/apple/swift-atomics.git",
@@ -19,6 +46,15 @@
           "version": "1.0.2"
         }
       },
+      {
+        "package": "swift-log",
+        "repositoryURL": "https://github.com/apple/swift-log.git",
+        "state": {
+          "branch": null,
+          "revision": "32e8d724467f8fe623624570367e3d50c5638e46",
+          "version": "1.5.2"
+        }
+      },
       {
         "package": "SwiftyJSON",
         "repositoryURL": "https://github.com/SwiftyJSON/SwiftyJSON.git",

Package.swift

@@ -15,14 +15,16 @@ let package = Package(
             targets: ["ABSmartly"])
     ],
     dependencies: [
+        .package(url: "https://github.com/stephencelis/SQLite.swift.git", .upToNextMajor(from: "0.14.1")),
+        .package(url: "https://github.com/Kitura/CircuitBreaker.git", .upToNextMajor(from: "5.0.3")),
         .package(url: "https://github.com/apple/swift-atomics.git", .upToNextMajor(from: "1.0.2")),
         .package(url: "https://github.com/mxcl/PromiseKit.git", .upToNextMajor(from: "6.8.4")),
         .package(url: "https://github.com/SwiftyJSON/SwiftyJSON.git", .upToNextMajor(from: "4.3.0"))
     ],
     targets: [
         .target(
             name: "ABSmartly",
-            dependencies: [.product(name: "Atomics", package: "swift-atomics"), "PromiseKit", "SwiftyJSON"],
+            dependencies: [.product(name: "Atomics", package: "swift-atomics"), "PromiseKit", "SwiftyJSON", "CircuitBreaker", .product(name: "SQLite", package: "SQLite.swift")],
             path: "Sources/ABSmartly"),
         .testTarget(
             name: "ABSmartlyTests",

Sources/ABSmartly/ABSmartlyConfig.swift

@@ -7,26 +7,36 @@ public class ABSmartlyConfig {
 	var contextEventLogger: ContextEventLogger?
 	var variableParser: VariableParser?
 	var client: Client?
+	var resilienceConfig: ResilienceConfig?
 
 	public init() {
 	}
 
 	public convenience init(client: Client) {
+		print("Hello, world!")
 		self.init(
 			contextDataProvider: nil, contextEventHandler: nil, contextEventLogger: nil, variableParser: nil,
-			scheduler: nil, client: client)
+			scheduler: nil, client: client, resilienceConfig: nil)
+	}
+
+	public convenience init(client: Client, resilienceConfig: ResilienceConfig) {
+		print("Hello, world!")
+		self.init(
+			contextDataProvider: nil, contextEventHandler: nil, contextEventLogger: nil, variableParser: nil,
+			scheduler: nil, client: client, resilienceConfig: resilienceConfig)
 	}
 
 	public init(
 		contextDataProvider: ContextDataProvider?, contextEventHandler: ContextEventHandler?,
 		contextEventLogger: ContextEventLogger?,
-		variableParser: VariableParser?, scheduler: Scheduler?, client: Client?
+		variableParser: VariableParser?, scheduler: Scheduler?, client: Client?, resilienceConfig: ResilienceConfig?
 	) {
 		self.scheduler = scheduler
 		self.contextDataProvider = contextDataProvider
 		self.contextEventHandler = contextEventHandler
 		self.contextEventLogger = contextEventLogger
 		self.variableParser = variableParser
 		self.client = client
+		self.resilienceConfig = resilienceConfig
 	}
 }

Sources/ABSmartly/ABSmartlySDK.swift

@@ -15,17 +15,29 @@ public final class ABSmartlySDK {
 		scheduler = config.scheduler ?? DefaultScheduler()
 		client = config.client
 
-		if config.contextDataProvider == nil || config.contextEventHandler == nil {
-			if client == nil {
-				throw ABSmartlyError("Missing Client instance")
-			}
-
-			contextDataProvider = config.contextDataProvider ?? DefaultContextDataProvider(client: client!)
-			contextEventHandler = config.contextEventHandler ?? DefaultContextEventHandler(client: client!)
+		if config.resilienceConfig != nil {
+			contextEventHandler = ResilientContextEventHandler(
+				client: client!,
+				resilienceConfig: config.resilienceConfig!
+			)
+			contextDataProvider = ResilientContextDataProvider(
+				client: client!,
+				localCache: config.resilienceConfig!.localCache
+			)
 		} else {
-			contextDataProvider = config.contextDataProvider!
-			contextEventHandler = config.contextEventHandler!
+			if config.contextDataProvider == nil || config.contextEventHandler == nil {
+				if client == nil {
+					throw ABSmartlyError("Missing Client instance")
+				}
+
+				contextDataProvider = config.contextDataProvider ?? DefaultContextDataProvider(client: client!)
+				contextEventHandler = config.contextEventHandler ?? DefaultContextEventHandler(client: client!)
+			} else {
+				contextDataProvider = config.contextDataProvider!
+				contextEventHandler = config.contextEventHandler!
+			}
 		}
+
 	}
 
 	public func createContextWithData(config: ContextConfig, contextData: ContextData) -> Context {

Sources/ABSmartly/Attribute.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public struct Attribute: Encodable, Equatable {
+public struct Attribute: Encodable, Equatable, Decodable {
 	public let name: String
 
 	public let value: JSON

Sources/ABSmartly/CircuitBreakerHelper.swift

@@ -0,0 +1,116 @@
+//
+// Created by Hermes Waldemarin on 14/03/2023.
+//
+
+import CircuitBreaker
+import Foundation
+import PromiseKit
+
+public class CircuitBreakerHelper {
+
+	private var circuitBreaker: CircuitBreaker<Promise<Void>, Resolver<BreakerError?>>!
+	private let scheduler: Scheduler = DefaultScheduler()
+	private let timeoutLock = NSLock()
+	private let flushLock = NSLock()
+	private var flushInExecution = false
+	private var timeout: ScheduledHandle?
+	private var backoffPeriodInMilliseconds: Int?
+	private var handler: ContextEventHandler?
+
+	public init(resilienceConfig: ResilienceConfig, handler: ContextEventHandler) {
+		self.backoffPeriodInMilliseconds = resilienceConfig.backoffPeriodInMilliseconds
+		self.circuitBreaker = CircuitBreaker(
+			name: "Circuit1",
+			timeout: resilienceConfig.timeoutInMilliseconds,
+			maxFailures: resilienceConfig.failureRateThreshold,
+			command: callFunction,
+			fallback: fallback)
+		self.handler = handler
+	}
+
+	public func decorate(promise: Promise<Void>, fallBackResolver: Resolver<BreakerError?>) -> Promise<Void> {
+		return Promise<Void> { seal in
+			circuitBreaker.run(commandArgs: promise, fallbackArgs: fallBackResolver)
+			seal.fulfill(())
+		}
+	}
+
+	func callFunction(invocation: Invocation<Promise<Void>, Resolver<BreakerError?>>) {
+		let promise = invocation.commandArgs
+		let fallBackResolver = invocation.fallbackArgs
+
+		promise.done { response in
+			fallBackResolver.fulfill(nil)
+			var state = self.circuitBreaker.breakerState
+			invocation.notifySuccess()
+			if (state == .halfopen) && !self.flushInExecution {
+				self.flushInExecution = true
+				DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
+					self.timeoutLock.lock()
+					defer { self.timeoutLock.unlock() }
+					self.handler?.flushCache()
+					self.flushInExecution = false
+				}
+			}
+
+		}.catch { error in
+			var key = ""
+			var message = ""
+			if error is LocalizedError {
+				let localizedError = error as! LocalizedError
+				key = localizedError._domain
+				message = localizedError.errorDescription ?? ""
+			} else {
+				let nsError = error as! NSError
+				key = error._domain
+				nsError.code
+				message = error.localizedDescription
+			}
+
+			invocation.notifyFailure(
+				error: BreakerError(
+					key: key,
+					reason: message
+				)
+			)
+		}
+	}
+
+	private func fallback(err: BreakerError, fallBackPromise: Resolver<BreakerError?>) {
+		fallBackPromise.fulfill(err)
+		if err == .fastFail {
+			setTimeout()
+		} else {
+		}
+	}
+
+	private func clearTimeout() {
+		if timeout != nil {
+			timeoutLock.lock()
+			defer { timeoutLock.unlock() }
+
+			timeout?.cancel()
+			timeout = nil
+		}
+	}
+
+	private func setTimeout() {
+		if timeout == nil {
+			timeoutLock.lock()
+			defer { timeoutLock.unlock() }
+
+			if timeout == nil {
+				timeout = scheduler.schedule(
+					after: Double((backoffPeriodInMilliseconds! / 1000)),
+					execute: { [self] in
+						clearTimeout()
+						if circuitBreaker.breakerState != State.closed {
+							print("Resilience entering in half open state")
+							circuitBreaker.forceHalfOpen()
+						}
+
+					})
+			}
+		}
+	}
+}

Sources/ABSmartly/Context.swift

@@ -137,6 +137,7 @@ public final class Context {
 				seal.fulfill(self)
 			} else if let ready = readyPromise {
 				_ = ready.done {
+					self.handler.flushCache()
 					seal.fulfill(self)
 				}
 			}
@@ -263,15 +264,15 @@ public final class Context {
 	}
 
 	public func getAttributes() -> [String: JSON] {
-		var result: [String:JSON] = [:]
+		var result: [String: JSON] = [:]
 
 		contextLock.lock()
 		defer { contextLock.unlock() }
 
 		for attribute in attributes {
 			result[attribute.name] = attribute.value
 		}
-		return result;
+		return result
 	}
 
 	public func setAttributes(_ attributes: [String: JSON]) {

Sources/ABSmartly/DefaultContextEventHandler.swift

@@ -11,4 +11,8 @@ public class DefaultContextEventHandler: ContextEventHandler {
 	public func publish(event: PublishEvent) -> Promise<Void> {
 		return client.publish(event: event)
 	}
+
+	public func flushCache() {
+
+	}
 }

Sources/ABSmartly/Exposure.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public struct Exposure: Encodable, Equatable {
+public struct Exposure: Encodable, Equatable, Decodable {
 	public let id: Int
 	public let name: String
 	public let unit: String?

Sources/ABSmartly/GoalAchievement.swift

@@ -1,6 +1,6 @@
 import Foundation
 
-public struct GoalAchievement: Encodable, Equatable {
+public struct GoalAchievement: Encodable, Equatable, Decodable {
 	public let name: String
 	public let achievedAt: Int64
 	public let properties: [String: JSON]?

Sources/ABSmartly/MemoryCache.swift

@@ -0,0 +1,25 @@
+//
+// Created by Hermes Waldemarin on 09/03/2023.
+//
+
+import Foundation
+import PromiseKit
+import SQLite
+
+public class MemoryCache: SqlliteCache {
+	public override init() {
+	}
+
+	public override func getConnection() -> Connection {
+		do {
+			if db == nil {
+				db = try! Connection(.inMemory)
+				setupDatabase()
+			}
+		} catch {
+			print(error)
+		}
+		return self.db!
+	}
+
+}

Sources/ABSmartly/Protocols/ContextEventHandler.swift

@@ -4,4 +4,5 @@ import PromiseKit
 // sourcery: AutoMockable
 public protocol ContextEventHandler {
 	func publish(event: PublishEvent) -> Promise<Void>
+	func flushCache()
 }

Sources/ABSmartly/Protocols/LocalCache.swift

@@ -0,0 +1,13 @@
+//
+// Created by Hermes Waldemarin on 09/03/2023.
+//
+
+import Foundation
+import PromiseKit
+
+public protocol LocalCache {
+	func writePublishEvent(event: PublishEvent)
+	func retrievePublishEvents() -> [PublishEvent]
+	func writeContextData(contextData: ContextData)
+	func getContextData() -> ContextData?
+}