fix: remove lazy initializations for thread safety (#422)

Remove lazy initializations for thread safety.

- refactor to complete prop settings after init
- add synchronization when delayed initialization is required.

Author: jaeopt

DemoObjCApp/DemoObjcApp.xcodeproj/project.pbxproj

@@ -435,7 +435,7 @@
 		6EF7496721E40467008B22A0 /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1240;
+				LastUpgradeCheck = 1250;
 				ORGANIZATIONNAME = Optimizely;
 				TargetAttributes = {
 					6EF7498D21E404BB008B22A0 = {

DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjciOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjctvOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

DemoSwiftApp/DemoSwiftApp.xcodeproj/project.pbxproj

@@ -555,7 +555,7 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 1230;
-				LastUpgradeCheck = 1240;
+				LastUpgradeCheck = 1250;
 				ORGANIZATIONNAME = Optimizely;
 				TargetAttributes = {
 					252D7DEC21C8800800134A7A = {

DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftiOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwifttvOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftwatchOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

OptimizelySwiftSDK.xcodeproj/project.pbxproj

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-iOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-macOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-tvOS.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1240"
+   LastUpgradeVersion = "1250"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-watchOS.xcscheme

@@ -20,8 +20,12 @@ open class DefaultDatafileHandler: OPTDatafileHandler {
     // endpoint used to get the datafile.  This is settable after you create a OptimizelyClient instance.
     public var endPointStringFormat = "https://cdn.optimizely.com/datafiles/%@.json"
 
-    // lazy load the logger from the logger factory.
-    lazy var logger = OPTLoggerFactory.getLogger()
+    // thread-safe lazy logger load (after HandlerRegisterService ready)
+    private var loggerInstance: OPTLogger?
+    var logger: OPTLogger {
+        return OPTLoggerFactory.getLoggerThreadSafe(&loggerInstance)
+    }
+        
     // the timers for all sdk keys are atomic to allow for thread access.
     var timers = AtomicProperty(property: [String: (timer: Timer?, interval: Int)]())
 

Sources/Customization/DefaultDatafileHandler.swift

@@ -37,7 +37,12 @@ open class DefaultEventDispatcher: BackgroundingCallbacks, OPTEventDispatcher {
         static let maxFailureCount = 3
     }
 
-    lazy var logger = OPTLoggerFactory.getLogger()
+    // thread-safe lazy logger load (after HandlerRegisterService ready)
+    private var loggerInstance: OPTLogger?
+    var logger: OPTLogger {
+        return OPTLoggerFactory.getLoggerThreadSafe(&loggerInstance)
+    }
+
     // for dispatching events
     let queueLock = DispatchQueue(label: "DefaultEventDispatcherQueue")
     // using a datastore queue with a backing file

Sources/Customization/DefaultEventDispatcher.swift

@@ -77,11 +77,31 @@ extension OPTLogger {
 }
 
 @objc public class OPTLoggerFactory: NSObject {
+    
     class func getLogger() -> OPTLogger {
         if let logger = HandlerRegistryService.shared.injectLogger() {
             return logger
         }
 
         return DefaultLogger()
     }
+    
+    // thread-safe lazy logger load (after HandlerRegisterService ready)
+    // - "lazy var" is not thread-safe
+    // - call this thread-safe version for types that can be initialized before (for customiziation) or at the same time with OptimizelyClient (so HandlerRegisterService is not ready yet).
+    // - DefaultDatafileHandler, DefaultEventDispatcher, DefaultDecisionService, DefaultBucketer
+
+    static let lock = DispatchQueue(label: "logger")
+    
+    class func getLoggerThreadSafe(_ instance: inout OPTLogger?) -> OPTLogger {
+        var result: OPTLogger?
+        lock.sync {
+            if instance == nil {
+                instance = OPTLoggerFactory.getLogger()
+            }
+            result = instance!
+        }
+        return result!
+    }
+    
 }

Sources/Customization/Protocols/OPTLogger.swift

@@ -18,97 +18,111 @@ import Foundation
 
 class ProjectConfig {
 
-    var project: Project!
-    
-    lazy var logger = OPTLoggerFactory.getLogger()
+    var project: Project! {
+        didSet {
+            updateProjectDependentProps()
+        }
+    }
+    let logger = OPTLoggerFactory.getLogger()
 
     // local runtime forcedVariations [UserId: [ExperimentId: VariationId]]
     // NOTE: experiment.forcedVariations use [ExperimentKey: VariationKey] instead of ids
-    
     var whitelistUsers = AtomicProperty(property: [String: [String: String]]())
 
-    lazy var experimentKeyMap: [String: Experiment] = {
-        var map = [String: Experiment]()
-        allExperiments.forEach { exp in
-            map[exp.key] = exp
-        }
-        return map
-    }()
-    
-    lazy var experimentIdMap: [String: Experiment] = {
-        var map = [String: Experiment]()
-        allExperiments.forEach { map[$0.id] = $0 }
-        return map
-    }()
-    
-    lazy var experimentFeatureMap: [String: [String]] = {
-        var experimentFeatureMap = [String: [String]]()
-        project.featureFlags.forEach { (ff) in
-            ff.experimentIds.forEach {
-                if var arr = experimentFeatureMap[$0] {
-                    arr.append(ff.id)
-                    experimentFeatureMap[$0] = arr
-                } else {
-                    experimentFeatureMap[$0] = [ff.id]
-                }
-            }
-        }
-        return experimentFeatureMap
-    }()
-    
-    lazy var eventKeyMap: [String: Event] = {
-        var eventKeyMap = [String: Event]()
-        project.events.forEach { eventKeyMap[$0.key] = $0 }
-        return eventKeyMap
-    }()
-    
-    lazy var attributeKeyMap: [String: Attribute] = {
-        var map = [String: Attribute]()
-        project.attributes.forEach { map[$0.key] = $0 }
-        return map
-    }()
-    
-    lazy var featureFlagKeyMap: [String: FeatureFlag] = {
-        var map = [String: FeatureFlag]()
-        project.featureFlags.forEach { map[$0.key] = $0 }
-        return map
-    }()
-    
-    lazy var featureFlagKeys: [String] = {
-        return project.featureFlags.map { $0.key }
-    }()
-
-    lazy var rolloutIdMap: [String: Rollout] = {
-        var map = [String: Rollout]()
-        project.rollouts.forEach { map[$0.id] = $0 }
-        return map
-    }()
-    
-    lazy var allExperiments: [Experiment] = {
-        return project.experiments + project.groups.map { $0.experiments }.flatMap { $0 }
-    }()
+    var experimentKeyMap = [String: Experiment]()
+    var experimentIdMap = [String: Experiment]()
+    var experimentFeatureMap = [String: [String]]()
+    var eventKeyMap = [String: Event]()
+    var attributeKeyMap = [String: Attribute]()
+    var featureFlagKeyMap = [String: FeatureFlag]()
+    var featureFlagKeys = [String]()
+    var rolloutIdMap = [String: Rollout]()
+    var allExperiments = [Experiment]()
 
     // MARK: - Init
 
     init(datafile: Data) throws {
+        var project: Project
         do {
-            self.project = try JSONDecoder().decode(Project.self, from: datafile)
-            
-            ProjectConfig.observer.update(project: project)
+            project = try JSONDecoder().decode(Project.self, from: datafile)
         } catch {
             throw OptimizelyError.dataFileInvalid
         }
 
-        if !isValidVersion(version: self.project.version) {
-            throw OptimizelyError.dataFileVersionInvalid(self.project.version)
+        if !isValidVersion(version: project.version) {
+            throw OptimizelyError.dataFileVersionInvalid(project.version)
         }
+
+        defer { self.project = project }  // deferred-init will call "didSet"
+        ProjectConfig.observer.update(project: project)
     }
 
     convenience init(datafile: String) throws {
         try self.init(datafile: Data(datafile.utf8))
     }
 
     init() {}
+    
+    func updateProjectDependentProps() {
+        self.allExperiments = project.experiments + project.groups.map { $0.experiments }.flatMap { $0 }
+        
+        self.experimentKeyMap = {
+            var map = [String: Experiment]()
+            allExperiments.forEach { exp in
+                map[exp.key] = exp
+            }
+            return map
+        }()
+        
+        self.experimentIdMap = {
+            var map = [String: Experiment]()
+            allExperiments.forEach { map[$0.id] = $0 }
+            return map
+        }()
+        
+        self.experimentFeatureMap = {
+            var experimentFeatureMap = [String: [String]]()
+            project.featureFlags.forEach { (ff) in
+                ff.experimentIds.forEach {
+                    if var arr = experimentFeatureMap[$0] {
+                        arr.append(ff.id)
+                        experimentFeatureMap[$0] = arr
+                    } else {
+                        experimentFeatureMap[$0] = [ff.id]
+                    }
+                }
+            }
+            return experimentFeatureMap
+        }()
+        
+        self.eventKeyMap = {
+            var eventKeyMap = [String: Event]()
+            project.events.forEach { eventKeyMap[$0.key] = $0 }
+            return eventKeyMap
+        }()
+        
+        self.attributeKeyMap = {
+            var map = [String: Attribute]()
+            project.attributes.forEach { map[$0.key] = $0 }
+            return map
+        }()
+        
+        self.featureFlagKeyMap = {
+            var map = [String: FeatureFlag]()
+            project.featureFlags.forEach { map[$0.key] = $0 }
+            return map
+        }()
+        
+        self.featureFlagKeys = {
+            return project.featureFlags.map { $0.key }
+        }()
+
+        self.rolloutIdMap = {
+            var map = [String: Rollout]()
+            project.rollouts.forEach { map[$0.id] = $0 }
+            return map
+        }()
+    }
 }
 
 // MARK: - Project Change Observer

Sources/Data Model/ProjectConfig.swift

@@ -23,8 +23,13 @@ open class DataStoreFile<T>: OPTDataStore where T: Codable {
     let lock: DispatchQueue
     let async: Bool
     public let url: URL
-    lazy var logger: OPTLogger? = OPTLoggerFactory.getLogger()
-    
+
+    // thread-safe lazy logger load (after HandlerRegisterService ready)
+    private var loggerInstance: OPTLogger?
+    var logger: OPTLogger {
+        return OPTLoggerFactory.getLoggerThreadSafe(&loggerInstance)
+    }
+
     public init(storeName: String, async: Bool = true) {
         self.async = async
         dataStoreName = storeName
@@ -71,7 +76,7 @@ open class DataStoreFile<T>: OPTDataStore where T: Codable {
                 }
             } catch let e as NSError {
                 if e.code != 260 {
-                    self.logger?.e(e.localizedDescription)
+                    self.logger.e(e.localizedDescription)
                 }
             }
         }
@@ -111,7 +116,7 @@ open class DataStoreFile<T>: OPTDataStore where T: Codable {
                     }
                 }
             } catch let e {
-                self.logger?.e(e.localizedDescription)
+                self.logger.e(e.localizedDescription)
             }
         }
     }
@@ -121,7 +126,7 @@ open class DataStoreFile<T>: OPTDataStore where T: Codable {
             do {
                 try FileManager.default.removeItem(at: self.url)
             } catch let e {
-                self.logger?.e(e.localizedDescription)
+                self.logger.e(e.localizedDescription)
             }
         }
 

Sources/Implementation/Datastore/DataStoreFile.swift

@@ -25,7 +25,6 @@ public class DataStoreMemory<T>: BackgroundingCallbacks, OPTDataStore where T: C
     var data: T?
     var backupDataStore: OPTDataStore
     public enum BackingStore { case userDefaults, file }
-    lazy var logger: OPTLogger? = OPTLoggerFactory.getLogger()
 
     init(storeName: String, backupStore: BackingStore = .file) {
         dataStoreName = storeName

Sources/Implementation/Datastore/DataStoreMemory.swift

@@ -26,8 +26,13 @@ public class DataStoreUserDefaults: OPTDataStore {
     static let MAX_DS_SIZE = 1000000
     #endif
     static let dispatchQueue = DispatchQueue(label: "OPTDataStoreQueueUserDefaults")
-    lazy var logger: OPTLogger = OPTLoggerFactory.getLogger()
-    
+
+    // thread-safe lazy logger load (after HandlerRegisterService ready)
+    private var loggerInstance: OPTLogger?
+    var logger: OPTLogger {
+        return OPTLoggerFactory.getLoggerThreadSafe(&loggerInstance)
+    }
+
     public func getItem(forKey: String) -> Any? {
 
         return DataStoreUserDefaults.dispatchQueue.sync {