logging: add more logging to understand cache step (#289)

debug init process

Sources/Statsig/Diagnostics/InitializeMarker.swift

@@ -2,9 +2,11 @@ class InitializeMarkers {
     let key = "initialize"
     let network: NetworkMarker
     let process: ProcessMarker
+    let readCache: ReadCacheMarker
 
     init(_ recorder: MarkerAtomicDict) {
         self.network = NetworkMarker(recorder, key: key)
         self.process = ProcessMarker(recorder, key: key)
+        self.readCache = ReadCacheMarker(recorder, key: key)
     }
 }

Sources/Statsig/Diagnostics/ReadCacheMarker.swift

@@ -0,0 +1,24 @@
+class ReadCacheMarker: MarkerBase {
+    convenience init(_ recorder: MarkerAtomicDict) {
+        self.init(recorder, context: .initialize, markerKey: "load_cache")
+    }
+
+    let step = "load_cache"
+
+    convenience init(_ recorder: MarkerAtomicDict, key: String) {
+        self.init(recorder, context: .initialize, markerKey: key)
+    }
+
+    func start() {
+        super.start([
+            "step": step,
+        ])
+    }
+
+    func end(success: Bool) {
+        super.end([
+            "step": step,
+            "success": success,
+        ])
+    }
+}

Sources/Statsig/InternalStore.swift

@@ -392,9 +392,11 @@ class InternalStore {
     let storeQueue = DispatchQueue(label: storeQueueLabel, qos: .userInitiated, attributes: .concurrent)
 
     init(_ sdkKey: String, _ user: StatsigUser, options: StatsigOptions) {
+        Diagnostics.mark?.initialize.readCache.start()
         cache = StatsigValuesCache(sdkKey, user, options)
         localOverrides = StatsigUserDefaults.defaults.dictionarySafe(forKey: InternalStore.localOverridesKey)
         ?? InternalStore.getEmptyOverrides()
+        Diagnostics.mark?.initialize.readCache.end(success: true)
     }
 
     func getLastUpdateTime(user: StatsigUser) -> UInt64 {