Fix unbounded memory usage

ios/Classes/CachingStreamHandler.swift

@@ -15,12 +15,12 @@ class CachingStreamHandler<T>: NSObject, FlutterStreamHandler {
     private let cacheSemaphore = DispatchSemaphore(value: 1)
 
     func add(_ taskId: String, _ value: T) {
-        cacheSemaphore.wait()
-        cache[taskId] = value
-        cacheSemaphore.signal()
-
         if let sink = eventSink {
             sink(value)
+        } else {
+            cacheSemaphore.wait()
+            cache[taskId] = value
+            cacheSemaphore.signal()
         }
     }
 
@@ -35,6 +35,7 @@ class CachingStreamHandler<T>: NSObject, FlutterStreamHandler {
         for cacheEntry in cache {
             events(cacheEntry.value)
         }
+        cache = [:]
         cacheSemaphore.signal()
 
         self.eventSink = events

ios/Classes/SwiftFlutterUploaderPlugin.swift

@@ -47,14 +47,6 @@ public class SwiftFlutterUploaderPlugin: NSObject, FlutterPlugin {
         self.resultHandler = CachingStreamHandler()
         resultEventChannel.setStreamHandler(resultHandler)
 
-        // load entries from database into StreamHandlers, which cache the values.
-        let resultDatabase = UploadResultDatabase.shared
-        for map in resultDatabase.results {
-            if let taskId = map[Key.taskId] as? String {
-                resultHandler.add(taskId, map)
-            }
-        }
-
         self.taskQueue = DispatchQueue(label: "chillisource.flutter_uploader.dispatch.queue")
         super.init()
 
@@ -66,7 +58,6 @@ public class SwiftFlutterUploaderPlugin: NSObject, FlutterPlugin {
         case "setBackgroundHandler":
             setBackgroundHandler(call, result)
         case "clearUploads":
-            UploadResultDatabase.shared.clear()
             resultHandler.clear()
             progressHandler.clear()
 

ios/Classes/URLSessionUploader.swift

@@ -120,8 +120,6 @@ class URLSessionUploader: NSObject {
 
         delegates.append(EngineManager())
 
-        delegates.append(UploadResultDatabase.shared)
-
         self.queue.name = "chillisource.flutter_uploader.queue"
 
         let mainBundle = Bundle.main