Merge pull request #483 from MatkovIvan/fix/wait-notification

Track sender activity only for background task
bitstadium · Dec 7, 2017 · 880181b · 880181b
2 parents dfb2a86 + f29296d
commit 880181b
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Showing 3 changed files with 52 additions and 47 deletions.
diff --git a/Classes/BITChannel.m b/Classes/BITChannel.m
@@ -33,10 +33,6 @@
 @interface BITChannel ()
 
 @property (nonatomic, weak, nullable) id appDidEnterBackgroundObserver;
-@property (nonatomic, weak, nullable) id persistenceSuccessObserver;
-@property (nonatomic, weak, nullable) id senderFinishSendingDataObserver;
-
-@property (nonatomic, nonnull) dispatch_group_t senderGroup;
 
 @end
 
@@ -61,8 +57,6 @@ - (instancetype)init {
     dispatch_queue_t serialQueue = dispatch_queue_create(BITDataItemsOperationsQueue, DISPATCH_QUEUE_SERIAL);
     _dataItemsOperations = serialQueue;
 
-    _senderGroup = dispatch_group_create();
-
     [self registerObservers];
   }
   return self;
@@ -107,26 +101,6 @@ - (void) registerObservers {
                                                               queue:NSOperationQueue.mainQueue
                                                          usingBlock:notificationBlock];
   }
-  if (nil == self.persistenceSuccessObserver) {
-    self.persistenceSuccessObserver =
-        [center addObserverForName:BITPersistenceSuccessNotification
-                            object:nil
-                             queue:nil
-                        usingBlock:^(NSNotification __unused *notification) {
-                          typeof(self) strongSelf = weakSelf;
-                          dispatch_group_enter(strongSelf.senderGroup);
-                        }];
-  }
-  if (nil == self.senderFinishSendingDataObserver) {
-    self.senderFinishSendingDataObserver =
-        [center addObserverForName:BITSenderFinishSendingDataNotification
-                            object:nil
-                             queue:nil
-                        usingBlock:^(NSNotification __unused *notification) {
-                          typeof(self) strongSelf = weakSelf;
-                          dispatch_group_leave(strongSelf.senderGroup);
-                        }];
-  }
 }
 
 - (void) unregisterObservers {
@@ -136,16 +110,6 @@ - (void) unregisterObservers {
     [center removeObserver:appDidEnterBackgroundObserver];
     self.appDidEnterBackgroundObserver = nil;
   }
-  id persistenceSuccessObserver = self.persistenceSuccessObserver;
-  if (persistenceSuccessObserver) {
-    [center removeObserver:persistenceSuccessObserver];
-    self.persistenceSuccessObserver = nil;
-  }
-  id senderFinishSendingDataObserver = self.senderFinishSendingDataObserver;
-  if (senderFinishSendingDataObserver) {
-    [center removeObserver:senderFinishSendingDataObserver];
-    self.senderFinishSendingDataObserver = nil;
-  }
 }
 
 #pragma mark - Queue management
@@ -201,37 +165,71 @@ - (void)persistDataItemQueueWithBackgroundTask:(UIApplication *)application {
     typeof(self) strongSelf = weakSelf;
     [strongSelf persistDataItemQueue:&BITTelemetryEventBuffer];
   });
-  [self createBackgroundTask:application withWaitingGroup:nil];
+  [self createBackgroundTaskWhileDataIsSending:application withWaitingGroup:nil];
 }
 
-- (void)createBackgroundTask:(UIApplication *)application withWaitingGroup:(nullable dispatch_group_t)group {
+- (void)createBackgroundTaskWhileDataIsSending:(UIApplication *)application
+                              withWaitingGroup:(nullable dispatch_group_t)group {
   if (application == nil) {
     return;
   }
+
+  // Queues needs for waiting consistently.
   NSArray *queues = @[
                       self.dataItemsOperations,           // For enqueue
                       self.persistence.persistenceQueue,  // For persist
                       dispatch_get_main_queue()           // For notification
                       ];
+
+  // Tracking for sender activity.
+  // BITPersistenceSuccessNotification - start sending
+  // BITSenderFinishSendingDataNotification - finish sending
+  __block dispatch_group_t senderGroup = dispatch_group_create();
+  __block NSInteger senderCounter = 0;
+  __block id persistenceSuccessObserver = [[NSNotificationCenter defaultCenter]
+      addObserverForName:BITPersistenceSuccessNotification
+                  object:nil
+                   queue:nil
+              usingBlock:^(__unused NSNotification *notification) {
+                dispatch_group_enter(senderGroup);
+                senderCounter++;
+                if (persistenceSuccessObserver) {
+                  [[NSNotificationCenter defaultCenter] removeObserver:persistenceSuccessObserver];
+                  persistenceSuccessObserver = nil;
+                }
+              }];
+  __block id senderFinishSendingDataObserver = [[NSNotificationCenter defaultCenter]
+      addObserverForName:BITSenderFinishSendingDataNotification
+                  object:nil
+                   queue:nil
+              usingBlock:^(__unused NSNotification *notification) {
+                if (senderCounter > 0) {
+                  dispatch_group_leave(senderGroup);
+                  senderCounter--;
+                }
+                if (senderFinishSendingDataObserver) {
+                  [[NSNotificationCenter defaultCenter] removeObserver:senderFinishSendingDataObserver];
+                  senderFinishSendingDataObserver = nil;
+                }
+              }];
+
   BITHockeyLogVerbose(@"BITChannel: Start background task");
   __block UIBackgroundTaskIdentifier backgroundTask = [application beginBackgroundTaskWithExpirationHandler:^{
     BITHockeyLogVerbose(@"BITChannel: Background task is expired");
     [application endBackgroundTask:backgroundTask];
     backgroundTask = UIBackgroundTaskInvalid;
   }];
   __block NSUInteger i = 0;
-  __weak typeof(self) weakSelf = self;
   __block __weak void (^weakWaitBlock)();
   void (^waitBlock)();
   weakWaitBlock = waitBlock = ^{
-    typeof(self) strongSelf = weakSelf;
     if (i < queues.count) {
       dispatch_queue_t queue = [queues objectAtIndex:i++];
       BITHockeyLogVerbose(@"BITChannel: Waiting queue: %@", [[NSString alloc] initWithUTF8String:dispatch_queue_get_label(queue)]);
       dispatch_async(queue, weakWaitBlock);
     } else {
       BITHockeyLogVerbose(@"BITChannel: Waiting sender");
-      dispatch_group_notify(strongSelf.senderGroup, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+      dispatch_group_notify(senderGroup, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
         if (backgroundTask != UIBackgroundTaskInvalid) {
           BITHockeyLogVerbose(@"BITChannel: Cancel background task");
           [application endBackgroundTask:backgroundTask];

diff --git a/Classes/BITChannelPrivate.h b/Classes/BITChannelPrivate.h
@@ -76,7 +76,8 @@ FOUNDATION_EXPORT NSString *const BITChannelBlockedNotification;
 /**
  *  Create background task for queues and group.
  */
-- (void)createBackgroundTask:(UIApplication *)application withWaitingGroup:(nullable dispatch_group_t)group;
+- (void)createBackgroundTaskWhileDataIsSending:(UIApplication *)application
+                              withWaitingGroup:(nullable dispatch_group_t)group;
 
 /**
  *  Adds the specified dictionary to the JSON Stream string.

diff --git a/Classes/BITMetricsManager.m b/Classes/BITMetricsManager.m
@@ -180,7 +180,9 @@ - (void)trackSessionWithState:(BITSessionState)state {
 #pragma mark Events
 
 - (void)trackEventWithName:(nonnull NSString *)eventName {
-  if (!eventName) { return; }
+  if (!eventName) {
+    return;
+  }
   if (self.disabled) {
     BITHockeyLogDebug(@"INFO: BITMetricsManager is disabled, therefore this tracking call was ignored.");
     return;
@@ -198,12 +200,16 @@ - (void)trackEventWithName:(nonnull NSString *)eventName {
   // If the app is running in the background.
   UIApplication *application = [UIApplication sharedApplication];
   if (application && application.applicationState == UIApplicationStateBackground) {
-    [self.channel createBackgroundTask:application withWaitingGroup:group];
+    [self.channel createBackgroundTaskWhileDataIsSending:application withWaitingGroup:group];
   }
 }
 
-- (void)trackEventWithName:(nonnull NSString *)eventName properties:(nullable NSDictionary<NSString *, NSString *> *)properties measurements:(nullable NSDictionary<NSString *, NSNumber *> *)measurements {
-  if (!eventName) { return; }
+- (void)trackEventWithName:(nonnull NSString *)eventName
+                properties:(nullable NSDictionary<NSString *, NSString *> *)properties
+              measurements:(nullable NSDictionary<NSString *, NSNumber *> *)measurements {
+  if (!eventName) {
+    return;
+  }
   if (self.disabled) {
     BITHockeyLogDebug(@"INFO: BITMetricsManager is disabled, therefore this tracking call was ignored.");
     return;
@@ -223,7 +229,7 @@ - (void)trackEventWithName:(nonnull NSString *)eventName properties:(nullable NS
   // If the app is running in the background.
   UIApplication *application = [UIApplication sharedApplication];
   if (application && application.applicationState == UIApplicationStateBackground) {
-    [self.channel createBackgroundTask:application withWaitingGroup:group];
+    [self.channel createBackgroundTaskWhileDataIsSending:application withWaitingGroup:group];
   }
 }