iCloud sync when eventual consistency takes a long time

- When creating a host, it may disappear immediately even if the host was
synchronized successfully to iCloud. This was because the data may take longer
than usual to then show up in queries. This way before we clear up local data,
we check what the timestamp is for that scenario and give some margin to become
consistent on the other side.

Settings/Network/BKiCloudSyncHandler.m

@@ -143,18 +143,19 @@ - (void)checkForReachabilityAndSync:(NSNotification *)notification
   }
 }
 
-- (void)deleteAllItems
+- (void)deleteSyncScheduledItems
 {
+
   NSMutableArray *deletedHosts = [NSMutableArray arrayWithArray:[syncItems objectForKey:BKiCloudSyncDeletedHosts]];
+  [syncItems removeObjectForKey:BKiCloudSyncDeletedHosts];
   for (CKRecordID *recordId in deletedHosts) {
     [self deleteRecord:recordId ofType:BKiCloudRecordTypeHosts];
   }
-  [syncItems removeObjectForKey:BKiCloudSyncDeletedHosts];
 }
 
 - (void)syncFromiCloud
 {
-  [self deleteAllItems];
+  [self deleteSyncScheduledItems];
   CKDatabase *database = [[CKContainer containerWithIdentifier:BKiCloudContainerIdentifier] privateCloudDatabase];
   CKQuery *hostQuery = [[CKQuery alloc] initWithRecordType:@"BKHost" predicate:[NSPredicate predicateWithValue:YES]];
   [database performQuery:hostQuery
@@ -174,18 +175,23 @@ - (void)deleteRecord:(CKRecordID *)recordId ofType:(BKiCloudRecordType)recordTyp
   if (recordType == BKiCloudRecordTypeHosts) {
     key = BKiCloudSyncDeletedHosts;
   }
-
+  NSLog(@"Host %@ scheduled for deletion", recordId);
   CKDatabase *database = [[CKContainer containerWithIdentifier:BKiCloudContainerIdentifier] privateCloudDatabase];
   [database deleteRecordWithID:recordId
 	     completionHandler:^(CKRecordID *_Nullable recordID, NSError *_Nullable error) {
 	       if (error) {
+      NSLog(@"Deletion failed. Syncing later %@", recordId);
+
 		 NSMutableArray *deletedItems = [NSMutableArray array];
 		 if ([syncItems objectForKey:key]) {
 		   deletedItems = [NSMutableArray arrayWithArray:[syncItems objectForKey:key]];
 		 }
 		 [deletedItems addObject:recordId];
 		 [syncItems setObject:deletedItems forKey:key];
-	       }
+           [BKiCloudSyncHandler saveSyncItems];
+         } else {
+           NSLog(@"Deleted %@", recordId);
+         }
 	     }];
 }
 
@@ -195,9 +201,15 @@ - (void)createNewHost:(BKHosts *)host
 {
   CKDatabase *database = [[CKContainer containerWithIdentifier:BKiCloudContainerIdentifier] privateCloudDatabase];
   CKRecord *hostRecord = [BKHosts recordFromHost:host];
+  NSLog(@"Host %@ scheduled for creation", host.host);
   [database saveRecord:hostRecord
      completionHandler:^(CKRecord *_Nullable record, NSError *_Nullable error) {
-       [BKHosts updateHost:host.host withiCloudId:record.recordID andLastModifiedTime:record.modificationDate];
+    if (error == nil) {
+      NSLog(@"Created host %@, record %@", host.host, record.recordID);
+      [BKHosts updateHost:host.host withiCloudId:record.recordID andLastModifiedTime:record.modificationDate];
+    } else {
+      NSLog(@"Host %@ upload to iCloud failed: %@", host.host, error);
+    }
      }];
 }
 
@@ -208,10 +220,10 @@ - (void)mergeHosts:(NSArray *)hostRecords
     if ([hostRecord valueForKey:@"host"]) {
       NSString *host = [hostRecord valueForKey:@"host"];
       BKHosts *hosts = [BKHosts withiCloudId:hostRecord.recordID];
-      //If host exists in system, Find which is new
+      //If host exists in system, Find which is newer
       if (hosts) {
         if ([hosts.lastModifiedTime compare:hostRecord.modificationDate] == NSOrderedDescending) {
-          //Local is new...Update iCloud to Local values
+          //Local is newer...Update iCloud to Local values
           CKDatabase *database = [[CKContainer containerWithIdentifier:BKiCloudContainerIdentifier] privateCloudDatabase];
           CKRecord *udpatedRecord = [BKHosts recordFromHost:hosts];
           CKModifyRecordsOperation *updateOperation = [[CKModifyRecordsOperation alloc] initWithRecordsToSave:@[ udpatedRecord ] recordIDsToDelete:nil];
@@ -223,12 +235,12 @@ - (void)mergeHosts:(NSArray *)hostRecords
           };
           [database addOperation:updateOperation];
         } else {
-          //iCloud is new, update local to reflect iCLoud values
+          //iCloud is newer, update local to reflect iCLoud values
           [self saveHostRecord:hostRecord withHost:host];
         }
       } else {
         //If hosts is new, see if it exists
-        //Check if name exists, if YES, Mark as conflict else, add to local
+        //Check if iCloud host exists locally by name. If YES, Mark as conflict. Otherwise store local copy.
         BKHosts *existingHost = [BKHosts withHost:host];
         if (existingHost) {
           [BKHosts markHost:host forRecord:hostRecord withConflict:YES];
@@ -244,19 +256,25 @@ - (void)mergeHosts:(NSArray *)hostRecords
     if (hosts.iCloudRecordId == nil && (!hosts.iCloudConflictDetected || !hosts.iCloudConflictDetected.boolValue)) {
       [self createNewHost:hosts];
     } else {
-      NSLog(@"Conflict detected Hence not saving to iCloud");
       //Find items deleted from iCloud
       if ((!hosts.iCloudConflictDetected || !hosts.iCloudConflictDetected.boolValue)) {
         NSPredicate *deletedPredicate = [NSPredicate predicateWithFormat:@"SELF.recordID.recordName contains %@", hosts.iCloudRecordId.recordName];
         NSArray *filteredAray = [hostRecords filteredArrayUsingPredicate:deletedPredicate];
-        if (filteredAray.count <= 0) {
+        NSTimeInterval timeDifference = [[NSDate date] timeIntervalSinceDate:hosts.lastModifiedTime];
+        // The DB is eventually consistent, so we cannot mark a host for deletion that may have just been created.
+        if (fabs(timeDifference) > 60.0 && filteredAray.count <= 0) {
+          NSLog(@"Host not found on iCloud, scheduled for deletion: %@, record: %@", hosts, hosts.iCloudRecordId);
           [itemsDeletedFromiCloud addObject:hosts];
         }
+      } else {
+        NSLog(@"Conflict detected Hence not saving to iCloud");
+        continue;
       }
     }
   }
   if (itemsDeletedFromiCloud.count > 0) {
     [[BKHosts all] removeObjectsInArray:itemsDeletedFromiCloud];
+    [BKHosts saveHosts];
   }