Batch updates, and fixing bug where daemon would crash when accessing IMCore stuff from different threads

kordophone/Bridge/MBIMUpdateQueue.m

@@ -10,6 +10,8 @@
 #import "IMMessageItem+Encoded.h"
 #import "IMChat+Encoded.h"
 
+static const NSUInteger kUpdateItemsCullingLength = 100;
+
 @interface MBIMUpdateItem (/*INTERNAL*/)
 @property (nonatomic, assign) NSUInteger messageSequenceNumber;
 @end
@@ -18,6 +20,9 @@
     NSUInteger           _messageSequenceNumber;
     dispatch_queue_t     _accessQueue;
     NSMutableArray      *_consumers;
+    
+    // Maps message sequence number to update item
+    NSMutableDictionary<NSNumber *, MBIMUpdateItem *> *_updateItemHistory;
 }
 
 + (instancetype)sharedInstance
@@ -38,16 +43,30 @@
         _accessQueue = dispatch_queue_create("net.buzzert.MBIMUpdateQueue", DISPATCH_QUEUE_SERIAL);
         _consumers = [[NSMutableArray alloc] init];
         _messageSequenceNumber = 0;
+        _updateItemHistory = [[NSMutableDictionary alloc] init];
     }
     
     return self;
 }
 
-- (void)addConsumer:(MBIMUpdateConsumer)consumer
+- (void)addConsumer:(MBIMUpdateConsumer)consumer withLastSyncedMessageSeq:(NSInteger)messageSeq
 {
     __weak NSMutableArray *consumers = _consumers;
+    __weak NSMutableDictionary *updateItemHistory = _updateItemHistory;
     dispatch_async(_accessQueue, ^{
-        [consumers addObject:consumer];
+        if ((messageSeq >= 0) && messageSeq < self->_messageSequenceNumber) {
+            NSMutableArray *batchedUpdates = [NSMutableArray array];
+            for (NSUInteger seq = messageSeq + 1; seq <= self->_messageSequenceNumber; seq++) {
+                MBIMUpdateItem *item = [updateItemHistory objectForKey:@(seq)];
+                if (item) {
+                    [batchedUpdates addObject:item];
+                }
+            }
+            
+            consumer(batchedUpdates);
+        } else {
+            [consumers addObject:consumer];
+        }
     });
 }
 
@@ -61,16 +80,36 @@
 
 - (void)enqueueUpdateItem:(MBIMUpdateItem *)item
 {
-    _messageSequenceNumber++;
-    item.messageSequenceNumber = _messageSequenceNumber;
-    
     __weak NSMutableArray *consumers = _consumers;
+    __weak NSMutableDictionary *updateItemHistory = _updateItemHistory;
     dispatch_async(_accessQueue, ^{
+        self->_messageSequenceNumber++;
+        item.messageSequenceNumber = self->_messageSequenceNumber;
+        
         for (MBIMUpdateConsumer consumer in consumers) {
-            consumer(item);
+            consumer(@[ item ]);
         }
         
         [consumers removeAllObjects];
+        [updateItemHistory setObject:item forKey:@(item.messageSequenceNumber)];
+        
+        [self _cullUpdateItems];
+    });
+}
+
+- (void)_cullUpdateItems
+{
+    __weak NSMutableDictionary *updateItemHistory = _updateItemHistory;
+    dispatch_async(_accessQueue, ^{
+        if ([updateItemHistory count] > kUpdateItemsCullingLength) {
+            NSArray *sortedKeys = [[updateItemHistory allKeys] sortedArrayUsingSelector:@selector(compare:)];
+            for (NSValue *key in sortedKeys) {
+                [updateItemHistory removeObjectForKey:key];
+                if ([updateItemHistory count] <= kUpdateItemsCullingLength) {
+                    break;
+                }
+            }
+        }
     });
 }
 
@@ -80,7 +119,7 @@
 - (NSDictionary *)dictionaryRepresentation
 {
     NSMutableDictionary *updateDict = [NSMutableDictionary dictionary];
-    updateDict[@"messageSequenceNumber"] = @(_messageSequenceNumber);
+    updateDict[@"messageSequenceNumber"] = @(self.messageSequenceNumber);
     
     if ([self changedChat]) {
         updateDict[@"conversation"] = [[self changedChat] mbim_dictionaryRepresentation];