Merge pull request segmentio#751 from segmentio/trim-queue

Ensure queue is always < 1000 items.

Analytics/Classes/Integrations/SEGIntegrationsManager.m

@@ -417,7 +417,7 @@ + (BOOL)isTrackEvent:(NSString *)event enabledForIntegration:(NSString *)key inP
     if ([key isEqualToString:@"Segment.io"]) {
         return YES;
     }
-    
+
     if (plan[@"track"][event]) {
         if ([plan[@"track"][event][@"enabled"] boolValue]) {
             return [self isIntegration:key enabledInOptions:plan[@"track"][event][@"integrations"]];

Analytics/Classes/Internal/SEGAnalyticsUtils.h

@@ -8,6 +8,8 @@ NSString *GenerateUUIDString(void);
 // Date Utils
 NSString *iso8601FormattedString(NSDate *date);
 
+void trimQueue(NSMutableArray *array, int size);
+
 // Async Utils
 dispatch_queue_t seg_dispatch_queue_create_specific(const char *label,
                                                     dispatch_queue_attr_t _Nullable attr);

Analytics/Classes/Internal/SEGAnalyticsUtils.m

@@ -25,6 +25,20 @@
     return [dateFormatter stringFromDate:date];
 }
 
+/** trim the queue so that it contains only upto `max` number of elements. */
+void trimQueue(NSMutableArray *queue, int max)
+{
+    if (queue.count < max) {
+        return;
+    }
+
+    // Previously we didn't cap the queue. Hence there are cases where
+    // the queue may already be larger than 1000 events. Delete as many
+    // events as required to trim the queue size.
+    NSRange range = NSMakeRange(0, queue.count - max);
+    [queue removeObjectsInRange:range];
+}
+
 // Async Utils
 dispatch_queue_t
 seg_dispatch_queue_create_specific(const char *label,

Analytics/Classes/Internal/SEGSegmentIntegration.m

@@ -461,10 +461,9 @@ - (void)enqueueAction:(NSString *)action dictionary:(NSMutableDictionary *)paylo
 - (void)queuePayload:(NSDictionary *)payload
 {
     @try {
-        if (self.queue.count > 1000) {
-            // Remove the oldest element.
-            [self.queue removeObjectAtIndex:0];
-        }
+        // We only queue upto 1000 items, so trim the queue to 1000-1=999
+        // before we add a new element.
+        trimQueue(self.queue, 999);
         [self.queue addObject:payload];
         [self persistQueue];
         [self flushQueueByLength];

AnalyticsTests/AnalyticsUtilTests.swift

@@ -13,12 +13,12 @@ import Analytics
 
 class AnalyticsUtilTests: QuickSpec {
   override func spec() {
-    
+
     it("format NSDate objects to RFC 3339 complaint string") {
       let date = Date(timeIntervalSince1970: 0)
       let formattedString = iso8601FormattedString(date)
       expect(formattedString) == "1970-01-01T00:00:00.000Z"
-      
+
       var components = DateComponents()
       components.year = 1992
       components.month = 8
@@ -33,7 +33,34 @@ class AnalyticsUtilTests: QuickSpec {
       let formattedString2 = iso8601FormattedString(date2)
       expect(formattedString2) == "1992-08-06T11:32:04.335Z"
     }
-
+
+    describe("trimQueue", {
+      it("does nothing when count < max") {
+        let queue = NSMutableArray(array: [])
+        for i in 1...4 {
+          queue.add(i)
+        }
+        trimQueue(queue, 5)
+        expect(queue) == [1, 2, 3, 4]
+      }
+
+      it("trims when count > max") {
+        let queue = NSMutableArray(array: [])
+        for i in 1...10 {
+          queue.add(i)
+        }
+        trimQueue(queue, 5)
+        expect(queue) == [6, 7, 8, 9, 10]
+      }
+
+      it("does not trim when count == max") {
+        let queue = NSMutableArray(array: [])
+        for i in 1...5 {
+          queue.add(i)
+        }
+        trimQueue(queue, 5)
+        expect(queue) == [1, 2, 3, 4, 5]
+      }
+    })
   }
-
 }