Add a maxQueueSize configuration option

Analytics/Classes/Internal/SEGAnalyticsUtils.h

@@ -8,7 +8,7 @@ NSString *GenerateUUIDString(void);
 // Date Utils
 NSString *iso8601FormattedString(NSDate *date);
 
-void trimQueue(NSMutableArray *array, int size);
+void trimQueue(NSMutableArray *array, NSUInteger size);
 
 // Async Utils
 dispatch_queue_t seg_dispatch_queue_create_specific(const char *label,

Analytics/Classes/Internal/SEGAnalyticsUtils.m

@@ -26,7 +26,7 @@
 }
 
 /** trim the queue so that it contains only upto `max` number of elements. */
-void trimQueue(NSMutableArray *queue, int max)
+void trimQueue(NSMutableArray *queue, NSUInteger max)
 {
     if (queue.count < max) {
         return;

Analytics/Classes/Internal/SEGSegmentIntegration.m

@@ -465,9 +465,8 @@ - (void)enqueueAction:(NSString *)action dictionary:(NSMutableDictionary *)paylo
 - (void)queuePayload:(NSDictionary *)payload
 {
     @try {
-        // We only queue upto 1000 items, so trim the queue to 1000-1=999
-        // before we add a new element.
-        trimQueue(self.queue, 999);
+        // Trim the queue to maxQueueSize - 1 before we add a new element.
+        trimQueue(self.queue, self.analytics.configuration.maxQueueSize - 1);
         [self.queue addObject:payload];
         [self persistQueue];
         [self flushQueueByLength];

Analytics/Classes/SEGAnalyticsConfiguration.h

@@ -69,6 +69,11 @@ typedef NSMutableURLRequest *_Nonnull (^SEGRequestFactory)(NSURL *_Nonnull);
  */
 @property (nonatomic, assign) NSTimeInterval flushInterval;
 
+/**
+ * The maximum number of items to queue before starting to drop old ones. This should be a value greater than zero, the behaviour is undefined otherwise. `1000` by default.
+ */
+@property (nonatomic, assign) NSUInteger maxQueueSize;
+
 /**
  * Whether the analytics client should automatically make a track call for application lifecycle events, such as "Application Installed", "Application Updated" and "Application Opened".
  */

Analytics/Classes/SEGAnalyticsConfiguration.m

@@ -56,6 +56,7 @@ - (instancetype)init
         self.shouldUseBluetooth = NO;
         self.flushAt = 20;
         self.flushInterval = 30;
+        self.maxQueueSize = 1000;
         _factories = [NSMutableArray array];
         Class applicationClass = NSClassFromString(@"UIApplication");
         if (applicationClass) {

AnalyticsTests/AnalyticsTests.swift

@@ -42,6 +42,7 @@ class AnalyticsTests: QuickSpec {
     it("initialized correctly") {
       expect(analytics.configuration.flushAt) == 20
       expect(analytics.configuration.flushInterval) == 30
+      expect(analytics.configuration.maxQueueSize) == 1000
       expect(analytics.configuration.writeKey) == "QUI5ydwIGeFFTa1IvCBUhxL9PyW5B0jE"
       expect(analytics.configuration.shouldUseLocationServices) == false
       expect(analytics.configuration.enableAdvertisingTracking) == true
@@ -108,6 +109,32 @@ class AnalyticsTests: QuickSpec {
       expect(testApplication.backgroundTasks.count).toEventually(equal(1))
       expect(testApplication.backgroundTasks[0].isEnded).toEventually(beFalse())
     }
+
+    it("respects maxQueueSize") {
+      let max = 72
+      config.maxQueueSize = UInt(max)
+
+      for i in 1...max * 2 {
+        analytics.track("test #\(i)")
+      }
+
+      let integration = analytics.test_integrationsManager()?.test_segmentIntegration()
+      expect(integration).notTo(beNil())
+
+      var sent = 0
+
+      analytics.flush()
+      integration?.test_dispatchBackground {
+        if let count = integration?.test_queue()?.count {
+          sent = count
+        }
+        else {
+          sent = -1
+        }
+      }
+
+      expect(sent).toEventually(be(max))
+    }
 
     it("protocol conformance should not interfere with UIApplication interface") {
       // In Xcode8/iOS10, UIApplication.h typedefs UIBackgroundTaskIdentifier as NSUInteger,

AnalyticsTests/Utils/TestUtils.swift

@@ -64,6 +64,12 @@ extension SEGSegmentIntegration {
   func test_batchRequest() -> URLSessionUploadTask? {
     return self.value(forKey: "batchRequest") as? URLSessionUploadTask
   }
+  func test_queue() -> [AnyObject]? {
+    return self.value(forKey: "queue") as? [AnyObject]
+  }
+  func test_dispatchBackground(block: @convention(block) () -> Void) {
+    self.perform(Selector(("dispatchBackground:")), with: block)
+  }
 }