Fix: Dont create transaction for unused ViewControllers

Sources/Sentry/SentryTracer.m

@@ -96,6 +96,7 @@ @implementation SentryTracer {
     dispatch_block_t _idleTimeoutBlock;
     NSMutableArray<id<SentrySpan>> *_children;
     BOOL _startTimeChanged;
+    BOOL _timeout;
     NSObject *_idleTimeoutLock;
 
 #if SENTRY_HAS_UIKIT
@@ -148,6 +149,8 @@ - (instancetype)initWithTransactionContext:(SentryTransactionContext *)transacti
     self.wasFinishCalled = NO;
     _measurements = [[NSMutableDictionary alloc] init];
     self.finishStatus = kSentrySpanStatusUndefined;
+    self.finishMustBeCalled = NO;
+    _timeout = YES;
 
     if (_configuration.timerFactory == nil) {
         _configuration.timerFactory = [[SentryNSTimerFactory alloc] init];
@@ -289,6 +292,8 @@ - (void)startDeadlineTimer
 - (void)deadlineTimerFired
 {
     SENTRY_LOG_DEBUG(@"Sentry tracer deadline fired");
+    _timeout = YES;
+
     @synchronized(self) {
         // This try to minimize a race condition with a proper call to `finishInternal`.
         if (self.isFinished) {
@@ -303,7 +308,8 @@ - (void)deadlineTimerFired
         }
     }
 
-    [self finishWithStatus:kSentrySpanStatusDeadlineExceeded];
+    _finishStatus = kSentrySpanStatusDeadlineExceeded;
+    [self finishInternal];
 }
 
 - (void)cancelDeadlineTimer
@@ -581,6 +587,12 @@ - (void)finishInternal
         }
     }];
 
+    if (self.finishMustBeCalled && !self.wasFinishCalled) {
+        SENTRY_LOG_DEBUG(
+            @"Not capturing transaction because finish was not called before timing out.");
+        return;
+    }
+
     @synchronized(_children) {
         if (_configuration.idleTimeout > 0.0 && _children.count == 0) {
             SENTRY_LOG_DEBUG(@"Was waiting for timeout for UI event trace but it had no children, "

Sources/Sentry/SentryUIViewControllerPerformanceTracker.m

@@ -125,6 +125,12 @@ - (void)createTransaction:(UIViewController *)controller
         SENTRY_LOG_DEBUG(@"Started span with id %@ to track view controller %@.",
             spanId.sentrySpanIdString, name);
 
+        id<SentrySpan> vcSpan = [self.tracker getSpan:spanId];
+        if ([vcSpan isKindOfClass:SentryTracer.class]) {
+            SentryTracer *vcTracer = (SentryTracer *)vcSpan;
+            vcTracer.finishMustBeCalled = YES;
+        }
+
         // Use the target itself to store the spanId to avoid using a global mapper.
         objc_setAssociatedObject(controller, &SENTRY_UI_PERFORMANCE_TRACKER_SPAN_ID, spanId,
             OBJC_ASSOCIATION_RETAIN_NONATOMIC);

Sources/Sentry/include/SentryTracer.h

@@ -43,6 +43,13 @@ static const NSTimeInterval SENTRY_AUTO_TRANSACTION_MAX_DURATION = 500.0;
 
 @property (nullable, nonatomic, copy) BOOL (^shouldIgnoreWaitForChildrenCallback)(id<SentrySpan>);
 
+/**
+ * This flag indicates whether the trace should be captured when the timeout triggers.
+ * If Yes, this tracer will be discarced in case the timeout triggers.
+ * Default @c NO
+ */
+@property (nonatomic) BOOL finishMustBeCalled;
+
 /**
  * All the spans that where created with this tracer but rootSpan.
  */

Tests/SentryTests/Transaction/SentryTracerTests.swift

@@ -1292,6 +1292,15 @@ class SentryTracerTests: XCTestCase {
     }
 #endif
 
+    func testFinishShouldBeCalled_Timeout_NotCaptured() {
+        fixture.dispatchQueue.blockBeforeMainBlock = { true }
+
+        let sut = fixture.getSut()
+        sut.finishMustBeCalled = true
+        fixture.timerFactory.fire()
+        assertTransactionNotCaptured(sut)
+    }
+
     @available(*, deprecated)
     func testSetExtra_ForwardsToSetData() {
         let sut = fixture.getSut()