fix(tracing): Trim idle transaction spans if they exceed final timeout (#8653)

Author: AbhiPrasad

packages/core/src/tracing/idletransaction.ts

@@ -158,15 +158,22 @@ export class IdleTransaction extends Transaction {
             logger.log('[Tracing] cancelling span since transaction ended early', JSON.stringify(span, undefined, 2));
         }
 
-        const keepSpan = span.startTimestamp < endTimestamp;
-        if (!keepSpan) {
-          __DEBUG_BUILD__ &&
-            logger.log(
-              '[Tracing] discarding Span since it happened after Transaction was finished',
-              JSON.stringify(span, undefined, 2),
-            );
+        const spanStartedBeforeTransactionFinish = span.startTimestamp < endTimestamp;
+
+        // Add a delta with idle timeout so that we prevent false positives
+        const timeoutWithMarginOfError = (this._finalTimeout + this._idleTimeout) / 1000;
+        const spanEndedBeforeFinalTimeout = span.endTimestamp - this.startTimestamp < timeoutWithMarginOfError;
+
+        if (__DEBUG_BUILD__) {
+          const stringifiedSpan = JSON.stringify(span, undefined, 2);
+          if (!spanStartedBeforeTransactionFinish) {
+            logger.log('[Tracing] discarding Span since it happened after Transaction was finished', stringifiedSpan);
+          } else if (!spanEndedBeforeFinalTimeout) {
+            logger.log('[Tracing] discarding Span since it finished after Transaction final timeout', stringifiedSpan);
+          }
         }
-        return keepSpan;
+
+        return spanStartedBeforeTransactionFinish && spanEndedBeforeFinalTimeout;
       });
 
       __DEBUG_BUILD__ && logger.log('[Tracing] flushing IdleTransaction');

packages/tracing/test/idletransaction.test.ts

@@ -202,6 +202,19 @@ describe('IdleTransaction', () => {
     }
   });
 
+  it('filters out spans that exceed final timeout', () => {
+    const transaction = new IdleTransaction({ name: 'foo', startTimestamp: 1234 }, hub, 1000, 3000);
+    transaction.initSpanRecorder(10);
+
+    const span = transaction.startChild({ startTimestamp: transaction.startTimestamp + 2 });
+    span.finish(span.startTimestamp + 10 + 30 + 1);
+
+    transaction.finish(transaction.startTimestamp + 50);
+
+    expect(transaction.spanRecorder).toBeDefined();
+    expect(transaction.spanRecorder!.spans).toHaveLength(1);
+  });
+
   it('should record dropped transactions', async () => {
     const transaction = new IdleTransaction({ name: 'foo', startTimestamp: 1234, sampled: false }, hub, 1000);