Merge pull request #127 from instana/caching_fix

INSTA-5506: Remove backend trace id for cached responses
instana · Oct 25, 2024 · 73ee785 · 73ee785
2 parents 2a0b101 + 67ef08d
commit 73ee785
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Showing 3 changed files with 21 additions and 3 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - Upgrade dev packages to address security issues
 - Refactored code for autoPageDetection
 - Fix autoPageDetection to set page name for initial page load
+- Remove backendTraceId for cached responses
 
 ## 1.7.2
 

diff --git a/lib/resources/timingSerializer.ts b/lib/resources/timingSerializer.ts
@@ -1,4 +1,5 @@
 import { cachingTypes, initiatorTypes } from './consts';
+import {info} from '../debug';
 import vars from '../vars';
 
 export function serializeEntryToArray(entry: PerformanceResourceTiming) {
@@ -10,14 +11,17 @@ export function serializeEntryToArray(entry: PerformanceResourceTiming) {
 
   // When timing data is available, we can provide additional information about
   // caching and resource sizes.
+  let isCached = false;
   if (typeof entry['transferSize'] === 'number' &&
       typeof entry['encodedBodySize'] === 'number' &&
       // All this information may not be available due to the timing allow origin check.
       entry['encodedBodySize'] > 0) {
     if (entry['transferSize'] === 0) {
       result.push(cachingTypes.cached);
+      isCached = true;
     } else if (entry['transferSize'] > 0 && (entry['encodedBodySize'] === 0 || entry['transferSize'] < entry['encodedBodySize'])) {
       result.push(cachingTypes.validated);
+      isCached = true;
     } else {
       result.push(cachingTypes.fullLoad);
     }
@@ -75,13 +79,20 @@ export function serializeEntryToArray(entry: PerformanceResourceTiming) {
         const serverTiming = serverTimings[i];
         if (serverTiming['name'] === vars.serverTimingBackendTraceIdEntryName) {
           backendTraceId = serverTiming['description'];
+          if (isCached) {
+            if (DEBUG) {
+              info('Response is cached, removed backendTraceId from response');
+            }
+            backendTraceId = '';
+          }
         }
       }
     }
   } catch (e) {
     // Some browsers may not grant access to the field when the Timing-Allow-Origin
     // check fails. Better be safe than sorry here.
   }
+
   result.push(backendTraceId);
 
   if (hasValidTimings) {

diff --git a/test/unit/resources.test.js b/test/unit/resources.test.js
@@ -57,7 +57,9 @@ describe('resources/timingSerializer', () => {
         decodedBodySize: 16786,
         serverTiming: []
       };
-      expect(toHumanReadableEntry(serializeEntry(entry))).toMatchSnapshot();
+      const result = toHumanReadableEntry(serializeEntry(entry));
+      expect(result).toMatchSnapshot();
+      expect(result['backendTraceId']).toBe('');
     });
 
     it('must identify full asset retrieval', () => {
@@ -90,7 +92,9 @@ describe('resources/timingSerializer', () => {
           }
         ]
       };
-      expect(toHumanReadableEntry(serializeEntry(entry))).toMatchSnapshot();
+      const result = toHumanReadableEntry(serializeEntry(entry));
+      expect(result).toMatchSnapshot();
+      expect(result['backendTraceId']).not.toBeNull();
     });
 
     it('must identify cache validation', () => {
@@ -118,7 +122,9 @@ describe('resources/timingSerializer', () => {
         decodedBodySize: 16786,
         serverTiming: []
       };
-      expect(toHumanReadableEntry(serializeEntry(entry))).toMatchSnapshot();
+      const result = toHumanReadableEntry(serializeEntry(entry));
+      expect(result).toMatchSnapshot();
+      expect(result['backendTraceId']).toBe('');
     });
   });
 });