core(network-request): loosen lightrider timing checksum (#15330)

GoogleChrome · Aug 3, 2023 · 81389e9 · 81389e9
1 parent d4dd645
commit 81389e9
Show file tree

Hide file tree

Showing 2 changed files with 27 additions and 4 deletions.
diff --git a/core/lib/network-request.js b/core/lib/network-request.js
@@ -489,7 +489,7 @@ class NetworkRequest {
     // Bail if there was no totalTime.
     if (!totalHeader) return;
 
-    const totalMs = parseInt(totalHeader.value);
+    let totalMs = parseInt(totalHeader.value);
     const TCPMsHeader = this.responseHeaders.find(item => item.name === HEADER_TCP);
     const SSLMsHeader = this.responseHeaders.find(item => item.name === HEADER_SSL);
     const requestMsHeader = this.responseHeaders.find(item => item.name === HEADER_REQ);
@@ -502,11 +502,20 @@ class NetworkRequest {
     const requestMs = requestMsHeader ? Math.max(0, parseInt(requestMsHeader.value)) : 0;
     const responseMs = responseMsHeader ? Math.max(0, parseInt(responseMsHeader.value)) : 0;
 
-    // Bail if the timings don't add up.
-    if (TCPMs + requestMs + responseMs !== totalMs) {
+    if (Number.isNaN(TCPMs + requestMs + responseMs + totalMs)) {
       return;
     }
 
+    // If things don't add up, tweak the total a bit.
+    if (TCPMs + requestMs + responseMs !== totalMs) {
+      const delta = Math.abs(TCPMs + requestMs + responseMs - totalMs);
+      // We didn't see total being more than 5ms less than the total of the components.
+      // Allow some discrepancy in the timing, but not too much.
+      if (delta >= 25) return;
+
+      totalMs = TCPMs + requestMs + responseMs;
+    }
+
     // Bail if SSL time is > TCP time.
     if (SSLMs > TCPMs) {
       return;

diff --git a/core/test/lib/network-request-test.js b/core/test/lib/network-request-test.js
@@ -183,7 +183,7 @@ describe('NetworkRequest', () => {
       expect(record.lrStatistics).toStrictEqual(undefined);
     });
 
-    it('does nothing if header timings do not add up', () => {
+    it('accepts if header timings only kinda do not add up', () => {
       const req = getRequest();
       const tcpHeader = req.responseHeaders[1];
       expect(tcpHeader.name).toStrictEqual(NetworkRequest.HEADER_TCP);
@@ -193,6 +193,20 @@ describe('NetworkRequest', () => {
       global.isLightrider = true;
       const record = NetworkRecorder.recordsFromLogs(devtoolsLog)[0];
 
+      expect(record).toMatchObject(req);
+      expect(record.lrStatistics).not.toStrictEqual(undefined);
+    });
+
+    it('does nothing if header timings _really_ do not add up', () => {
+      const req = getRequest();
+      const tcpHeader = req.responseHeaders[1];
+      expect(tcpHeader.name).toStrictEqual(NetworkRequest.HEADER_TCP);
+      tcpHeader.value = '8000';
+
+      const devtoolsLog = networkRecordsToDevtoolsLog([req]);
+      global.isLightrider = true;
+      const record = NetworkRecorder.recordsFromLogs(devtoolsLog)[0];
+
       expect(record).toMatchObject(req);
       expect(record.lrStatistics).toStrictEqual(undefined);
     });