core(network-analyzer): fix num of roundtrips for h3 estimates (#15102)

GoogleChrome · May 24, 2023 · d0233f5 · d0233f5
1 parent e06430b
commit d0233f5
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/core/computed/metrics/time-to-first-byte.js b/core/computed/metrics/time-to-first-byte.js
@@ -26,7 +26,8 @@ class TimeToFirstByte extends NavigationMetric {
 
     // Estimate when the connection is not warm.
     // TTFB = DNS + (SSL)? + TCP handshake + 1 RT for request + server response time
-    let roundTrips = 3;
+    let roundTrips = 2;
+    if (!mainResource.protocol.startsWith('h3')) roundTrips += 1; // TCP
     if (mainResource.parsedURL.scheme === 'https') roundTrips += 1;
     const estimatedTTFB = data.settings.throttling.rttMs * roundTrips + observedResponseTime;
 

diff --git a/core/lib/dependency-graph/simulator/network-analyzer.js b/core/lib/dependency-graph/simulator/network-analyzer.js
@@ -194,7 +194,8 @@ class NetworkAnalyzer {
 
       // Assume everything before sendStart was just DNS + (SSL)? + TCP handshake
       // 1 RT for DNS, 1 RT (maybe) for SSL, 1 RT for TCP
-      let roundTrips = 2;
+      let roundTrips = 1;
+      if (!record.protocol.startsWith('h3')) roundTrips += 1; // TCP
       if (record.parsedURL.scheme === 'https') roundTrips += 1;
       return timing.sendStart / roundTrips;
     });
@@ -227,8 +228,8 @@ class NetworkAnalyzer {
       // TTFB = DNS + (SSL)? + TCP handshake + 1 RT for request + server response time
       if (!connectionReused) {
         roundTrips += 1; // DNS
+        if (!record.protocol.startsWith('h3')) roundTrips += 1; // TCP
         if (record.parsedURL.scheme === 'https') roundTrips += 1; // SSL
-        roundTrips += 1; // TCP handshake
       }
 
       // subtract out our estimated server response time