report first steady ping after initial resources loaded

Author: vzaidman

front_end/core/host/RNPerfMetrics.ts

@@ -29,6 +29,7 @@ class RNPerfMetrics {
   #telemetryInfo: Object = {};
   // map of panel location to panel name
   #currentPanels = new Map<PanelLocation, string>();
+  #initialResourcesLoadedInfo: null|{count: number} = null;
 
   isEnabled(): boolean {
     return globalThis.enableReactNativePerfMetrics === true;
@@ -186,13 +187,10 @@ class RNPerfMetrics {
     });
   }
 
-  allInitialDeveloperResourcesLoadingFinished(count: number): void {
-    this.sendEvent({
-      eventName: 'DeveloperResource.AllInitialLoadingFinished',
-      params: {
-        count,
-      },
-    });
+  initialResourcesLoaded(count: number): void {
+    // eslint-disable-next-line no-console
+    console.info('Initial %d resources are loaded after %sms', count, performance.now());
+    this.#initialResourcesLoadedInfo = {count};
   }
 
   fuseboxSetClientMetadataStarted(): void {
@@ -215,10 +213,21 @@ class RNPerfMetrics {
     }
   }
 
-  firstSteadyPing(): void {
+  tryReportingSteadyPing(): boolean {
+    if (this.#initialResourcesLoadedInfo === null) {
+      return false;
+    }
+
+    // eslint-disable-next-line no-console
+    console.info('Startup time is %s', performance.now());
+
     this.sendEvent({
-      eventName: 'FirstSteadyPing',
+      eventName: 'FirstSteadyPingAfterInitialResourcesLoaded',
+      params: {
+        bundleCount: this.#initialResourcesLoadedInfo.count,
+      }
     });
+    return true;
   }
 
   heapSnapshotStarted(): void {
@@ -432,13 +441,6 @@ export type DeveloperResourceLoadingFinishedEvent = Readonly<{
   }>,
 }>;
 
-export type AllInitialDeveloperResourcesLoadingFinished = Readonly<{
-  eventName: 'DeveloperResource.AllInitialLoadingFinished',
-  params: Readonly<{
-    count: number,
-  }>,
-}>;
-
 export type FuseboxSetClientMetadataStartedEvent = Readonly<{
   eventName: 'FuseboxSetClientMetadataStarted',
 }>;
@@ -511,16 +513,19 @@ export type StackTraceFrameUrlResolutionFailed = Readonly<{
   }>,
 }>;
 
-export type FirstSteadyPing = Readonly<{
-  eventName: 'FirstSteadyPing',
+export type FirstSteadyPingAfterInitialResourcesLoaded = Readonly<{
+  eventName: 'FirstSteadyPingAfterInitialResourcesLoaded',
+  params: Readonly<{
+    bundleCount: number,
+  }>,
 }>;
 
 export type ReactNativeChromeDevToolsEvent =
     EntrypointLoadingStartedEvent|EntrypointLoadingFinishedEvent|DebuggerReadyEvent|BrowserVisibilityChangeEvent|
     BrowserErrorEvent|RemoteDebuggingTerminatedEvent|DeveloperResourceLoadingStartedEvent|
-    DeveloperResourceLoadingFinishedEvent|AllInitialDeveloperResourcesLoadingFinished|FuseboxSetClientMetadataStartedEvent|
+    DeveloperResourceLoadingFinishedEvent|FuseboxSetClientMetadataStartedEvent|
     FuseboxSetClientMetadataFinishedEvent|MemoryPanelActionStartedEvent|MemoryPanelActionFinishedEvent|
     PanelShownEvent|PanelClosedEvent|StackTraceSymbolicationSucceeded|StackTraceSymbolicationFailed|
-    StackTraceFrameUrlResolutionSucceeded|StackTraceFrameUrlResolutionFailed|FirstSteadyPing;
+    StackTraceFrameUrlResolutionSucceeded|StackTraceFrameUrlResolutionFailed|FirstSteadyPingAfterInitialResourcesLoaded;
 
 export type DecoratedReactNativeChromeDevToolsEvent = CommonEventFields&ReactNativeChromeDevToolsEvent;

front_end/core/sdk/PageResourceLoader.ts

@@ -82,7 +82,7 @@ interface LoadQueueEntry {
  */
 export class PageResourceLoader extends Common.ObjectWrapper.ObjectWrapper<EventTypes> {
   #currentlyLoading = 0;
-  #reportedAllInitialResourcesLoaded = false;
+  #reportedInitialResourcesLoaded = false;
   #currentlyLoadingPerTarget = new Map<Protocol.Target.TargetID|'main', number>();
   readonly #maxConcurrentLoads: number;
   #pageResources = new Map<string, PageResource>();
@@ -356,13 +356,15 @@ export class PageResourceLoader extends Common.ObjectWrapper.ObjectWrapper<Event
     Host.rnPerfMetrics.developerResourceLoadingFinished(
         parsedURL, Host.UserMetrics.DeveloperResourceLoaded.FALLBACK_AFTER_FAILURE, result);
 
-    // Will be decreased to 0 right after this function in "releaseLoadSlot".
-    // Tracking it here so it is next to the rest of "rnPerfMetrics" in this file.
-    const allResourcesLoaded = this.#currentlyLoading === 1;
-    if (allResourcesLoaded && !this.#reportedAllInitialResourcesLoaded) {
-      Host.rnPerfMetrics.allInitialDeveloperResourcesLoadingFinished(this.getNumberOfResources().resources);
-      this.#reportedAllInitialResourcesLoaded = true;
-    }
+    // Wait for several seconds to ensure no new resources were loaded
+    // by the resources that just finished loading
+    setTimeout(() => {
+      const allResourcesLoaded = this.#currentlyLoading === 0;
+      if (allResourcesLoaded && !this.#reportedInitialResourcesLoaded) {
+        Host.rnPerfMetrics.initialResourcesLoaded(this.getNumberOfResources().resources);
+        this.#reportedInitialResourcesLoaded = true;
+      }
+    }, 3000);
 
     return result;
   }

front_end/entrypoints/inspector_main/InspectorMain.ts

@@ -68,6 +68,11 @@ export class InspectorMainImpl implements Common.Runnable.Runnable {
     }
 
     const startMs = Date.now();
+    // Issues and waits for a response from a simple "Debugger.enable" when the debugger is enabled
+    // which noops and retuns a truthy response:
+    // https://github.com/facebook/hermes/blob/ae235193b9329867afaa2838183cbffa34aca098/API/hermes/cdp/DebuggerDomainAgent.cpp#L224-L228
+    // https://github.com/facebook/hermes/blob/ae235193b9329867afaa2838183cbffa34aca098/API/hermes/cdp/DebuggerDomainAgent.cpp#L183-L185
+    // It measures the round trip time for CDP message after being queued in the CDP queue in each direction.
     await debuggerModel.syncDebuggerId();
     const ping = Date.now() - startMs;
 
@@ -77,10 +82,15 @@ export class InspectorMainImpl implements Common.Runnable.Runnable {
       this.#consecutiveLowPing++;
     }
 
+    let reportedSteadyPing = false;
     if (this.#consecutiveLowPing > 1) {
-      Host.rnPerfMetrics.firstSteadyPing();
-    } else {
-      setTimeout(() => void this.#measureMainConnectionPing(debuggerModel), COOLDOWN_BETWEEN_PINGS);
+      reportedSteadyPing = Host.rnPerfMetrics.tryReportingSteadyPing();
+    }
+
+    if (!reportedSteadyPing) {
+      setTimeout(() => {
+        void this.#measureMainConnectionPing(debuggerModel);
+      }, COOLDOWN_BETWEEN_PINGS);
     }
   }