test(performance): stabilize Xtream benchmark startup (#1304)

* test(performance): stabilize Xtream benchmark startup

* test(performance): bound cancellation clock skew

apps/electron-backend-e2e/src/performance/xtream-benchmark-iteration-support.ts

@@ -50,6 +50,14 @@ export interface SeedXtreamExistingPortalOptions {
 export async function prearmXtreamDatabaseWorker(
     app: LaunchedElectronApp
 ): Promise<void> {
+    // Main owns schema creation but loads the renderer first. Fence that
+    // startup promise before the independent worker opens the fresh database.
+    const downloads = await app.mainWindow.evaluate(() =>
+        window.electron.downloadsGetList()
+    );
+    if (!Array.isArray(downloads)) {
+        throw new Error('xtream-main-database-readiness-invalid');
+    }
     const playlists = await app.mainWindow.evaluate(() =>
         window.electron.dbGetAppPlaylists()
     );

apps/electron-backend-e2e/src/performance/xtream-iteration-assembler.spec.ts

@@ -173,6 +173,60 @@ describe('Xtream raw iteration assembler', () => {
         );
     });
 
+    it('accepts sub-millisecond skew between renderer and main cancellation clocks', () => {
+        const input = createXtreamAssemblerFixture(
+            XTREAM_SCENARIO_ID.CANCEL_IMPORT
+        );
+        const workerTerminal = input.mainCapture.cancelTimeline.find(
+            ({ type }) => type === 'db-cancel-terminal-received'
+        );
+        assert.ok(workerTerminal);
+        const rendererTerminalEpochMs = workerTerminal.epochMs - 0.1;
+        assert.ok(
+            rendererTerminalEpochMs >
+                Number(input.rendererCapture.probe.cancellationClickEpochMs)
+        );
+
+        assert.doesNotThrow(() =>
+            assembleXtreamRawIteration({
+                ...input,
+                rendererCapture: {
+                    ...input.rendererCapture,
+                    probe: {
+                        ...input.rendererCapture.probe,
+                        dbCancellationTerminalEpochMs: rendererTerminalEpochMs,
+                    },
+                },
+            })
+        );
+    });
+
+    it('rejects a cancellation terminal that substantially predates the main receipt', () => {
+        const input = createXtreamAssemblerFixture(
+            XTREAM_SCENARIO_ID.CANCEL_IMPORT
+        );
+        const workerTerminal = input.mainCapture.cancelTimeline.find(
+            ({ type }) => type === 'db-cancel-terminal-received'
+        );
+        assert.ok(workerTerminal);
+
+        assert.throws(
+            () =>
+                assembleXtreamRawIteration({
+                    ...input,
+                    rendererCapture: {
+                        ...input.rendererCapture,
+                        probe: {
+                            ...input.rendererCapture.probe,
+                            dbCancellationTerminalEpochMs:
+                                workerTerminal.epochMs - 2,
+                        },
+                    },
+                }),
+            /xtream-iteration-assembly-invalid/
+        );
+    });
+
     it('accepts main observing a network cancel response after the next renderer IPC starts', () => {
         const input = createXtreamAssemblerFixture(
             XTREAM_SCENARIO_ID.CANCEL_IMPORT

apps/electron-backend-e2e/src/performance/xtream-iteration-assembly-scenarios.ts

@@ -26,6 +26,8 @@ import {
     type XtreamUiActionSample,
 } from './xtream-ui-action-probe';
 
+const CANCELLATION_CLOCK_SKEW_TOLERANCE_MS = 1;
+
 export interface XtreamScenarioAssembly {
     readonly backgroundMetrics: {
         readonly actionLatencyMs: number;
@@ -264,6 +266,8 @@ function cancellationEvidence(
     const preload = ipcPair(input.phaseCapture.ipcSpans, 'dbCancelOperation');
     const authoritative = request.responseEpochMs;
     const painted = requireNumber(renderer.uiPaintedEpochMs);
+    // Renderer and main sample independent clocks, so allow their correlated
+    // terminal timestamps to invert only within the known sub-millisecond skew.
     if (
         !dispatch ||
         !receipt ||
@@ -271,7 +275,8 @@ function cancellationEvidence(
         dispatch.type !== 'db-cancel-dispatched' ||
         receipt.type !== 'db-cancel-received' ||
         workerTerminal.type !== 'db-cancel-terminal-received' ||
-        renderer.dbCancellationTerminalEpochMs < workerTerminal.epochMs ||
+        renderer.dbCancellationTerminalEpochMs <
+            workerTerminal.epochMs - CANCELLATION_CLOCK_SKEW_TOLERANCE_MS ||
         renderer.dbCancellationTerminalEpochMs > painted ||
         authoritative > painted
     ) {

apps/electron-backend-e2e/src/performance/xtream-scenario-driver-wiring.spec.ts

@@ -145,7 +145,14 @@ describe('Xtream scenario driver source wiring', () => {
             support,
             /export async function prearmXtreamDatabaseWorker/
         );
-        assert.match(support, /window\.electron\.dbGetAppPlaylists\(\)/);
+        const mainDatabaseReady = support.indexOf(
+            'window.electron.downloadsGetList()'
+        );
+        const workerPrearm = support.indexOf(
+            'window.electron.dbGetAppPlaylists()'
+        );
+        assert.ok(mainDatabaseReady >= 0);
+        assert.ok(workerPrearm > mainDatabaseReady);
         assert.ok(install >= 0);
         assert.ok(prearm > install);
         assert.ok(captureOptions > prearm);