add missing file

Author: cscheid

src/core/performance/perfetto-utils.ts

@@ -0,0 +1,89 @@
+/*
+ * perfetto-utils.ts
+ *
+ * Some utility functions for working with Perfetto traces.
+ *
+ * Copyright (C) 2025 Posit Software, PBC
+ */
+
+type PerfettoTraceEvent = {
+  ph: "B" | "E" | "X" | "I" | "C" | "S" | "F";
+  ts: number;
+  dur?: number;
+  name?: string;
+  cat?: string;
+};
+
+export function convertCombinedLuaProfileToCSV(
+  profileName: string,
+) {
+  const combinedInformation = JSON.parse(
+    Deno.readTextFileSync(profileName),
+  );
+
+  const lines: string[] = ["filter,name,time"];
+
+  Object.entries(combinedInformation).forEach(([cat, data]) => {
+    // deno-lint-ignore no-explicit-any
+    Object.entries(data as any).forEach(([fileName, time]) => {
+      lines.push(`${cat},${fileName},${time}`);
+    });
+  });
+  Deno.writeTextFileSync(profileName, lines.join("\n"));
+}
+
+export function appendToCombinedLuaProfile(
+  inputFileName: string,
+  individualTraceFile: string,
+  combinedInformationFile: string,
+) {
+  const individualTrace = JSON.parse(
+    Deno.readTextFileSync(individualTraceFile),
+  );
+  let combinedInformation: Record<string, Record<string, number>> = {};
+  try {
+    combinedInformation = JSON.parse(
+      Deno.readTextFileSync(combinedInformationFile),
+    );
+  } catch (_) {
+    // ignore
+  }
+
+  const earliestBEventByCat: Record<string, number> = {};
+  const latestEEventByCat: Record<string, number> = {};
+
+  individualTrace.traceEvents.forEach((event: Record<string, unknown>) => {
+    const e = event as PerfettoTraceEvent;
+    if (e.cat && (e.ph === "B")) {
+      if (
+        earliestBEventByCat[e.cat] === undefined ||
+        e.ts < earliestBEventByCat[e.cat]
+      ) {
+        earliestBEventByCat[e.cat] = e.ts;
+      }
+    } else if (e.cat && (e.ph === "E")) {
+      if (
+        latestEEventByCat[e.cat] === undefined ||
+        e.ts > latestEEventByCat[e.cat]
+      ) {
+        latestEEventByCat[e.cat] = e.ts;
+      }
+    }
+  });
+
+  Object.entries(earliestBEventByCat).forEach(([cat, start]) => {
+    if (latestEEventByCat[cat] === undefined) {
+      console.error("No end event for category", cat);
+      return;
+    }
+
+    if (!combinedInformation[cat]) {
+      combinedInformation[cat] = {};
+    }
+    combinedInformation[cat][inputFileName] = latestEEventByCat[cat] - start;
+  });
+  Deno.writeTextFileSync(
+    combinedInformationFile,
+    JSON.stringify(combinedInformation, null, 2),
+  );
+}