Function computeProfileCallScripting

performance-tests/trace-parser.mjs:547–746

(events, mainPid, mainTid, windowMinUs, windowMaxUs)

// any visible scripting events. These samples would be synthesized as ProfileCall
// events by DevTools SamplesIntegrator and contribute scripting time.
function computeProfileCallScripting(events, mainPid, mainTid, windowMinUs, windowMaxUs) {
  // Find Profile event (gives start time for CPU profiling)
  const profileEvent = events.find(e => e.name === 'Profile' && e.pid === mainPid);

  if (!profileEvent || !profileEvent.args?.data?.startTime) {
    return 0;
  }

  const cpuStartTime = profileEvent.args.data.startTime; // μs absolute

  // Merge all ProfileChunk events into a single timeline
  const chunks = events
    .filter(e => e.name === 'ProfileChunk' && e.pid === mainPid)
    .sort((a, b) => a.ts - b.ts);

  if (chunks.length === 0) {
    return 0;
  }

  const allSamples = [];
  const allDeltas = [];
  const allNodes = new Map();

  for (const chunk of chunks) {
    const d = chunk.args?.data;

    if (!d) {
      continue;
    }
    if (d.cpuProfile?.samples) {
      allSamples.push(...d.cpuProfile.samples);
    }
    if (d.timeDeltas) {
      allDeltas.push(...d.timeDeltas);
    }
    if (d.cpuProfile?.nodes) {
      for (const n of d.cpuProfile.nodes) {
        allNodes.set(n.id, n);
      }
    }
  }

  if (allSamples.length === 0) {
    return 0;
  }

  // Compute absolute timestamps for each sample
  let t = cpuStartTime;
  const timestamps = allDeltas.map((d) => {
    t += d;

    return t;
  });

  // Idle function names (ProfileCall events for these are filtered out)
  const IDLE_NAMES = new Set(['(idle)', '(program)', '(root)', '']);

  // Helper: merge overlapping intervals for correct binary search