Function computeUpdateCountersRanges

performance-tests/trace-parser.mjs:764–824

(events, mainThread)

 * Matches DevTools decimal labels: kb = bytes/1000, Mb = bytes/1e6.
 */
export function computeUpdateCountersRanges(events, mainThread) {
  const list = events.filter(
    e =>
      e.name === 'UpdateCounters' &&
      e.ph === 'I' &&
      e.args?.data &&
      (!mainThread || (e.pid === mainThread.pid && e.tid === mainThread.tid)),
  );

  if (list.length === 0) {
    return null;
  }

  let jsHeapMin = Infinity;
  let jsHeapMax = -Infinity;
  let documentsMin = Infinity;
  let documentsMax = -Infinity;
  let nodesMin = Infinity;
  let nodesMax = -Infinity;
  let listenersMin = Infinity;
  let listenersMax = -Infinity;

  for (const e of list) {
    const d = e.args.data;

    if (typeof d.jsHeapSizeUsed === 'number') {
      jsHeapMin = Math.min(jsHeapMin, d.jsHeapSizeUsed);
      jsHeapMax = Math.max(jsHeapMax, d.jsHeapSizeUsed);
    }
    if (typeof d.documents === 'number') {
      documentsMin = Math.min(documentsMin, d.documents);
      documentsMax = Math.max(documentsMax, d.documents);
    }
    if (typeof d.nodes === 'number') {
      nodesMin = Math.min(nodesMin, d.nodes);
      nodesMax = Math.max(nodesMax, d.nodes);
    }
    if (typeof d.jsEventListeners === 'number') {
      listenersMin = Math.min(listenersMin, d.jsEventListeners);
      listenersMax = Math.max(listenersMax, d.jsEventListeners);
    }
  }

  if (!Number.isFinite(jsHeapMin)) {
    return null;
  }

  return {
    sampleCount: list.length,
    jsHeapMinBytes: jsHeapMin,
    jsHeapMaxBytes: jsHeapMax,
    jsHeapMinLabel: formatHeapMinBytesLabel(jsHeapMin),
    jsHeapMaxLabel: formatHeapMaxBytesLabel(jsHeapMax),
    documentsMin: Number.isFinite(documentsMin) ? documentsMin : null,
    documentsMax: Number.isFinite(documentsMax) ? documentsMax : null,
    nodesMin: Number.isFinite(nodesMin) ? nodesMin : null,
    nodesMax: Number.isFinite(nodesMax) ? nodesMax : null,
    listenersMin: Number.isFinite(listenersMin) ? listenersMin : null,