gecko-dev/toolkit/components/telemetry/tests/browser/browser_TelemetryGC.js

"use strict";

/*
 *********************************************************************************
 *                                                                               *
 *                                  WARNING                                      *
 *                                                                               *
 * If you adjust any of the constants here (slice limit, number of keys, etc.)   *
 * make sure to update the JSON schema at:                                       *
 * https://github.com/mozilla-services/mozilla-pipeline-schemas/blob/master/     *
 * telemetry/main.schema.json                                                    *
 *                                                                               *
 * Otherwise, pings may be dropped by the telemetry backend!                     *
 *                                                                               *
 ********************************************************************************/

const { GCTelemetry } = ChromeUtils.import(
  "resource://gre/modules/GCTelemetry.jsm"
);

const MAX_PHASES = 73;

function check(entries) {
  const FIELDS = ["random", "worst"];

  // Check that all FIELDS are in |entries|.
  for (let f of FIELDS) {
    ok(f in entries, `${f} found in entries`);
  }

  // Check that only FIELDS are in |entries|.
  for (let k of Object.keys(entries)) {
    ok(FIELDS.includes(k), `${k} found in FIELDS`);
  }

  for (let f of FIELDS) {
    ok(Array.isArray(entries[f]), "have an array of GCs");

    ok(entries[f].length <= 2, "not too many GCs");

    for (let gc of entries[f]) {
      isnot(gc, null, "GC is non-null");

      ok(Object.keys(gc).length <= 24, "number of keys in GC is not too large");

      // Sanity check the GC data.
      ok("status" in gc, "status field present");
      is(gc.status, "completed", "status field correct");
      ok("total_time" in gc, "total_time field present");
      ok("max_pause" in gc, "max_pause field present");

      ok("slices_list" in gc, "slices_list field present");
      ok(Array.isArray(gc.slices_list), "slices_list is an array");
      ok(!!gc.slices_list.length, "slices_list array non-empty");
      ok(gc.slices_list.length <= 4, "slices_list array is not too long");

      ok("totals" in gc, "totals field present");
      is(typeof gc.totals, "object", "totals is an object");
      ok(
        Object.keys(gc.totals).length <= MAX_PHASES,
        "totals array is not too long"
      );

      // Make sure we don't skip any big objects.
      for (let key in gc) {
        if (key != "slices_list" && key != "totals") {
          isnot(
            typeof gc[key],
            "object",
            `${key} property should be primitive`
          );
        }
      }

      let phases = new Set();

      for (let slice of gc.slices_list) {
        ok(Object.keys(slice).length <= 12, "slice is not too large");

        ok("pause" in slice, "pause field present in slice");
        ok("reason" in slice, "reason field present in slice");
        ok("times" in slice, "times field present in slice");

        // Make sure we don't skip any big objects.
        for (let key in slice) {
          if (key != "times") {
            isnot(
              typeof slice[key],
              "object",
              `${key} property should be primitive`
            );
          }
        }

        ok(Object.keys(slice.times).length <= 65, "no more than 65 phases");

        for (let phase in slice.times) {
          phases.add(phase);
          is(
            typeof slice.times[phase],
            "number",
            `${phase} property should be a number`
          );
        }
      }

      let totals = gc.totals;
      // Make sure we don't skip any big objects.
      for (let phase in totals) {
        is(
          typeof totals[phase],
          "number",
          `${phase} property should be a number`
        );
      }

      for (let phase of phases) {
        ok(phase in totals, `${phase} is in totals`);
      }
    }
  }
}

add_task(async function test() {
  let multiprocess = Services.appinfo.browserTabsRemoteAutostart;

  // Set these prefs to ensure that we get measurements.
  await SpecialPowers.pushPrefEnv({
    set: [["javascript.options.mem.notify", true]],
  });

  if (multiprocess) {
    await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
      const { GCTelemetry } = ChromeUtils.import(
        "resource://gre/modules/GCTelemetry.jsm"
      );

      /*
       * Don't shut down GC telemetry if it was already running before the test!
       * Note: We need to use a multiline comment here since this code is turned into a data: URI.
       */
      content.shutdown = GCTelemetry.init();
      content.GCTelemetry = GCTelemetry;
    });
  }

  // Don't shut down GC telemetry if it was already running before the test!
  let shutdown = GCTelemetry.init();

  let localPromise = new Promise(resolve => {
    function obs() {
      Services.obs.removeObserver(obs, "garbage-collection-statistics");
      resolve();
    }
    Services.obs.addObserver(obs, "garbage-collection-statistics");
  });

  let remotePromise;
  if (multiprocess) {
    remotePromise = new Promise(resolve => {
      function obs() {
        Services.ppmm.removeMessageListener("Telemetry:GCStatistics", obs);
        resolve();
      }
      Services.ppmm.addMessageListener("Telemetry:GCStatistics", obs);
    });
  } else {
    remotePromise = Promise.resolve();
  }

  // Make sure we have a GC to work with in both processes.
  Cu.forceGC();
  if (multiprocess) {
    await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
      Cu.forceGC();
    });
  }

  info("Waiting for GCs");

  await Promise.all([localPromise, remotePromise]);

  let localEntries = GCTelemetry.entries("main", true);
  let remoteEntries = multiprocess
    ? GCTelemetry.entries("content", true)
    : localEntries;

  check(localEntries);
  check(remoteEntries);

  localEntries = GCTelemetry.entries("main", false);
  remoteEntries = multiprocess
    ? GCTelemetry.entries("content", false)
    : localEntries;

  is(localEntries.random.length, 0, "no random GCs after reset");
  is(localEntries.worst.length, 0, "no worst GCs after reset");

  is(remoteEntries.random.length, 0, "no random GCs after reset");
  is(remoteEntries.worst.length, 0, "no worst GCs after reset");

  if (shutdown) {
    GCTelemetry.shutdown();
  }

  if (multiprocess) {
    await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
      if (content.shutdown) {
        content.GCTelemetry.shutdown();
      }
    });
  }
});