firefox/toolkit/components/backgroundhangmonitor/BHRTelemetryService.sys.mjs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  TelemetryController: "resource://gre/modules/TelemetryController.sys.mjs",
});

export function BHRTelemetryService() {
  // Allow tests to get access to this object to verify it works correctly.
  this.wrappedJSObject = this;

  Services.obs.addObserver(this, "profile-before-change");
  Services.obs.addObserver(this, "bhr-thread-hang");
  Services.obs.addObserver(this, "idle-daily");

  this.resetPayload();
}

BHRTelemetryService.prototype = Object.freeze({
  classID: Components.ID("{117c8cdf-69e6-4f31-a439-b8a654c67127}"),
  QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),

  TRANSMIT_HANG_COUNT: 50,

  resetPayload() {
    this.startTime = +new Date();
    this.payload = {
      modules: [],
      hangs: [],
    };
    this.clearPermahangFile = false;
  },

  recordHang({
    duration,
    thread,
    runnableName,
    process,
    stack,
    remoteType,
    modules,
    annotations,
    wasPersisted,
  }) {
    if (!Services.telemetry.canRecordExtended) {
      return;
    }

    // Create a mapping from module indicies in the original nsIHangDetails
    // object to this.payload.modules indicies.
    let moduleIdxs = modules.map(module => {
      let idx = this.payload.modules.findIndex(m => {
        return m[0] === module[0] && m[1] === module[1];
      });
      if (idx === -1) {
        idx = this.payload.modules.length;
        this.payload.modules.push(module);
      }
      return idx;
    });

    // Native stack frames are [modIdx, offset] arrays. If we have a valid
    // module index, we want to map it to the this.payload.modules array.
    for (let i = 0; i < stack.length; ++i) {
      if (Array.isArray(stack[i]) && stack[i][0] !== -1) {
        stack[i][0] = moduleIdxs[stack[i][0]];
      } else if (typeof stack[i] == "string") {
        // This is just a precaution - we don't currently know of sensitive
        // URLs being included in label frames' dynamic strings which we
        // include here, but this is just an added guard. Here we strip any
        // string with a :// in it that isn't a chrome:// or resource://
        // URL. This is not completely robust, but we are already trying to
        // protect against this by only including dynamic strings from the
        // opt-in AUTO_PROFILER_..._NONSENSITIVE macros.
        let match = /[^\s]+:\/\/.*/.exec(stack[i]);
        if (
          match &&
          !match[0].startsWith("chrome://") &&
          !match[0].startsWith("resource://")
        ) {
          stack[i] = stack[i].replace(match[0], "(excluded)");
        }
      }
    }

    // Create the hang object to record in the payload.
    this.payload.hangs.push({
      duration,
      thread,
      runnableName,
      process,
      remoteType,
      annotations,
      stack,
    });

    if (wasPersisted) {
      this.clearPermahangFile = true;
    }

    // If we have collected enough hangs, we can submit the hangs we have
    // collected to telemetry.
    if (this.payload.hangs.length > this.TRANSMIT_HANG_COUNT) {
      this.submit();
    }
  },

  submit() {
    if (this.clearPermahangFile) {
      // NB: This is async but it is called from an Observer callback.
      IOUtils.remove(
        PathUtils.join(PathUtils.profileDir, "last_permahang.bin")
      );
    }

    if (!Services.telemetry.canRecordExtended) {
      return;
    }

    // NOTE: We check a separate bhrPing.enabled pref here. This pref is unset
    // when running tests so that we run as much of BHR as possible (to catch
    // errors) while avoiding timeouts caused by invoking `pingsender` during
    // testing.
    if (
      Services.prefs.getBoolPref("toolkit.telemetry.bhrPing.enabled", false) &&
      this.payload.hangs.length
    ) {
      this.payload.timeSinceLastPing = new Date() - this.startTime;
      lazy.TelemetryController.submitExternalPing("bhr", this.payload, {
        addEnvironment: true,
      });

      Glean.hangs.modules.set(this.payload.modules);
      let gleanHangs = this.payload.hangs.map(
        ({ stack, duration, ...restOfHang }) => ({
          stack: stack.map(frame =>
            typeof frame == "string"
              ? { frame }
              : { module: frame[0], frame: frame[1] }
          ),
          duration: Math.round(duration),
          ...restOfHang,
        })
      );
      Glean.hangs.reports.set(gleanHangs);
      GleanPings.hangReport.submit();
    }
    this.resetPayload();
  },

  shutdown() {
    Services.obs.removeObserver(this, "profile-before-change");
    Services.obs.removeObserver(this, "bhr-thread-hang");
    Services.obs.removeObserver(this, "idle-daily");
    this.submit();
  },

  observe(aSubject, aTopic) {
    switch (aTopic) {
      case "profile-after-change":
        this.resetPayload();
        break;
      case "bhr-thread-hang":
        this.recordHang(aSubject.QueryInterface(Ci.nsIHangDetails));
        break;
      case "profile-before-change":
        this.shutdown();
        break;
      case "idle-daily":
        this.submit();
        break;
    }
  },
});