summaryrefslogtreecommitdiffstats
path: root/services/sync/modules/telemetry.sys.mjs
blob: 9a12be9714f7341745a5d417035a57c56a5b8586 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
/* 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/. */

// Support for Sync-and-FxA-related telemetry, which is submitted in a special-purpose
// telemetry ping called the "sync ping", documented here:
//
//  ../../../toolkit/components/telemetry/docs/data/sync-ping.rst
//
// The sync ping contains identifiers that are linked to the user's Firefox Account
// and are separate from the main telemetry client_id, so this file is also responsible
// for ensuring that we can delete those pings upon user request, by plumbing its
// identifiers into the "deletion-request" ping.

import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";

import { Log } from "resource://gre/modules/Log.sys.mjs";

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  Async: "resource://services-common/async.sys.mjs",
  AuthenticationError: "resource://services-sync/sync_auth.sys.mjs",
  FxAccounts: "resource://gre/modules/FxAccounts.sys.mjs",
  Observers: "resource://services-common/observers.sys.mjs",
  Resource: "resource://services-sync/resource.sys.mjs",
  Status: "resource://services-sync/status.sys.mjs",
  Svc: "resource://services-sync/util.sys.mjs",
  TelemetryController: "resource://gre/modules/TelemetryController.sys.mjs",
  TelemetryEnvironment: "resource://gre/modules/TelemetryEnvironment.sys.mjs",
  TelemetryUtils: "resource://gre/modules/TelemetryUtils.sys.mjs",
  Weave: "resource://services-sync/main.sys.mjs",
});

XPCOMUtils.defineLazyModuleGetters(lazy, {
  ObjectUtils: "resource://gre/modules/ObjectUtils.jsm",
});

XPCOMUtils.defineLazyGetter(lazy, "fxAccounts", () => {
  return ChromeUtils.importESModule(
    "resource://gre/modules/FxAccounts.sys.mjs"
  ).getFxAccountsSingleton();
});

import * as constants from "resource://services-sync/constants.sys.mjs";

XPCOMUtils.defineLazyGetter(
  lazy,
  "WeaveService",
  () => Cc["@mozilla.org/weave/service;1"].getService().wrappedJSObject
);
const log = Log.repository.getLogger("Sync.Telemetry");

const TOPICS = [
  // For tracking change to account/device identifiers.
  "fxaccounts:new_device_id",
  "fxaccounts:onlogout",
  "weave:service:ready",
  "weave:service:login:got-hashed-id",

  // For whole-of-sync metrics.
  "weave:service:sync:start",
  "weave:service:sync:finish",
  "weave:service:sync:error",

  // For individual engine metrics.
  "weave:engine:sync:start",
  "weave:engine:sync:finish",
  "weave:engine:sync:error",
  "weave:engine:sync:applied",
  "weave:engine:sync:step",
  "weave:engine:sync:uploaded",
  "weave:engine:validate:finish",
  "weave:engine:validate:error",

  // For ad-hoc telemetry events.
  "weave:telemetry:event",
  "weave:telemetry:histogram",
  "fxa:telemetry:event",

  "weave:telemetry:migration",
];

const PING_FORMAT_VERSION = 1;

const EMPTY_UID = "0".repeat(32);

// The set of engines we record telemetry for - any other engines are ignored.
const ENGINES = new Set([
  "addons",
  "bookmarks",
  "clients",
  "forms",
  "history",
  "passwords",
  "prefs",
  "tabs",
  "extension-storage",
  "addresses",
  "creditcards",
]);

function tryGetMonotonicTimestamp() {
  try {
    return Services.telemetry.msSinceProcessStart();
  } catch (e) {
    log.warn("Unable to get a monotonic timestamp!");
    return -1;
  }
}

function timeDeltaFrom(monotonicStartTime) {
  let now = tryGetMonotonicTimestamp();
  if (monotonicStartTime !== -1 && now !== -1) {
    return Math.round(now - monotonicStartTime);
  }
  return -1;
}

const NS_ERROR_MODULE_BASE_OFFSET = 0x45;
const NS_ERROR_MODULE_NETWORK = 6;

// A reimplementation of NS_ERROR_GET_MODULE, which surprisingly doesn't seem
// to exist anywhere in .js code in a way that can be reused.
// This is taken from DownloadCore.sys.mjs.
function NS_ERROR_GET_MODULE(code) {
  return ((code & 0x7fff0000) >> 16) - NS_ERROR_MODULE_BASE_OFFSET;
}

// Converts extra integer fields to strings, rounds floats to three
// decimal places (nanosecond precision for timings), and removes profile
// directory paths and URLs from potential error messages.
function normalizeExtraTelemetryFields(extra) {
  let result = {};
  for (let key in extra) {
    let value = extra[key];
    let type = typeof value;
    if (type == "string") {
      result[key] = ErrorSanitizer.cleanErrorMessage(value);
    } else if (type == "number") {
      result[key] = Number.isInteger(value)
        ? value.toString(10)
        : value.toFixed(3);
    } else if (type != "undefined") {
      throw new TypeError(
        `Invalid type ${type} for extra telemetry field ${key}`
      );
    }
  }
  return lazy.ObjectUtils.isEmpty(result) ? undefined : result;
}

// Keps track of the counts of individual records fate during a sync cycle
// The main reason this is a class is to keep track of reasons individual records
// failure reasons without huge memory overhead.
export class SyncedRecordsTelemetry {
  // applied    => number of items that should be applied.
  // failed     => number of items that failed in this sync.
  // newFailed  => number of items that failed for the first time in this sync.
  // reconciled => number of items that were reconciled.
  // failedReasons => {name, count} of reasons a record failed
  incomingCounts = {
    applied: 0,
    failed: 0,
    newFailed: 0,
    reconciled: 0,
    failedReasons: null,
  };
  outgoingCounts = { failed: 0, sent: 0, failedReasons: null };

  addIncomingFailedReason(reason) {
    if (!this.incomingCounts.failedReasons) {
      this.incomingCounts.failedReasons = [];
    }
    let transformedReason = SyncTelemetry.transformError(reason);
    // Some errors like http/nss errors don't have an error object
    // those will be caught by the higher level telemetry
    if (!transformedReason.error) {
      return;
    }

    let index = this.incomingCounts.failedReasons.findIndex(
      reasons => reasons.name === transformedReason.error
    );

    if (index >= 0) {
      this.incomingCounts.failedReasons[index].count += 1;
    } else {
      this.incomingCounts.failedReasons.push({
        name: transformedReason.error,
        count: 1,
      });
    }
  }

  addOutgoingFailedReason(reason) {
    if (!this.outgoingCounts.failedReasons) {
      this.outgoingCounts.failedReasons = [];
    }
    let transformedReason = SyncTelemetry.transformError(reason);
    // Some errors like http/nss errors don't have an error object
    // those will be caught by the higher level telemetry
    if (!transformedReason.error) {
      return;
    }
    let index = this.outgoingCounts.failedReasons.findIndex(
      reasons => reasons.name === transformedReason.error
    );
    if (index >= 0) {
      this.outgoingCounts.failedReasons[index].count += 1;
    } else {
      this.outgoingCounts.failedReasons.push({
        name: transformedReason.error,
        count: 1,
      });
    }
  }
}

// The `ErrorSanitizer` has 2 main jobs:
// * Remove PII from errors, such as the profile dir or URLs the user might
//   have visited.
// * Normalize errors so different locales or operating systems etc don't
//   generate different messages for the same underlying error.
// * [TODO] Normalize errors so environmental factors don't influence message.
//   For example, timestamps or GUIDs should be replaced with something static.
export class ErrorSanitizer {
  // Things we normalize - this isn't exhaustive, but covers the common error messages we see.
  // Eg:
  // > Win error 112 during operation write on file [profileDir]\weave\addonsreconciler.json (Espacio en disco insuficiente. )
  // > Win error 112 during operation write on file [profileDir]\weave\addonsreconciler.json (Diskte yeterli yer yok. )
  // > <snip many other translations of the error>
  // > Unix error 28 during operation write on file [profileDir]/weave/addonsreconciler.json (No space left on device)
  // These tend to crowd out other errors we might care about (eg, top 5 errors for some engines are
  // variations of the "no space left on device")

  // Note that only errors that have same-but-different errors on Windows and Unix are here - we
  // still sanitize ones that aren't in these maps to remove the translations etc - eg,
  // `ERROR_SHARING_VIOLATION` doesn't really have a unix equivalent, so doesn't appear here, but
  // we still strip the translations to avoid the variants.
  static E_NO_SPACE_ON_DEVICE = "OS error [No space left on device]";
  static E_PERMISSION_DENIED = "OS error [Permission denied]";
  static E_NO_FILE_OR_DIR = "OS error [File/Path not found]";
  static E_NO_MEM = "OS error [No memory]";

  static WindowsErrorSubstitutions = {
    2: this.E_NO_FILE_OR_DIR, // ERROR_FILE_NOT_FOUND
    3: this.E_NO_FILE_OR_DIR, // ERROR_PATH_NOT_FOUND
    5: this.E_PERMISSION_DENIED, // ERROR_ACCESS_DENIED
    8: this.E_NO_MEM, // ERROR_NOT_ENOUGH_MEMORY
    112: this.E_NO_SPACE_ON_DEVICE, // ERROR_DISK_FULL
  };

  static UnixErrorSubstitutions = {
    2: this.E_NO_FILE_OR_DIR, // ENOENT
    12: this.E_NO_MEM, // ENOMEM
    13: this.E_PERMISSION_DENIED, // EACCESS
    28: this.E_NO_SPACE_ON_DEVICE, // ENOSPC
  };

  static DOMErrorSubstitutions = {
    NotFoundError: this.E_NO_FILE_OR_DIR,
    NotAllowedError: this.E_PERMISSION_DENIED,
  };

  static reWinError =
    /^(?<head>Win error (?<errno>\d+))(?<detail>.*) \(.*\r?\n?\)$/m;
  static reUnixError =
    /^(?<head>Unix error (?<errno>\d+))(?<detail>.*) \(.*\)$/;

  static #cleanOSErrorMessage(message, error = undefined) {
    if (DOMException.isInstance(error)) {
      const sub = this.DOMErrorSubstitutions[error.name];
      message = message.replaceAll("\\", "/");
      if (sub) {
        return `${sub} ${message}`;
      }
    }

    let match = this.reWinError.exec(message);
    if (match) {
      let head =
        this.WindowsErrorSubstitutions[match.groups.errno] || match.groups.head;
      return head + match.groups.detail.replaceAll("\\", "/");
    }
    match = this.reUnixError.exec(message);
    if (match) {
      let head =
        this.UnixErrorSubstitutions[match.groups.errno] || match.groups.head;
      return head + match.groups.detail;
    }
    return message;
  }

  // A regex we can use to replace the profile dir in error messages. We use a
  // regexp so we can simply replace all case-insensitive occurences.
  // This escaping function is from:
  // https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions
  static reProfileDir = new RegExp(
    PathUtils.profileDir.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"),
    "gi"
  );

  /**
   * Clean an error message, removing PII and normalizing OS-specific messages.
   *
   * @param {string} message The error message
   * @param {Error?} error The error class instance, if any.
   */
  static cleanErrorMessage(message, error = undefined) {
    // There's a chance the profiledir is in the error string which is PII we
    // want to avoid including in the ping.
    message = message.replace(this.reProfileDir, "[profileDir]");
    // MSG_INVALID_URL from /dom/bindings/Errors.msg -- no way to access this
    // directly from JS.
    if (message.endsWith("is not a valid URL.")) {
      message = "<URL> is not a valid URL.";
    }
    // Try to filter things that look somewhat like a URL (in that they contain a
    // colon in the middle of non-whitespace), in case anything else is including
    // these in error messages. Note that JSON.stringified stuff comes through
    // here, so we explicitly ignore double-quotes as well.
    message = message.replace(/[^\s"]+:[^\s"]+/g, "<URL>");

    // Anywhere that's normalized the guid in errors we can easily filter
    // to make it easier to aggregate these types of errors
    message = message.replace(/<guid: ([^>]+)>/g, "<GUID>");

    return this.#cleanOSErrorMessage(message, error);
  }
}

// This function validates the payload of a telemetry "event" - this can be
// removed once there are APIs available for the telemetry modules to collect
// these events (bug 1329530) - but for now we simulate that planned API as
// best we can.
function validateTelemetryEvent(eventDetails) {
  let { object, method, value, extra } = eventDetails;
  // Do do basic validation of the params - everything except "extra" must
  // be a string. method and object are required.
  if (
    typeof method != "string" ||
    typeof object != "string" ||
    (value && typeof value != "string") ||
    (extra && typeof extra != "object")
  ) {
    log.warn("Invalid event parameters - wrong types", eventDetails);
    return false;
  }
  // length checks.
  if (
    method.length > 20 ||
    object.length > 20 ||
    (value && value.length > 80)
  ) {
    log.warn("Invalid event parameters - wrong lengths", eventDetails);
    return false;
  }

  // extra can be falsey, or an object with string names and values.
  if (extra) {
    if (Object.keys(extra).length > 10) {
      log.warn("Invalid event parameters - too many extra keys", eventDetails);
      return false;
    }
    for (let [ename, evalue] of Object.entries(extra)) {
      if (
        typeof ename != "string" ||
        ename.length > 15 ||
        typeof evalue != "string" ||
        evalue.length > 85
      ) {
        log.warn(
          `Invalid event parameters: extra item "${ename} is invalid`,
          eventDetails
        );
        return false;
      }
    }
  }
  return true;
}

class EngineRecord {
  constructor(name) {
    // startTime is in ms from process start, but is monotonic (unlike Date.now())
    // so we need to keep both it and when.
    this.startTime = tryGetMonotonicTimestamp();
    this.name = name;

    // This allows cases like bookmarks-buffered to have a separate name from
    // the bookmarks engine.
    let engineImpl = lazy.Weave.Service.engineManager.get(name);
    if (engineImpl && engineImpl.overrideTelemetryName) {
      this.overrideTelemetryName = engineImpl.overrideTelemetryName;
    }
  }

  toJSON() {
    let result = { name: this.overrideTelemetryName || this.name };
    let properties = [
      "took",
      "status",
      "failureReason",
      "incoming",
      "outgoing",
      "validation",
      "steps",
    ];
    for (let property of properties) {
      result[property] = this[property];
    }
    return result;
  }

  finished(error) {
    let took = timeDeltaFrom(this.startTime);
    if (took > 0) {
      this.took = took;
    }
    if (error) {
      this.failureReason = SyncTelemetry.transformError(error);
    }
  }

  recordApplied(counts) {
    if (this.incoming) {
      log.error(
        `Incoming records applied multiple times for engine ${this.name}!`
      );
      return;
    }
    if (this.name === "clients" && !counts.failed) {
      // ignore successful application of client records
      // since otherwise they show up every time and are meaningless.
      return;
    }

    let incomingData = {};

    if (counts.failedReasons) {
      // sort the failed reasons in desc by count, then take top 10
      counts.failedReasons = counts.failedReasons
        .sort((a, b) => b.count - a.count)
        .slice(0, 10);
    }
    // Counts has extra stuff used for logging, but we only care about a few
    let properties = ["applied", "failed", "failedReasons"];
    // Only record non-zero properties and only record incoming at all if
    // there's at least one property we care about.
    for (let property of properties) {
      if (counts[property]) {
        incomingData[property] = counts[property];
        this.incoming = incomingData;
      }
    }
  }

  recordStep(stepResult) {
    let step = {
      name: stepResult.name,
    };
    if (stepResult.took > 0) {
      step.took = Math.round(stepResult.took);
    }
    if (stepResult.counts) {
      let counts = stepResult.counts.filter(({ count }) => count > 0);
      if (counts.length) {
        step.counts = counts;
      }
    }
    if (this.steps) {
      this.steps.push(step);
    } else {
      this.steps = [step];
    }
  }

  recordValidation(validationResult) {
    if (this.validation) {
      log.error(`Multiple validations occurred for engine ${this.name}!`);
      return;
    }
    let { problems, version, took, checked } = validationResult;
    let validation = {
      version: version || 0,
      checked: checked || 0,
    };
    if (took > 0) {
      validation.took = Math.round(took);
    }
    let summarized = problems.filter(({ count }) => count > 0);
    if (summarized.length) {
      validation.problems = summarized;
    }
    this.validation = validation;
  }

  recordValidationError(e) {
    if (this.validation) {
      log.error(`Multiple validations occurred for engine ${this.name}!`);
      return;
    }

    this.validation = {
      failureReason: SyncTelemetry.transformError(e),
    };
  }

  recordUploaded(counts) {
    if (counts.sent || counts.failed) {
      if (!this.outgoing) {
        this.outgoing = [];
      }
      if (counts.failedReasons) {
        // sort the failed reasons in desc by count, then take top 10
        counts.failedReasons = counts.failedReasons
          .sort((a, b) => b.count - a.count)
          .slice(0, 10);
      }
      this.outgoing.push({
        sent: counts.sent || undefined,
        failed: counts.failed || undefined,
        failedReasons: counts.failedReasons || undefined,
      });
    }
  }
}

// The record of a single "sync" - typically many of these are submitted in
// a single ping (ie, as a 'syncs' array)
export class SyncRecord {
  constructor(allowedEngines, why) {
    this.allowedEngines = allowedEngines;
    // Our failure reason. This property only exists in the generated ping if an
    // error actually occurred.
    this.failureReason = undefined;
    this.syncNodeType = null;
    this.when = Date.now();
    this.startTime = tryGetMonotonicTimestamp();
    this.took = 0; // will be set later.
    this.why = why;

    // All engines that have finished (ie, does not include the "current" one)
    // We omit this from the ping if it's empty.
    this.engines = [];
    // The engine that has started but not yet stopped.
    this.currentEngine = null;
  }

  toJSON() {
    let result = {
      when: this.when,
      took: this.took,
      failureReason: this.failureReason,
      status: this.status,
    };
    if (this.why) {
      result.why = this.why;
    }
    let engines = [];
    for (let engine of this.engines) {
      engines.push(engine.toJSON());
    }
    if (engines.length) {
      result.engines = engines;
    }
    return result;
  }

  finished(error) {
    this.took = timeDeltaFrom(this.startTime);
    if (this.currentEngine != null) {
      log.error(
        "Finished called for the sync before the current engine finished"
      );
      this.currentEngine.finished(null);
      this.onEngineStop(this.currentEngine.name);
    }
    if (error) {
      this.failureReason = SyncTelemetry.transformError(error);
    }

    this.syncNodeType = lazy.Weave.Service.identity.telemetryNodeType;

    // Check for engine statuses. -- We do this now, and not in engine.finished
    // to make sure any statuses that get set "late" are recorded
    for (let engine of this.engines) {
      let status = lazy.Status.engines[engine.name];
      if (status && status !== constants.ENGINE_SUCCEEDED) {
        engine.status = status;
      }
    }

    let statusObject = {};

    let serviceStatus = lazy.Status.service;
    if (serviceStatus && serviceStatus !== constants.STATUS_OK) {
      statusObject.service = serviceStatus;
      this.status = statusObject;
    }
    let syncStatus = lazy.Status.sync;
    if (syncStatus && syncStatus !== constants.SYNC_SUCCEEDED) {
      statusObject.sync = syncStatus;
      this.status = statusObject;
    }
  }

  onEngineStart(engineName) {
    if (this._shouldIgnoreEngine(engineName, false)) {
      return;
    }

    if (this.currentEngine) {
      log.error(
        `Being told that engine ${engineName} has started, but current engine ${this.currentEngine.name} hasn't stopped`
      );
      // Just discard the current engine rather than making up data for it.
    }
    this.currentEngine = new EngineRecord(engineName);
  }

  onEngineStop(engineName, error) {
    // We only care if it's the current engine if we have a current engine.
    if (this._shouldIgnoreEngine(engineName, !!this.currentEngine)) {
      return;
    }
    if (!this.currentEngine) {
      // It's possible for us to get an error before the start message of an engine
      // (somehow), in which case we still want to record that error.
      if (!error) {
        return;
      }
      log.error(
        `Error triggered on ${engineName} when no current engine exists: ${error}`
      );
      this.currentEngine = new EngineRecord(engineName);
    }
    this.currentEngine.finished(error);
    this.engines.push(this.currentEngine);
    this.currentEngine = null;
  }

  onEngineApplied(engineName, counts) {
    if (this._shouldIgnoreEngine(engineName)) {
      return;
    }
    this.currentEngine.recordApplied(counts);
  }

  onEngineStep(engineName, step) {
    if (this._shouldIgnoreEngine(engineName)) {
      return;
    }
    this.currentEngine.recordStep(step);
  }

  onEngineValidated(engineName, validationData) {
    if (this._shouldIgnoreEngine(engineName, false)) {
      return;
    }
    let engine = this.engines.find(e => e.name === engineName);
    if (
      !engine &&
      this.currentEngine &&
      engineName === this.currentEngine.name
    ) {
      engine = this.currentEngine;
    }
    if (engine) {
      engine.recordValidation(validationData);
    } else {
      log.warn(
        `Validation event triggered for engine ${engineName}, which hasn't been synced!`
      );
    }
  }

  onEngineValidateError(engineName, error) {
    if (this._shouldIgnoreEngine(engineName, false)) {
      return;
    }
    let engine = this.engines.find(e => e.name === engineName);
    if (
      !engine &&
      this.currentEngine &&
      engineName === this.currentEngine.name
    ) {
      engine = this.currentEngine;
    }
    if (engine) {
      engine.recordValidationError(error);
    } else {
      log.warn(
        `Validation failure event triggered for engine ${engineName}, which hasn't been synced!`
      );
    }
  }

  onEngineUploaded(engineName, counts) {
    if (this._shouldIgnoreEngine(engineName)) {
      return;
    }
    this.currentEngine.recordUploaded(counts);
  }

  _shouldIgnoreEngine(engineName, shouldBeCurrent = true) {
    if (!this.allowedEngines.has(engineName)) {
      log.info(
        `Notification for engine ${engineName}, but we aren't recording telemetry for it`
      );
      return true;
    }
    if (shouldBeCurrent) {
      if (!this.currentEngine || engineName != this.currentEngine.name) {
        log.info(`Notification for engine ${engineName} but it isn't current`);
        return true;
      }
    }
    return false;
  }
}

// The entire "sync ping" - it includes all the syncs, events etc recorded in
// the ping.
class SyncTelemetryImpl {
  constructor(allowedEngines) {
    log.manageLevelFromPref("services.sync.log.logger.telemetry");
    // This is accessible so we can enable custom engines during tests.
    this.allowedEngines = allowedEngines;
    this.current = null;
    this.setupObservers();

    this.payloads = [];
    this.discarded = 0;
    this.events = [];
    this.histograms = {};
    this.migrations = [];
    this.maxEventsCount = lazy.Svc.Prefs.get("telemetry.maxEventsCount", 1000);
    this.maxPayloadCount = lazy.Svc.Prefs.get("telemetry.maxPayloadCount");
    this.submissionInterval =
      lazy.Svc.Prefs.get("telemetry.submissionInterval") * 1000;
    this.lastSubmissionTime = Services.telemetry.msSinceProcessStart();
    this.lastUID = EMPTY_UID;
    this.lastSyncNodeType = null;
    this.currentSyncNodeType = null;
    // Note that the sessionStartDate is somewhat arbitrary - the telemetry
    // modules themselves just use `new Date()`. This means that our startDate
    // isn't going to be the same as the sessionStartDate in the main pings,
    // but that's OK for now - if it's a problem we'd need to change the
    // telemetry modules to expose what it thinks the sessionStartDate is.
    let sessionStartDate = new Date();
    this.sessionStartDate = lazy.TelemetryUtils.toLocalTimeISOString(
      lazy.TelemetryUtils.truncateToHours(sessionStartDate)
    );
    lazy.TelemetryController.registerSyncPingShutdown(() => this.shutdown());
  }

  sanitizeFxaDeviceId(deviceId) {
    return lazy.fxAccounts.telemetry.sanitizeDeviceId(deviceId);
  }

  prepareFxaDevices(devices) {
    // For non-sync users, the data per device is limited -- just an id and a
    // type (and not even the id yet). For sync users, if we can correctly map
    // the fxaDevice to a sync device, then we can get os and version info,
    // which would be quite unfortunate to lose.
    let extraInfoMap = new Map();
    if (this.syncIsEnabled()) {
      for (let client of this.getClientsEngineRecords()) {
        if (client.fxaDeviceId) {
          extraInfoMap.set(client.fxaDeviceId, {
            os: client.os,
            version: client.version,
            syncID: this.sanitizeFxaDeviceId(client.id),
          });
        }
      }
    }
    // Finally, sanitize and convert to the proper format.
    return devices.map(d => {
      let { os, version, syncID } = extraInfoMap.get(d.id) || {
        os: undefined,
        version: undefined,
        syncID: undefined,
      };
      return {
        id: this.sanitizeFxaDeviceId(d.id) || EMPTY_UID,
        type: d.type,
        os,
        version,
        syncID,
      };
    });
  }

  syncIsEnabled() {
    return lazy.WeaveService.enabled && lazy.WeaveService.ready;
  }

  // Separate for testing.
  getClientsEngineRecords() {
    if (!this.syncIsEnabled()) {
      throw new Error("Bug: syncIsEnabled() must be true, check it first");
    }
    return lazy.Weave.Service.clientsEngine.remoteClients;
  }

  updateFxaDevices(devices) {
    if (!devices) {
      return {};
    }
    let me = devices.find(d => d.isCurrentDevice);
    let id = me ? this.sanitizeFxaDeviceId(me.id) : undefined;
    let cleanDevices = this.prepareFxaDevices(devices);
    return { deviceID: id, devices: cleanDevices };
  }

  getFxaDevices() {
    return lazy.fxAccounts.device.recentDeviceList;
  }

  getPingJSON(reason) {
    let { devices, deviceID } = this.updateFxaDevices(this.getFxaDevices());
    return {
      os: lazy.TelemetryEnvironment.currentEnvironment.system.os,
      why: reason,
      devices,
      discarded: this.discarded || undefined,
      version: PING_FORMAT_VERSION,
      syncs: this.payloads.slice(),
      uid: this.lastUID,
      syncNodeType: this.lastSyncNodeType || undefined,
      deviceID,
      sessionStartDate: this.sessionStartDate,
      events: !this.events.length ? undefined : this.events,
      migrations: !this.migrations.length ? undefined : this.migrations,
      histograms: !Object.keys(this.histograms).length
        ? undefined
        : this.histograms,
    };
  }

  _addMigrationRecord(type, info) {
    log.debug("Saw telemetry migration info", type, info);
    // Updates to this need to be documented in `sync-ping.rst`
    switch (type) {
      case "webext-storage":
        this.migrations.push({
          type: "webext-storage",
          entries: +info.entries,
          entriesSuccessful: +info.entries_successful,
          extensions: +info.extensions,
          extensionsSuccessful: +info.extensions_successful,
          openFailure: !!info.open_failure,
        });
        break;
      default:
        throw new Error("Bug: Unknown migration record type " + type);
    }
  }

  finish(reason) {
    // Note that we might be in the middle of a sync right now, and so we don't
    // want to touch this.current.
    let result = this.getPingJSON(reason);
    this.payloads = [];
    this.discarded = 0;
    this.events = [];
    this.migrations = [];
    this.histograms = {};
    this.submit(result);
  }

  setupObservers() {
    for (let topic of TOPICS) {
      lazy.Observers.add(topic, this, this);
    }
  }

  shutdown() {
    this.finish("shutdown");
    for (let topic of TOPICS) {
      lazy.Observers.remove(topic, this, this);
    }
  }

  submit(record) {
    if (!this.isProductionSyncUser()) {
      return false;
    }
    // We still call submit() with possibly illegal payloads so that tests can
    // know that the ping was built. We don't end up submitting them, however.
    let numEvents = record.events ? record.events.length : 0;
    let numMigrations = record.migrations ? record.migrations.length : 0;
    if (record.syncs.length || numEvents || numMigrations) {
      log.trace(
        `submitting ${record.syncs.length} sync record(s) and ` +
          `${numEvents} event(s) to telemetry`
      );
      lazy.TelemetryController.submitExternalPing("sync", record, {
        usePingSender: true,
      }).catch(err => {
        log.error("failed to submit ping", err);
      });
      return true;
    }
    return false;
  }

  isProductionSyncUser() {
    // If FxA isn't production then we treat sync as not being production.
    // Further, there's the deprecated "services.sync.tokenServerURI" pref we
    // need to consider - fxa doesn't consider that as if that's the only
    // pref set, they *are* running a production fxa, just not production sync.
    if (
      !lazy.FxAccounts.config.isProductionConfig() ||
      Services.prefs.prefHasUserValue("services.sync.tokenServerURI")
    ) {
      log.trace(`Not sending telemetry ping for self-hosted Sync user`);
      return false;
    }
    return true;
  }

  onSyncStarted(data) {
    const why = data && JSON.parse(data).why;
    if (this.current) {
      log.warn(
        "Observed weave:service:sync:start, but we're already recording a sync!"
      );
      // Just discard the old record, consistent with our handling of engines, above.
      this.current = null;
    }
    this.current = new SyncRecord(this.allowedEngines, why);
  }

  // We need to ensure that the telemetry `deletion-request` ping always contains the user's
  // current sync device ID, because if the user opts out of telemetry then the deletion ping
  // will be immediately triggered for sending, and we won't have a chance to fill it in later.
  // This keeps the `deletion-ping` up-to-date when the user's account state changes.
  onAccountInitOrChange() {
    // We don't submit sync pings for self-hosters, so don't need to collect their device ids either.
    if (!this.isProductionSyncUser()) {
      return;
    }
    // Awkwardly async, but no need to await. If the user's account state changes while
    // this promise is in flight, it will reject and we won't record any data in the ping.
    // (And a new notification will trigger us to try again with the new state).
    lazy.fxAccounts.device
      .getLocalId()
      .then(deviceId => {
        let sanitizedDeviceId =
          lazy.fxAccounts.telemetry.sanitizeDeviceId(deviceId);
        // In the past we did not persist the FxA metrics identifiers to disk,
        // so this might be missing until we can fetch it from the server for the
        // first time. There will be a fresh notification tirggered when it's available.
        if (sanitizedDeviceId) {
          // Sanitized device ids are 64 characters long, but telemetry limits scalar strings to 50.
          // The first 32 chars are sufficient to uniquely identify the device, so just send those.
          // It's hard to change the sync ping itself to only send 32 chars, to b/w compat reasons.
          sanitizedDeviceId = sanitizedDeviceId.substr(0, 32);
          Services.telemetry.scalarSet(
            "deletion.request.sync_device_id",
            sanitizedDeviceId
          );
        }
      })
      .catch(err => {
        log.warn(
          `Failed to set sync identifiers in the deletion-request ping: ${err}`
        );
      });
  }

  // This keeps the `deletion-request` ping up-to-date when the user signs out,
  // clearing the now-nonexistent sync device id.
  onAccountLogout() {
    Services.telemetry.scalarSet("deletion.request.sync_device_id", "");
  }

  _checkCurrent(topic) {
    if (!this.current) {
      // This is only `info` because it happens when we do a tabs "quick-write"
      log.info(
        `Observed notification ${topic} but no current sync is being recorded.`
      );
      return false;
    }
    return true;
  }

  _shouldSubmitForDataChange() {
    let newID = lazy.fxAccounts.telemetry.getSanitizedUID() || EMPTY_UID;
    let oldID = this.lastUID;
    if (
      newID != EMPTY_UID &&
      oldID != EMPTY_UID &&
      // Both are "real" uids, so we care if they've changed.
      newID != oldID
    ) {
      log.trace(
        `shouldSubmitForDataChange - uid from '${oldID}' -> '${newID}'`
      );
      return true;
    }
    // We've gone from knowing one of the ids to not knowing it (which we
    // ignore) or we've gone from not knowing it to knowing it (which is fine),
    // Now check the node type because a change there also means we should
    // submit.
    if (
      this.lastSyncNodeType &&
      this.currentSyncNodeType != this.lastSyncNodeType
    ) {
      log.trace(
        `shouldSubmitForDataChange - nodeType from '${this.lastSyncNodeType}' -> '${this.currentSyncNodeType}'`
      );
      return true;
    }
    log.trace("shouldSubmitForDataChange - no need to submit");
    return false;
  }

  maybeSubmitForDataChange() {
    if (this._shouldSubmitForDataChange()) {
      log.info(
        "Early submission of sync telemetry due to changed IDs/NodeType"
      );
      this.finish("idchange"); // this actually submits.
      this.lastSubmissionTime = Services.telemetry.msSinceProcessStart();
    }

    // Only update the last UIDs if we actually know them.
    let current_uid = lazy.fxAccounts.telemetry.getSanitizedUID();
    if (current_uid) {
      this.lastUID = current_uid;
    }
    if (this.currentSyncNodeType) {
      this.lastSyncNodeType = this.currentSyncNodeType;
    }
  }

  maybeSubmitForInterval() {
    // We want to submit the ping every `this.submissionInterval` but only when
    // there's no current sync in progress, otherwise we may end up submitting
    // the sync and the events caused by it in different pings.
    if (
      this.current == null &&
      Services.telemetry.msSinceProcessStart() - this.lastSubmissionTime >
        this.submissionInterval
    ) {
      this.finish("schedule");
      this.lastSubmissionTime = Services.telemetry.msSinceProcessStart();
    }
  }

  onSyncFinished(error) {
    if (!this.current) {
      log.warn("onSyncFinished but we aren't recording");
      return;
    }
    this.current.finished(error);
    this.currentSyncNodeType = this.current.syncNodeType;
    let current = this.current;
    this.current = null;
    this.takeTelemetryRecord(current);
  }

  takeTelemetryRecord(record) {
    // We check for "data change" before appending the current sync to payloads,
    // as it is the current sync which has the data with the new data, and thus
    // must go in the *next* submission.
    this.maybeSubmitForDataChange();
    if (this.payloads.length < this.maxPayloadCount) {
      this.payloads.push(record.toJSON());
    } else {
      ++this.discarded;
    }
    // If we are submitting due to timing, it's desirable that the most recent
    // sync is included, so we check after appending the record.
    this.maybeSubmitForInterval();
  }

  _addHistogram(hist) {
    let histogram = Services.telemetry.getHistogramById(hist);
    let s = histogram.snapshot();
    this.histograms[hist] = s;
  }

  _recordEvent(eventDetails) {
    this.maybeSubmitForDataChange();

    if (this.events.length >= this.maxEventsCount) {
      log.warn("discarding event - already queued our maximum", eventDetails);
      return;
    }

    let { object, method, value, extra } = eventDetails;
    if (extra) {
      extra = normalizeExtraTelemetryFields(extra);
      eventDetails = { object, method, value, extra };
    }

    if (!validateTelemetryEvent(eventDetails)) {
      // we've already logged what the problem is...
      return;
    }
    log.debug("recording event", eventDetails);

    if (extra && lazy.Resource.serverTime && !extra.serverTime) {
      extra.serverTime = String(lazy.Resource.serverTime);
    }
    let category = "sync";
    let ts = Math.floor(tryGetMonotonicTimestamp());

    // An event record is a simple array with at least 4 items.
    let event = [ts, category, method, object];
    // It may have up to 6 elements if |extra| is defined
    if (value) {
      event.push(value);
      if (extra) {
        event.push(extra);
      }
    } else if (extra) {
      event.push(null); // a null for the empty value.
      event.push(extra);
    }
    this.events.push(event);
    this.maybeSubmitForInterval();
  }

  observe(subject, topic, data) {
    log.trace(`observed ${topic} ${data}`);

    switch (topic) {
      case "weave:service:ready":
      case "weave:service:login:got-hashed-id":
      case "fxaccounts:new_device_id":
        this.onAccountInitOrChange();
        break;

      case "fxaccounts:onlogout":
        this.onAccountLogout();
        break;

      /* sync itself state changes */
      case "weave:service:sync:start":
        this.onSyncStarted(data);
        break;

      case "weave:service:sync:finish":
        if (this._checkCurrent(topic)) {
          this.onSyncFinished(null);
        }
        break;

      case "weave:service:sync:error":
        // argument needs to be truthy (this should always be the case)
        this.onSyncFinished(subject || "Unknown");
        break;

      /* engine sync state changes */
      case "weave:engine:sync:start":
        if (this._checkCurrent(topic)) {
          this.current.onEngineStart(data);
        }
        break;
      case "weave:engine:sync:finish":
        if (this._checkCurrent(topic)) {
          this.current.onEngineStop(data, null);
        }
        break;

      case "weave:engine:sync:error":
        if (this._checkCurrent(topic)) {
          // argument needs to be truthy (this should always be the case)
          this.current.onEngineStop(data, subject || "Unknown");
        }
        break;

      /* engine counts */
      case "weave:engine:sync:applied":
        if (this._checkCurrent(topic)) {
          this.current.onEngineApplied(data, subject);
        }
        break;

      case "weave:engine:sync:step":
        if (this._checkCurrent(topic)) {
          this.current.onEngineStep(data, subject);
        }
        break;

      case "weave:engine:sync:uploaded":
        if (this._checkCurrent(topic)) {
          this.current.onEngineUploaded(data, subject);
        }
        break;

      case "weave:engine:validate:finish":
        if (this._checkCurrent(topic)) {
          this.current.onEngineValidated(data, subject);
        }
        break;

      case "weave:engine:validate:error":
        if (this._checkCurrent(topic)) {
          this.current.onEngineValidateError(data, subject || "Unknown");
        }
        break;

      case "weave:telemetry:event":
      case "fxa:telemetry:event":
        this._recordEvent(subject);
        break;

      case "weave:telemetry:histogram":
        this._addHistogram(data);
        break;

      case "weave:telemetry:migration":
        this._addMigrationRecord(data, subject);
        break;

      default:
        log.warn(`unexpected observer topic ${topic}`);
        break;
    }
  }

  // Transform an exception into a standard description. Exposed here for when
  // this module isn't directly responsible for knowing the transform should
  // happen (for example, when including an error in the |extra| field of
  // event telemetry)
  transformError(error) {
    // Certain parts of sync will use this pattern as a way to communicate to
    // processIncoming to abort the processing. However, there's no guarantee
    // this can only happen then.
    if (typeof error == "object" && error.code && error.cause) {
      error = error.cause;
    }
    if (lazy.Async.isShutdownException(error)) {
      return { name: "shutdownerror" };
    }

    if (typeof error === "string") {
      if (error.startsWith("error.")) {
        // This is hacky, but I can't imagine that it's not also accurate.
        return { name: "othererror", error };
      }
      error = ErrorSanitizer.cleanErrorMessage(error);
      return { name: "unexpectederror", error };
    }

    if (error instanceof lazy.AuthenticationError) {
      return { name: "autherror", from: error.source };
    }

    if (DOMException.isInstance(error)) {
      return {
        name: "unexpectederror",
        error: ErrorSanitizer.cleanErrorMessage(error.message, error),
      };
    }

    let httpCode =
      error.status || (error.response && error.response.status) || error.code;

    if (httpCode) {
      return { name: "httperror", code: httpCode };
    }

    if (error.failureCode) {
      return { name: "othererror", error: error.failureCode };
    }

    if (error.result) {
      // many "nsresult" errors are actually network errors - if they are
      // associated with the "network" module we assume that's true.
      // We also assume NS_ERROR_ABORT is such an error - for almost everything
      // we care about, it acually is (eg, if the connection fails early enough
      // or if we have a captive portal etc) - we don't lose anything by this
      // assumption, it's just that the error will no longer be in the "nserror"
      // category, so our analysis can still find them.
      if (
        error.result == Cr.NS_ERROR_ABORT ||
        NS_ERROR_GET_MODULE(error.result) == NS_ERROR_MODULE_NETWORK
      ) {
        return { name: "httperror", code: error.result };
      }
      return { name: "nserror", code: error.result };
    }
    // It's probably an Error object, but it also could be some
    // other object that may or may not override toString to do
    // something useful.
    let msg = String(error);
    if (msg.startsWith("[object")) {
      // Nothing useful in the default, check for a string "message" property.
      if (typeof error.message == "string") {
        msg = String(error.message);
      } else {
        // Hopefully it won't come to this...
        msg = JSON.stringify(error);
      }
    }
    return {
      name: "unexpectederror",
      error: ErrorSanitizer.cleanErrorMessage(msg),
    };
  }
}

export var SyncTelemetry = new SyncTelemetryImpl(ENGINES);