[unified_analytics] Crash on flutter master branch

[dcharkes]

$ flutter --version

Unhandled exception:
type 'Null' is not a subtype of type 'int' in type cast
#0      Session._refreshSessionData.parseContents (package:unified_analytics/src/session.dart:94:43)
#1      Session._refreshSessionData (package:unified_analytics/src/session.dart:98:7)
#2      new Session (package:unified_analytics/src/session.dart:37:27)
#3      new AnalyticsImpl (package:unified_analytics/src/analytics.dart:429:23)
#4      new Analytics (package:unified_analytics/src/analytics.dart:87:12)
#5      getAnalytics (package:flutter_tools/src/reporting/unified_analytics.dart:51:10)
#6      runInContext.<anonymous closure> (package:flutter_tools/src/context_runner.dart:92:24)
#7      AppContext._generateIfNecessary.<anonymous closure> (package:flutter_tools/src/base/context.dart:107:42)
#8      _LinkedHashMapMixin.putIfAbsent (dart:collection-patch/compact_hash.dart:543:23)
#9      AppContext._generateIfNecessary (package:flutter_tools/src/base/context.dart:95:20)
#10     AppContext.get (package:flutter_tools/src/base/context.dart:124:32)
#11     analytics (package:flutter_tools/src/globals.dart:98:36)
#12     _handleToolError (package:flutter_tools/runner.dart:190:13)
#13     run.<anonymous closure>.<anonymous closure> (package:flutter_tools/runner.dart:142:13)
#14     _rootRunBinary (dart:async/zone.dart:1423:47)
#15     _CustomZone.runBinary (dart:async/zone.dart:1315:19)
#16     runZonedGuarded.<anonymous closure> (dart:async/zone.dart:1798:18)
#17     _Zone._processUncaughtError (dart:async/zone.dart:1081:14)
#18     _CustomZone.handleUncaughtError (dart:async/zone.dart:1285:5)
#19     Future._propagateToListeners (dart:async/future_impl.dart:797:16)
#20     Future._completeError (dart:async/future_impl.dart:660:5)
#21     Future._asyncCompleteError.<anonymous closure> (dart:async/future_impl.dart:746:7)
#22     _rootRun (dart:async/zone.dart:1399:13)
#23     _CustomZone.run (dart:async/zone.dart:1301:19)
#24     _CustomZone.runGuarded (dart:async/zone.dart:1209:7)
#25     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1249:23)
#26     _microtaskLoop (dart:async/schedule_microtask.dart:40:21)
#27     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)
#28     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
#29     _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:185:5)

[eliasyishak]

Hey @dcharkes, thanks for sharing! Would you mind sharing if this happens every time or flakey?

[dcharkes]

Every time, I'm not even able to make a clean checkout at the moment:

"/Users/dacoharkes/flt/engine/src/third_party/dart/tools/sdks/dart-sdk/bin/dart pub get --offline" failed in "/Users/dacoharkes/flt/engine/src/flutter/ci" with status 255:
b"An unexpected error was encountered by the Dart CLI.\nPlease file an issue at https://github.com/dart-lang/sdk/issues/new with the following details:\n\nInvocation: 'dart pub get --offline'\nException: 'type 'Null' is not a subtype of type 'int' in type cast'\nStack Trace:\n#0      Session._refreshSessionData.parseContents (package:unified_analytics/src/session.dart:85:43)\n#1      Session._refreshSessionData (package:unified_analytics/src/session.dart:89:7)\n#2      new Session (package:unified_analytics/src/session.dart:28:5)\n#3      new AnalyticsImpl (package:unified_analytics/src/analytics.dart:421:23)\n#4      new Analytics (package:unified_analytics/src/analytics.dart:83:12)\n#5      createUnifiedAnalytics (package:dartdev/src/unified_analytics.dart:23:10)\n#6      DartdevRunner.runCommand (package:dartdev/dartdev.dart:177:27)\n#7      CommandRunner.run.<anonymous closure> (package:args/command_runner.dart:122:25)\n#8      new Future.sync (dart:async/future.dart:306:31)\n#9      CommandRunner.run (package:args/command_runner.dart:122:14)\n#10     runDartdev (package:dartdev/dartdev.dart:58:29)\n#11     main (file:///Volumes/Work/s/w/ir/x/w/sdk/pkg/dartdev/bin/dartdev.dart:11:9)\n#12     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:293:33)\n#13     _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)\n\n"

The problematic dart version:

dacoharkes-macbookpro2:build-hhh dacoharkes$ /Users/dacoharkes/flt/engine/src/third_party/dart/tools/sdks/dart-sdk/bin/dart --version
Dart SDK version: 3.4.0-108.0.dev (dev) (Mon Feb 5 00:03:28 2024 -0800) on "macos_arm64"

[eliasyishak]

Thanks for the detailed info.. chatted a bit offline about this but to clear up the error, this is likely due to a version update in package:unified_analytics that changed the file for the session file.

{"session_id": 123, "last_ping": 124} // old

{"session_id": 123} // new

This change was made in a previous PR aimed at reducing how many times we write to disk.

So if you end up upgrading the flutter-tool (or another client of package:unified_analytics) to a version that changes this json file to the new format.... and then later you change the flutter-tool version to an older version, you will run into this error since it will try to look up last_ping in the json but it will fail to find it, causing a type error

Workaround: delete the session json file and it will trigger error handling in the package to recreate it as expected rm ~/.dart-tool/dart-flutter-telemetry-session.json

[davidmorgan]

Getting this one too.

I think this catch

      parseContents();
    } on FormatException catch (err) {

should be more generous: parsing can fail in other ways than FormatException.

Or, equivalently, make parseContents do a try+catch internally and rethrow anything as a FormatException, that's a bit nicer.

Then this will work as intended for future changes, recreating the data when the format changes :)

[mit-mit]

For anyone seeing this issue, please see the note at the top of dart-lang/sdk#55212

[christopherfujino]

To summarize the state of the world:

1. The patched good version of unified_analytics is v5.8.8
2. the Flutter CLI tool has this version rolled at HEAD as of March 15: flutter/flutter@8d54abf
3. the Dart SDK (and thus any dart tooling maintained in dart-lang/sdk) picked up this change at HEAD as of March 18 dart-lang/sdk@87473f8
4. This Dart SDK revision rolled to flutter/engine on March 18 in Roll Dart SDK from f874a4976038 to 3e64b8fcbfb7 (1 revision) flutter/engine#51509
5. This engine revision rolled to flutter/flutter on March 18: flutter/flutter@ca864c0

Thus, at the HEAD of the master channel for the Flutter SDK, this issue should be fixed, save for any tools that are maintained outside of flutter/flutter or dart-lang/sdk.

[mit-mit]

@christopherfujino with that, can we resolve this issue, or are there more changes needed?

[christopherfujino]

@christopherfujino with that, can we resolve this issue, or are there more changes needed?

Let me take a look right now, see if there are any loose ends I missed, and then I will close.