Add `blocked_main_thread` to sync file spans

[denrase]

:scroll: Description

Add blocked_main_thread to sync file spans

:bulb: Motivation and Context

Relates to #1727

:green_heart: How did you test it?

Unit tests

:pencil: Checklist

• [x] I reviewed submitted code
• [x] I added tests to verify changes
• [ ] No new PII added or SDK only sends newly added PII if sendDefaultPii is enabled
• [ ] I updated the docs if needed
• [x] All tests passing
• [x] No breaking changes

[github-actions[bot]]

Android Performance metrics :rocket:

	Plain	With Sentry	Diff
Startup time	405.09 ms	476.65 ms	71.57 ms
Size	6.33 MiB	7.26 MiB	950.19 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
636cb61552ee37d8206f06e518009b036a877f24	366.59 ms	448.14 ms	81.55 ms
4b29d6e00433309052c4edd19c448fb33dd371f5	386.80 ms	430.86 ms	44.06 ms
0be962b89300bfbf99fd411a182336ceed7359d0	325.54 ms	382.83 ms	57.29 ms
7f75f32d9707c5a5abdb869a9eb5de05dd91bed8	347.36 ms	419.58 ms	72.22 ms
64e4616c0444f9dd46605b79140797623a76b10b	349.82 ms	436.96 ms	87.14 ms
683fd34f35c964a36534f6df6b3d4cb325f5069c	336.53 ms	418.10 ms	81.57 ms
a7acb24b1deda7eb424909eeb9e0f6897cba2cf0	301.00 ms	357.38 ms	56.38 ms
8932ece117c0cfe9eb98048e40c31da8507bd8a2	309.56 ms	377.28 ms	67.72 ms
1b663585afa7efcc1a0b17a35e0d20edd78546d5	314.96 ms	363.39 ms	48.43 ms
df16b96fceb6ce836e4d52d33120d7b1d922d5a7	326.08 ms	391.82 ms	65.74 ms

App size

Revision	Plain	With Sentry	Diff
636cb61552ee37d8206f06e518009b036a877f24	6.27 MiB	7.20 MiB	959.08 KiB
4b29d6e00433309052c4edd19c448fb33dd371f5	6.33 MiB	7.26 MiB	946.14 KiB
0be962b89300bfbf99fd411a182336ceed7359d0	6.06 MiB	7.03 MiB	990.29 KiB
7f75f32d9707c5a5abdb869a9eb5de05dd91bed8	6.26 MiB	7.20 MiB	959.18 KiB
64e4616c0444f9dd46605b79140797623a76b10b	6.27 MiB	7.20 MiB	956.52 KiB
683fd34f35c964a36534f6df6b3d4cb325f5069c	6.27 MiB	7.20 MiB	960.43 KiB
a7acb24b1deda7eb424909eeb9e0f6897cba2cf0	5.94 MiB	6.95 MiB	1.01 MiB
8932ece117c0cfe9eb98048e40c31da8507bd8a2	6.16 MiB	7.13 MiB	1000.89 KiB
1b663585afa7efcc1a0b17a35e0d20edd78546d5	6.06 MiB	7.09 MiB	1.03 MiB
df16b96fceb6ce836e4d52d33120d7b1d922d5a7	6.06 MiB	7.03 MiB	988.94 KiB

Previous results on branch: enha/file-isolate-name

Startup times

Revision	Plain	With Sentry	Diff
906e92a16be9a4b89280bab164c0df61f081c81a	619.53 ms	714.16 ms	94.63 ms
7e4b32bc1362615c9b88760b6bfd76fea55b7f81	445.00 ms	546.73 ms	101.73 ms
053d6e5d04240cd4d4f1baac34e0776e29b4a68f	379.48 ms	430.35 ms	50.87 ms
03663b0e6ff4ada136836b6bcb6b41d8a2f0f23a	407.98 ms	502.52 ms	94.54 ms
53df9a1b21d41e0de1a168b19a924db29ebd9c78	377.64 ms	453.04 ms	75.40 ms
1627c58640bb5ae7b719fb92cc082cdb880ef7c5	335.62 ms	413.39 ms	77.77 ms

App size

Revision	Plain	With Sentry	Diff
906e92a16be9a4b89280bab164c0df61f081c81a	6.33 MiB	7.26 MiB	950.38 KiB
7e4b32bc1362615c9b88760b6bfd76fea55b7f81	6.33 MiB	7.26 MiB	950.12 KiB
053d6e5d04240cd4d4f1baac34e0776e29b4a68f	6.33 MiB	7.26 MiB	949.77 KiB
03663b0e6ff4ada136836b6bcb6b41d8a2f0f23a	6.33 MiB	7.26 MiB	950.37 KiB
53df9a1b21d41e0de1a168b19a924db29ebd9c78	6.33 MiB	7.26 MiB	949.77 KiB
1627c58640bb5ae7b719fb92cc082cdb880ef7c5	6.33 MiB	7.26 MiB	950.14 KiB

[github-actions[bot]]

iOS Performance metrics :rocket:

	Plain	With Sentry	Diff
Startup time	1225.13 ms	1242.44 ms	17.31 ms
Size	8.32 MiB	9.38 MiB	1.06 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
117d988b347861588d574fcc789ecbb4f7c8bdb5	1200.83 ms	1223.24 ms	22.41 ms
955541a50762f04c301c83eb25aef0077742c29a	1230.22 ms	1252.96 ms	22.73 ms
f83bc1d235973d25cb628df973083f4093ed5282	1247.12 ms	1249.78 ms	2.65 ms
5e8d2b31f616e76a7562ee5349c9eb781ae238a6	1255.71 ms	1267.98 ms	12.27 ms
86d48419a55b5e88a17d31b0574e7e2974d4c18b	1225.69 ms	1241.12 ms	15.43 ms
68677de9e2f81479c18b887d8cc58d21d9d22e12	1245.20 ms	1273.51 ms	28.31 ms
3de8b9b92406e56cedb15086ae779e72d5cdfb08	1234.22 ms	1251.94 ms	17.72 ms
1cdcacf02367fc5937faac0a53973741676d7e40	1208.35 ms	1235.13 ms	26.77 ms
0ceb89ca0b313636a4afdb0f3171e26d89b705e2	1252.02 ms	1271.78 ms	19.75 ms
8932ece117c0cfe9eb98048e40c31da8507bd8a2	1234.31 ms	1238.90 ms	4.59 ms

App size

Revision	Plain	With Sentry	Diff
117d988b347861588d574fcc789ecbb4f7c8bdb5	8.32 MiB	9.38 MiB	1.05 MiB
955541a50762f04c301c83eb25aef0077742c29a	8.28 MiB	9.34 MiB	1.06 MiB
f83bc1d235973d25cb628df973083f4093ed5282	8.28 MiB	9.34 MiB	1.05 MiB
5e8d2b31f616e76a7562ee5349c9eb781ae238a6	8.29 MiB	9.36 MiB	1.07 MiB
86d48419a55b5e88a17d31b0574e7e2974d4c18b	8.29 MiB	9.36 MiB	1.07 MiB
68677de9e2f81479c18b887d8cc58d21d9d22e12	8.10 MiB	9.16 MiB	1.07 MiB
3de8b9b92406e56cedb15086ae779e72d5cdfb08	8.28 MiB	9.34 MiB	1.06 MiB
1cdcacf02367fc5937faac0a53973741676d7e40	8.32 MiB	9.39 MiB	1.06 MiB
0ceb89ca0b313636a4afdb0f3171e26d89b705e2	8.15 MiB	9.12 MiB	989.78 KiB
8932ece117c0cfe9eb98048e40c31da8507bd8a2	8.29 MiB	9.36 MiB	1.07 MiB

Previous results on branch: enha/file-isolate-name

Startup times

Revision	Plain	With Sentry	Diff
906e92a16be9a4b89280bab164c0df61f081c81a	1226.29 ms	1247.96 ms	21.67 ms
7e4b32bc1362615c9b88760b6bfd76fea55b7f81	1296.69 ms	1352.51 ms	55.82 ms
03663b0e6ff4ada136836b6bcb6b41d8a2f0f23a	1242.71 ms	1265.73 ms	23.01 ms
53df9a1b21d41e0de1a168b19a924db29ebd9c78	1214.55 ms	1242.00 ms	27.45 ms
1627c58640bb5ae7b719fb92cc082cdb880ef7c5	1215.58 ms	1229.35 ms	13.76 ms
053d6e5d04240cd4d4f1baac34e0776e29b4a68f	1207.80 ms	1227.45 ms	19.65 ms

App size

Revision	Plain	With Sentry	Diff
906e92a16be9a4b89280bab164c0df61f081c81a	8.32 MiB	9.38 MiB	1.06 MiB
7e4b32bc1362615c9b88760b6bfd76fea55b7f81	8.32 MiB	9.38 MiB	1.06 MiB
03663b0e6ff4ada136836b6bcb6b41d8a2f0f23a	8.32 MiB	9.38 MiB	1.06 MiB
53df9a1b21d41e0de1a168b19a924db29ebd9c78	8.32 MiB	9.39 MiB	1.06 MiB
1627c58640bb5ae7b719fb92cc082cdb880ef7c5	8.32 MiB	9.38 MiB	1.06 MiB
053d6e5d04240cd4d4f1baac34e0776e29b4a68f	8.32 MiB	9.38 MiB	1.06 MiB

[codecov[bot]]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (42b79b3) 91.17% compared to head (a5d3d15) 88.55%. Report is 12 commits behind head on main.

Files	Patch %	Lines
dart/lib/src/sentry_options.dart	0.00%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1801      +/-   ##
==========================================
- Coverage   91.17%   88.55%   -2.63%     
==========================================
  Files         172      207      +35     
  Lines        5418     6901    +1483     
==========================================
+ Hits         4940     6111    +1171     
- Misses        478      790     +312     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[denrase]

@buenaflor I'm not sure we can guarantee that the debugName will always return main on the main isolate. AFAIK there is no other way to check in dart only code.

[buenaflor]

@denrase do we know any scenarios where it won't work?

[ueman]

@denrase do we know any scenarios where it won't work?

Probably when someone calls PlatformDispatcher.setIsolateDebugName() in the main isolate from Flutter, but it's probably not that likely. I'm not sure for Dart only code though.

[buenaflor]

Got it, If we can't guarantee that it's always correct maybe it should be opt-in?

How to proceed with backend implementation?

https://docs.sentry.io/product/issues/issue-details/performance-issues/file-main-thread-io/

it should already be in place and all we need is to add the correct span data. If I looked correctly it should be

blocked_main_thread: true/false

examples: java, cocoa

[denrase]

@buenaflor Think i found a good solution. Added a callback to options to check for the main Isolate. When using the dart SDK we use the debugName, and on flutter we use ServicesBinding.rootIsolateToken to determine if we are on the main Isolate. So for flutter this should always be correct, and in dart only it should be correct as long as 'main' is returned as a value.

[buenaflor]

ServicesBinding.rootIsolateToken is only available on Flutter >= 3.7.0. See here: look for https://github.com/flutter/flutter/pull/111712

I guess we need to fall back to debugName if someone is using a lower Flutter version.

Maybe we can leverage the dynamic - NoSuchMethod approach again here?

[denrase]

@buenaflor It looks like this won't work in this case, as this is a static property on on ServicesBinding. So we don't have an instance which we can cast to dynamic.

Is there another way to check this? 🤔

If not, it looks like we can only fall back to the Isolate debug name.

[denrase]

@buenaflor Removed ServicesBinding.rootIsolateToken check for now, since I'm not aware how to call static API that is not present in older flutter versions. Maybe @marandaneto has an idea?

[marandaneto]

@buenaflor Removed ServicesBinding.rootIsolateToken check for now, since I'm not aware how to call static API that is not present in older flutter versions. Maybe @marandaneto has an idea?

All rootIsolateToken does is to call RootIsolateToken.instance and this class and property exists in older versions, right? All you need is to result = RootIsolateToken.instance != null I guess?

[denrase]

@marandaneto I checked andRootIsolateToken.instance was introduced to flutter/engine on 8. September 2022 as far as I can tell. I did not find any direct reference to it in release notes in the repos.

https://github.com/flutter/engine/pull/35174

Flutter 3.3.2, released on 14.9.2022, was the first flutter release after this PR merge.

So I'm guessig that flutter versions < 3.3.2 do not have this API, and per our oubspec.yaml we support Flutter >= 3.0.0.

I have not seen the class definition in other repositories, expept in dart-lang/flute, which is used for benchmarking.

I wanted to test this and downgrade to Flutter 3, but with no luck so far on macOS.

[marandaneto]

@marandaneto I checked andRootIsolateToken.instance was introduced to flutter/engine on 8. September 2022 as far as I can tell. I did not find any direct reference to it in release notes in the repos.

flutter/engine#35174

Flutter 3.3.2, released on 14.9.2022, was the first flutter release after this PR merge.

So I'm guessig that flutter versions < 3.3.2 do not have this API, and per our oubspec.yaml we support Flutter >= 3.0.0.

I have not seen the class definition in other repositories, expept in dart-lang/flute, which is used for benchmarking.

I wanted to test this and downgrade to Flutter 3, but with no luck so far on macOS.

https://github.com/leoafarias/fvm

[denrase]

Like expected, we do not have access to RootIsolateToken. Installed Flutter version 3.3.10. Had to remove several sentry plugins from the example app, as those do not all support the same low SDK versions as the main package to finally get the compilation error.

denis@Deniss-MBP example % fvm doctor

FVM Version: 2.4.1
___________________________________________________

FVM config found:
___________________________________________________

Project: example
Directory: /Users/denis/Repos/sentry/sentry-dart/flutter/example
Version: 3.3.10
Project Flavor: None selected
___________________________________________________

Version is currently cached locally.

Cache Path: /Users/denis/fvm/versions/3.3.10
Channel: false
SDK Version: 3.3.10

IDE Links
VSCode: .fvm/flutter_sdk
Android Studio: /Users/denis/Repos/sentry/sentry-dart/flutter/example/.fvm/flutter_sdk


Configured env paths:
___________________________________________________

Flutter:
/Users/denis/Repos/flutter/bin/flutter

Dart:
/opt/homebrew/bin/dart

FVM_HOME:
not set

denis@Deniss-MBP example % fvm flutter run -d 6B9B6A68-2804-4447-9959-3CCAB49E9501
Launching lib/main.dart on iPhone 15 Pro in debug mode...
Running Xcode build...                                          
Xcode build done.                                            8,5s
Failed to build iOS app
Error output from Xcode build:
↳
    --- xcodebuild: WARNING: Using the first of multiple matching destinations:
    { platform:iOS Simulator, id:6B9B6A68-2804-4447-9959-3CCAB49E9501, OS:17.2, name:iPhone 15 Pro }
    { platform:iOS Simulator, id:6B9B6A68-2804-4447-9959-3CCAB49E9501, OS:17.2, name:iPhone 15 Pro }
    ** BUILD FAILED **


Xcode's output:
↳
    Writing result bundle at path:
    	/var/folders/_n/s4t83kqj137f_9465c5z63k40000gn/T/flutter_tools.3jOctp/flutter_ios_build_temp_dirGarRkE/temporary_xcresult_bundle

    ../lib/src/sentry_flutter.dart:127:14: Error: Undefined name 'RootIsolateToken'.
          return RootIsolateToken.instance != null;
                 ^^^^^^^^^^^^^^^^
    Failed to package /Users/denis/Repos/sentry/sentry-dart/flutter/example.
    Command PhaseScriptExecution failed with a nonzero exit code
    note: Run script build phase 'Run Script' will be run during every build because the option to run the script phase "Based on dependency analysis" is unchecked. (in target 'Runner' from project 'Runner')
    note: Run script build phase 'Thin Binary' will be run during every build because the option to run the script phase "Based on dependency analysis" is unchecked. (in target 'Runner' from project 'Runner')

Could not build the application for the simulator.
Error launching application on iPhone 15 Pro.
denis@Deniss-MBP example % 

[marandaneto]

RootIsolateToken.instance

@denrase background isolates is Flutter >= 3.7 So in this case, either do not use this class/field and do not set the blocked_main_thread at all or bump the min. Flutter version. Isolate.current.debugName is mutable so it can lead to false positives since it can be changed.

[denrase]

@marandaneto Exactly.

• Can't use [rootIsolateToken](https://api.flutter.dev/flutter/services/ServicesBinding/rootIsolateToken.html) without bumping the Flutter SDK.
• It is a static and we can't use the (instance as dynamic).anyMethod approach for versions < 3.7
• Using Isolate.current.debugName is not reliable.

Only way as I see it to reliably and automatically detect this is to bump to Flutter 3.7

[denrase]

@buenaflor The PR still has the caveat that users might override the debugName we are using.

https://github.com/getsentry/sentry-dart/issues/1727#issuecomment-1840756267

[buenaflor]

Let's keep this blocked by flutter min 3.7 wdyt? @denrase

[denrase]

@buenaflor Sounds good to me. 👍