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@cbracken cbracken commented Oct 17, 2024

This reverts commit 2484ae1.
This relands commit 449df25.

Migrates FlutterEngine from manual reference counting to ARC. Migrates properties from retain to strong and assign to weak (where referencing an Obj-C object).

Includes two additional fixes on top of the original:

  • In waitForFirstFrame:callback: we ensure FlutterEngine isn't released on a background thread, but instead is always freed on the platform thread.
  • In testViewControllerIsReleased we call loadView prior to calling viewDidLoad. viewDidLoad calls [FlutterEngine attachView] which calls [PlatformViewIOS::attachView] which asserts that the view is loaded.

No semantic changes, therefore no changes to tests.

Issue: flutter/flutter#137801
Issue: flutter/flutter#156177

Pre-launch Checklist

  • I read the Contributor Guide and followed the process outlined there for submitting PRs.
  • I read the Tree Hygiene wiki page, which explains my responsibilities.
  • I read and followed the Flutter Style Guide and the C++, Objective-C, Java style guides.
  • I listed at least one issue that this PR fixes in the description above.
  • I added new tests to check the change I am making or feature I am adding, or the PR is test-exempt. See testing the engine for instructions on writing and running engine tests.
  • I updated/added relevant documentation (doc comments with ///).
  • I signed the CLA.
  • All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

This reverts commit 2484ae1.
This relands commit 449df25.

Migrates `FlutterEngine` from manual reference counting to ARC. Migrates
properties from `retain` to strong and `assign` to `weak` (where
referencing an Obj-C object).

Includes two additional fixes on top of the original:
* In `waitForFirstFrame:callback:` we ensure FlutterEngine isn't
  released on a background thread, but instead is always freed on the
  platform thread.
* In `testViewControllerIsReleased` we call loadView prior to calling
  `viewDidLoad`. `viewDidLoad` calls `[FlutterEngine attachView]` which
  calls `[PlatformViewIOS::attachView]` which asserts that the view is
  loaded.

No semantic changes, therefore no changes to tests.

Issue: flutter/flutter#137801
`[FlutterViewController viewDidLoad]` calls `[FlutterEngine attachView]`
which calls `PlatformViewIOS::attachView` which asserts that the view is
loaded.
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First commit is the original patch, unmodified.
Second and third commits are the two fixes to fix the flakes.

@cbracken cbracken added the autosubmit Merge PR when tree becomes green via auto submit App label Oct 17, 2024
@auto-submit auto-submit bot merged commit 02fc8a4 into flutter:main Oct 17, 2024
@cbracken cbracken deleted the re-arc-flutterengine branch October 18, 2024 00:07
engine-flutter-autoroll added a commit to engine-flutter-autoroll/flutter that referenced this pull request Oct 18, 2024
engine-flutter-autoroll added a commit to engine-flutter-autoroll/flutter that referenced this pull request Oct 18, 2024
auto-submit bot pushed a commit to flutter/flutter that referenced this pull request Oct 18, 2024
…157143)

flutter/engine@09598f6...0bb6b1f

2024-10-18 [email protected] Move redispatch_event from FlKeyboardViewDelegate to FlKeyboardManager (flutter/engine#55941)
2024-10-18 [email protected] Remove FlKeyResponder and use the two responder classes directly. (flutter/engine#55925)
2024-10-17 [email protected] Reland "iOS: Migrate FlutterEngine to ARC" (flutter/engine#55937)
2024-10-17 [email protected] [Flutter GPU] Remove Command/VertexBuffer usage from Flutter GPU. (flutter/engine#55893)

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jonahwilliams pushed a commit that referenced this pull request Oct 18, 2024
There are still a couple closures where on engine shutdown, the last
live reference to FlutterEngine may be on a thread other than the
platform thread.

Specifically, the profiling data capture callback can result in the last
live reference to a FlutterEngine being on a profiling thread, resulting
in an assertion failure in the destructor of the PlatformViewsController
held by FlutterEngine, because PlatformViewsController holds a
WeakPtrFactory whose destructor asserts that it be on the platform
thread.

See:

https://github.com/flutter/engine/blob/ad9e4fef451a73427285826455db5fbdde502bd7/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm#L511-L515

Backtrace of such a crash:
```
=================================================================
Main Thread Checker: UI API called on a background thread: -[UIView removeFromSuperview]
PID: 46919, TID: 333147, Thread name: FlutterEngine.166.profiler, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4   libios_test_flutter.dylib           0x000000014b658aed -[FlutterTextInputPlugin dealloc] + 27
5   libobjc.A.dylib                     0x00007ff800055228 _ZN11objc_object17sidetable_releaseEbb + 204
6   libios_test_flutter.dylib           0x000000014b63df5a -[FlutterEngine .cxx_destruct] + 135
7   libobjc.A.dylib                     0x00007ff800035766 _ZL27object_cxxDestructFromClassP11objc_objectP10objc_class + 83
8   libobjc.A.dylib                     0x00007ff80004ddfc objc_destructInstance + 61
9   CoreFoundation                      0x00007ff8004a286b -[NSObject(NSObject) __dealloc_zombie] + 159
10  libios_test_flutter.dylib           0x000000014b635fea -[FlutterEngine dealloc] + 334
11  libobjc.A.dylib                     0x00007ff800055228 _ZN11objc_object17sidetable_releaseEbb + 204
12  libios_test_flutter.dylib           0x000000014b63eda9 _ZNSt3_fl10__function6__funcIZ30-[FlutterEngine startProfiler]E3$_0NS_9allocatorIS2_EEFN7flutter13ProfileSampleEvEEclEv + 69
13  libios_test_flutter.dylib           0x000000014bcd8eaa _ZNSt3_fl10__function6__funcIZNK7flutter16SamplingProfiler16SampleRepeatedlyEN3fml9TimeDeltaEE3$_0NS_9allocatorIS6_EEFvvEEclEv + 40
14  libios_test_flutter.dylib           0x000000014b868786 _ZN3fml15MessageLoopImpl10FlushTasksENS_9FlushTypeE + 156
15  libios_test_flutter.dylib           0x000000014b86ecca _ZN3fml17MessageLoopDarwin11OnTimerFireEP16__CFRunLoopTimerPS0_ + 26
16  CoreFoundation                      0x00007ff8003ea4a5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
17  CoreFoundation                      0x00007ff8003ea032 __CFRunLoopDoTimer + 801
18  CoreFoundation                      0x00007ff8003e97b6 __CFRunLoopDoTimers + 243
19  CoreFoundation                      0x00007ff8003e4028 __CFRunLoopRun + 2108
20  CoreFoundation                      0x00007ff8003e3409 CFRunLoopRunSpecific + 557
21  libios_test_flutter.dylib           0x000000014b86ee07 _ZN3fml17MessageLoopDarwin3RunEv + 65
22  libios_test_flutter.dylib           0x000000014b8686a4 _ZN3fml15MessageLoopImpl5DoRunEv + 22
23  libios_test_flutter.dylib           0x000000014b86dce5 _ZNSt3_fl10__function6__funcIZN3fml6ThreadC1ERKNS_8functionIFvRKNS3_12ThreadConfigEEEES7_E3$_0NS_9allocatorISC_EEFvvEEclEv + 135
24  libios_test_flutter.dylib           0x000000014b86da87 _ZZN3fml12ThreadHandleC1EONSt3_fl8functionIFvvEEEEN3$_08__invokeEPv + 27
25  libsystem_pthread.dylib             0x000000010d6a818b _pthread_start + 99
26  libsystem_pthread.dylib             0x000000010d6a3ae3 thread_start + 15
2024-10-18 09:31:27.549111-0700 IosUnitTests[46919:333147] [reports] Main Thread Checker: UI API called on a background thread: -[UIView removeFromSuperview]
PID: 46919, TID: 333147, Thread name: FlutterEngine.166.profiler, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4   libios_test_flutter.dylib           0x000000014b658aed -[FlutterTextInputPlugin dealloc] + 27
5   libobjc.A.dylib                     0x00007ff800055228 _ZN11objc_object17sidetable_releaseEbb + 204
6   libios_test_flutter.dylib           0x000000014b63df5a -[FlutterEngine .cxx_destruct] + 135
7   libobjc.A.dylib                     0x00007ff800035766 _ZL27object_cxxDestructFromClassP11objc_objectP10objc_class + 83
8   libobjc.A.dylib                     0x00007ff80004ddfc objc_destructInstance + 61
9   CoreFoundation                      0x00007ff8004a286b -[NSObject(NSObject) __dealloc_zombie] + 159
10  libios_test_flutter.dylib           0x000000014b635fea -[FlutterEngine dealloc] + 334
11  libobjc.A.dylib                     0x00007ff800055228 _ZN11objc_object17sidetable_releaseEbb + 204
12  libios_test_flutter.dylib           0x000000014b63eda9 _ZNSt3_fl10__function6__funcIZ30-[FlutterEngine startProfiler]E3$_0NS_9allocatorIS2_EEFN7flutter13ProfileSampleEvEEclEv + 69
13  libios_test_flutter.dylib           0x000000014bcd8eaa _ZNSt3_fl10__function6__funcIZNK7flutter16SamplingProfiler16SampleRepeatedlyEN3fml9TimeDeltaEE3$_0NS_9allocatorIS6_EEFvvEEclEv + 40
14  libios_test_flutter.dylib           0x000000014b868786 _ZN3fml15MessageLoopImpl10FlushTasksENS_9FlushTypeE + 156
15  libios_test_flutter.dylib           0x000000014b86ecca _ZN3fml17MessageLoopDarwin11OnTimerFireEP16__CFRunLoopTimerPS0_ + 26
16  CoreFoundation                      0x00007ff8003ea4a5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
17  CoreFoundation                      0x00007ff8003ea032 __CFRunLoopDoTimer + 801
18  CoreFoundation                      0x00007ff8003e97b6 __CFRunLoopDoTimers + 243
19  CoreFoundation                      0x00007ff8003e4028 __CFRunLoopRun + 2108
20  CoreFoundation                      0x00007ff8003e3409 CFRunLoopRunSpecific + 557
21  libios_test_flutter.dylib           0x000000014b86ee07 _ZN3fml17MessageLoopDarwin3RunEv + 65
22  libios_test_flutter.dylib           0x000000014b8686a4 _ZN3fml15MessageLoopImpl5DoRunEv + 22
23  libios_test_flutter.dylib           0x000000014b86dce5 _ZNSt3_fl10__function6__funcIZN3fml6ThreadC1ERKNS_8functionIFvRKNS3_12ThreadConfigEEEES7_E3$_0NS_9allocatorISC_EEFvvEEclEv + 135
24  libios_test_flutter.dylib           0x000000014b86da87 _ZZN3fml12ThreadHandleC1EONSt3_fl8functionIFvvEEEEN3$_08__invokeEPv + 27
25  libsystem_pthread.dylib             0x000000010d6a818b _pthread_start + 99
26  libsystem_pthread.dylib             0x000000010d6a3ae3 thread_start + 15
IosUnitTests(47009,0x10ec76240) malloc: enabling scribbling to detect mods to free blocks
IosUnitTests(47009) MallocStackLogging: could not tag MSL-related memory as no_footprint, so those pages will be included in process footprint - (null)
IosUnitTests(47009) MallocStackLogging: stack logs being written to /private/tmp/stack-logs.47009.1057b6000.IosUnitTests.0o4HgN.index
IosUnitTests(47009) MallocStackLogging: recording malloc and VM allocation stacks to disk using standard recorder
IosUnitTests(47009) MallocStackLogging: process 46919 no longer exists, stack logs deleted from /tmp/stack-logs.46919.10d1fc000.IosUnitTests.kFionm.index
```

This reverts commit 02fc8a4.

## Pre-launch Checklist

- [X] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [X] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [X] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [X] I listed at least one issue that this PR fixes in the description
above.
- [X] I added new tests to check the change I am making or feature I am
adding, or the PR is [test-exempt]. See [testing the engine] for
instructions on writing and running engine tests.
- [X] I updated/added relevant documentation (doc comments with `///`).
- [X] I signed the [CLA].
- [X] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

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nick9822 pushed a commit to nick9822/flutter that referenced this pull request Dec 18, 2024
This reverts commit 773c37a.
This relands commit a2ac734.

Migrates `FlutterEngine` from manual reference counting to ARC. Migrates properties from `retain` to strong and `assign` to `weak` (where referencing an Obj-C object).

Includes two additional fixes on top of the original:
* In `waitForFirstFrame:callback:` we ensure FlutterEngine isn't released on a background thread, but instead is always freed on the platform thread.
* In `testViewControllerIsReleased` we call loadView prior to calling `viewDidLoad`. `viewDidLoad` calls `[FlutterEngine attachView]` which calls `[PlatformViewIOS::attachView]` which asserts that the view is loaded.

No semantic changes, therefore no changes to tests.

Issue: flutter#137801
Issue: flutter#156177

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
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