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[iOS] Soften TaskRunner.postTask(delay:task:) delay check#185729

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cbracken:soften-delay-check
Apr 29, 2026
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[iOS] Soften TaskRunner.postTask(delay:task:) delay check#185729
cbracken merged 1 commit into
flutter:masterfrom
cbracken:soften-delay-check

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@cbracken cbracken commented Apr 29, 2026

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Previously, we were performing a hard check that the task was executed at least 100ms after it was posted. All clocks in our tests make use of mach_absolute_time() under the hood, including std::chrono::steady_clock from libcxx, but error could be introduced from at least two sources:

  • Floating point rounding, particularly with 0.1; we could fix this by using 0.25 instead. Pretty low chance of triggering a failure, but certainly possible.
  • Clock drift, e.g. due to a really badly timed NTP update. Exceedingly unlikely but possible, and probably maddening if it did occur.

Issue: #157140

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@cbracken cbracken requested a review from a team as a code owner April 29, 2026 08:28
@flutter-dashboard flutter-dashboard Bot added the CICD Run CI/CD label Apr 29, 2026
@github-actions github-actions Bot added platform-ios iOS applications specifically engine flutter/engine related. See also e: labels. team-ios Owned by iOS platform team labels Apr 29, 2026
@cbracken cbracken requested a review from hellohuanlin April 29, 2026 08:28
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Code Review

This pull request modifies the testPostDelayedTask in TaskRunnerTests.swift to include an epsilon tolerance in the timing assertion. A review comment suggests reducing the epsilon value from 0.05 to 0.001 to ensure the test remains valid and does not allow tasks to execute significantly earlier than the intended delay.

Comment thread engine/src/flutter/shell/platform/darwin/ios/framework/Source/TaskRunnerTests.swift Outdated
@cbracken
[iOS] Soften TaskRunner.postTask(delay:task:) delay check
bf92698 
Previously, we were performing a hard check that the task was executed
at least 100ms after it was posted. All clocks in our tests make use of
mach_absolute_time() under the hood, including std::chrono::steady_clock 
from libcxx, but error could be introduced from at least two sources:

* Floating point rounding, particularly with 0.1; we could fix this by
  using 0.25 instead. Pretty low chance of triggering a failure, but
  certainly possible.
* Clock drift, e.g. due to a really badly timed NTP update. Exceedingly
  unlikely but possible, and probably maddening if it did occur.

Issue: flutter#157140
@cbracken cbracken force-pushed the soften-delay-check branch from 94a67d3 to bf92698 Compare April 29, 2026 09:19
@github-actions github-actions Bot removed the CICD Run CI/CD label Apr 29, 2026
@cbracken cbracken added the CICD Run CI/CD label Apr 29, 2026
@cbracken cbracken mentioned this pull request Apr 29, 2026
Merged
10 tasks
@cbracken cbracken added this pull request to the merge queue Apr 29, 2026
Merged via the queue into flutter:master with commit ac260a4 Apr 29, 2026
195 checks passed
@cbracken cbracken deleted the soften-delay-check branch April 29, 2026 22:17
This was referenced Apr 30, 2026
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auto-submit Bot pushed a commit to flutter/packages that referenced this pull request May 1, 2026
@engine-flutter-autoroll
Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions) (#11630)
a8e3cce 
Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions)

flutter/flutter@81bc3d6...707dbc0

2026-05-01 Rusino@users.noreply.github.com Removing TODOs from the WebParagraph code and addressing technical debts. (flutter/flutter#185168)
2026-05-01 mbrase@google.com Ensure that vulkan_interface.h gets included before vk_mem_alloc.h (flutter/flutter#185777)
2026-05-01 nshahan@google.com [flutter_tools] Bump dwds dependency to v27.1.1 (flutter/flutter#185357)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from 6d4a319cbdac to 9aa7097f2e3e (3 revisions) (flutter/flutter#185888)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from fa1dcb289709 to 7ac6d42f2fd0 (1 revision) (flutter/flutter#185887)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 54cc00adde38 to fa1dcb289709 (3 revisions) (flutter/flutter#185880)
2026-05-01 chris@bracken.jp [iOS] Migrate to FlutterFMLTaskRunner(s) (flutter/flutter#185815)
2026-05-01 ad13dtu@gmail.com Remove material imports from navigator_on_did_remove_page_test and scrollable_in_overlay_test (flutter/flutter#182546)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 2e279266f06a to 54cc00adde38 (3 revisions) (flutter/flutter#185872)
2026-05-01 srawlins@google.com dev: Remove unused parameters (flutter/flutter#185345)
2026-05-01 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from HN5VYzftnf_B8T-n9... to VnzuUefDQR0UhQ1L1... (flutter/flutter#185870)
2026-05-01 robert.ancell@canonical.com Use g_free when using glib memory allocation (flutter/flutter#185519)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from d30df3428f2e to 6d4a319cbdac (2 revisions) (flutter/flutter#185862)
2026-05-01 73785960+xfce0@users.noreply.github.com Remove trivial test utility cross-imports from material and cupertino… (flutter/flutter#184295)
2026-05-01 129008657+DaveT1991@users.noreply.github.com Inline test callback painter in tab scaffold test (flutter/flutter#184851)
2026-05-01 jhy03261997@gmail.com [a11y] Add support for high contrast themes in the a11y assessments app  (flutter/flutter#185801)
2026-05-01 jhy03261997@gmail.com [a11y assessment app] Use default color for banner (flutter/flutter#185804)
2026-04-30 73091075+MohamedRisaldarTA@users.noreply.github.com Added name to AUTHORS (flutter/flutter#185586)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from raw_material_button_test.dart (flutter/flutter#184806)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from user_accounts_drawer_header_test.dart (flutter/flutter#184809)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 7b88c5c281e5 to 2e279266f06a (5 revisions) (flutter/flutter#185854)
2026-04-30 evanwall@buffalo.edu Handle symmetric rectangular and elliptical round super ellipses in the uber SDF renderer  (flutter/flutter#185695)
2026-04-30 15619084+vashworth@users.noreply.github.com Match on process name before killing for SwiftPM (flutter/flutter#185774)
2026-04-30 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185838)
2026-04-30 engine-flutter-autoroll@skia.org Roll Dart SDK from 25910e31a6d2 to d30df3428f2e (5 revisions) (flutter/flutter#185839)
2026-04-30 brackenavaron@gmail.com Check cross imports test subfolders (flutter/flutter#185493)
2026-04-30 112751483+shivanshu877@users.noreply.github.com test: inline TestCallbackPainter in cupertino/picker_test.dart (flutter/flutter#185398)
2026-04-30 97480502+b-luk@users.noreply.github.com Update customer testing version (flutter/flutter#185830)
2026-04-30 jason-simmons@users.noreply.github.com Adapt the Metal shader library output list for debug versus release mode (flutter/flutter#185798)
2026-04-30 jason-simmons@users.noreply.github.com [Impeller] Port a recent Vulkan swapchain fence waiting fix to the AHB version of the swapchain (flutter/flutter#185763)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 26a59aa71eff to 7b88c5c281e5 (1 revision) (flutter/flutter#185821)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 6b4167b4e204 to 26a59aa71eff (4 revisions) (flutter/flutter#185808)
2026-04-30 jhy03261997@gmail.com [a11y] Mark SemanticsNode dirty when customSemanticsActions change  (flutter/flutter#185707)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 1bd2f1cc2746 to 6b4167b4e204 (8 revisions) (flutter/flutter#185799)
2026-04-30 chris@bracken.jp [iOS] Extract FlutterVSyncClient from vsync_waiter_ios (flutter/flutter#185737)
2026-04-30 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from nnv8-SSam6yE8dw4z... to HN5VYzftnf_B8T-n9... (flutter/flutter#185782)
2026-04-29 chris@bracken.jp [iOS] Soften TaskRunner.postTask(delay:task:) delay check (flutter/flutter#185729)
2026-04-29 koji.wakamiya@gmail.com Add reportErrors to ImageStreamListener (flutter/flutter#180327)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from f5c781c083c7 to 1bd2f1cc2746 (5 revisions) (flutter/flutter#185761)
2026-04-29 47866232+chunhtai@users.noreply.github.com Update merge semantics logic to merge sibling nodes (flutter/flutter#183745)
2026-04-29 engine-flutter-autoroll@skia.org Roll Packages from ba80f8f to cde5b36 (12 revisions) (flutter/flutter#185748)
2026-04-29 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185346)
2026-04-29 nate.w5687@gmail.com Update TickerMode.getValuesNotifier to handle initialization during State.dispose (flutter/flutter#185248)
2026-04-29 katelovett@google.com Update triage links (flutter/flutter#185714)
2026-04-29 42399845+xxxOVALxxx@users.noreply.github.com Add support for high contrast and color inversion on Android (flutter/flutter#182263)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from 05251260fda6 to f5c781c083c7 (2 revisions) (flutter/flutter#185743)
...
creatorpiyush pushed a commit to creatorpiyush/packages that referenced this pull request Jun 10, 2026
@engine-flutter-autoroll
Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions) (flutte…
f0ac9fe 
…r#11630)

Roll Flutter from 81bc3d69535f to 707dbc0420a3 (85 revisions)

flutter/flutter@81bc3d6...707dbc0

2026-05-01 Rusino@users.noreply.github.com Removing TODOs from the WebParagraph code and addressing technical debts. (flutter/flutter#185168)
2026-05-01 mbrase@google.com Ensure that vulkan_interface.h gets included before vk_mem_alloc.h (flutter/flutter#185777)
2026-05-01 nshahan@google.com [flutter_tools] Bump dwds dependency to v27.1.1 (flutter/flutter#185357)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from 6d4a319cbdac to 9aa7097f2e3e (3 revisions) (flutter/flutter#185888)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from fa1dcb289709 to 7ac6d42f2fd0 (1 revision) (flutter/flutter#185887)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 54cc00adde38 to fa1dcb289709 (3 revisions) (flutter/flutter#185880)
2026-05-01 chris@bracken.jp [iOS] Migrate to FlutterFMLTaskRunner(s) (flutter/flutter#185815)
2026-05-01 ad13dtu@gmail.com Remove material imports from navigator_on_did_remove_page_test and scrollable_in_overlay_test (flutter/flutter#182546)
2026-05-01 engine-flutter-autoroll@skia.org Roll Skia from 2e279266f06a to 54cc00adde38 (3 revisions) (flutter/flutter#185872)
2026-05-01 srawlins@google.com dev: Remove unused parameters (flutter/flutter#185345)
2026-05-01 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from HN5VYzftnf_B8T-n9... to VnzuUefDQR0UhQ1L1... (flutter/flutter#185870)
2026-05-01 robert.ancell@canonical.com Use g_free when using glib memory allocation (flutter/flutter#185519)
2026-05-01 engine-flutter-autoroll@skia.org Roll Dart SDK from d30df3428f2e to 6d4a319cbdac (2 revisions) (flutter/flutter#185862)
2026-05-01 73785960+xfce0@users.noreply.github.com Remove trivial test utility cross-imports from material and cupertino… (flutter/flutter#184295)
2026-05-01 129008657+DaveT1991@users.noreply.github.com Inline test callback painter in tab scaffold test (flutter/flutter#184851)
2026-05-01 jhy03261997@gmail.com [a11y] Add support for high contrast themes in the a11y assessments app  (flutter/flutter#185801)
2026-05-01 jhy03261997@gmail.com [a11y assessment app] Use default color for banner (flutter/flutter#185804)
2026-04-30 73091075+MohamedRisaldarTA@users.noreply.github.com Added name to AUTHORS (flutter/flutter#185586)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from raw_material_button_test.dart (flutter/flutter#184806)
2026-04-30 sanaullah.383@hotmail.com Remove semantics_tester import from user_accounts_drawer_header_test.dart (flutter/flutter#184809)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 7b88c5c281e5 to 2e279266f06a (5 revisions) (flutter/flutter#185854)
2026-04-30 evanwall@buffalo.edu Handle symmetric rectangular and elliptical round super ellipses in the uber SDF renderer  (flutter/flutter#185695)
2026-04-30 15619084+vashworth@users.noreply.github.com Match on process name before killing for SwiftPM (flutter/flutter#185774)
2026-04-30 154381524+flutteractionsbot@users.noreply.github.com Sync CHANGELOG.md from stable (flutter/flutter#185838)
2026-04-30 engine-flutter-autoroll@skia.org Roll Dart SDK from 25910e31a6d2 to d30df3428f2e (5 revisions) (flutter/flutter#185839)
2026-04-30 brackenavaron@gmail.com Check cross imports test subfolders (flutter/flutter#185493)
2026-04-30 112751483+shivanshu877@users.noreply.github.com test: inline TestCallbackPainter in cupertino/picker_test.dart (flutter/flutter#185398)
2026-04-30 97480502+b-luk@users.noreply.github.com Update customer testing version (flutter/flutter#185830)
2026-04-30 jason-simmons@users.noreply.github.com Adapt the Metal shader library output list for debug versus release mode (flutter/flutter#185798)
2026-04-30 jason-simmons@users.noreply.github.com [Impeller] Port a recent Vulkan swapchain fence waiting fix to the AHB version of the swapchain (flutter/flutter#185763)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 26a59aa71eff to 7b88c5c281e5 (1 revision) (flutter/flutter#185821)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 6b4167b4e204 to 26a59aa71eff (4 revisions) (flutter/flutter#185808)
2026-04-30 jhy03261997@gmail.com [a11y] Mark SemanticsNode dirty when customSemanticsActions change  (flutter/flutter#185707)
2026-04-30 engine-flutter-autoroll@skia.org Roll Skia from 1bd2f1cc2746 to 6b4167b4e204 (8 revisions) (flutter/flutter#185799)
2026-04-30 chris@bracken.jp [iOS] Extract FlutterVSyncClient from vsync_waiter_ios (flutter/flutter#185737)
2026-04-30 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from nnv8-SSam6yE8dw4z... to HN5VYzftnf_B8T-n9... (flutter/flutter#185782)
2026-04-29 chris@bracken.jp [iOS] Soften TaskRunner.postTask(delay:task:) delay check (flutter/flutter#185729)
2026-04-29 koji.wakamiya@gmail.com Add reportErrors to ImageStreamListener (flutter/flutter#180327)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from f5c781c083c7 to 1bd2f1cc2746 (5 revisions) (flutter/flutter#185761)
2026-04-29 47866232+chunhtai@users.noreply.github.com Update merge semantics logic to merge sibling nodes (flutter/flutter#183745)
2026-04-29 engine-flutter-autoroll@skia.org Roll Packages from ba80f8f to cde5b36 (12 revisions) (flutter/flutter#185748)
2026-04-29 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185346)
2026-04-29 nate.w5687@gmail.com Update TickerMode.getValuesNotifier to handle initialization during State.dispose (flutter/flutter#185248)
2026-04-29 katelovett@google.com Update triage links (flutter/flutter#185714)
2026-04-29 42399845+xxxOVALxxx@users.noreply.github.com Add support for high contrast and color inversion on Android (flutter/flutter#182263)
2026-04-29 engine-flutter-autoroll@skia.org Roll Skia from 05251260fda6 to f5c781c083c7 (2 revisions) (flutter/flutter#185743)
...
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