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[win32] Fix overflow in TaskRunnerWindow. #182822

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Merged
knopp merged 5 commits into from
Feb 24, 2026
Merged

[win32] Fix overflow in TaskRunnerWindow. #182822

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bbb2992
[win32] Empty TaskRunner::ProcessTasks must return nanoseconds::max.
knopp Feb 24, 2026
40f941e
Add comment
knopp Feb 24, 2026
b39058e
Fix typo
knopp Feb 24, 2026
ca439ec
Update TaskRunnerWindow::SetTimer to prevent overflow.
knopp Feb 24, 2026
6da471c
Remove obsolete comment.
knopp Feb 24, 2026
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9 changes: 5 additions & 4 deletions engine/src/flutter/shell/platform/windows/task_runner.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -63,10 +63,11 @@ std::chrono::nanoseconds TaskRunner::ProcessTasks() {
// Calculate duration to sleep for on next iteration.
{
std::lock_guard<std::mutex> lock(task_queue_mutex_);
const auto next_wake = task_queue_.empty() ? TaskTimePoint::max()
: task_queue_.top().fire_time;

return std::min(next_wake - now, std::chrono::nanoseconds::max());
if (task_queue_.empty()) {
return std::chrono::nanoseconds::max();
} else {
return task_queue_.top().fire_time - now;
}
}
}

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6 changes: 6 additions & 0 deletions engine/src/flutter/shell/platform/windows/task_runner_unittests.cc
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Expand Up @@ -121,6 +121,12 @@ class TestTaskRunnerWindow : public TaskRunnerWindow {
TestTaskRunnerWindow() : TaskRunnerWindow() {}
};

TEST(TaskRunnerTest, EmptyTaskRunnerReturnsNanoSecondsMax) {
TaskRunner runner(MockGetCurrentTime, [](const FlutterTask*) {});
auto res = runner.ProcessTasks();
EXPECT_EQ(res, std::chrono::nanoseconds::max());
}

TEST(TaskRunnerTest, TaskRunnerWindowCoalescesWakeUpMessages) {
class Delegate : public TaskRunnerWindow::Delegate {
public:
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11 changes: 5 additions & 6 deletions engine/src/flutter/shell/platform/windows/task_runner_window.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -185,12 +185,11 @@ void TaskRunnerWindow::ProcessTasks() {
}

void TaskRunnerWindow::SetTimer(std::chrono::nanoseconds when) {
if (when == std::chrono::nanoseconds::max()) {
timer_thread_.ScheduleAt(
std::chrono::time_point<std::chrono::high_resolution_clock>::max());
} else {
timer_thread_.ScheduleAt(std::chrono::high_resolution_clock::now() + when);
}
auto now = std::chrono::high_resolution_clock::now();
auto remaining_to_max =
std::chrono::nanoseconds::max() - now.time_since_epoch();
when = std::min(when, remaining_to_max);
timer_thread_.ScheduleAt(now + when);
}

WNDCLASS TaskRunnerWindow::RegisterWindowClass() {
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