Fix ios_WaitTimer ceiling rounding and tighten unit test timing assertions

Agent-Logs-Url: https://github.com/microsoft/libHttpClient/sessions/8aa3ddd0-2395-4c1e-b6a0-b407f9877369

Co-authored-by: jhugard <250834+jhugard@users.noreply.github.com>

Author: Copilot

Source/Task/iOS/ios_WaitTimer.mm

@@ -55,9 +55,13 @@ uint64_t DueTimeFromDeadline(Deadline deadline) noexcept
     Cancel();
 
     // NSTimer consumes a relative interval, so convert the stored steady-clock
-    // deadline back into a relative delay right before arming it.
-    auto timePoint = DeadlineFromDueTime(dueTime) - Clock::now();
-    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(timePoint);
+    // deadline back into a relative delay right before arming it. Use ceiling
+    // rounding so that a sub-millisecond remainder is rounded up rather than
+    // truncated to zero, and clamp to zero so a past deadline never produces a
+    // negative interval that would cause a tight re-arm loop.
+    auto remaining = DeadlineFromDueTime(dueTime) - Clock::now();
+    auto ms = std::max(std::chrono::milliseconds(0),
+                       std::chrono::ceil<std::chrono::milliseconds>(remaining));
 
     m_timer = [NSTimer scheduledTimerWithTimeInterval:ms.count() / 1000.0
                                                 target:m_target

Tests/UnitTests/Tests/TaskQueueTests.cpp

@@ -2182,9 +2182,10 @@ DEFINE_TEST_CLASS(TaskQueueTests)
 
         VERIFY_IS_TRUE(siblingState.invoked.load(std::memory_order_acquire));
         VERIFY_IS_FALSE(siblingState.canceled.load(std::memory_order_acquire));
+        // The sibling delay is 300 ms; allow up to 50 ms of scheduling jitter.
         VERIFY_IS_GREATER_THAN_OR_EQUAL(
             siblingState.firedAtTicks.load(std::memory_order_acquire) - siblingSubmittedAt,
-            static_cast<uint64_t>(200));
+            static_cast<uint64_t>(250));
 
         XTaskQueueTerminate(siblingQueue, false, nullptr, nullptr);
         while (XTaskQueueDispatch(root, XTaskQueuePort::Work, 0))
@@ -2229,6 +2230,7 @@ DEFINE_TEST_CLASS(TaskQueueTests)
             &firstState,
             &CallbackState::Invoke));
 
+        const uint64_t secondSubmittedAt = GetTickCount64();
         VERIFY_SUCCEEDED(XTaskQueueSubmitDelayedCallback(
             queue,
             XTaskQueuePort::Work,
@@ -2257,8 +2259,9 @@ DEFINE_TEST_CLASS(TaskQueueTests)
         VERIFY_IS_TRUE(XTaskQueueDispatch(queue, XTaskQueuePort::Work, 2000));
         VERIFY_IS_TRUE(secondState.invoked.load(std::memory_order_acquire));
         VERIFY_IS_FALSE(secondState.canceled.load(std::memory_order_acquire));
+        // The second delay is 1000 ms; allow up to 100 ms of scheduling jitter.
         VERIFY_IS_GREATER_THAN_OR_EQUAL(
-            secondState.firedAtTicks.load(std::memory_order_acquire) - submittedAt,
-            static_cast<uint64_t>(600));
+            secondState.firedAtTicks.load(std::memory_order_acquire) - secondSubmittedAt,
+            static_cast<uint64_t>(900));
     }
 };