timing refactor

tests/RenderCadenceCompositorFrameExchangeTests.cpp

@@ -57,32 +57,29 @@ void TestAcquirePublishesAndSchedules()
 	Expect(metrics.scheduledFrames == 1, "scheduled metric is counted");
 }
 
-void TestAcquireDropsOldestCompletedUnscheduled()
+void TestAcquirePreservesCompletedFrames()
 {
 	SystemFrameExchange exchange(MakeConfig(2));
 
 	SystemFrame first;
 	SystemFrame second;
 	SystemFrame third;
-	Expect(exchange.AcquireForRender(first), "first frame can be acquired");
+	Expect(exchange.AcquireForRender(first), "first preserving frame can be acquired");
 	first.frameIndex = 1;
-	Expect(exchange.PublishCompleted(first), "first frame can be completed");
-	Expect(exchange.AcquireForRender(second), "second frame can be acquired");
+	Expect(exchange.PublishCompleted(first), "first preserving frame can be completed");
+	Expect(exchange.AcquireForRender(second), "second preserving frame can be acquired");
 	second.frameIndex = 2;
-	Expect(exchange.PublishCompleted(second), "second frame can be completed");
+	Expect(exchange.PublishCompleted(second), "second preserving frame can be completed");
 
-	Expect(exchange.AcquireForRender(third), "third acquire drops the oldest completed frame");
-	Expect(third.index == first.index, "oldest completed slot is reused");
+	Expect(!exchange.AcquireForRender(third), "render acquire refuses to drop completed frames");
 
 	SystemFrame scheduled;
-	Expect(exchange.ConsumeCompletedForSchedule(scheduled), "remaining completed frame can be scheduled");
-	Expect(scheduled.index == second.index, "newer completed frame survives drop");
-	Expect(scheduled.frameIndex == 2, "newer frame index survives drop");
+	Expect(exchange.ConsumeCompletedForSchedule(scheduled), "oldest completed frame survives acquire miss");
+	Expect(scheduled.frameIndex == 1, "preserving acquire keeps FIFO output continuity");
 
 	SystemFrameExchangeMetrics metrics = exchange.Metrics();
-	Expect(metrics.completedDrops == 1, "drop metric is counted");
-	Expect(metrics.renderingCount == 1, "reused slot is rendering");
-	Expect(metrics.scheduledCount == 1, "consumed slot is scheduled");
+	Expect(metrics.completedDrops == 0, "preserving acquire does not count completed drops");
+	Expect(metrics.acquireMisses == 1, "preserving acquire miss is counted");
 }
 
 void TestScheduledFramesAreNotDropped()
@@ -179,7 +176,7 @@ void TestStableCompletedDepthTimesOut()
 int main()
 {
 	TestAcquirePublishesAndSchedules();
-	TestAcquireDropsOldestCompletedUnscheduled();
+	TestAcquirePreservesCompletedFrames();
 	TestScheduledFramesAreNotDropped();
 	TestGenerationValidationRejectsStaleFrames();
 	TestPixelFormatAwareSizing();