Clock updates

apps/RenderCadenceCompositor/frames/InputFrameMailbox.cpp

@@ -112,6 +112,7 @@ bool InputFrameMailbox::SubmitFrame(const void* bytes, unsigned rowBytes, uint64
 	slot.frameIndex = frameIndex;
 	++slot.generation;
 	mReadyIndices.push_back(slotIndex);
+	TrimReadyFramesLocked();
 	++mCounters.submittedFrames;
 	mCounters.latestFrameIndex = frameIndex;
 	mCounters.hasSubmittedFrame = true;
@@ -151,6 +152,27 @@ bool InputFrameMailbox::TryAcquireLatest(InputFrame& frame)
 	return false;
 }
 
+bool InputFrameMailbox::TryAcquireOldest(InputFrame& frame)
+{
+	std::lock_guard<std::mutex> lock(mMutex);
+	while (!mReadyIndices.empty())
+	{
+		const std::size_t index = mReadyIndices.front();
+		mReadyIndices.pop_front();
+		if (index >= mSlots.size() || mSlots[index].state != InputFrameSlotState::Ready)
+			continue;
+
+		mSlots[index].state = InputFrameSlotState::Reading;
+		FillFrameLocked(index, frame);
+		++mCounters.consumedFrames;
+		return true;
+	}
+
+	frame = InputFrame();
+	++mCounters.consumeMisses;
+	return false;
+}
+
 bool InputFrameMailbox::Release(const InputFrame& frame)
 {
 	std::lock_guard<std::mutex> lock(mMutex);
@@ -246,6 +268,14 @@ bool InputFrameMailbox::DropOldestReadyLocked()
 	return false;
 }
 
+void InputFrameMailbox::TrimReadyFramesLocked()
+{
+	if (mConfig.maxReadyFrames == 0)
+		return;
+	while (mReadyIndices.size() > mConfig.maxReadyFrames)
+		DropOldestReadyLocked();
+}
+
 std::size_t InputFrameMailbox::FrameByteCount() const
 {
 	return static_cast<std::size_t>(mConfig.rowBytes) * static_cast<std::size_t>(mConfig.height);