CNA-BUG-078: Game::PollEvents fires the renderer's test-only context-loss hooks on F9/F10 in every build

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

A non-repeated F9 or F10 press in any CNA game calls the renderer's DebugSimulateContextLoss() or DebugRestoreContext(), a channel CNA itself describes as a test seam, with no build, option or opt-out guard.

Identifier

CNA-BUG-078

Category

Bug

Subsystem

Core & runtime

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Severity

Medium (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

Microsoft::Xna::Framework::Game::Run() / Tick() (through the private PollEvents); CNA::Internal::Renderers::IGraphicsRenderer::DebugSimulateContextLoss() and DebugRestoreContext()

Expected behaviour

XNA's Game reserves no keys: a key press only reaches the game's input state. CNA's own sources call the DebugSimulateContextLoss()/DebugRestoreContext() channel “one-directional and test-only” (the RendererDeviceEvent comment in IGraphicsRenderer.hpp) and “a deliberate, named test seam” (GraphicsDevice.cpp), and the DirectX 11 header documents the hook as entering “the deterministic lost-device state used by lifecycle tests”. A shipped game should therefore not reach it from a player's key press, or only through an explicit debug opt-in.

Actual behaviour at TARGET

• After passing each event to PlatformInputBridge::ProcessEvent, Game::PollEvents calls GraphicsDevice_.GetRenderer().DebugSimulateContextLoss() for a pressed, non-repeated KeyCode::F9 and DebugRestoreContext() for F10, unconditionally (no build, option or opt-out guard). The game still sees the key, and the framework action happens as well. What the press does depends on the renderer (read at 009d40f5):
• EasyGL on the desktop: F9 and F10 both print a line to std::cerr, notify MetaGL of a context loss, recreate the native context through the platform, reload the GL entry points and recreate every registered resource. EasyGLTextureRenderer::recreate_gl_resource re-uploads level 0 from the CPU shadow; DXT1/DXT3/DXT5 textures are re-uploaded from their retained compressed blocks (UploadLevel falls back to compressedLevels_ when it is given no pixels); a texture with no surviving shadow (context recovery disabled) is re-created as zeros.
• DirectX 9, 11 and 12: F9 marks the device lost and reports RendererDeviceEvent::Lost; the DirectX 11 and 12 renderers then refuse CanBeginDrawEXT(), so the game stops drawing until F10 performs the reset.
• Direct2D: F9 recreates the complete device-resource domain.
• WebGPU: F9 throws System::NotSupportedException while a TextureCube, RenderTargetCube, Texture3D, occlusion query or custom ShaderEffect is alive; nothing in PollEvents, Tick or Run catches it, so natively it ends Run() and in the browser loop it is logged and the loop stops.
• GDI overrides both hooks with empty bodies; the remaining renderers use the no-op defaults.

Source locations

• modules/runtime/src/Game.cpp — Game::PollEvents, KeyEvent branch
• modules/graphics/include/CNA/Internal/Renderers/Common/IGraphicsRenderer.hpp — DebugSimulateContextLoss/DebugRestoreContext defaults; RendererDeviceEvent comment calling the channel test-only
• modules/graphics/src/Xna/GraphicsDevice.cpp — isRendererListedIn comment naming the channel a test seam
• modules/renderers/easygl/src/EasyGLRenderer.cpp — EasyGLRenderer::DebugSimulateContextLoss / DebugRestoreContext; EasyGLTextureRenderer::recreate_gl_resource
• modules/renderers/directx11/src/DirectX11Renderer.cpp — DirectX11Renderer::DebugSimulateContextLoss / DebugRestoreContext
• modules/renderers/webgpu/src/WebGPURenderer.cpp — WebGPURenderer::DebugSimulateContextLoss refusal (NotSupportedException)
• modules/runtime/tests/Microsoft/Xna/Framework/GameEventSemanticsGoldenTests.cpp — debug-hotkey-f9 scenarios in the golden event transcript

Evidence

Checked by reading Game.cpp (PollEvents) and every override of the two hooks at 009d40f5 (EasyGL, DirectX 9/11/12, Direct2D, WebGPU, GDI). GameEventSemanticsGoldenTests.cpp records a debug-hotkey-f9 scenario, so the key handling is known and pinned as observable behaviour; nothing documents it as a user-facing feature. Not executed.

Uncertain: the exact visible effect on each Direct3D family (whether a game notices beyond the paused drawing) and whether any CNA sample binds F9 or F10.

Independently observed as a separate finding (merged): A non-repeated F9 or F10 press in any CNA game calls the renderer's DebugSimulateContextLoss() or DebugRestoreContext(), which CNA describes as a test seam, with no build guard or opt-out.

Independently observed as a separate finding (merged): Any F9 press calls DebugSimulateContextLoss and any F10 press DebugRestoreContext on the active renderer, in release builds too, and games cannot turn it off.

Independent re-verification: Checked by reading Game.cpp (PollEvents) and every override of the two hooks at 009d40f5 (EasyGL, DirectX 9/11/12, Direct2D, WebGPU, GDI). The earlier statement that DXT textures come back blank on EasyGL is withdrawn: UploadLevel takes the retained compressed blocks from compressedLevels_ when recreate_gl_resource passes no pixels, so the reproduction's 'DXT texture is re-created without data' does not occur; the visible EasyGL effect is the two stderr lines and a full context recreation. The golden transcript records a debug-hotkey-f9 scenario, so the handler is known and pinned as observable behaviour; nothing documents it as a user-facing feature. Not executed.

Focused reproduction

Illustrative: any game on an EasyGL desktop profile. Run it with at least one DXT-compressed texture loaded and press F9; the standard error stream receives “[CNA] Simulating desktop GL context loss + immediate recreate” and the DXT texture is re-created without data. On WebGPU, create a TextureCube and press F9: Run() ends with System::NotSupportedException.

Current tests

The golden transcript (platform-event-semantics.txt) runs the F9 press and the F9 repeat through a real Game::RunOneFrame() and captures public state only; renderer-side recovery tests (for example webgpu_context_recovery_test, easygl_gltf_context_loss_test) call the hooks directly. No test asserts that an ordinary key press leaves the renderer alone.

Regression test

A runtime test with a renderer double that counts DebugSimulateContextLoss() calls: feed a non-repeated F9 KeyEvent through GameTestPeer::PollEvents and expect zero calls unless the chosen opt-in (a build option or a CNAEXT property) is enabled. Update the golden transcript accordingly.

Blast radius

Every Game on every platform that delivers key events, on the EasyGL, DirectX 9/11/12, Direct2D and WebGPU renderer families. Games that use F9 or F10 as gameplay keys (quick-save and quick-load are common bindings) trigger it on every press. Headless, software and other renderers with the default no-op hooks are unaffected, as are games driven without PollEvents.

Workaround

No workaround is known.