fix: stop shader compilation on game exit

[brucenguyen]

Attempting to mitigate #1130.

Basically the game process gets held hostage by the while loop modified in this PR. Since it's technically polling already, I just added an extra check for quitGame.

To quote my comment on the issue:

Seems like SKSE behaviour (or some other mod behaviour, I didn't test on a clean setup) is to keep the process running even if closed but plugins are still loading (before menu logo). CS exacerbates this because it's technically still loading if shaders are compiling, so the process gets held hostage for longer.

While we can just force close the app, I feel like we should leave that behaviour up to SKSE. The safest solution would be to gracefully abort the shader compilation which would unblock the sleep loop for kDataLoaded, set the appropriate error states so CS is aware things weren't completed properly, then let SKSE figure out the rest.

For clarity, this does not make the process exit immediately. It just unblocks so SKSE can handle the rest of the clean up. So there's still a short delay.

I guess Unified Water could benefit from this but it doesn't take as long and most people quit the game before that point anyway.

Some further improvements:

• notify the shader cache to stop its remaining tasks, this can free up the CPU faster but won't close the process, that's still up to SKSE

Summary by CodeRabbit

• Bug Fixes
  • Prevented hangs during shutdown when shader compilation is active; quitting now proceeds reliably.
  • Added an early-exit path with logging when the app is terminating while background compilation remains.
  • Ensure shader compilation is stopped when the game window closes to improve shutdown stability and feedback.
  • Added a shutdown guard to break background wait loops promptly during exit.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a game-shutdown-aware early-exit to the shader compilation DataLoaded wait loop, introduces a global RE::Main* main set during data load, and wires window-close handling to stop in-progress shader compilation.

Changes

Cohort / File(s)	Summary
DataLoaded / shader wait src/XSEPlugin.cpp	Wait loop now also checks globals::game::main->quitGame; after the loop, returns early and logs if the game is quitting.
Globals: main pointer & lifecycle hook src/Globals.cpp, src/Globals.h	Add globals::game::main (initialized in OnDataLoaded) and declare globals::OnGameWindowClose() to expose game main and a window-close hook.
Window hook integration src/Hooks.cpp	Call globals::OnGameWindowClose() when WM_CLOSE is received in the window procedure hook.
ShaderCache stop API src/ShaderCache.cpp, src/ShaderCache.h	Add ShaderCache::StopCompilation() public method to request cancellation of ongoing shader compilation and log remaining tasks.

Sequence Diagram(s)

sequenceDiagram
  participant Window as Game Window
  participant Hook as Window Proc Hook
  participant Globals as globals::OnGameWindowClose
  participant Shader as ShaderCache

  Window->>Hook: WM_CLOSE
  Hook->>Globals: OnGameWindowClose()
  Globals->>Shader: ShaderCache::StopCompilation()
  Shader-->>Globals: stop requested / acknowledge

Loading

sequenceDiagram
  participant DataLoad as DataLoaded flow
  participant GlobalsMain as globals::game::main
  participant Shader as ShaderCache

  DataLoad->>GlobalsMain: poll main->quitGame in wait loop
  alt quitGame == true
    DataLoad->>DataLoad: log and early-exit
  else
    DataLoad->>Shader: continue disk cache / compilation flow
  end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix(filesystem): improve file deletion error handling #1217 — Touches ShaderCache (Clear/file-deletion logic); may conflict or interact with StopCompilation and cache behavior.
• Refactor ProcessCompilationSet to utilize stop token. #1121 — Implements cancellation handling for shader compilation and stop_token usage; strongly related to StopCompilation wiring.

Suggested reviewers

• doodlum
• alandtse

Poem

🐇 I watched the loop and found the sign,
A gentle quit flag saved compile time.
When windows close I hush the race,
I hop away with tidy grace. ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Merge Conflict Detection	⚠️ Warning	❌ Merge conflicts detected (34 files): ⚔️ package/Shaders/RunGrass.hlsl (content) ⚔️ src/Features/GrassLighting.h (content) ⚔️ src/Features/WeatherEditor.cpp (content) ⚔️ src/Features/WeatherEditor.h (content) ⚔️ src/Globals.cpp (content) ⚔️ src/Globals.h (content) ⚔️ src/Hooks.cpp (content) ⚔️ src/Menu.cpp (content) ⚔️ src/Menu/OverlayRenderer.cpp (content) ⚔️ src/ShaderCache.cpp (content) ⚔️ src/ShaderCache.h (content) ⚔️ src/WeatherEditor/EditorWindow.cpp (content) ⚔️ src/WeatherEditor/EditorWindow.h (content) ⚔️ src/WeatherEditor/Weather/CellLightingWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/CellLightingWidget.h (content) ⚔️ src/WeatherEditor/Weather/ImageSpaceWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/ImageSpaceWidget.h (content) ⚔️ src/WeatherEditor/Weather/LensFlareWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/LensFlareWidget.h (content) ⚔️ src/WeatherEditor/Weather/LightingTemplateWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/LightingTemplateWidget.h (content) ⚔️ src/WeatherEditor/Weather/PrecipitationWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/PrecipitationWidget.h (content) ⚔️ src/WeatherEditor/Weather/ReferenceEffectWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/ReferenceEffectWidget.h (content) ⚔️ src/WeatherEditor/Weather/VolumetricLightingWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/VolumetricLightingWidget.h (content) ⚔️ src/WeatherEditor/Weather/WeatherWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/WeatherWidget.h (content) ⚔️ src/WeatherEditor/Weather/WorldSpaceWidget.cpp (content) ⚔️ src/WeatherEditor/Weather/WorldSpaceWidget.h (content) ⚔️ src/WeatherEditor/Widget.cpp (content) ⚔️ src/WeatherEditor/Widget.h (content) ⚔️ src/XSEPlugin.cpp (content) These conflicts must be resolved before merging into dev.	Resolve conflicts locally and push changes to this branch.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: stop shader compilation on game exit' directly corresponds to the main change: adding logic to halt shader compilation when the game is closing via the StopCompilation() method and related exit handling.

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[github-actions]

Using provided base ref: b3243f3
Using base ref: b3243f3
Base commit date: 2026-02-13T10:38:46+10:00 (Friday, February 13, 2026 10:38 AM)
No actionable suggestions for changed features.

[github-actions]

✅ A pre-release build is available for this PR:
Download

[alandtse]

Are you sure this actually solves the issue? This while loops doesn't control the shader compile tasks, it controls whether the CS menu will become visible/usable.

The control of compilation loop is in the shader cache. You would have to pass the stop to the bstaskpool so each of the compilation items stop.

[brucenguyen]

Are you sure this actually solves the issue? This while loops doesn't control the shader compile tasks, it controls whether the CS menu will become visible/usable.

The control of compilation loop is in the shader cache. You would have to pass the stop to the bstaskpool so each of the compilation items stop.

Unfortunately the root cause of the issue doesn't seem to be CS itself. Without CS installed, I can reproduce it, so it's something with either the Skyrim engine or SKSE. The cache threads themselves don't seem to be causing issues.

TLDR: game will not close until main menu is loaded, CS shader cache does not let main menu load, so process keeps running until shader cache is done.

Perhaps the PR title is a misnomer, that's on me.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/XSEPlugin.cpp`:
- Around line 117-126: Add a null check for globals::game::main before
dereferencing it: after assigning auto* main = globals::game::main check if main
is nullptr and if so log a warning via logger::info (or similar) and break out
of the loop; only enter the while that checks shaderCache->IsCompiling() /
shaderCache->backgroundCompilation and inspect main->quitGame if main is
non-null, and likewise guard the subsequent if (main->quitGame) branch so main
is not dereferenced when null.

[brucenguyen]

Ok I've gone ahead and notified the shader cache task pool to stop when the game is closed. Though I couldn't find if there was an existing way to listen to game close so I added a function in globals. Turns out that freeing up resources will get to the main menu more quickly.

I've left the main->quitGame check so we can skip the feature DataLoaded calls, the intention is to avoid running Unified Water caching which will delay the process exit further.

Still sort of new to the codebase so feel free to be nitpicky.

[alandtse]

If you've tested and this solves it, I'm good. Please do resolve the last issue about the nullptr check for Main. (i.e., click it closed).

[brucenguyen]

Based on rough testing:

• Before - Process hung until shader compilation was finished (5+ min) with high CPU usage.
• Initial changes - Process hung for about 1 minute before closing with high CPU usage.
• Recent changes - CPU usage relieved immediately. Process hung for ~30s, which is similar to without CS installed on my Skyrim setup