fix: compiler remaining tasks

[davo0411]

[15:54:03.843] [28964] [I] [ShaderTiming] Very slow 12317ms | queue_wait=0ms | remaining=18446744073709551615 | defines=5 | src=111008B | prio=3350 | Lighting:Pixel:GLINT TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_VARIATION TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS LANDSCAPE MULTI_TEXTURE ANISO_LIGHTING VC

Previously it shows something like that ^ with nonsense for "remaining"
Now correctly shows the below, accurately counting down the remaining shaders to compile:
[16:52:52.354] [28832] [I] [ShaderTiming] Very slow 11714ms | queue_wait=115ms | remaining=5 | defines=4 | src=109690B | prio=2320 | Lighting:Pixel:GLINT TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS ANISO_LIGHTING VC
[16:52:52.638] [8144 ] [I] [ShaderTiming] Very slow 12022ms | queue_wait=52ms | remaining=4 | defines=5 | src=109690B | prio=2350 | Lighting:Pixel:GLINT TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS ANISO_LIGHTING DO_ALPHA_TEST VC
[16:53:07.486] [24744] [I] [ShaderTiming] Very slow 26880ms | queue_wait=49ms | remaining=3 | defines=6 | src=109690B | prio=3080 | Lighting:Pixel:TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_VARIATION TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS LOD_LAND_BLEND LANDSCAPE MULTI_TEXTURE VC
[16:53:13.901] [10880] [I] [ShaderTiming] Very slow 33314ms | queue_wait=30ms | remaining=2 | defines=5 | src=109690B | prio=3350 | Lighting:Pixel:GLINT TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_VARIATION TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS LANDSCAPE MULTI_TEXTURE ANISO_LIGHTING VC
[16:53:14.455] [8924 ] [I] [ShaderTiming] Very slow 33895ms | queue_wait=2ms | remaining=1 | defines=7 | src=109690B | prio=3410 | Lighting:Pixel:GLINT TRUE_PBR DEFERRED WETNESS_EFFECTS WATER_EFFECTS VOLUMETRIC_SHADOWS UNIFIED_WATER TERRAIN_VARIATION TERRAIN_SHADOWS SSS SCREEN_SPACE_SHADOWS LOD_BLENDING ISL LIGHT_LIMIT_FIX CS_HAIR EXTENDED_TRANSLUCENCY EXTENDED_MATERIALS EXP_HEIGHT_FOG CLOUD_SHADOWS TERRAIN_BLENDING SKYLIGHTING IBL DYNAMIC_CUBEMAPS LOD_LAND_BLEND LANDSCAPE MULTI_TEXTURE ANISO_LIGHTING VC

Summary by CodeRabbit

• Bug Fixes
  • Improved shader compilation timing logs so concurrent updates no longer produce invalid or negative "remaining" values, yielding consistent and reliable debug output during parallel shader builds.

[coderabbitai]

📝 Walkthrough

Walkthrough

ProcessCompilationSet's remaining-task logging now snapshots atomic counters and uses saturating arithmetic to compute remaining tasks, avoiding unsigned underflow when counters race (e.g., totalTasks can transiently be zero).

Changes

Shader Timing Underflow Prevention

Layer / File(s)	Summary
Atomic Snapshot src/ShaderCache.cpp	Atomically load totalTasks, completedTasks, and failedTasks to capture a consistent snapshot for logging.
Saturating Computation src/ShaderCache.cpp	Compute done = completed + failed; set doneIncludingCurrent = (done < total) ? done + 1 : done; compute remaining = (total > doneIncludingCurrent) ? (total - doneIncludingCurrent) : 0 to avoid unsigned underflow.
Logging Site src/ShaderCache.cpp	Use the computed remaining value in [ShaderTiming] logging output instead of previous direct unsigned subtraction.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• feat: update shader compile elapsed time every second #1587: Related changes in ShaderCache timing and completion reporting that touch remaining-count logic and timing.
• perf(shadercache): use faster clock #1275: Related modifications to shader compilation timing/ETA handling in ShaderCache.cpp.

Suggested reviewers

• alandtse
• doodlum

Poem

🐰
I peeked at counters, soft and small,
I added checks to guard their fall.
No more wrap-around in the night,
Remaining tasks are now polite.
A tiny hop, a careful fix — delight! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

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.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title 'fix: compiler remaining tasks' directly relates to the main change: fixing incorrect remaining task calculations in shader compiler logging by replacing unsafe subtraction with saturating arithmetic.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

No actionable suggestions for changed features.

[Copilot]

Pull request overview

This PR updates shader-compilation telemetry in ShaderCache so the developer-facing timing logs no longer underflow the remaining count when async compilation state is reset during a build.

Changes:

• Replaced the direct total - completed - failed subtraction with a saturating calculation.
• Reads totalTasks, completedTasks, and failedTasks explicitly from atomics for the log-only remaining value.
• Documents the race with Clear() that previously produced uint64_t underflow in shader timing logs.

[coderabbitai]

🧹 Nitpick comments (1)

src/ShaderCache.cpp (1)

2969-2974: ⚡ Quick win

Factor out the saturated remaining-count calculation.

This fixes the timing log, but StopCompilation() still uses raw subtraction for the same counters, so the same race can still leak into logs there. A shared helper would keep both call sites consistent.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/ShaderCache.cpp` around lines 2969 - 2974, Create a shared helper that
computes the saturated remaining task count from a compilation set instead of
duplicating the subtraction logic: implement a function (e.g.,
computeSaturatedRemaining or saturatedRemainingFor) that reads
compilationSet.totalTasks, compilationSet.completedTasks, and
compilationSet.failedTasks with the same memory_order_relaxed loads and returns
(total > done ? total - done : 0); replace the inline calculation in
ShaderCache.cpp (the current remaining computation using total/completed/failed)
and update StopCompilation() to call this helper so both call sites use the same
race-safe saturated subtraction logic.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/ShaderCache.cpp`:
- Around line 2969-2974: Create a shared helper that computes the saturated
remaining task count from a compilation set instead of duplicating the
subtraction logic: implement a function (e.g., computeSaturatedRemaining or
saturatedRemainingFor) that reads compilationSet.totalTasks,
compilationSet.completedTasks, and compilationSet.failedTasks with the same
memory_order_relaxed loads and returns (total > done ? total - done : 0);
replace the inline calculation in ShaderCache.cpp (the current remaining
computation using total/completed/failed) and update StopCompilation() to call
this helper so both call sites use the same race-safe saturated subtraction
logic.

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between d919016 and fed05b3.

📒 Files selected for processing (1)

• src/ShaderCache.cpp

[github-actions]

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