perf(cg): skip prefill loop on cache-warm frames via generation tracking by softmarshmallow · Pull Request #618 · gridaco/grida

softmarshmallow · 2026-03-31T16:41:30Z

Add a monotonically increasing generation counter to PictureCache that increments on any mutation (insert, invalidate). The prefill loop now compares the current generation, variant key, and layer count against the last successful prefill — when all match, the entire O(N) iteration is skipped in O(1).

On 135K-node scenes, this eliminates ~800µs of HashMap lookups per cache-warm frame. Measured improvements on 01-135k.perf.grida:

rt_pan_fast_fit p50: 111µs → 76µs (-32%)
rt_pan_fast_fit p95: 263µs → 153µs (-42%)
pan_settle_slow_fit settle: 1034µs → 709µs (-31%)
Criterion large_baseline/pan: -14.0% (p < 0.01)

Summary by CodeRabbit

Refactor
- Improved rendering performance with optimized scene caching that reduces unnecessary processing when scenes remain unchanged.
Documentation
- Added documentation describing cache validation optimization techniques and performance benefits for scene rendering.

…y fixtures Removed all 12 original fixtures that relied on unsupported CSS features (grid, margin, tables, viewport units). Added 21 new fixtures organized by category (layout, box, paint, text, mixed), each testing a specific CSS property group using only features the HTML→IR pipeline supports. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add csscascade adapter, cascade driver, and arena DOM modules - Add HTML import module (html/mod.rs) with Stylo-based CSS resolution - Wire grida-dev to load .html files via from_html_str - Support ~35 CSS properties: layout (flex, block, display:none), box model (width/height/min/max/padding/overflow), paint (backgrounds, gradients, borders, shadows, opacity), text (font, color, align, line-height, letter-spacing, word-spacing, text-transform, decoration), and inline style attributes - Map block containers to flex-column for correct flex-child sizing - Emit text-only elements as Container+TextSpan to preserve box model Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Keep HTML import pipeline additions alongside main's raster image refactoring (load_raster/RasterScene). Remove duplicate pub mod query. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

The CSS cascade adapter uses a process-global DEMO_DOM static, so concurrent from_html_str calls race on that shared slot causing Stylo debug_assert panics. Added a mutex to serialize HTML tests. Also ran cargo fmt to fix formatting. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Replace css_box_shadow_to_cg with comprehensive css_effects_to_cg handling box-shadow, filter: blur(), filter: drop-shadow(), and backdrop-filter: blur() in a single pass - Add css_text_shadow_to_effects for text-shadow on TextSpan nodes - Add css_blend_mode_to_cg mapping all 16 CSS mix-blend-mode values - Wire effects + blend_mode into all three emitters (container, rect, text) - Fix test mutex poisoning cascade with lock_html() helper - Add 8 deterministic tests for effects properties Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Wire text-decoration-color and text-decoration-style from Stylo into TextDecorationRec. Mark thickness and skip-ink as TODO (gecko-only in Stylo servo mode). Add L0 fixtures for text-decoration variants and 2D CSS transforms (implementation pending). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add docs/wg/format/ with canonical tracking docs for the Grida IR schema and its mapping from CSS, HTML, and SVG. Tables are oxfmt- formatted to minimize diffs on future edits. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add docs/wg/format/index.md as docusaurus entry point. Add format:md frontmatter to grida.md, css.md, svg.md for MDX compatibility. Link format mapping docs from format/README.md, format/AGENTS.md, and docs/AGENTS.md. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Remove CSS_PROPERTY_MAPPING.md (aspirational, marked unimplemented features as done) and html/TODO.md (superseded by docs/wg/format/). Update csscascade README roadmap to reflect current state. Add doc pointer in html/mod.rs to the canonical tracking docs. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Remove dead no-op code (is_none → assign None) in emit_container - Remove unconditional eprintln in from_html_str (library code) - Add thread safety warning to from_html_str doc comment - Document text-decoration single-line limitation with TODO - Fix index.md missing format:md frontmatter - Fix svg.md stroke table missing Notes header column - Fix fixture title claiming "Thickness" coverage - Remove text-shadow/text-transform from README excluded list Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

feat: HTML/CSS → Grida IR import pipeline

Add a monotonically increasing generation counter to PictureCache that increments on any mutation (insert, invalidate). The prefill loop now compares the current generation, variant key, and layer count against the last successful prefill — when all match, the entire O(N) iteration is skipped in O(1). On 135K-node scenes, this eliminates ~800µs of HashMap lookups per cache-warm frame. Measured improvements on 01-135k.perf.grida: - rt_pan_fast_fit p50: 111µs → 76µs (-32%) - rt_pan_fast_fit p95: 263µs → 153µs (-42%) - pan_settle_slow_fit settle: 1034µs → 709µs (-31%) - Criterion large_baseline/pan: -14.0% (p < 0.01) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vercel · 2026-03-31T16:41:44Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Mar 31, 2026 5:53pm

6 Skipped Deployments

Project	Deployment	Updated (UTC)
code	Ignored	Mar 31, 2026 5:53pm
legacy	Ignored	Mar 31, 2026 5:53pm
backgrounds	Skipped	Mar 31, 2026 5:53pm
blog	Skipped	Mar 31, 2026 5:53pm
grida	Skipped	Mar 31, 2026 5:53pm
viewer	Skipped	Mar 31, 2026 5:53pm

coderabbitai · 2026-03-31T16:42:06Z

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 44af7f27-859c-466e-b36f-69cef2ca729c

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

🔍 Trigger review

Walkthrough

The PR adds a generation-based cache invalidation optimization to skip redundant picture cache prefill operations. A monotonic counter in PictureCache increments on mutations; Renderer records the generation plus metadata (variant key and layer count) after prefill, then skips the O(N) iteration on subsequent frames if all three values remain unchanged.

Changes

Cohort / File(s)	Summary
Picture Cache Mutation Tracking `crates/grida-canvas/src/cache/picture.rs`	Added `generation: u64` field and public `generation()` accessor. Cache mutations (`set_node_picture`, `set_node_picture_variant`, `invalidate`, `invalidate_node`) now increment generation using `wrapping_add(1)`. Added `variant_store_is_empty()` helper. Restructured `set_node_picture_variant` control flow to ensure consistent generation increments across all insert paths.
Prefill Skip Optimization `crates/grida-canvas/src/runtime/scene.rs`	Added three tracking fields to `Renderer`: `last_prefill_generation`, `last_prefill_variant_key`, and `last_prefill_layer_count`. In `prefill_picture_cache_for_plan`, a new fast-path computes effective variant key and visible layer count; if all three tracking values match current cache state, prefill iteration is skipped. Tracking fields updated after successful prefill and initialized to sentinel values (`u64::MAX/u64::MAX/0`).
Optimization Documentation `docs/wg/feat-2d/optimization.md`	Added new section describing the "Picture Cache Prefill Skip" mechanism, explaining generation counter semantics, variant key unification for effect-free scenes, skip-path correctness across stable/unstable transitions, and performance deltas.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

perf(cg): unify picture cache variants for effects-free nodes #614: Introduces variant key unification (storing effect-free nodes under variant_key=0), which this PR builds upon with the generation counter and skip-path logic.
perf(canvas): use FxHash for NodeId-keyed caches #600: Modifies the same PictureCache struct, replacing internal HashMap types while this PR adds generation tracking and accessors.

Suggested labels

cg, performance

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main optimization: skipping the prefill loop on cache-warm frames using generation tracking.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch feature/stupefied-mendeleev

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 5ddb8f6f89

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector · 2026-03-31T16:44:30Z

crates/grida-canvas/src/runtime/scene.rs

+        if current_gen == self.last_prefill_generation
+            && effective_key_for_tracking == self.last_prefill_variant_key
+            && layer_count == self.last_prefill_layer_count
+        {


Include visible-set identity in prefill skip key

The new fast-path returns early when generation, variant_key, and only the count of planned layers match, but panning can change which nodes are visible while keeping the same count. In that case this check skips prefill_picture_cache_for_plan() even though newly visible nodes are not cached yet; since prefill is the only path that inserts node pictures, those nodes can remain uncached across frames (same generation/count), causing sustained cache misses and a performance regression during viewport movement.

Useful? React with 👍 / 👎.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

softmarshmallow and others added 13 commits March 29, 2026 19:32

merge: resolve conflicts with origin/main

7822147

Keep HTML import pipeline additions alongside main's raster image refactoring (load_raster/RasterScene). Remove duplicate pub mod query. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

feat: add L0 fixtures for effects CSS properties

7f02f7b

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs: add format mapping reference and TODO trackers

53324e4

Add docs/wg/format/ with canonical tracking docs for the Grida IR schema and its mapping from CSS, HTML, and SVG. Tables are oxfmt- formatted to minimize diffs on future edits. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Merge pull request #608 from gridaco/feature/elastic-tesla

3501b8f

feat: HTML/CSS → Grida IR import pipeline

softmarshmallow changed the base branch from main to canary March 31, 2026 16:41

vercel bot deployed to Preview – viewer March 31, 2026 16:42 View deployment

vercel bot deployed to Preview – docs March 31, 2026 16:43 View deployment

vercel bot deployed to Preview – grida March 31, 2026 16:44 View deployment

vercel bot deployed to Preview – blog March 31, 2026 16:44 View deployment

chatgpt-codex-connector bot reviewed Mar 31, 2026

View reviewed changes

style(cg): cargo fmt – fix formatting in scene.rs

491413e

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vercel bot temporarily deployed to Preview – blog March 31, 2026 17:52 Inactive

vercel bot temporarily deployed to Preview – viewer March 31, 2026 17:52 Inactive

vercel bot temporarily deployed to Preview – backgrounds March 31, 2026 17:52 Inactive

vercel bot temporarily deployed to Preview – grida March 31, 2026 17:52 Inactive

vercel bot deployed to Preview – docs March 31, 2026 17:53 View deployment

softmarshmallow merged commit 855e48c into canary Mar 31, 2026
14 checks passed

softmarshmallow added the performance label Mar 31, 2026

coderabbitai bot mentioned this pull request Apr 1, 2026

perf(cg): render cost prediction module, prefill skip optimization, and Skia benchmarks #619

Merged

This was referenced Apr 6, 2026

feat(canvas): headless Editor for non-browser testing #630

Merged

perf(canvas): sub-pixel node culling at low zoom #636

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

perf(cg): skip prefill loop on cache-warm frames via generation tracking#618

perf(cg): skip prefill loop on cache-warm frames via generation tracking#618
softmarshmallow merged 14 commits intocanaryfrom
feature/stupefied-mendeleev

softmarshmallow commented Mar 31, 2026 •

edited by coderabbitai bot

Loading

Uh oh!

vercel bot commented Mar 31, 2026 •

edited

Loading

Uh oh!

coderabbitai bot commented Mar 31, 2026 •

edited

Loading

Review skipped

Uh oh!

chatgpt-codex-connector bot left a comment

Uh oh!

chatgpt-codex-connector bot Mar 31, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Conversation

softmarshmallow commented Mar 31, 2026 • edited by coderabbitai bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary by CodeRabbit

Uh oh!

vercel bot commented Mar 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

coderabbitai bot commented Mar 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Review skipped

Walkthrough

Changes

Estimated code review effort

Possibly related PRs

Suggested labels

Uh oh!

chatgpt-codex-connector bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

chatgpt-codex-connector bot Mar 31, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

softmarshmallow commented Mar 31, 2026 •

edited by coderabbitai bot

Loading

vercel bot commented Mar 31, 2026 •

edited

Loading

coderabbitai bot commented Mar 31, 2026 •

edited

Loading