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Posted to commits@maka.apache.org by "liuxiaocs7 (via GitHub)" <gi...@apache.org> on 2026/09/12 19:03:43 UTC
[PR] perf(core): count diff lines without materializing display rows [maka]
liuxiaocs7 opened a new pull request, #5243:
URL: https://github.com/apache/maka/pull/5243
## Summary
Fixes #5242
`countDiffLineStats` previously built every display row and a complete split-line array just to return additions/deletions. Share one structural scanner with `parseUnifiedDiffRows`; counting now skips display objects and body substrings while preserving hunk semantics, row shapes, and public APIs.
Includes boundary tests, 1,000 seeded multi-file fixtures with independently generated expected rows/counts, and a reproducible benchmark with raw samples. The 100,000-line replacement fixture counts 2.86× faster and creates zero display rows.
## Verification
- Passed: `npm run lint`, `npm run format:check`, `npm run build`, `npm run typecheck`.
- Passed: `npx --no-install knip --workspace apps/desktop` and `npx --no-install knip --workspace packages/ui`.
- Affected tests: 837 core tests; 137 Git review / CLI transcript / UI tool-activity tests; 16 runtime file-tool tests; one model-history replay test. **991 passed, 3 Windows-only cases skipped, 0 failed.** Rebuilt all workspaces and reran the affected suites before submission.
- An additional 10,000 seeded mixed/malformed inputs produced identical rows and counts against the baseline.
- The allocation probe failed before the fix (even a one-line addition created two display objects). The benchmark now asserts zero display-row creations and zero full-line splits in all seven count scenarios. Semantic tests intentionally pass against the baseline too, to verify compatibility.
- Full cross-workspace test suite, Electron E2E, and Windows execution were not run locally.
### Benchmark
Apple M4 Pro, macOS arm64, Node v24.14.0 / V8 13.6.233.17-node.41. Baseline: `d2e1be5db93101ffcc0fb6a107a0d51764ace28b`. Eight warmup batches, 21 timing samples with alternating version order, forced GC before each batch; medians below are milliseconds per call. Fixture generation, Git/I/O and rendering are outside timing.
| Count scenario | Input MiB | Before ms | After ms | Speedup |
| --- | ---: | ---: | ---: | ---: |
| 400 replacement lines | 0.019 | 0.0092 | 0.0038 | 2.39× |
| 10,000 replacement lines | 0.477 | 0.2422 | 0.0979 | 2.47× |
| 100,000 replacement lines | 4.768 | 2.7539 | 0.9617 | 2.86× |
| 500,000 replacement lines | 23.842 | 13.9292 | 4.6446 | 3.00× |
| 100,000 lines, 98% context | 4.768 | 2.9051 | 0.9448 | 3.07× |
| 100 files / 1,000 hunks / 100,000 lines | 4.796 | 2.9791 | 1.0385 | 2.87× |
| 200 lines, ~32 KiB each | 6.250 | 0.1295 | 0.1253 | 1.03× |
For 100,000 replacement lines, median per-call `heapUsed` delta dropped **11.021 MiB → 576 B**, and display objects **100,001 → 0**. The 1,000-hunk input dropped **11.339 MiB → 272,408 B** because header regex matches still allocate. Heap measurements use nine separate samples after forced GC; these are before/after deltas, **not total allocated bytes or exact peaks**. The 576 B result is near the measurement overhead.
Display parsing was also checked for identical output and no measured slowdown: the 100,000-line fixture changed **2.6189 → 1.9725 ms**. Long-line inputs show little speedup because text scanning dominates. The 500,000-line fixture is a core stress case exceeding the Git review input cap; these numbers do not imply equivalent end-to-end UI gains.
Reproduce:
```sh
node --expose-gc packages/core/scripts/benchmark-unified-diff.mjs d2e1be5db93101ffcc0fb6a107a0d51764ace28b
```
[Benchmark script](https://github.com/liuxiaocs7/maka/blob/perf/count-diff-without-display-rows/packages/core/scripts/benchmark-unified-diff.mjs) · [Raw samples](https://github.com/liuxiaocs7/maka/blob/perf/count-diff-without-display-rows/docs/performance/c083-unified-diff-2026-09-13.json) · [Detailed report](https://github.com/liuxiaocs7/maka/blob/perf/count-diff-without-display-rows/docs/performance/c083-unified-diff-2026-09-13.zh-CN.md)
## AI use
Select exactly one:
- [ ] No generative tool made a substantive contribution
- [x] Generative tooling made a substantive contribution
Tool(s) and scope: Codex assisted with diagnosis, implementation, tests, benchmarking, and this submission. This automated submission was requested by @liuxiaocs7, the human contributor of record. The commit includes `Generated-by: Codex`.
## Checklist
- [x] Tests cover the change and fail without it
- [x] Lint, format, typecheck and the affected suites pass locally
Does this PR entail a change in behavior?
- [ ] Yes — described under Summary above
- [x] No
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Re: [PR] perf(core): count diff lines without materializing display rows [maka]
Posted by "Astro-Han (via GitHub)" <gi...@apache.org>.
Astro-Han merged PR #5243:
URL: https://github.com/apache/maka/pull/5243
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