csskit_arena: Reuse reservations across arenas - #1430
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Reserving a region costs a pair of syscalls. Small parse steps pay a steep cost for this if they're allocating a fresh arena, then dropping. A reservation could outlives its arena, therefore amortizing this cost when a program resets and renews an arena. This change does just that - reservations go on a thread-local free list, keyed by usable size, and the next arena of that size takes it.
keithamus
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August 22, 2026 13:49
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## [0.0.30] - 2026-08-22 ### Css_ast - css_ast: Allow symbolic-counter-style in content syntax (#1419) ([#1419](#1419)) - css_ast: Boxup rare nodes to reduce allocation size (#1421) ([#1421](#1421)) - css_ast: Clean up & improve NodeWithMetadata derives, add value_kinds (#1422) ([#1422](#1422)) - csskit_transform: implement ReduceCharsetRule (#1427) ([#1427](#1427)) - css_ast: Add missing webkit pseudo elements (#1428) ([#1428](#1428)) - css_ast: Implement InitialLetterAlignStyleValue (#1429) ([#1429](#1429)) - css_ast: Allow prelude-less `@layer` (#1434) ([#1434](#1434)) ### Css_lexer - css_lexer/css_parse: Ensure parsed whitespace survives minification (#1420) ([#1420](#1420)) ### Csskit - chore(deps): update dependencies (patch) (#1407) ([#1407](#1407)) ### Csskit_arena - csskit_arena: Reuse reservations across arenas (#1430) ([#1430](#1430)) - csskit_arena: Clean up and consolidate allocation modes (#1431) ([#1431](#1431)) - csskit_arena: Add a detailed readme (#1433) ([#1433](#1433)) ### Csskit_transform - coverage: update css-minify-tests (#1423) ([#1423](#1423)) - csskit_transform: skip subtrees which don't match metadata (#1424) ([#1424](#1424)) ### Csskit_vscode - chore(deps): update dependency mocha to v11.8.0 (#1410) ([#1410](#1410)) - chore(deps): update dependency oxlint to v1.76.0 (#1411) ([#1411](#1411)) - chore(deps): update dependency oxlint to v1.78.0 (#1413) ([#1413](#1413)) ### Derive_atom_set - derive_atom_set: Don't case fold on punctuation. (#1426) ([#1426](#1426)) - derive_atom_set: Expand readme with more detail (#1432) ([#1432](#1432)) [forcebuild]
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Aug 22, 2026
## [0.0.30] - 2026-08-22 ### Css_ast - css_ast: Allow symbolic-counter-style in content syntax (#1419) ([#1419](#1419)) - css_ast: Boxup rare nodes to reduce allocation size (#1421) ([#1421](#1421)) - css_ast: Clean up & improve NodeWithMetadata derives, add value_kinds (#1422) ([#1422](#1422)) - csskit_transform: implement ReduceCharsetRule (#1427) ([#1427](#1427)) - css_ast: Add missing webkit pseudo elements (#1428) ([#1428](#1428)) - css_ast: Implement InitialLetterAlignStyleValue (#1429) ([#1429](#1429)) - css_ast: Allow prelude-less `@layer` (#1434) ([#1434](#1434)) ### Css_lexer - css_lexer/css_parse: Ensure parsed whitespace survives minification (#1420) ([#1420](#1420)) ### Csskit - chore(deps): update dependencies (patch) (#1407) ([#1407](#1407)) ### Csskit_arena - csskit_arena: Reuse reservations across arenas (#1430) ([#1430](#1430)) - csskit_arena: Clean up and consolidate allocation modes (#1431) ([#1431](#1431)) - csskit_arena: Add a detailed readme (#1433) ([#1433](#1433)) ### Csskit_transform - coverage: update css-minify-tests (#1423) ([#1423](#1423)) - csskit_transform: skip subtrees which don't match metadata (#1424) ([#1424](#1424)) ### Csskit_vscode - chore(deps): update dependency mocha to v11.8.0 (#1410) ([#1410](#1410)) - chore(deps): update dependency oxlint to v1.76.0 (#1411) ([#1411](#1411)) - chore(deps): update dependency oxlint to v1.78.0 (#1413) ([#1413](#1413)) ### Derive_atom_set - derive_atom_set: Don't case fold on punctuation. (#1426) ([#1426](#1426)) - derive_atom_set: Expand readme with more detail (#1432) ([#1432](#1432))
keithamus
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Aug 23, 2026
- css_ast: Allow symbolic-counter-style in content syntax (#1419) ([#1419](#1419)) - css_ast: Boxup rare nodes to reduce allocation size (#1421) ([#1421](#1421)) - css_ast: Clean up & improve NodeWithMetadata derives, add value_kinds (#1422) ([#1422](#1422)) - csskit_transform: implement ReduceCharsetRule (#1427) ([#1427](#1427)) - css_ast: Add missing webkit pseudo elements (#1428) ([#1428](#1428)) - css_ast: Implement InitialLetterAlignStyleValue (#1429) ([#1429](#1429)) - css_ast: Allow prelude-less `@layer` (#1434) ([#1434](#1434)) - css_lexer/css_parse: Ensure parsed whitespace survives minification (#1420) ([#1420](#1420)) - chore(deps): update dependencies (patch) (#1407) ([#1407](#1407)) - csskit_arena: Reuse reservations across arenas (#1430) ([#1430](#1430)) - csskit_arena: Clean up and consolidate allocation modes (#1431) ([#1431](#1431)) - csskit_arena: Add a detailed readme (#1433) ([#1433](#1433)) - coverage: update css-minify-tests (#1423) ([#1423](#1423)) - csskit_transform: skip subtrees which don't match metadata (#1424) ([#1424](#1424)) - chore(deps): update dependency mocha to v11.8.0 (#1410) ([#1410](#1410)) - chore(deps): update dependency oxlint to v1.76.0 (#1411) ([#1411](#1411)) - chore(deps): update dependency oxlint to v1.78.0 (#1413) ([#1413](#1413)) - derive_atom_set: Don't case fold on punctuation. (#1426) ([#1426](#1426)) - derive_atom_set: Expand readme with more detail (#1432) ([#1432](#1432)) [forcebuild]
keithamus
added a commit
that referenced
this pull request
Aug 23, 2026
## [0.0.30] - 2026-08-22 ### Css_ast - css_ast: Allow symbolic-counter-style in content syntax (#1419) ([#1419](#1419)) - css_ast: Boxup rare nodes to reduce allocation size (#1421) ([#1421](#1421)) - css_ast: Clean up & improve NodeWithMetadata derives, add value_kinds (#1422) ([#1422](#1422)) - csskit_transform: implement ReduceCharsetRule (#1427) ([#1427](#1427)) - css_ast: Add missing webkit pseudo elements (#1428) ([#1428](#1428)) - css_ast: Implement InitialLetterAlignStyleValue (#1429) ([#1429](#1429)) - css_ast: Allow prelude-less `@layer` (#1434) ([#1434](#1434)) ### Css_lexer - css_lexer/css_parse: Ensure parsed whitespace survives minification (#1420) ([#1420](#1420)) ### Csskit - chore(deps): update dependencies (patch) (#1407) ([#1407](#1407)) ### Csskit_arena - csskit_arena: Reuse reservations across arenas (#1430) ([#1430](#1430)) - csskit_arena: Clean up and consolidate allocation modes (#1431) ([#1431](#1431)) - csskit_arena: Add a detailed readme (#1433) ([#1433](#1433)) ### Csskit_transform - coverage: update css-minify-tests (#1423) ([#1423](#1423)) - csskit_transform: skip subtrees which don't match metadata (#1424) ([#1424](#1424)) ### Csskit_vscode - chore(deps): update dependency mocha to v11.8.0 (#1410) ([#1410](#1410)) - chore(deps): update dependency oxlint to v1.76.0 (#1411) ([#1411](#1411)) - chore(deps): update dependency oxlint to v1.78.0 (#1413) ([#1413](#1413)) ### Derive_atom_set - derive_atom_set: Don't case fold on punctuation. (#1426) ([#1426](#1426)) - derive_atom_set: Expand readme with more detail (#1432) ([#1432](#1432))
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Reserving a region costs a pair of syscalls. Small parse steps pay a steep cost
for this if they're allocating a fresh arena, then dropping. A reservation could
outlives its arena, therefore amortizing this cost when a program resets and
renews an arena.
This change does just that - reservations go on a thread-local free list, keyed
by usable size, and the next arena of that size takes it.