Optimize schema-comparator diffing performance#94
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swalkinshaw merged 1 commit intomainfrom Mar 23, 2026
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| let src = std::fs::read_to_string(data_path(name)).unwrap(); | ||
| let doc: DefinitionDocument = DefinitionDocument::parse(Box::leak(src.into_boxed_str())) | ||
| .result | ||
| .expect("Schema had parse errors"); | ||
| let leaked = Box::leak(Box::new(doc)); |
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Could we use include_str! to avoid some of the leaking? Or would that slow down compiles a lot?
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It could impact compile time since the schema is massive, but anyway Claude said there's two leaks and this would only fix one since SchemaDefinition borrows from DefinitionDocument. Not sure it's a worth dealing with since it's only in the benchmark?
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| #[cold] |
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| changes.extend( | ||
| directive_additions::<S, _>(self.old_type_definition, self.new_type_definition).map( | ||
| |directive| Change::DirectiveAdded { | ||
| directive, | ||
| location: DirectiveLocation::InputFieldDefinition, | ||
| member_name: self.old_field_definition.name(), | ||
| }, | ||
| ), | ||
| ); | ||
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| changes.extend( | ||
| directive_removals::<S, _>(self.old_type_definition, self.new_type_definition).map( | ||
| |directive| Change::DirectiveRemoved { | ||
| directive, | ||
| location: DirectiveLocation::InputFieldDefinition, | ||
| member_name: self.old_field_definition.name(), | ||
| }, | ||
| ), | ||
| ); |
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Yep it was, the diff was checking the parent input object instead of the actual input field
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…schemas) Key optimizations: - Eliminate intermediate Vec allocations via diff_into(&mut Vec) pattern - Single-pass field matching: merge removals + common diffs into one iteration - Unified diff_directives_into replacing 3 separate directive functions - Ptr equality fast path for identical schemas (0µs) - HashMap fallback for types with 64+ fields (O(1) lookups on large types) - CriticalityLevel enum to avoid Cow string allocations during sorting - Early exits for empty directives/arguments, #[inline] hints on hot paths - Pre-allocate changes Vec with capacity 256 - Criterion benchmark suite with real schema fixtures Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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adampetro
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Optimize schema-comparator diffing performance (~65% faster on large schemas)
Key optimizations:
Note: this is a manually curated (with the help of Claude) and cleaned up version of an
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