Eliminate hot-path allocations in Map.Get, Map.Without, Set.Has - #88
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The generics migration introduced 6 allocs/call on Map.Get and 4 on Set.Has due to Go's GCShape stenciling boxing struct types through any(x). This change eliminates all allocations on read paths for concrete key types (string, int, etc.) and reduces interface key types to at most 1 alloc. Key changes: - Cache DefaultNPEqArgs per type (was allocating fresh EqArgs per call) - Add string specializations in resolveHashFunc and EqualFuncFor to avoid boxing through any(x) - Add GetSeededHashFunc for non-boxing seeded hashing of map keys - Rewrite mapEntryHashFunc to hash keys directly instead of boxing the mapEntry struct through the Hashable interface - Add Tree.GetWith/WithoutWith accepting pre-built EqArgs - Map.Get/Without use cached specialized EqArgs with GetWith/WithoutWith Benchmarks (arrai, Apple M4 Max): Map[string,Value].Get: 6 allocs ~120ns → 0 allocs ~26ns (4.6x) TupleGet: 6 allocs ~120ns → 0 allocs ~27ns (4.5x) Set[string].Has: 4 allocs → 0 allocs ~20ns Set[Value].Has: 4 allocs → 1 alloc ~45ns Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
DefaultNPEqArgsper type to avoid fresh*EqArgsallocation per callstringspecializations inresolveHashFuncandEqualFuncForto avoid boxing throughany(x)GetSeededHashFuncfor non-boxing seeded hashing of map keysmapEntryHashFuncto hash keys directly instead of boxing the mapEntry struct through the Hashable interfaceTree.GetWith/WithoutWithaccepting pre-built EqArgsMap.Get/Withoutuse cached specialized EqArgs withGetWith/WithoutWithBenchmarks (arrai, Apple M4 Max)
Map[string,Value].GetTupleGetSet[string].HasSet[Value].HasThe remaining 1 alloc on
Set[Value].Hasis theequalEqualerboxing path for interface types — deferred as it's low-impact (interface-to-any boxing is cheap).Test plan
go test ./...)go test ./...)-count=5🤖 Generated with Claude Code