feat: optional lazy unpack wrappers (#40) - #25691
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- unpack(buf, { lazy: true }) wraps maps/arrays as accessors
- keep the msgpack zone and source Buffer alive with the wrapper
- toJSON fully materializes; util.inspect does not hang
- Copy the caller Buffer before msgpack_unpack_next when lazy is set - str/bin aliases session-owned bytes, not the transferable backing store - Add a transfer test for str and bin after structuredClone detach
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Summary
unpack(buf, { lazy: true })so MessagePack maps/arrays become accessor wrappers instead of fully converting nested values up front (issue Optinally wrap msgpack_object instead of converting to V8 object #40).unpack(buf)is still eager. Nested values convert on read;toJSON/inspect.customfully materialize soJSON.stringifyandutil.inspectdo not hang.__proto__/constructorstay own properties, same as eager unpack. Incomplete input still returnsnull; oversized headers still throw.This branch is stacked on unmerged
feat/pack-type-hints(#52 / PR #25690). Merge that first, or this PR will include those commits.Test plan
npm test— 208 tests, 0 failures (23 new intest/lazy.test.js)npm run coverage:js— 100% statements / branches / functions / lines onlib/+bin/npm run coverage:native— 95.7% lines (1002/1047), 95.5% branches (976/1022), 100% functions (66/66); gate is 95%unpack({a:1,b:2,c:[1,2,3]})one-arg still deep-equals the sourceunpack(buf, {lazy:true}).c[1] === 2without readinga/bJSON.stringifyof lazy unpack matches eager unpack__proto__/constructordo not pollute prototypesnull; oversized array/map headers still throwOptional microbench on a small nested object (100k iters, this sandbox): JSON.parse 0.72 µs/op, eager unpack 2.28 µs/op, lazy wrap 4.68 µs/op, lazy then
.c[1]7.05 µs/op. Wrapper overhead dominates small payloads; the point of lazy is skipping unread nested conversion on large maps, not beating eager on tiny objects.Closes #40