fix: strong wrapper cache — weak identity was a GC race - #20
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The four wrapper-identity specs failed on the Windows CI matrix (188 examples, 4 failures; mac/linux green): ObjectSpace::WeakMap holds values weakly, so between two doc.root calls the first wrapper was referenced only by the map — any GC sweep evicted it and the second call built a fresh object. Identity was a GC timing race, not a property of the interface. The cache is now a plain Hash owned by the Document and cleared in free. Cost: at most one wrapper per node actually visited, held until the document dies. Full suite 188/188 locally; doc.root.equal?(doc.root) survives 50 forced GC.start rounds.
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Summary
Fixes the four Windows-only wrapper-identity failures in PR #19.
The cache was an ObjectSpace::WeakMap — values held weakly — so wrapper identity was a GC race: between two
doc.rootcalls the first wrapper was referenced only by the map, any sweep evicted it, and the second call built a fresh object. Windows CI lost that race (188 examples, the 4 identity specs); mac/linux happened to win it.Now a plain Hash owned by the Document, cleared in
free. Cost: one wrapper per node actually visited, held until the document dies.Test plan
doc.root.equal?(doc.root)survives 50 forcedGC.startrounds.