events: fix weak listener retention overwrite#64024
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The weakListeners() retention map in EventTarget stored a single listener per retainer key. Multiple addEventListener() calls sharing the same retainer (e.g. two listeners on one target using the same AbortSignal) silently evicted each other's strong reference, allowing the evicted listener to be garbage collected before its signal aborted, so only the most recently registered listener was ever actually removed on abort. Changed the retention map to store a Set of listeners per retainer key instead of a single listener, and added matching cleanup in remove() so entries are released once their retainer's set is empty. This also fixes the same class of bug in events.aborted() and the streams kWeakHandler usage, since both go through the same EventTarget.prototype.addEventListener() code path. Fixes: nodejs#63954 Signed-off-by: aryan7905 <[email protected]>
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The weakListeners() retention map in EventTarget stored a single listener per retainer key. Multiple addEventListener() calls sharing the same retainer (e.g. two listeners on one target using the same AbortSignal) silently evicted each other's strong reference, allowing the evicted listener to be garbage collected before its signal aborted, so only the most recently registered listener was ever actually removed on abort.
Changed the retention map to store a Set of listeners per retainer key instead of a single listener, and added matching cleanup in remove() so entries are released once their retainer's set is empty.
This also fixes the same class of bug in events.aborted() and the streams kWeakHandler usage, since both go through the same EventTarget.prototype.addEventListener() code path.
Fixes: #63954