Reset capacity_ in ShareData and ShareDiff#7115
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After ShareData/ShareDiff, stale capacity_ can cause Reshape to skip reallocation while pointing at shared memory incorrectly. Co-authored-by: Cursor <cursoragent@cursor.com>
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Bug
After
Blob::ShareData()orShareDiff(), a blob can retain a stalecapacity_value even though its memory is now shared with another blob. A laterReshape()may skip reallocation whencount_ <= capacity_, leaving the blob in an inconsistent state (#5439).Root cause
ShareData/ShareDiffreassign theSyncedMemorypointer but never invalidatecapacity_, soReshape()treats the blob as still owning its previous allocation size.Why this fix is correct
Resetting
capacity_to 0 marks the allocation as invalid after sharing, forcingReshape()to allocate fresh memory when the blob's shape changes. This matches the behavior described in #5439 and confirmed by a maintainer.Fixes #5439
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