The Lock-Free Eviction Queue: Weak Pointers and Sequence Numbers
The eviction queue is a lock-free MPMC queue of weak_ptr plus a monotonic sequence number; dead nodes are detected and purged in bulk every 4096 inserts.
Cache
Pinning Is Ownership: DuckDB's Buffer Handle Is a shared_ptr
Pinning a block in DuckDB is just holding a shared_ptr: eviction is impossible under a live handle, and the readers counter is only an eviction hint.