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There were more large constants that needed UINT64CONST. And one variable was declared as "int", when it needed to be uint64. These bugs were only visible on 32-bit systems; clearly I should've tested on one, given that this code does a lot of work with 64-bit integers. Also, in the test "huge distances" test, the code created some values with random distances between them, but the test logic didn't take into account the possibility that the random distance was exactly 1. That never actually happens with the seed we're using, but let's be tidy.
This directory contains a general purpose data structures, for use anywhere in the backend: binaryheap.c - a binary heap bipartite_match.c - Hopcroft-Karp maximum cardinality algorithm for bipartite graphs bloomfilter.c - probabilistic, space-efficient set membership testing dshash.c - concurrent hash tables backed by dynamic shared memory areas hyperloglog.c - a streaming cardinality estimator ilist.c - single and double-linked lists integerset.c - a data structure for holding large set of integers knapsack.c - knapsack problem solver pairingheap.c - a pairing heap rbtree.c - a red-black tree stringinfo.c - an extensible string type Aside from the inherent characteristics of the data structures, there are a few practical differences between the binary heap and the pairing heap. The binary heap is fully allocated at creation, and cannot be expanded beyond the allocated size. The pairing heap on the other hand has no inherent maximum size, but the caller needs to allocate each element being stored in the heap, while the binary heap works with plain Datums or pointers. The linked-lists in ilist.c can be embedded directly into other structs, as opposed to the List interface in nodes/pg_list.h.