26aaf97b68
There's plenty places in frontend code that could benefit from a string buffer implementation. Some because it yields simpler and faster code, and some others because of the desire to share code between backend and frontend. While there is a string buffer implementation available to frontend code, libpq's PQExpBuffer, it is clunkier than stringinfo, it introduces a libpq dependency, doesn't allow for sharing between frontend and backend code, and has a higher API/ABI stability requirement due to being exposed via libpq. Therefore it seems best to just making StringInfo being usable by frontend code. There's not much to do for that, except for rewriting two subsequent elog/ereport calls into others types of error reporting, and deciding on a maximum string length. For the maximum string size I decided to privately define MaxAllocSize to the same value as used in the backend. It seems likely that we'll want to reconsider this for both backend and frontend code in the not too far away future. For now I've left stringinfo.h in lib/, rather than common/, to reduce the likelihood of unnecessary breakage. We could alternatively decide to provide a redirecting stringinfo.h in lib/, or just not provide compatibility. Author: Andres Freund Reviewed-By: Kyotaro Horiguchi, Daniel Gustafsson Discussion: https://postgr.es/m/20190920051857.2fhnvhvx4qdddviz@alap3.anarazel.de |
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| .. | ||
| Makefile | ||
| README | ||
| binaryheap.c | ||
| bipartite_match.c | ||
| bloomfilter.c | ||
| dshash.c | ||
| hyperloglog.c | ||
| ilist.c | ||
| integerset.c | ||
| knapsack.c | ||
| pairingheap.c | ||
| rbtree.c | ||
README
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.