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Reimplement oidset using khash.h in order to reduce its memory footprint and make it faster. Performance of a command that mainly checks for duplicate objects using an oidset, with master and Clang 6.0.1: $ cmd="./git-cat-file --batch-all-objects --unordered --buffer --batch-check='%(objectname)'" $ /usr/bin/time $cmd >/dev/null 0.22user 0.03system 0:00.25elapsed 99%CPU (0avgtext+0avgdata 48484maxresident)k 0inputs+0outputs (0major+11204minor)pagefaults 0swaps $ hyperfine "$cmd" Benchmark #1: ./git-cat-file --batch-all-objects --unordered --buffer --batch-check='%(objectname)' Time (mean ± σ): 250.0 ms ± 6.0 ms [User: 225.9 ms, System: 23.6 ms] Range (min … max): 242.0 ms … 261.1 ms And with this patch: $ /usr/bin/time $cmd >/dev/null 0.14user 0.00system 0:00.15elapsed 100%CPU (0avgtext+0avgdata 41396maxresident)k 0inputs+0outputs (0major+8318minor)pagefaults 0swaps $ hyperfine "$cmd" Benchmark #1: ./git-cat-file --batch-all-objects --unordered --buffer --batch-check='%(objectname)' Time (mean ± σ): 151.9 ms ± 4.9 ms [User: 130.5 ms, System: 21.2 ms] Range (min … max): 148.2 ms … 170.4 ms Initial-patch-by: Jeff King <peff@peff.net> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
104 lines
2.4 KiB
C
104 lines
2.4 KiB
C
#ifndef OIDSET_H
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#define OIDSET_H
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#include "hashmap.h"
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#include "khash.h"
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/**
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* This API is similar to sha1-array, in that it maintains a set of object ids
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* in a memory-efficient way. The major differences are:
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*
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* 1. It uses a hash, so we can do online duplicate removal, rather than
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* sort-and-uniq at the end. This can reduce memory footprint if you have
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* a large list of oids with many duplicates.
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*
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* 2. The per-unique-oid memory footprint is slightly higher due to hash
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* table overhead.
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*/
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static inline unsigned int oid_hash(struct object_id oid)
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{
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return sha1hash(oid.hash);
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}
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static inline int oid_equal(struct object_id a, struct object_id b)
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{
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return oideq(&a, &b);
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}
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KHASH_INIT(oid, struct object_id, int, 0, oid_hash, oid_equal)
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/**
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* A single oidset; should be zero-initialized (or use OIDSET_INIT).
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*/
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struct oidset {
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kh_oid_t set;
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};
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#define OIDSET_INIT { { 0 } }
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static inline void oidset_init(struct oidset *set, size_t initial_size)
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{
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memset(&set->set, 0, sizeof(set->set));
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if (initial_size)
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kh_resize_oid(&set->set, initial_size);
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}
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/**
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* Returns true iff `set` contains `oid`.
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*/
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int oidset_contains(const struct oidset *set, const struct object_id *oid);
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/**
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* Insert the oid into the set; a copy is made, so "oid" does not need
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* to persist after this function is called.
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*
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* Returns 1 if the oid was already in the set, 0 otherwise. This can be used
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* to perform an efficient check-and-add.
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*/
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int oidset_insert(struct oidset *set, const struct object_id *oid);
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/**
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* Remove the oid from the set.
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*
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* Returns 1 if the oid was present in the set, 0 otherwise.
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*/
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int oidset_remove(struct oidset *set, const struct object_id *oid);
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/**
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* Remove all entries from the oidset, freeing any resources associated with
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* it.
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*/
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void oidset_clear(struct oidset *set);
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struct oidset_iter {
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kh_oid_t *set;
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khiter_t iter;
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};
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static inline void oidset_iter_init(struct oidset *set,
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struct oidset_iter *iter)
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{
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iter->set = &set->set;
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iter->iter = kh_begin(iter->set);
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}
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static inline struct object_id *oidset_iter_next(struct oidset_iter *iter)
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{
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for (; iter->iter != kh_end(iter->set); iter->iter++) {
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if (kh_exist(iter->set, iter->iter))
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return &kh_key(iter->set, iter->iter++);
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}
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return NULL;
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}
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static inline struct object_id *oidset_iter_first(struct oidset *set,
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struct oidset_iter *iter)
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{
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oidset_iter_init(set, iter);
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return oidset_iter_next(iter);
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}
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#endif /* OIDSET_H */
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