fsck: rename and touch up init_skiplist()
[git/git.git] / oidset.h
1 #ifndef OIDSET_H
2 #define OIDSET_H
3
4 #include "hashmap.h"
5 #include "khash.h"
6
7 /**
8 * This API is similar to sha1-array, in that it maintains a set of object ids
9 * in a memory-efficient way. The major differences are:
10 *
11 * 1. It uses a hash, so we can do online duplicate removal, rather than
12 * sort-and-uniq at the end. This can reduce memory footprint if you have
13 * a large list of oids with many duplicates.
14 *
15 * 2. The per-unique-oid memory footprint is slightly higher due to hash
16 * table overhead.
17 */
18
19 static inline unsigned int oid_hash(struct object_id oid)
20 {
21 return sha1hash(oid.hash);
22 }
23
24 static inline int oid_equal(struct object_id a, struct object_id b)
25 {
26 return oideq(&a, &b);
27 }
28
29 KHASH_INIT(oid, struct object_id, int, 0, oid_hash, oid_equal)
30
31 /**
32 * A single oidset; should be zero-initialized (or use OIDSET_INIT).
33 */
34 struct oidset {
35 kh_oid_t set;
36 };
37
38 #define OIDSET_INIT { { 0 } }
39
40
41 /**
42 * Initialize the oidset structure `set`.
43 *
44 * If `initial_size` is bigger than 0 then preallocate to allow inserting
45 * the specified number of elements without further allocations.
46 */
47 void oidset_init(struct oidset *set, size_t initial_size);
48
49 /**
50 * Returns true iff `set` contains `oid`.
51 */
52 int oidset_contains(const struct oidset *set, const struct object_id *oid);
53
54 /**
55 * Insert the oid into the set; a copy is made, so "oid" does not need
56 * to persist after this function is called.
57 *
58 * Returns 1 if the oid was already in the set, 0 otherwise. This can be used
59 * to perform an efficient check-and-add.
60 */
61 int oidset_insert(struct oidset *set, const struct object_id *oid);
62
63 /**
64 * Remove the oid from the set.
65 *
66 * Returns 1 if the oid was present in the set, 0 otherwise.
67 */
68 int oidset_remove(struct oidset *set, const struct object_id *oid);
69
70 /**
71 * Remove all entries from the oidset, freeing any resources associated with
72 * it.
73 */
74 void oidset_clear(struct oidset *set);
75
76 struct oidset_iter {
77 kh_oid_t *set;
78 khiter_t iter;
79 };
80
81 static inline void oidset_iter_init(struct oidset *set,
82 struct oidset_iter *iter)
83 {
84 iter->set = &set->set;
85 iter->iter = kh_begin(iter->set);
86 }
87
88 static inline struct object_id *oidset_iter_next(struct oidset_iter *iter)
89 {
90 for (; iter->iter != kh_end(iter->set); iter->iter++) {
91 if (kh_exist(iter->set, iter->iter))
92 return &kh_key(iter->set, iter->iter++);
93 }
94 return NULL;
95 }
96
97 static inline struct object_id *oidset_iter_first(struct oidset *set,
98 struct oidset_iter *iter)
99 {
100 oidset_iter_init(set, iter);
101 return oidset_iter_next(iter);
102 }
103
104 #endif /* OIDSET_H */