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   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
  19static inline unsigned int oid_hash(struct object_id oid)
  20{
  21        return sha1hash(oid.hash);
  22}
  23
  24static inline int oid_equal(struct object_id a, struct object_id b)
  25{
  26        return oideq(&a, &b);
  27}
  28
  29KHASH_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 */
  34struct 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 */
  47void oidset_init(struct oidset *set, size_t initial_size);
  48
  49/**
  50 * Returns true iff `set` contains `oid`.
  51 */
  52int 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 */
  61int 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 */
  68int 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 */
  74void oidset_clear(struct oidset *set);
  75
  76struct oidset_iter {
  77        kh_oid_t *set;
  78        khiter_t iter;
  79};
  80
  81static 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
  88static 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
  97static 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 */