Andrew's git - gitweb.git/blob

   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
  41static inline void oidset_init(struct oidset *set, size_t initial_size)
  42{
  43        memset(&set->set, 0, sizeof(set->set));
  44        if (initial_size)
  45                kh_resize_oid(&set->set, initial_size);
  46}
  47
  48/**
  49 * Returns true iff `set` contains `oid`.
  50 */
  51int oidset_contains(const struct oidset *set, const struct object_id *oid);
  52
  53/**
  54 * Insert the oid into the set; a copy is made, so "oid" does not need
  55 * to persist after this function is called.
  56 *
  57 * Returns 1 if the oid was already in the set, 0 otherwise. This can be used
  58 * to perform an efficient check-and-add.
  59 */
  60int oidset_insert(struct oidset *set, const struct object_id *oid);
  61
  62/**
  63 * Remove the oid from the set.
  64 *
  65 * Returns 1 if the oid was present in the set, 0 otherwise.
  66 */
  67int oidset_remove(struct oidset *set, const struct object_id *oid);
  68
  69/**
  70 * Remove all entries from the oidset, freeing any resources associated with
  71 * it.
  72 */
  73void oidset_clear(struct oidset *set);
  74
  75struct oidset_iter {
  76        kh_oid_t *set;
  77        khiter_t iter;
  78};
  79
  80static inline void oidset_iter_init(struct oidset *set,
  81                                    struct oidset_iter *iter)
  82{
  83        iter->set = &set->set;
  84        iter->iter = kh_begin(iter->set);
  85}
  86
  87static inline struct object_id *oidset_iter_next(struct oidset_iter *iter)
  88{
  89        for (; iter->iter != kh_end(iter->set); iter->iter++) {
  90                if (kh_exist(iter->set, iter->iter))
  91                        return &kh_key(iter->set, iter->iter++);
  92        }
  93        return NULL;
  94}
  95
  96static inline struct object_id *oidset_iter_first(struct oidset *set,
  97                                                  struct oidset_iter *iter)
  98{
  99        oidset_iter_init(set, iter);
 100        return oidset_iter_next(iter);
 101}
 102
 103#endif /* OIDSET_H */