mirror of
https://github.com/git/git.git
synced 2024-12-01 05:54:16 +08:00
29c2bd5fa8
This is similar to many of our uses of sha1-array, but it overcomes one limitation of a sha1-array: when you are de-duplicating a large input with relatively few unique entries, sha1-array uses 20 bytes per non-unique entry. Whereas this set will use memory linear in the number of unique entries (albeit a few more than 20 bytes due to hashmap overhead). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
#ifndef OIDSET_H
|
|
#define OIDSET_H
|
|
|
|
/**
|
|
* This API is similar to sha1-array, in that it maintains a set of object ids
|
|
* in a memory-efficient way. The major differences are:
|
|
*
|
|
* 1. It uses a hash, so we can do online duplicate removal, rather than
|
|
* sort-and-uniq at the end. This can reduce memory footprint if you have
|
|
* a large list of oids with many duplicates.
|
|
*
|
|
* 2. The per-unique-oid memory footprint is slightly higher due to hash
|
|
* table overhead.
|
|
*/
|
|
|
|
/**
|
|
* A single oidset; should be zero-initialized (or use OIDSET_INIT).
|
|
*/
|
|
struct oidset {
|
|
struct hashmap map;
|
|
};
|
|
|
|
#define OIDSET_INIT { { NULL } }
|
|
|
|
/**
|
|
* Returns true iff `set` contains `oid`.
|
|
*/
|
|
int oidset_contains(const struct oidset *set, const struct object_id *oid);
|
|
|
|
/**
|
|
* Insert the oid into the set; a copy is made, so "oid" does not need
|
|
* to persist after this function is called.
|
|
*
|
|
* Returns 1 if the oid was already in the set, 0 otherwise. This can be used
|
|
* to perform an efficient check-and-add.
|
|
*/
|
|
int oidset_insert(struct oidset *set, const struct object_id *oid);
|
|
|
|
/**
|
|
* Remove all entries from the oidset, freeing any resources associated with
|
|
* it.
|
|
*/
|
|
void oidset_clear(struct oidset *set);
|
|
|
|
#endif /* OIDSET_H */
|