git/strmap.c
Elijah Newren 6ccdfc2a20 strmap: enable faster clearing and reusing of strmaps
When strmaps are used heavily, such as is done by my new merge-ort
algorithm, and strmaps need to be cleared but then re-used (because of
e.g. picking multiple commits to cherry-pick, or due to a recursive
merge having several different merges while recursing), free-ing and
reallocating map->table repeatedly can add up in time, especially since
it will likely be reallocated to a much smaller size but the previous
merge provides a good guide to the right size to use for the next merge.

Introduce strmap_partial_clear() to take advantage of this type of
situation; it will act similar to strmap_clear() except that
map->table's entries are zeroed instead of map->table being free'd.
Making use of this function reduced the cost of
clear_or_reinit_internal_opts() by about 20% in mert-ort, and dropped
the overall runtime of my rebase testcase by just under 2%.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-04 17:09:49 -08:00

126 lines
2.9 KiB
C

#include "git-compat-util.h"
#include "strmap.h"
int cmp_strmap_entry(const void *hashmap_cmp_fn_data,
const struct hashmap_entry *entry1,
const struct hashmap_entry *entry2,
const void *keydata)
{
const struct strmap_entry *e1, *e2;
e1 = container_of(entry1, const struct strmap_entry, ent);
e2 = container_of(entry2, const struct strmap_entry, ent);
return strcmp(e1->key, e2->key);
}
static struct strmap_entry *find_strmap_entry(struct strmap *map,
const char *str)
{
struct strmap_entry entry;
hashmap_entry_init(&entry.ent, strhash(str));
entry.key = str;
return hashmap_get_entry(&map->map, &entry, ent, NULL);
}
void strmap_init(struct strmap *map)
{
strmap_init_with_options(map, 1);
}
void strmap_init_with_options(struct strmap *map,
int strdup_strings)
{
hashmap_init(&map->map, cmp_strmap_entry, NULL, 0);
map->strdup_strings = strdup_strings;
}
static void strmap_free_entries_(struct strmap *map, int free_values)
{
struct hashmap_iter iter;
struct strmap_entry *e;
if (!map)
return;
/*
* We need to iterate over the hashmap entries and free
* e->key and e->value ourselves; hashmap has no API to
* take care of that for us. Since we're already iterating over
* the hashmap, though, might as well free e too and avoid the need
* to make some call into the hashmap API to do that.
*/
hashmap_for_each_entry(&map->map, &iter, e, ent) {
if (free_values)
free(e->value);
if (map->strdup_strings)
free((char*)e->key);
free(e);
}
}
void strmap_clear(struct strmap *map, int free_values)
{
strmap_free_entries_(map, free_values);
hashmap_clear(&map->map);
}
void strmap_partial_clear(struct strmap *map, int free_values)
{
strmap_free_entries_(map, free_values);
hashmap_partial_clear(&map->map);
}
void *strmap_put(struct strmap *map, const char *str, void *data)
{
struct strmap_entry *entry = find_strmap_entry(map, str);
void *old = NULL;
if (entry) {
old = entry->value;
entry->value = data;
} else {
const char *key = str;
entry = xmalloc(sizeof(*entry));
hashmap_entry_init(&entry->ent, strhash(str));
if (map->strdup_strings)
key = xstrdup(str);
entry->key = key;
entry->value = data;
hashmap_add(&map->map, &entry->ent);
}
return old;
}
struct strmap_entry *strmap_get_entry(struct strmap *map, const char *str)
{
return find_strmap_entry(map, str);
}
void *strmap_get(struct strmap *map, const char *str)
{
struct strmap_entry *entry = find_strmap_entry(map, str);
return entry ? entry->value : NULL;
}
int strmap_contains(struct strmap *map, const char *str)
{
return find_strmap_entry(map, str) != NULL;
}
void strmap_remove(struct strmap *map, const char *str, int free_value)
{
struct strmap_entry entry, *ret;
hashmap_entry_init(&entry.ent, strhash(str));
entry.key = str;
ret = hashmap_remove_entry(&map->map, &entry, ent, NULL);
if (!ret)
return;
if (free_value)
free(ret->value);
if (map->strdup_strings)
free((char*)ret->key);
free(ret);
}