hashmap: introduce hash_ops to make struct Hashmap smaller

It is redundant to store 'hash' and 'compare' function pointers in
struct Hashmap separately. The functions always comprise a pair.
Store a single pointer to struct hash_ops instead.

systemd keeps hundreds of hashmaps, so this saves a little bit of
memory.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/shared/hashmap.h b/src/shared/hashmap.h
index b739262ab3..53b04eb033 100644
--- a/src/shared/hashmap.h
+++ b/src/shared/hashmap.h
@@ -41,27 +41,34 @@ typedef _IteratorStruct* Iterator;
 typedef unsigned long (*hash_func_t)(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]);
 typedef int (*compare_func_t)(const void *a, const void *b);
 
+struct hash_ops {
+        hash_func_t hash;
+        compare_func_t compare;
+};
+
 unsigned long string_hash_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) _pure_;
 int string_compare_func(const void *a, const void *b) _pure_;
+extern const struct hash_ops string_hash_ops;
 
 /* This will compare the passed pointers directly, and will not
  * dereference them. This is hence not useful for strings or
  * suchlike. */
 unsigned long trivial_hash_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) _pure_;
 int trivial_compare_func(const void *a, const void *b) _const_;
+extern const struct hash_ops trivial_hash_ops;
 
-Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func);
+Hashmap *hashmap_new(const struct hash_ops *hash_ops);
 void hashmap_free(Hashmap *h);
 void hashmap_free_free(Hashmap *h);
 
 int hashmap_put(Hashmap *h, const void *key, void *value);
 void *hashmap_get(Hashmap *h, const void *key);
+void *hashmap_get2(Hashmap *h, const void *key, void **rkey);
 bool hashmap_contains(Hashmap *h, const void *key);
 
 unsigned hashmap_size(Hashmap *h) _pure_;
 
 void *hashmap_iterate(Hashmap *h, Iterator *i, const void **key);
-void *hashmap_iterate_backwards(Hashmap *h, Iterator *i, const void **key);
 
 void hashmap_clear(Hashmap *h);
 void hashmap_clear_free(Hashmap *h);