ghash and edgehash api, allow newly defined hashes to take in the size of the hash as an arg (avoids resizing in simple cases when the hash is created and filled immediately).

1 files changed, 20 insertions, 2 deletions

diff --git a/source/blender/blenlib/intern/BLI_ghash.c b/source/blender/blenlib/intern/BLI_ghash.c
index 10a425ca12c..a1cbf8a5ce0 100644
--- a/source/blender/blenlib/intern/BLI_ghash.c
+++ b/source/blender/blenlib/intern/BLI_ghash.c
@@ -86,6 +86,11 @@ struct GHash {
 
 /* internal utility API */
 
+BLI_INLINE bool ghash_test_expand_buckets(const unsigned int nentries, const unsigned int nbuckets)
+{
+	return (nentries > nbuckets / 2);
+}
+
 BLI_INLINE unsigned int ghash_keyhash(GHash *gh, const void *key)
 {
 	return gh->hashfp(key) % gh->nbuckets;
@@ -122,7 +127,7 @@ static void ghash_insert_ex(GHash *gh, void *key, void *val,
 	e->val = val;
 	gh->buckets[hash] = e;
 
-	if (UNLIKELY(++gh->nentries > gh->nbuckets / 2)) {
+	if (UNLIKELY(ghash_test_expand_buckets(++gh->nentries, gh->nbuckets))) {
 		Entry **old = gh->buckets;
 		const unsigned nold = gh->nbuckets;
 		unsigned int i;
@@ -147,7 +152,8 @@ static void ghash_insert_ex(GHash *gh, void *key, void *val,
 
 /* Public API */
 
-GHash *BLI_ghash_new(GHashHashFP hashfp, GHashCmpFP cmpfp, const char *info)
+GHash *BLI_ghash_new_ex(GHashHashFP hashfp, GHashCmpFP cmpfp, const char *info,
+                        const unsigned int nentries_reserve)
 {
 	GHash *gh = MEM_mallocN(sizeof(*gh), info);
 
@@ -159,12 +165,24 @@ GHash *BLI_ghash_new(GHashHashFP hashfp, GHashCmpFP cmpfp, const char *info)
 	gh->cursize = 0;
 	gh->flag = 0;
 
+	/* if we have reserved the number of elements that this hash will contain */
+	if (nentries_reserve) {
+		while (ghash_test_expand_buckets(nentries_reserve, gh->nbuckets)) {
+			gh->nbuckets = hashsizes[++gh->cursize];
+		}
+	}
+
 	gh->buckets = MEM_callocN(gh->nbuckets * sizeof(*gh->buckets), "buckets");
 	gh->entrypool = BLI_mempool_create(sizeof(Entry), 64, 64, 0);
 
 	return gh;
 }
 
+GHash *BLI_ghash_new(GHashHashFP hashfp, GHashCmpFP cmpfp, const char *info)
+{
+	return BLI_ghash_new_ex(hashfp, cmpfp, info, 0);
+}
+
 int BLI_ghash_size(GHash *gh)
 {
 	return (int)gh->nentries;