[PATCH 02/12] lib: Replace str_hash/strcase_hash with xxh64

Replaces the old ASU-derived shift-and-XOR hash with xxh64_to_32(),
which provides better distribution and avalanche properties.
strcase_hash feeds each i_toupper()'d byte through the streaming API.

Gbp-Pq: Name 0002-lib-Replace-str_hash-strcase_hash-with-xxh64.patch

diff --git a/src/lib/hash.c b/src/lib/hash.c
index aceef29b23ba951c7d075c2de44fcdd7601d9b1e..8f4cd7d9b41b371d005b53c2172611ee8afdd723 100644 (file)
--- a/src/lib/hash.c
+++ b/src/lib/hash.c
@@ -5,6 +5,7 @@
 #include "lib.h"
 #include "hash.h"
 #include "primes.h"
+#include "xxh64.h"
 
 #include <ctype.h>
 
@@ -519,42 +520,22 @@ void hash_table_copy(struct hash_table *dest, struct hash_table *src)
        hash_table_thaw(dest);
 }
 
-/* a char* hash function from ASU -- from glib */
-unsigned int ATTR_NO_SANITIZE_INTEGER
-str_hash(const char *p)
+unsigned int str_hash(const char *p)
 {
-       const unsigned char *s = (const unsigned char *)p;
-       unsigned int g, h = 0;
-
-       while (*s != '\0') {
-               h = (h << 4) + *s;
-               if ((g = h & 0xf0000000UL) != 0) {
-                       h = h ^ (g >> 24);
-                       h = h ^ g;
-               }
-               s++;
-       }
-
-       return h;
+       return xxh64_to_32(xxh64_data(p, strlen(p), 0));
 }
 
-/* a char* hash function from ASU -- from glib */
-unsigned int ATTR_NO_SANITIZE_INTEGER
-strcase_hash(const char *p)
+unsigned int strcase_hash(const char *p)
 {
-       const unsigned char *s = (const unsigned char *)p;
-       unsigned int g, h = 0;
+       struct xxh64_context ctx;
+       unsigned char c;
 
-       while (*s != '\0') {
-               h = (h << 4) + i_toupper(*s);
-               if ((g = h & 0xf0000000UL) != 0) {
-                       h = h ^ (g >> 24);
-                       h = h ^ g;
-               }
-               s++;
+       xxh64_init(&ctx, 0);
+       while (*p != '\0') {
+               c = (unsigned char)i_toupper(*p++);
+               xxh64_loop(&ctx, &c, 1);
        }
-
-       return h;
+       return xxh64_to_32(xxh64_result(&ctx));
 }
 
 unsigned int ATTR_NO_SANITIZE_INTEGER