- PERL_HASH_FUNC_SDBM
- PERL_HASH_FUNC_DJB2
- PERL_HASH_FUNC_SUPERFAST
- PERL_HASH_FUNC_MURMUR3
- PERL_HASH_FUNC_ONE_AT_A_TIME
- PERL_HASH_FUNC_ONE_AT_A_TIME_HARD
- PERL_HASH_FUNC_ONE_AT_A_TIME_OLD
-
-Perl 5.18 randomizes the order returned by keys(), values(), and each(),
-and allows controlling this behavior by using of the PERL_PERTURB_KEYS
-option. You can disable this option entirely with the define:
+ PERL_HASH_FUNC_SIPHASH13
+ PERL_HASH_FUNC_ZAPHOD32
+ PERL_HASH_FUNC_STADTX
+
+In addition, these, (or custom hash functions), may be "fronted" by the
+SBOX32 hash function for keys under a chosen size. This hash function is
+special in that it has proven theoretical security properties, and is very
+fast to hash, but which by nature is restricted to a maximum key length,
+and which has rather expensive setup costs (relatively speaking), both in
+terms of performance and more importantly in terms of memory. SBOX32
+requires 1k of storage per character it can hash, and it must populate that
+storage with 256 32-bit random values as well. In practice the RNG we use
+for seeding the SBOX32 storage is very efficient and populating the table
+required for hashing even fairly long keys is negligible as we only do it
+during startup. By default we build with SBOX32 enabled, but you change that
+by setting
+
+ PERL_HASH_USE_SBOX32_ALSO
+
+to zero in configure. By default Perl will use SBOX32 to hash strings 24 bytes
+or shorter, you can change this length by setting
+
+ SBOX32_MAX_LEN
+
+to the desired length, with the maximum length being 256.
+
+As of Perl 5.18 the order returned by keys(), values(), and each() is
+non-deterministic and distinct per hash, and the insert order for
+colliding keys is randomized as well, and perl allows for controlling this
+by the PERL_PERTURB_KEYS environment setting. You can disable this behavior
+entirely with the define