From 2b3e06380d5a339efc94e748aa57985d3bb80223 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Wed, 13 Sep 2017 18:43:46 -0700 Subject: [PATCH 4/8] Add inline murmurhash32(int32) function. The function already existed in tidbitmap.c but more users requiring fast hashing of 32bit ints are coming up. --- src/backend/nodes/tidbitmap.c | 20 ++------------------ src/include/utils/hashutils.h | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+), 18 deletions(-) diff --git a/src/backend/nodes/tidbitmap.c b/src/backend/nodes/tidbitmap.c index c4e53adb0c..01d6bc5c11 100644 --- a/src/backend/nodes/tidbitmap.c +++ b/src/backend/nodes/tidbitmap.c @@ -45,6 +45,7 @@ #include "nodes/tidbitmap.h" #include "storage/lwlock.h" #include "utils/dsa.h" +#include "utils/hashutils.h" /* * The maximum number of tuples per page is not large (typically 256 with @@ -237,30 +238,13 @@ static int tbm_comparator(const void *left, const void *right); static int tbm_shared_comparator(const void *left, const void *right, void *arg); -/* - * Simple inline murmur hash implementation for the exact width required, for - * performance. - */ -static inline uint32 -hash_blockno(BlockNumber b) -{ - uint32 h = b; - - h ^= h >> 16; - h *= 0x85ebca6b; - h ^= h >> 13; - h *= 0xc2b2ae35; - h ^= h >> 16; - return h; -} - /* define hashtable mapping block numbers to PagetableEntry's */ #define SH_USE_NONDEFAULT_ALLOCATOR #define SH_PREFIX pagetable #define SH_ELEMENT_TYPE PagetableEntry #define SH_KEY_TYPE BlockNumber #define SH_KEY blockno -#define SH_HASH_KEY(tb, key) hash_blockno(key) +#define SH_HASH_KEY(tb, key) murmurhash32(key) #define SH_EQUAL(tb, a, b) a == b #define SH_SCOPE static inline #define SH_DEFINE diff --git a/src/include/utils/hashutils.h b/src/include/utils/hashutils.h index 56b7bfc9cb..35281689e8 100644 --- a/src/include/utils/hashutils.h +++ b/src/include/utils/hashutils.h @@ -20,4 +20,22 @@ hash_combine(uint32 a, uint32 b) return a; } + +/* + * Simple inline murmur hash implementation hashing a 32 bit ingeger, for + * performance. + */ +static inline uint32 +murmurhash32(uint32 data) +{ + uint32 h = data; + + h ^= h >> 16; + h *= 0x85ebca6b; + h ^= h >> 13; + h *= 0xc2b2ae35; + h ^= h >> 16; + return h; +} + #endif /* HASHUTILS_H */ -- 2.14.1.536.g6867272d5b.dirty