Changeset: fce06d888f5b for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=fce06d888f5b
Modified Files:
gdk/gdk.h
gdk/gdk_hash.c
gdk/gdk_hash.h
Branch: leftmart
Log Message:
prime number hash function for lng, int, oid etc.
This is a test implementation of the FNV hashing function.
diffs (134 lines):
diff --git a/gdk/gdk.h b/gdk/gdk.h
--- a/gdk/gdk.h
+++ b/gdk/gdk.h
@@ -671,6 +671,7 @@ typedef struct {
BUN nil; /* nil representation */
BUN lim; /* collision list size */
BUN mask; /* number of hash buckets-1 (power of 2) */
+ int n; /* the power of 2 (aka log_2(mask+1)) */
void *Hash; /* hash table */
void *Link; /* collision list */
Heap *heap; /* heap where the hash is stored */
diff --git a/gdk/gdk_hash.c b/gdk/gdk_hash.c
--- a/gdk/gdk_hash.c
+++ b/gdk/gdk_hash.c
@@ -87,6 +87,17 @@ HASHclear(Hash *h)
memset(h->Hash, 0xFF, (h->mask + 1) * h->width);
}
+static int
+log2mask(BUN m) {
+ int n = 0;
+
+ while (m) {
+ m >>= 1;
+ n++;
+ }
+ return n;
+}
+
#define HASH_VERSION 1
#define HASH_HEADER_SIZE 5 /* nr of size_t fields in header */
@@ -104,6 +115,7 @@ HASHnew(Heap *hp, int tpe, BUN size, BUN
return NULL;
h->lim = size;
h->mask = mask - 1;
+ h->n = log2mask(mask);
h->width = width;
switch (width) {
case BUN2:
@@ -230,6 +242,7 @@ BATcheckhash(BAT *b)
h->lim = (BUN) hdata[1];
h->type = ATOMtype(b->ttype);
h->mask = (BUN) (hdata[2] - 1);
+ h->n = log2mask(h->mask+1);
h->heap = hp;
h->width = (int) hdata[3];
switch (h->width) {
@@ -254,6 +267,8 @@ BATcheckhash(BAT *b)
b->T->hash = h;
ALGODEBUG fprintf(stderr,
"#BATcheckhash: reusing persisted hash %s\n", BATgetId(b));
MT_lock_unset(&GDKhashLock(abs(b->batCacheid)));
+ IDXACCESS fprintf(stderr,
"[%4d->%4d]:%s (" BUNFMT ") #BATcheckhash: load persistent hash index (ms="
LLFMT
+ ")\n",
b->batCacheid,-VIEWtparent(b), "type", BATcount(b), GDKusec() - t);
return 1;
}
GDKfree(h);
@@ -514,9 +529,10 @@ BAThash(BAT *b, BUN masksize)
b->T->hash = h;
t1 = GDKusec();
ALGODEBUG fprintf(stderr, "#BAThash: hash construction " LLFMT
" usec\n", t1 - t0);
- ALGODEBUG HASHcollisions(b, b->T->hash);
+ HASHcollisions(b, b->T->hash);
}
MT_lock_unset(&GDKhashLock(abs(b->batCacheid)));
+ IDXACCESS fprintf(stderr, "[%4d->%4d]:%s (" BUNFMT ") #BAThash: create
hash index (ms=" LLFMT ")\n", b->batCacheid,-VIEWtparent(b), "type",
BATcount(b), t1 - t0);
return GDK_SUCCEED;
}
diff --git a/gdk/gdk_hash.h b/gdk/gdk_hash.h
--- a/gdk/gdk_hash.h
+++ b/gdk/gdk_hash.h
@@ -128,6 +128,49 @@ gdk_export BUN HASHlist(Hash *h, BUN i);
} while (0)
#endif
+
+/* FNV hash */
+
+#if SIZEOF_BUN == 8
+#define FNV_PRIME 0x100000001b3ULL
+#define FNV_INIT 0xcbf29ce484222325ULL
+#else
+#define FNV_PRIME 0x01000193
+#define FNV_INIT 0x811c9dc5
+#endif
+
+static inline BUN fnvhash_int(const void *v) {
+ unsigned int v_int = *(unsigned int *) v;
+ BUN r = FNV_INIT;
+#if SIZEOF_INT == 8
+ int octets = 8;
+#else
+ int octets = 4;
+#endif
+ while (octets--) {
+ r ^= (v_int & 0xff);
+ v_int >>= 8;
+ r *= FNV_PRIME;
+ }
+ return r;
+}
+
+static inline BUN fnvhash_lng(const void *v) {
+ ulng v_int = *(ulng *) v;
+ BUN r = FNV_INIT;
+ int octets = 8;
+ while (octets--) {
+ r ^= (v_int & 0xff);
+ v_int >>= 8;
+ r *= FNV_PRIME;
+ }
+ return r;
+}
+
+#define hash_int2(H,R) ((H)->n > 32 ? ((BUN) ((R) >> (H)->n) ^ ((R) &
(H)->mask)) : ((BUN) ((((R) >> (H)->n) ^ (R)) & (H)->mask)))
+#define hash_int(H,V) hash_int2(H, fnvhash_int(V))
+#define hash_lng(H,V) hash_int2(H, fnvhash_lng(V))
+
#define mix_bte(X) ((unsigned int) (unsigned char) (X))
#define mix_sht(X) ((unsigned int) (unsigned short) (X))
#define mix_int(X) (((unsigned int) (X) >> 7) ^ \
@@ -145,9 +188,9 @@ gdk_export BUN HASHlist(Hash *h, BUN i);
#define heap_hash_any(hp,H,V) ((hp) && (hp)->hashash ? ((BUN *) (V))[-1] &
(H)->mask : hash_any(H,V))
#define hash_bte(H,V) (assert(((H)->mask & 0xFF) == 0xFF), (BUN)
mix_bte(*(const unsigned char*) (V)))
#define hash_sht(H,V) (assert(((H)->mask & 0xFFFF) == 0xFFFF), (BUN)
mix_sht(*(const unsigned short*) (V)))
-#define hash_int(H,V) ((BUN) mix_int(*(const unsigned int *) (V)) & (H)->mask)
+/*#define hash_int(H,V) ((BUN) mix_int(*(const unsigned int *) (V)) &
(H)->mask)*/
/* XXX return size_t-sized value for 8-byte oid? */
-#define hash_lng(H,V) ((BUN) mix_lng(*(const ulng *) (V)) & (H)->mask)
+/*#define hash_lng(H,V) ((BUN) mix_lng(*(const ulng *) (V)) &
(H)->mask)*/
#ifdef HAVE_HGE
#define hash_hge(H,V) ((BUN) mix_hge(*(const uhge *) (V)) & (H)->mask)
#endif
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