Changeset: 1599d7d72d6c for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=1599d7d72d6c
Added Files:
gdk/xoshiro128starstar.h
Modified Files:
gdk/gdk.h
gdk/gdk_sample.c
Branch: sample-with-seed
Log Message:
Introducing BATsample_with_seed using xoshiro128starstar as prg.
diffs (114 lines):
diff --git a/gdk/gdk.h b/gdk/gdk.h
--- a/gdk/gdk.h
+++ b/gdk/gdk.h
@@ -2763,6 +2763,7 @@ gdk_export gdk_return BATfirstn(BAT **to
*
*/
gdk_export BAT *BATsample(BAT *b, BUN n);
+gdk_export BAT *BATsample_with_seed(BAT *b, BUN n, uint32_t seed);
/*
*
diff --git a/gdk/gdk_sample.c b/gdk/gdk_sample.c
--- a/gdk/gdk_sample.c
+++ b/gdk/gdk_sample.c
@@ -26,6 +26,7 @@
#include "monetdb_config.h"
#include "gdk.h"
#include "gdk_private.h"
+#include "xoshiro128starstar.h"
#undef BATsample
@@ -108,7 +109,7 @@ OIDTreeToBATAntiset(struct oidtreenode *
/* BATsample implements sampling for void headed BATs */
BAT *
-BATsample(BAT *b, BUN n)
+BATsample_with_seed(BAT *b, BUN n, uint32_t seed)
{
BAT *bn;
BUN cnt, slen;
@@ -128,6 +129,9 @@ BATsample(BAT *b, BUN n)
} else {
oid minoid = b->hseqbase;
oid maxoid = b->hseqbase + cnt;
+ random_state_engine rse;
+
+
/* if someone samples more than half of our tree, we
* do the antiset */
bool antiset = n > cnt / 2;
@@ -144,12 +148,17 @@ BATsample(BAT *b, BUN n)
GDKfree(tree);
return NULL;
}
+
+ init_random_state_engine(&rse, seed);
+
/* while we do not have enough sample OIDs yet */
for (rescnt = 0; rescnt < n; rescnt++) {
oid candoid;
do {
+ double random_double = next_double(rse);
+
/* generate a new random OID */
- candoid = (oid) (minoid + DRAND * (maxoid -
minoid));
+ candoid = (oid) (minoid + random_double *
(maxoid - minoid));
/* if that candidate OID was already
* generated, try again */
} while (!OIDTreeMaybeInsert(tree, candoid, rescnt));
@@ -172,3 +181,11 @@ BATsample(BAT *b, BUN n)
ALGOBATPAR(b), n, ALGOOPTBATPAR(bn));
return bn;
}
+
+BAT *
+BATsample(BAT *b, BUN n)
+{
+ uint32_t some_random_seed = (uint32_t) rand();
+
+ return BATsample_with_seed(b, n,some_random_seed);
+}
diff --git a/gdk/xoshiro128starstar.h b/gdk/xoshiro128starstar.h
new file mode 100644
--- /dev/null
+++ b/gdk/xoshiro128starstar.h
@@ -0,0 +1,37 @@
+#include <stdint.h>
+#include <string.h>
+
+static inline uint32_t rotl(const uint32_t x, int k) {
+ return (x << k) | (x >> (32 - k));
+}
+
+typedef uint32_t random_state_engine[4];
+
+void init_random_state_engine(random_state_engine* engine, uint32_t seed);
+void init_random_state_engine(random_state_engine* engine, uint32_t seed) {
+
+ random_state_engine s = { seed };
+
+ memcpy(engine, &s, sizeof(random_state_engine));
+}
+
+static inline uint32_t next_uint32(random_state_engine rse) {
+ uint32_t output = rotl(rse[0] * 5, 7) * 9;
+
+ const uint32_t t = rse[1] << 9;
+
+ rse[2] ^= rse[0];
+ rse[3] ^= rse[1];
+ rse[1] ^= rse[2];
+ rse[0] ^= rse[3];
+
+ rse[2] ^= t;
+
+ rse[3] = rotl(rse[3], 11);
+
+ return output;
+}
+
+static inline double next_double(random_state_engine rse) {
+ return (double) next_uint32(rse) / UINT32_MAX;
+}
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