Adding upstream version 1:10.11.6.upstream/1%10.11.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 93 insertions, 0 deletions

diff --git a/storage/innobase/ut/ut0rnd.cc b/storage/innobase/ut/ut0rnd.cc
new file mode 100644
index 00000000..a2e56951
--- /dev/null
+++ b/storage/innobase/ut/ut0rnd.cc
@@ -0,0 +1,93 @@
+/*****************************************************************************
+
+Copyright (c) 1994, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2019, 2020, MariaDB Corporation.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
+
+*****************************************************************************/
+
+/***************************************************************//**
+@file ut/ut0rnd.cc
+Random numbers and hashing
+
+Created 5/11/1994 Heikki Tuuri
+********************************************************************/
+
+#include "ut0rnd.h"
+
+/** Seed value of ut_rnd_gen() */
+std::atomic<uint32_t> ut_rnd_current;
+
+/** These random numbers are used in ut_find_prime */
+/*@{*/
+#define	UT_RANDOM_1	1.0412321
+#define	UT_RANDOM_2	1.1131347
+#define UT_RANDOM_3	1.0132677
+/*@}*/
+
+/***********************************************************//**
+Looks for a prime number slightly greater than the given argument.
+The prime is chosen so that it is not near any power of 2.
+@return prime */
+ulint
+ut_find_prime(
+/*==========*/
+	ulint	n)	/*!< in: positive number > 100 */
+{
+	ulint	pow2;
+	ulint	i;
+
+	n += 100;
+
+	pow2 = 1;
+	while (pow2 * 2 < n) {
+		pow2 = 2 * pow2;
+	}
+
+	if ((double) n < 1.05 * (double) pow2) {
+		n = (ulint) ((double) n * UT_RANDOM_1);
+	}
+
+	pow2 = 2 * pow2;
+
+	if ((double) n > 0.95 * (double) pow2) {
+		n = (ulint) ((double) n * UT_RANDOM_2);
+	}
+
+	if (n > pow2 - 20) {
+		n += 30;
+	}
+
+	/* Now we have n far enough from powers of 2. To make
+	n more random (especially, if it was not near
+	a power of 2), we then multiply it by a random number. */
+
+	n = (ulint) ((double) n * UT_RANDOM_3);
+
+	for (;; n++) {
+		i = 2;
+		while (i * i <= n) {
+			if (n % i == 0) {
+				goto next_n;
+			}
+			i++;
+		}
+
+		/* Found a prime */
+		break;
+next_n:		;
+	}
+
+	return(n);
+}