1 /* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 // vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
3 #ident "$Id$"
4 /*======
5 This file is part of PerconaFT.
6
7
8 Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
9
10 PerconaFT is free software: you can redistribute it and/or modify
11 it under the terms of the GNU General Public License, version 2,
12 as published by the Free Software Foundation.
13
14 PerconaFT is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
21
22 ----------------------------------------
23
24 PerconaFT is free software: you can redistribute it and/or modify
25 it under the terms of the GNU Affero General Public License, version 3,
26 as published by the Free Software Foundation.
27
28 PerconaFT is distributed in the hope that it will be useful,
29 but WITHOUT ANY WARRANTY; without even the implied warranty of
30 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
31 GNU Affero General Public License for more details.
32
33 You should have received a copy of the GNU Affero General Public License
34 along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
35 ======= */
36
37 #ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
38
39 #pragma once
40
41 #include <portability/toku_config.h>
42 #include <toku_portability.h>
43 #include <toku_assert.h>
44 #include <stdlib.h>
45 #include <stdint.h>
46 #include <limits.h>
47
48 #if defined(HAVE_RANDOM_R)
49 // Definition of randu62 and randu64 assume myrandom_r generates 31 low-order bits
50 static_assert(RAND_MAX == INT32_MAX, "Unexpected RAND_MAX");
51 static inline int
myinitstate_r(unsigned int seed,char * statebuf,size_t statelen,struct random_data * buf)52 myinitstate_r(unsigned int seed, char *statebuf, size_t statelen, struct random_data *buf)
53 {
54 return initstate_r(seed, statebuf, statelen, buf);
55 }
56 static inline int32_t
myrandom_r(struct random_data * buf)57 myrandom_r(struct random_data *buf)
58 {
59 int32_t x;
60 int r = random_r(buf, &x);
61 lazy_assert_zero(r);
62 return x;
63 }
64 #elif defined(HAVE_NRAND48)
65 struct random_data {
66 unsigned short xsubi[3];
67 };
68 static inline int
myinitstate_r(unsigned int seed,char * UU (statebuf),size_t UU (statelen),struct random_data * buf)69 myinitstate_r(unsigned int seed, char *UU(statebuf), size_t UU(statelen), struct random_data *buf)
70 {
71 buf->xsubi[0] = (seed & 0xffff0000) >> 16;
72 buf->xsubi[0] = (seed & 0x0000ffff);
73 buf->xsubi[2] = (seed & 0x00ffff00) >> 8;
74 return 0;
75 }
76 static inline int32_t
myrandom_r(struct random_data * buf)77 myrandom_r(struct random_data *buf)
78 {
79 int32_t x = nrand48(buf->xsubi);
80 return x;
81 }
82 #else
83 # error "no suitable reentrant random function available (checked random_r and nrand48)"
84 #endif
85
86 static inline uint64_t
randu62(struct random_data * buf)87 randu62(struct random_data *buf)
88 {
89 uint64_t a = myrandom_r(buf);
90 uint64_t b = myrandom_r(buf);
91 return (a | (b << 31));
92 }
93
94 static inline uint64_t
randu64(struct random_data * buf)95 randu64(struct random_data *buf)
96 {
97 uint64_t r62 = randu62(buf);
98 uint64_t c = myrandom_r(buf);
99 return (r62 | ((c & 0x3) << 62));
100 }
101
102 static inline uint32_t
rand_choices(struct random_data * buf,uint32_t choices)103 rand_choices(struct random_data *buf, uint32_t choices) {
104 invariant(choices >= 2);
105 invariant(choices < INT32_MAX);
106 uint32_t bits = 2;
107 while (bits < choices) {
108 bits *= 2;
109 }
110 --bits;
111
112 uint32_t result;
113 do {
114 result = myrandom_r(buf) & bits;
115 } while (result >= choices);
116
117 return result;
118 }
119