// random.h
/* Copyright 2012 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see .
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include
namespace mongo {
/**
* Uses http://en.wikipedia.org/wiki/Xorshift
*/
class PseudoRandom {
public:
PseudoRandom(int32_t seed);
PseudoRandom(uint32_t seed);
PseudoRandom(int64_t seed);
int32_t nextInt32();
int64_t nextInt64();
/**
* Returns a random number in the range [0, 1).
*/
double nextCanonicalDouble();
/**
* @return a number between 0 and max
*/
int32_t nextInt32(int32_t max) {
return static_cast(nextInt32()) % static_cast(max);
}
/**
* @return a number between 0 and max
*/
int64_t nextInt64(int64_t max) {
return static_cast(nextInt64()) % static_cast(max);
}
/**
* @return a number between 0 and max
*
* This makes PseudoRandom instances passable as the third argument to std::random_shuffle
*/
intptr_t operator()(intptr_t max) {
if (sizeof(intptr_t) == 4)
return static_cast(nextInt32(static_cast(max)));
return static_cast(nextInt64(static_cast(max)));
}
private:
uint32_t nextUInt32();
uint32_t _x;
uint32_t _y;
uint32_t _z;
uint32_t _w;
};
/**
* More secure random numbers
* Suitable for nonce/crypto
* Slower than PseudoRandom, so only use when really need
*/
class SecureRandom {
public:
virtual ~SecureRandom();
virtual int64_t nextInt64() = 0;
static SecureRandom* create();
};
} // namespace mongo