/*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#pragma once
#define FOLLY_RANDOM_H_
-#include <type_traits>
+#include <array>
+#include <cstdint>
#include <random>
-#include <stdint.h>
+#include <type_traits>
+
#include <folly/Portability.h>
+#include <folly/Traits.h>
#if FOLLY_HAVE_EXTRANDOM_SFMT19937
#include <ext/random>
* However, if you are worried about performance, you can memoize the TLS
* lookups that get the per thread state by manually using this class:
*
- * ThreadLocalPRNG rng = Random::threadLocalPRNG()
+ * ThreadLocalPRNG rng;
* for (...) {
* Random::rand32(rng);
* }
ThreadLocalPRNG();
- private:
class LocalInstancePRNG;
+ private:
static result_type getImpl(LocalInstancePRNG* local);
LocalInstancePRNG* local_;
};
* Returns a random uint32_t
*/
static uint32_t rand32() {
- ThreadLocalPRNG prng;
- return rand32(prng);
+ return rand32(ThreadLocalPRNG());
}
/**
* Returns a random uint32_t given a specific RNG
*/
template <class RNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint32_t rand32(RNG rng) {
- uint32_t r = rng.operator()();
- return r;
+ static uint32_t rand32(RNG&& rng) {
+ return rng();
}
/**
* Returns a random uint32_t in [0, max). If max == 0, returns 0.
*/
static uint32_t rand32(uint32_t max) {
- ThreadLocalPRNG prng;
- return rand32(max, prng);
+ return rand32(0, max, ThreadLocalPRNG());
}
/**
* If max == 0, returns 0.
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint32_t rand32(uint32_t max, RNG rng = RNG()) {
- if (max == 0) {
- return 0;
- }
-
- return std::uniform_int_distribution<uint32_t>(0, max - 1)(rng);
+ static uint32_t rand32(uint32_t max, RNG&& rng) {
+ return rand32(0, max, rng);
}
/**
* Returns a random uint32_t in [min, max). If min == max, returns 0.
*/
+ static uint32_t rand32(uint32_t min, uint32_t max) {
+ return rand32(min, max, ThreadLocalPRNG());
+ }
+
+ /**
+ * Returns a random uint32_t in [min, max) given a specific RNG.
+ * If min == max, returns 0.
+ */
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint32_t rand32(uint32_t min, uint32_t max, RNG rng = RNG()) {
+ static uint32_t rand32(uint32_t min, uint32_t max, RNG&& rng) {
if (min == max) {
return 0;
}
-
return std::uniform_int_distribution<uint32_t>(min, max - 1)(rng);
}
+ /**
+ * Returns a random uint64_t
+ */
+ static uint64_t rand64() {
+ return rand64(ThreadLocalPRNG());
+ }
+
/**
* Returns a random uint64_t
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint64_t rand64(RNG rng = RNG()) {
- return ((uint64_t) rng() << 32) | rng();
+ static uint64_t rand64(RNG&& rng) {
+ return ((uint64_t)rng() << 32) | rng();
+ }
+
+ /**
+ * Returns a random uint64_t in [0, max). If max == 0, returns 0.
+ */
+ static uint64_t rand64(uint64_t max) {
+ return rand64(0, max, ThreadLocalPRNG());
}
/**
* Returns a random uint64_t in [0, max). If max == 0, returns 0.
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint64_t rand64(uint64_t max, RNG rng = RNG()) {
- if (max == 0) {
- return 0;
- }
+ static uint64_t rand64(uint64_t max, RNG&& rng) {
+ return rand64(0, max, rng);
+ }
- return std::uniform_int_distribution<uint64_t>(0, max - 1)(rng);
+ /**
+ * Returns a random uint64_t in [min, max). If min == max, returns 0.
+ */
+ static uint64_t rand64(uint64_t min, uint64_t max) {
+ return rand64(min, max, ThreadLocalPRNG());
}
/**
* Returns a random uint64_t in [min, max). If min == max, returns 0.
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static uint64_t rand64(uint64_t min, uint64_t max, RNG rng = RNG()) {
+ static uint64_t rand64(uint64_t min, uint64_t max, RNG&& rng) {
if (min == max) {
return 0;
}
-
return std::uniform_int_distribution<uint64_t>(min, max - 1)(rng);
}
+ /**
+ * Returns true 1/n of the time. If n == 0, always returns false
+ */
+ static bool oneIn(uint32_t n) {
+ return oneIn(n, ThreadLocalPRNG());
+ }
+
/**
* Returns true 1/n of the time. If n == 0, always returns false
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static bool oneIn(uint32_t n, ValidRNG<RNG> rng = RNG()) {
+ static bool oneIn(uint32_t n, RNG&& rng) {
if (n == 0) {
return false;
}
+ return rand32(0, n, rng) == 0;
+ }
- return rand32(n, rng) == 0;
+ /**
+ * Returns a double in [0, 1)
+ */
+ static double randDouble01() {
+ return randDouble01(ThreadLocalPRNG());
}
/**
* Returns a double in [0, 1)
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static double randDouble01(RNG rng = RNG()) {
- return std::generate_canonical<double, std::numeric_limits<double>::digits>
- (rng);
+ static double randDouble01(RNG&& rng) {
+ return std::generate_canonical<double, std::numeric_limits<double>::digits>(
+ rng);
+ }
+
+ /**
+ * Returns a double in [min, max), if min == max, returns 0.
+ */
+ static double randDouble(double min, double max) {
+ return randDouble(min, max, ThreadLocalPRNG());
}
/**
* Returns a double in [min, max), if min == max, returns 0.
*/
template <class RNG = ThreadLocalPRNG, class /* EnableIf */ = ValidRNG<RNG>>
- static double randDouble(double min, double max, RNG rng = RNG()) {
+ static double randDouble(double min, double max, RNG&& rng) {
if (std::fabs(max - min) < std::numeric_limits<double>::epsilon()) {
return 0;
}
return Random::rand32();
}
-}
+} // namespace folly
#include <folly/Random-inl.h>
projects / folly.git / blobdiff