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random: Add FastRandomContext::rand_uniform_delay

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MarcoFalke 2022-04-08 12:56:25 +02:00 • committed by MacroFake
parent faa5c62967
commit fa4fb8d98b
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2 changed files with 21 additions and 0 deletions
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11
src/random.h
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@ -223,6 +223,17 @@ public:
/** Generate a random boolean. */
bool randbool() noexcept { return randbits(1); }
/** Return the time point advanced by a uniform random duration. */
template <typename Tp>
Tp rand_uniform_delay(const Tp& time, typename Tp::duration range)
{
using Dur = typename Tp::duration;
Dur dur{range.count() > 0 ? /* interval [0..range) */ Dur{randrange(range.count())} :
range.count() < 0 ? /* interval (range..0] */ -Dur{randrange(-range.count())} :
/* interval [0..0] */ Dur{0}};
return time + dur;
}
// Compatibility with the C++11 UniformRandomBitGenerator concept
typedef uint64_t result_type;
static constexpr uint64_t min() { return 0; }

10
src/test/random_tests.cpp
View file

@ -31,6 +31,16 @@ BOOST_AUTO_TEST_CASE(fastrandom_tests)
BOOST_CHECK_EQUAL(GetRandMicros(std::chrono::hours{1}).count(), 2917185654);
BOOST_CHECK_EQUAL(GetRandMillis(std::chrono::hours{1}).count(), 2144374);
}
{
constexpr SteadySeconds time_point{1s};
FastRandomContext ctx{true};
BOOST_CHECK_EQUAL(7, ctx.rand_uniform_delay(time_point, 9s).time_since_epoch().count());
BOOST_CHECK_EQUAL(-6, ctx.rand_uniform_delay(time_point, -9s).time_since_epoch().count());
BOOST_CHECK_EQUAL(1, ctx.rand_uniform_delay(time_point, 0s).time_since_epoch().count());
BOOST_CHECK_EQUAL(1467825113502396065, ctx.rand_uniform_delay(time_point, 9223372036854775807s).time_since_epoch().count());
BOOST_CHECK_EQUAL(-970181367944767837, ctx.rand_uniform_delay(time_point, -9223372036854775807s).time_since_epoch().count());
BOOST_CHECK_EQUAL(24761, ctx.rand_uniform_delay(time_point, 9h).time_since_epoch().count());
}
BOOST_CHECK_EQUAL(ctx1.rand32(), ctx2.rand32());
BOOST_CHECK_EQUAL(ctx1.rand32(), ctx2.rand32());
BOOST_CHECK_EQUAL(ctx1.rand64(), ctx2.rand64());