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author | 2019-06-21 13:11:42 -0700 | |
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committer | 2019-06-21 16:18:10 -0400 | |
commit | e9324d926a9189e222741fce6e676f0944661a72 (patch) | |
tree | a08568a709940c376454da34c9d8aac021378e5f /absl/random/random.h | |
parent | 43ef2148c0936ebf7cb4be6b19927a9d9d145b8f (diff) |
Export of internal Abseil changes.
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7a6ff16a85beb730c172d5d25cf1b5e1be885c56 by Laramie Leavitt <lar@google.com>:
Internal change.
PiperOrigin-RevId: 254454546
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ff8f9bafaefc26d451f576ea4a06d150aed63f6f by Andy Soffer <asoffer@google.com>:
Internal changes
PiperOrigin-RevId: 254451562
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deefc5b651b479ce36f0b4ef203e119c0c8936f2 by CJ Johnson <johnsoncj@google.com>:
Account for subtracting unsigned values from the size of InlinedVector
PiperOrigin-RevId: 254450625
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3c677316a27bcadc17e41957c809ca472d5fef14 by Andy Soffer <asoffer@google.com>:
Add C++17's std::make_from_tuple to absl/utility/utility.h
PiperOrigin-RevId: 254411573
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4ee3536a918830eeec402a28fc31a62c7c90b940 by CJ Johnson <johnsoncj@google.com>:
Adds benchmark for the rest of the InlinedVector public API
PiperOrigin-RevId: 254408378
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e5a21a00700ee83498ff1efbf649169756463ee4 by CJ Johnson <johnsoncj@google.com>:
Updates the definition of InlinedVector::shrink_to_fit() to be exception safe and adds exception safety tests for it.
PiperOrigin-RevId: 254401387
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2ea82e72b86d82d78b4e4712a63a55981b53c64b by Laramie Leavitt <lar@google.com>:
Use absl::InsecureBitGen in place of std::mt19937
in tests absl/random/...distribution_test.cc
PiperOrigin-RevId: 254289444
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fa099e02c413a7ffda732415e8105cad26a90337 by Andy Soffer <asoffer@google.com>:
Internal changes
PiperOrigin-RevId: 254286334
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ce34b7f36933b30cfa35b9c9a5697a792b5666e4 by Andy Soffer <asoffer@google.com>:
Internal changes
PiperOrigin-RevId: 254273059
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6f9c473da7c2090c2e85a37c5f00622e8a912a89 by Jorg Brown <jorg@google.com>:
Change absl::container_internal::CompressedTuple to instantiate its
internal Storage class with the name of the type it's holding, rather
than the name of the Tuple. This is not an externally-visible change,
other than less compiler memory is used and less debug information is
generated.
PiperOrigin-RevId: 254269285
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8bd3c186bf2fc0c55d8a2dd6f28a5327502c9fba by Andy Soffer <asoffer@google.com>:
Adding short-hand IntervalClosed for IntervalClosedClosed and IntervalOpen for
IntervalOpenOpen.
PiperOrigin-RevId: 254252419
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ea957f99b6a04fccd42aa05605605f3b44b1ecfd by Abseil Team <absl-team@google.com>:
Do not directly use __SIZEOF_INT128__.
In order to avoid linker errors when building with clang-cl (__fixunsdfti, __udivti3 and __fixunssfti are undefined), this CL uses ABSL_HAVE_INTRINSIC_INT128 which is not defined for clang-cl.
PiperOrigin-RevId: 254250739
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89ab385cd26b34d64130bce856253aaba96d2345 by Andy Soffer <asoffer@google.com>:
Internal changes
PiperOrigin-RevId: 254242321
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cffc793d93eca6d6bdf7de733847b6ab4a255ae9 by CJ Johnson <johnsoncj@google.com>:
Adds benchmark for InlinedVector::reserve(size_type)
PiperOrigin-RevId: 254199226
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c90c7a9fa3c8f0c9d5114036979548b055ea2f2a by Gennadiy Rozental <rogeeff@google.com>:
Import of CCTZ from GitHub.
PiperOrigin-RevId: 254072387
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c4c388beae016c9570ab54ffa1d52660e4a85b7b by Laramie Leavitt <lar@google.com>:
Internal cleanup.
PiperOrigin-RevId: 254062381
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d3c992e221cc74e5372d0c8fa410170b6a43c062 by Tom Manshreck <shreck@google.com>:
Update distributions.h to Abseil standards
PiperOrigin-RevId: 254054946
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d15ad0035c34ef11b14fadc5a4a2d3ec415f5518 by CJ Johnson <johnsoncj@google.com>:
Removes functions with only one caller from the implementation details of InlinedVector by manually inlining the definitions
PiperOrigin-RevId: 254005427
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2f37e807efc3a8ef1f4b539bdd379917d4151520 by Andy Soffer <asoffer@google.com>:
Initial release of Abseil Random
PiperOrigin-RevId: 253999861
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24ed1694b6430791d781ed533a8f8ccf6cac5856 by CJ Johnson <johnsoncj@google.com>:
Updates the definition of InlinedVector::assign(...)/InlinedVector::operator=(...) to new, exception-safe implementations with exception safety tests to boot
PiperOrigin-RevId: 253993691
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5613d95f5a7e34a535cfaeadce801441e990843e by CJ Johnson <johnsoncj@google.com>:
Adds benchmarks for InlinedVector::shrink_to_fit()
PiperOrigin-RevId: 253989647
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2a96ddfdac40bbb8cb6a7f1aeab90917067c6e63 by Abseil Team <absl-team@google.com>:
Initial release of Abseil Random
PiperOrigin-RevId: 253927497
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bf1aff8fc9ffa921ad74643e9525ecf25b0d8dc1 by Andy Soffer <asoffer@google.com>:
Initial release of Abseil Random
PiperOrigin-RevId: 253920512
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bfc03f4a3dcda3cf3a4b84bdb84cda24e3394f41 by Laramie Leavitt <lar@google.com>:
Internal change.
PiperOrigin-RevId: 253886486
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05036cfcc078ca7c5f581a00dfb0daed568cbb69 by Eric Fiselier <ericwf@google.com>:
Don't include `winsock2.h` because it drags in `windows.h` and friends,
and they define awful macros like OPAQUE, ERROR, and more. This has the
potential to break abseil users.
Instead we only forward declare `timeval` and require Windows users
include `winsock2.h` themselves. This is both inconsistent and poor QoI, but so
including 'windows.h' is bad too.
PiperOrigin-RevId: 253852615
GitOrigin-RevId: 7a6ff16a85beb730c172d5d25cf1b5e1be885c56
Change-Id: Icd6aff87da26f29ec8915da856f051129987cef6
Diffstat (limited to 'absl/random/random.h')
-rw-r--r-- | absl/random/random.h | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/absl/random/random.h b/absl/random/random.h new file mode 100644 index 00000000..dc6852f4 --- /dev/null +++ b/absl/random/random.h @@ -0,0 +1,187 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// ----------------------------------------------------------------------------- +// File: random.h +// ----------------------------------------------------------------------------- +// +// This header defines the recommended Uniform Random Bit Generator (URBG) +// types for use within the Abseil Random library. These types are not +// suitable for security-related use-cases, but should suffice for most other +// uses of generating random values. +// +// The Abseil random library provides the following URBG types: +// +// * BitGen, a good general-purpose bit generator, optimized for generating +// random (but not cryptographically secure) values +// * InsecureBitGen, a slightly faster, though less random, bit generator, for +// cases where the existing BitGen is a drag on performance. + +#ifndef ABSL_RANDOM_RANDOM_H_ +#define ABSL_RANDOM_RANDOM_H_ + +#include <random> + +#include "absl/random/distributions.h" // IWYU pragma: export +#include "absl/random/internal/nonsecure_base.h" // IWYU pragma: export +#include "absl/random/internal/pcg_engine.h" // IWYU pragma: export +#include "absl/random/internal/pool_urbg.h" +#include "absl/random/internal/randen_engine.h" +#include "absl/random/seed_sequences.h" // IWYU pragma: export + +namespace absl { + +// ----------------------------------------------------------------------------- +// absl::BitGen +// ----------------------------------------------------------------------------- +// +// `absl::BitGen` is a general-purpose random bit generator for generating +// random values for use within the Abseil random library. Typically, you use a +// bit generator in combination with a distribution to provide random values. +// +// Example: +// +// // Create an absl::BitGen. There is no need to seed this bit generator. +// absl::BitGen gen; +// +// // Generate an integer value in the closed interval [1,6] +// int die_roll = absl::uniform_int_distribution<int>(1, 6)(gen); +// +// `absl::BitGen` is seeded by default with non-deterministic data to produce +// different sequences of random values across different instances, including +// different binary invocations. This behavior is different than the standard +// library bit generators, which use golden values as their seeds. Default +// construction intentionally provides no stability guarantees, to avoid +// accidental dependence on such a property. +// +// `absl::BitGen` may be constructed with an optional seed sequence type, +// conforming to [rand.req.seed_seq], which will be mixed with additional +// non-deterministic data. +// +// Example: +// +// // Create an absl::BitGen using an std::seed_seq seed sequence +// std::seed_seq seq{1,2,3}; +// absl::BitGen gen_with_seed(seq); +// +// // Generate an integer value in the closed interval [1,6] +// int die_roll2 = absl::uniform_int_distribution<int>(1, 6)(gen_with_seed); +// +// `absl::BitGen` meets the requirements of the Uniform Random Bit Generator +// (URBG) concept as per the C++17 standard [rand.req.urng] though differs +// slightly with [rand.req.eng]. Like its standard library equivalents (e.g. +// `std::mersenne_twister_engine`) `absl::BitGen` is not cryptographically +// secure. +// +// Constructing two `absl::BitGen`s with the same seed sequence in the same +// binary will produce the same sequence of variates within the same binary, but +// need not do so across multiple binary invocations. +// +// This type has been optimized to perform better than Mersenne Twister +// (https://en.wikipedia.org/wiki/Mersenne_Twister) and many other complex URBG +// types on modern x86, ARM, and PPC architectures. +// +// This type is thread-compatible, but not thread-safe. + +// --------------------------------------------------------------------------- +// absl::BitGen member functions +// --------------------------------------------------------------------------- + +// absl::BitGen::operator()() +// +// Calls the BitGen, returning a generated value. + +// absl::BitGen::min() +// +// Returns the smallest possible value from this bit generator. + +// absl::BitGen::max() +// +// Returns the largest possible value from this bit generator., and + +// absl::BitGen::discard(num) +// +// Advances the internal state of this bit generator by `num` times, and +// discards the intermediate results. +// --------------------------------------------------------------------------- + +using BitGen = random_internal::NonsecureURBGBase< + random_internal::randen_engine<uint64_t>>; + +// ----------------------------------------------------------------------------- +// absl::InsecureBitGen +// ----------------------------------------------------------------------------- +// +// `absl::InsecureBitGen` is an efficient random bit generator for generating +// random values, recommended only for performance-sensitive use cases where +// `absl::BitGen` is not satisfactory when compute-bounded by bit generation +// costs. +// +// Example: +// +// // Create an absl::InsecureBitGen +// absl::InsecureBitGen gen; +// for (size_t i = 0; i < 1000000; i++) { +// +// // Generate a bunch of random values from some complex distribution +// auto my_rnd = some_distribution(gen, 1, 1000); +// } +// +// Like `absl::BitGen`, `absl::InsecureBitGen` is seeded by default with +// non-deterministic data to produce different sequences of random values across +// different instances, including different binary invocations. (This behavior +// is different than the standard library bit generators, which use golden +// values as their seeds.) +// +// `absl::InsecureBitGen` may be constructed with an optional seed sequence +// type, conforming to [rand.req.seed_seq], which will be mixed with additional +// non-deterministic data. (See std_seed_seq.h for more information.) +// +// `absl::InsecureBitGen` meets the requirements of the Uniform Random Bit +// Generator (URBG) concept as per the C++17 standard [rand.req.urng] though +// its implementation differs slightly with [rand.req.eng]. Like its standard +// library equivalents (e.g. `std::mersenne_twister_engine`) +// `absl::InsecureBitGen` is not cryptographically secure. +// +// Prefer `absl::BitGen` over `absl::InsecureBitGen` as the general type is +// often fast enough for the vast majority of applications. + +using InsecureBitGen = + random_internal::NonsecureURBGBase<random_internal::pcg64_2018_engine>; + +// --------------------------------------------------------------------------- +// absl::InsecureBitGen member functions +// --------------------------------------------------------------------------- + +// absl::InsecureBitGen::operator()() +// +// Calls the InsecureBitGen, returning a generated value. + +// absl::InsecureBitGen::min() +// +// Returns the smallest possible value from this bit generator. + +// absl::InsecureBitGen::max() +// +// Returns the largest possible value from this bit generator. + +// absl::InsecureBitGen::discard(num) +// +// Advances the internal state of this bit generator by `num` times, and +// discards the intermediate results. +// --------------------------------------------------------------------------- + +} // namespace absl + +#endif // ABSL_RANDOM_RANDOM_H_ |