tvl-depot/absl/random/internal/seed_material.h
Abseil Team e9324d926a 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

--
bfc03f4a3dcda3cf3a4b84bdb84cda24e3394f41 by Laramie Leavitt <lar@google.com>:

Internal change.

PiperOrigin-RevId: 253886486

--
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
2019-06-21 16:18:10 -04:00

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3.5 KiB
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// 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.
#ifndef ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_
#define ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <string>
#include <vector>
#include "absl/base/attributes.h"
#include "absl/random/internal/fast_uniform_bits.h"
#include "absl/types/optional.h"
#include "absl/types/span.h"
namespace absl {
namespace random_internal {
// Returns the number of 32-bit blocks needed to contain the given number of
// bits.
constexpr size_t SeedBitsToBlocks(size_t seed_size) {
return (seed_size + 31) / 32;
}
// Amount of entropy (measured in bits) used to instantiate a Seed Sequence,
// with which to create a URBG.
constexpr size_t kEntropyBitsNeeded = 256;
// Amount of entropy (measured in 32-bit blocks) used to instantiate a Seed
// Sequence, with which to create a URBG.
constexpr size_t kEntropyBlocksNeeded =
random_internal::SeedBitsToBlocks(kEntropyBitsNeeded);
static_assert(kEntropyBlocksNeeded > 0,
"Entropy used to seed URBGs must be nonzero.");
// Attempts to fill a span of uint32_t-values using an OS-provided source of
// true entropy (eg. /dev/urandom) into an array of uint32_t blocks of data. The
// resulting array may be used to initialize an instance of a class conforming
// to the C++ Standard "Seed Sequence" concept [rand.req.seedseq].
//
// If values.data() == nullptr, the behavior is undefined.
ABSL_MUST_USE_RESULT
bool ReadSeedMaterialFromOSEntropy(absl::Span<uint32_t> values);
// Attempts to fill a span of uint32_t-values using variates generated by an
// existing instance of a class conforming to the C++ Standard "Uniform Random
// Bit Generator" concept [rand.req.urng]. The resulting data may be used to
// initialize an instance of a class conforming to the C++ Standard
// "Seed Sequence" concept [rand.req.seedseq].
//
// If urbg == nullptr or values.data() == nullptr, the behavior is undefined.
template <typename URBG>
ABSL_MUST_USE_RESULT bool ReadSeedMaterialFromURBG(
URBG* urbg, absl::Span<uint32_t> values) {
random_internal::FastUniformBits<uint32_t> distr;
assert(urbg != nullptr && values.data() != nullptr);
if (urbg == nullptr || values.data() == nullptr) {
return false;
}
for (uint32_t& seed_value : values) {
seed_value = distr(*urbg);
}
return true;
}
// Mixes given sequence of values with into given sequence of seed material.
// Time complexity of this function is O(sequence.size() *
// seed_material.size()).
//
// Algorithm is based on code available at
// https://gist.github.com/imneme/540829265469e673d045
// by Melissa O'Neill.
void MixIntoSeedMaterial(absl::Span<const uint32_t> sequence,
absl::Span<uint32_t> seed_material);
// Returns salt value.
//
// Salt is obtained only once and stored in static variable.
//
// May return empty value if optaining the salt was not possible.
absl::optional<uint32_t> GetSaltMaterial();
} // namespace random_internal
} // namespace absl
#endif // ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_