diff options
author | Vincent Ambo <mail@tazj.in> | 2022-02-07T23·05+0300 |
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committer | clbot <clbot@tvl.fyi> | 2022-02-07T23·09+0000 |
commit | 5aa5d282eac56a21e74611c1cdbaa97bb5db2dca (patch) | |
tree | 8cc5dce8157a1470ff76719dd15d65f648a05522 /third_party/abseil_cpp/absl/random/internal/pool_urbg.cc | |
parent | a25675804c4f429fab5ee5201fe25e89865dfd13 (diff) |
chore(3p/abseil_cpp): unvendor abseil_cpp r/3786
we weren't actually using these sources anymore, okay? Change-Id: If701571d9716de308d3512e1eb22c35db0877a66 Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su>
Diffstat (limited to 'third_party/abseil_cpp/absl/random/internal/pool_urbg.cc')
-rw-r--r-- | third_party/abseil_cpp/absl/random/internal/pool_urbg.cc | 254 |
1 files changed, 0 insertions, 254 deletions
diff --git a/third_party/abseil_cpp/absl/random/internal/pool_urbg.cc b/third_party/abseil_cpp/absl/random/internal/pool_urbg.cc deleted file mode 100644 index 5bee530770eb..000000000000 --- a/third_party/abseil_cpp/absl/random/internal/pool_urbg.cc +++ /dev/null @@ -1,254 +0,0 @@ -// 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. - -#include "absl/random/internal/pool_urbg.h" - -#include <algorithm> -#include <atomic> -#include <cstdint> -#include <cstring> -#include <iterator> - -#include "absl/base/attributes.h" -#include "absl/base/call_once.h" -#include "absl/base/config.h" -#include "absl/base/internal/endian.h" -#include "absl/base/internal/raw_logging.h" -#include "absl/base/internal/spinlock.h" -#include "absl/base/internal/sysinfo.h" -#include "absl/base/internal/unaligned_access.h" -#include "absl/base/optimization.h" -#include "absl/random/internal/randen.h" -#include "absl/random/internal/seed_material.h" -#include "absl/random/seed_gen_exception.h" - -using absl::base_internal::SpinLock; -using absl::base_internal::SpinLockHolder; - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace random_internal { -namespace { - -// RandenPoolEntry is a thread-safe pseudorandom bit generator, implementing a -// single generator within a RandenPool<T>. It is an internal implementation -// detail, and does not aim to conform to [rand.req.urng]. -// -// NOTE: There are alignment issues when used on ARM, for instance. -// See the allocation code in PoolAlignedAlloc(). -class RandenPoolEntry { - public: - static constexpr size_t kState = RandenTraits::kStateBytes / sizeof(uint32_t); - static constexpr size_t kCapacity = - RandenTraits::kCapacityBytes / sizeof(uint32_t); - - void Init(absl::Span<const uint32_t> data) { - SpinLockHolder l(&mu_); // Always uncontested. - std::copy(data.begin(), data.end(), std::begin(state_)); - next_ = kState; - } - - // Copy bytes into out. - void Fill(uint8_t* out, size_t bytes) ABSL_LOCKS_EXCLUDED(mu_); - - // Returns random bits from the buffer in units of T. - template <typename T> - inline T Generate() ABSL_LOCKS_EXCLUDED(mu_); - - inline void MaybeRefill() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mu_) { - if (next_ >= kState) { - next_ = kCapacity; - impl_.Generate(state_); - } - } - - private: - // Randen URBG state. - uint32_t state_[kState] ABSL_GUARDED_BY(mu_); // First to satisfy alignment. - SpinLock mu_; - const Randen impl_; - size_t next_ ABSL_GUARDED_BY(mu_); -}; - -template <> -inline uint8_t RandenPoolEntry::Generate<uint8_t>() { - SpinLockHolder l(&mu_); - MaybeRefill(); - return static_cast<uint8_t>(state_[next_++]); -} - -template <> -inline uint16_t RandenPoolEntry::Generate<uint16_t>() { - SpinLockHolder l(&mu_); - MaybeRefill(); - return static_cast<uint16_t>(state_[next_++]); -} - -template <> -inline uint32_t RandenPoolEntry::Generate<uint32_t>() { - SpinLockHolder l(&mu_); - MaybeRefill(); - return state_[next_++]; -} - -template <> -inline uint64_t RandenPoolEntry::Generate<uint64_t>() { - SpinLockHolder l(&mu_); - if (next_ >= kState - 1) { - next_ = kCapacity; - impl_.Generate(state_); - } - auto p = state_ + next_; - next_ += 2; - - uint64_t result; - std::memcpy(&result, p, sizeof(result)); - return result; -} - -void RandenPoolEntry::Fill(uint8_t* out, size_t bytes) { - SpinLockHolder l(&mu_); - while (bytes > 0) { - MaybeRefill(); - size_t remaining = (kState - next_) * sizeof(state_[0]); - size_t to_copy = std::min(bytes, remaining); - std::memcpy(out, &state_[next_], to_copy); - out += to_copy; - bytes -= to_copy; - next_ += (to_copy + sizeof(state_[0]) - 1) / sizeof(state_[0]); - } -} - -// Number of pooled urbg entries. -static constexpr int kPoolSize = 8; - -// Shared pool entries. -static absl::once_flag pool_once; -ABSL_CACHELINE_ALIGNED static RandenPoolEntry* shared_pools[kPoolSize]; - -// Returns an id in the range [0 ... kPoolSize), which indexes into the -// pool of random engines. -// -// Each thread to access the pool is assigned a sequential ID (without reuse) -// from the pool-id space; the id is cached in a thread_local variable. -// This id is assigned based on the arrival-order of the thread to the -// GetPoolID call; this has no binary, CL, or runtime stability because -// on subsequent runs the order within the same program may be significantly -// different. However, as other thread IDs are not assigned sequentially, -// this is not expected to matter. -int GetPoolID() { - static_assert(kPoolSize >= 1, - "At least one urbg instance is required for PoolURBG"); - - ABSL_CONST_INIT static std::atomic<int64_t> sequence{0}; - -#ifdef ABSL_HAVE_THREAD_LOCAL - static thread_local int my_pool_id = -1; - if (ABSL_PREDICT_FALSE(my_pool_id < 0)) { - my_pool_id = (sequence++ % kPoolSize); - } - return my_pool_id; -#else - static pthread_key_t tid_key = [] { - pthread_key_t tmp_key; - int err = pthread_key_create(&tmp_key, nullptr); - if (err) { - ABSL_RAW_LOG(FATAL, "pthread_key_create failed with %d", err); - } - return tmp_key; - }(); - - // Store the value in the pthread_{get/set}specific. However an uninitialized - // value is 0, so add +1 to distinguish from the null value. - intptr_t my_pool_id = - reinterpret_cast<intptr_t>(pthread_getspecific(tid_key)); - if (ABSL_PREDICT_FALSE(my_pool_id == 0)) { - // No allocated ID, allocate the next value, cache it, and return. - my_pool_id = (sequence++ % kPoolSize) + 1; - int err = pthread_setspecific(tid_key, reinterpret_cast<void*>(my_pool_id)); - if (err) { - ABSL_RAW_LOG(FATAL, "pthread_setspecific failed with %d", err); - } - } - return my_pool_id - 1; -#endif -} - -// Allocate a RandenPoolEntry with at least 32-byte alignment, which is required -// by ARM platform code. -RandenPoolEntry* PoolAlignedAlloc() { - constexpr size_t kAlignment = - ABSL_CACHELINE_SIZE > 32 ? ABSL_CACHELINE_SIZE : 32; - - // Not all the platforms that we build for have std::aligned_alloc, however - // since we never free these objects, we can over allocate and munge the - // pointers to the correct alignment. - void* memory = std::malloc(sizeof(RandenPoolEntry) + kAlignment); - auto x = reinterpret_cast<intptr_t>(memory); - auto y = x % kAlignment; - void* aligned = - (y == 0) ? memory : reinterpret_cast<void*>(x + kAlignment - y); - return new (aligned) RandenPoolEntry(); -} - -// Allocate and initialize kPoolSize objects of type RandenPoolEntry. -// -// The initialization strategy is to initialize one object directly from -// OS entropy, then to use that object to seed all of the individual -// pool instances. -void InitPoolURBG() { - static constexpr size_t kSeedSize = - RandenTraits::kStateBytes / sizeof(uint32_t); - // Read the seed data from OS entropy once. - uint32_t seed_material[kPoolSize * kSeedSize]; - if (!random_internal::ReadSeedMaterialFromOSEntropy( - absl::MakeSpan(seed_material))) { - random_internal::ThrowSeedGenException(); - } - for (int i = 0; i < kPoolSize; i++) { - shared_pools[i] = PoolAlignedAlloc(); - shared_pools[i]->Init( - absl::MakeSpan(&seed_material[i * kSeedSize], kSeedSize)); - } -} - -// Returns the pool entry for the current thread. -RandenPoolEntry* GetPoolForCurrentThread() { - absl::call_once(pool_once, InitPoolURBG); - return shared_pools[GetPoolID()]; -} - -} // namespace - -template <typename T> -typename RandenPool<T>::result_type RandenPool<T>::Generate() { - auto* pool = GetPoolForCurrentThread(); - return pool->Generate<T>(); -} - -template <typename T> -void RandenPool<T>::Fill(absl::Span<result_type> data) { - auto* pool = GetPoolForCurrentThread(); - pool->Fill(reinterpret_cast<uint8_t*>(data.data()), - data.size() * sizeof(result_type)); -} - -template class RandenPool<uint8_t>; -template class RandenPool<uint16_t>; -template class RandenPool<uint32_t>; -template class RandenPool<uint64_t>; - -} // namespace random_internal -ABSL_NAMESPACE_END -} // namespace absl |