Abseil Common Libraries (C++) (grcp 依赖)
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106 lines
3.8 KiB
106 lines
3.8 KiB
// Copyright 2017 The Abseil Authors. |
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// |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// http://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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// This file is a no-op if the required LowLevelAlloc support is missing. |
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#include "absl/base/internal/low_level_alloc.h" |
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#ifndef ABSL_LOW_LEVEL_ALLOC_MISSING |
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#include "absl/synchronization/internal/per_thread_sem.h" |
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#include <atomic> |
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#include "absl/base/attributes.h" |
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#include "absl/base/internal/malloc_extension.h" |
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#include "absl/base/internal/thread_identity.h" |
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#include "absl/synchronization/internal/waiter.h" |
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namespace absl { |
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namespace synchronization_internal { |
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void PerThreadSem::SetThreadBlockedCounter(std::atomic<int> *counter) { |
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base_internal::ThreadIdentity *identity; |
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identity = GetOrCreateCurrentThreadIdentity(); |
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identity->blocked_count_ptr = counter; |
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} |
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std::atomic<int> *PerThreadSem::GetThreadBlockedCounter() { |
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base_internal::ThreadIdentity *identity; |
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identity = GetOrCreateCurrentThreadIdentity(); |
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return identity->blocked_count_ptr; |
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} |
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void PerThreadSem::Init(base_internal::ThreadIdentity *identity) { |
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Waiter::GetWaiter(identity)->Init(); |
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identity->ticker.store(0, std::memory_order_relaxed); |
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identity->wait_start.store(0, std::memory_order_relaxed); |
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identity->is_idle.store(false, std::memory_order_relaxed); |
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} |
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void PerThreadSem::Tick(base_internal::ThreadIdentity *identity) { |
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const int ticker = |
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identity->ticker.fetch_add(1, std::memory_order_relaxed) + 1; |
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const int wait_start = identity->wait_start.load(std::memory_order_relaxed); |
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const bool is_idle = identity->is_idle.load(std::memory_order_relaxed); |
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if (wait_start && (ticker - wait_start > Waiter::kIdlePeriods) && !is_idle) { |
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// Wakeup the waiting thread since it is time for it to become idle. |
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Waiter::GetWaiter(identity)->Poke(); |
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} |
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} |
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} // namespace synchronization_internal |
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} // namespace absl |
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extern "C" { |
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ABSL_ATTRIBUTE_WEAK void AbslInternalPerThreadSemPost( |
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absl::base_internal::ThreadIdentity *identity) { |
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absl::synchronization_internal::Waiter::GetWaiter(identity)->Post(); |
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} |
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ABSL_ATTRIBUTE_WEAK bool AbslInternalPerThreadSemWait( |
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absl::synchronization_internal::KernelTimeout t) { |
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bool timeout = false; |
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absl::base_internal::ThreadIdentity *identity; |
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identity = absl::synchronization_internal::GetOrCreateCurrentThreadIdentity(); |
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// Ensure wait_start != 0. |
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int ticker = identity->ticker.load(std::memory_order_relaxed); |
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identity->wait_start.store(ticker ? ticker : 1, std::memory_order_relaxed); |
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identity->is_idle.store(false, std::memory_order_relaxed); |
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if (identity->blocked_count_ptr != nullptr) { |
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// Increment count of threads blocked in a given thread pool. |
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identity->blocked_count_ptr->fetch_add(1, std::memory_order_relaxed); |
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} |
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timeout = |
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!absl::synchronization_internal::Waiter::GetWaiter(identity)->Wait(t); |
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if (identity->blocked_count_ptr != nullptr) { |
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identity->blocked_count_ptr->fetch_sub(1, std::memory_order_relaxed); |
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} |
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if (identity->is_idle.load(std::memory_order_relaxed)) { |
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// We became idle during the wait; become non-idle again so that |
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// performance of deallocations done from now on does not suffer. |
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absl::base_internal::MallocExtension::instance()->MarkThreadBusy(); |
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} |
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identity->is_idle.store(false, std::memory_order_relaxed); |
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identity->wait_start.store(0, std::memory_order_relaxed); |
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return !timeout; |
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} |
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} // extern "C" |
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#endif // ABSL_LOW_LEVEL_ALLOC_MISSING
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