Abseil Common Libraries (C++) (grcp 依赖)
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53 lines
1.5 KiB
53 lines
1.5 KiB
// Copyright 2019 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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// https://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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#include "absl/base/internal/periodic_sampler.h" |
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#include <atomic> |
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#include "absl/base/internal/exponential_biased.h" |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace base_internal { |
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int64_t PeriodicSamplerBase::GetExponentialBiased(int period) noexcept { |
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return rng_.GetStride(period); |
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} |
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bool PeriodicSamplerBase::SubtleConfirmSample() noexcept { |
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int current_period = period(); |
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// Deal with period case 0 (always off) and 1 (always on) |
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if (ABSL_PREDICT_FALSE(current_period < 2)) { |
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stride_ = 0; |
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return current_period == 1; |
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} |
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// Check if this is the first call to Sample() |
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if (ABSL_PREDICT_FALSE(stride_ == 1)) { |
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stride_ = static_cast<uint64_t>(-GetExponentialBiased(current_period)); |
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if (static_cast<int64_t>(stride_) < -1) { |
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++stride_; |
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return false; |
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} |
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} |
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stride_ = static_cast<uint64_t>(-GetExponentialBiased(current_period)); |
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return true; |
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} |
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} // namespace base_internal |
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ABSL_NAMESPACE_END |
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} // namespace absl
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