3df7b52a6a
-- 3a871e2cd854a46770a9416189953b2b38980bcf by Andy Getzendanner <durandal@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 280660534 -- f5a155fb056dcf68b089c21aebb5bf5159dc0eb3 by Tom Manshreck <shreck@google.com>: Nit: fix format of algorithm.h comments PiperOrigin-RevId: 280474139 -- 08b117a18353c0daf51b33b45100e5a007e5ab0c by Abseil Team <absl-team@google.com>: Allow absl::Notification::HasBeenNotified to be inlined. PiperOrigin-RevId: 280453271 -- 26d33dd2bad72945f1987f7b2669dbec3a6247e6 by Derek Mauro <dmauro@google.com>: Fix unused variable warnings on Windows PiperOrigin-RevId: 280324417 -- 907e9b23029be683af3b443bafd6a577a595922f by Abseil Team <absl-team@google.com>: PeriodicSampler implementation (for internal-use only) PiperOrigin-RevId: 280257168 GitOrigin-RevId: 3a871e2cd854a46770a9416189953b2b38980bcf Change-Id: I6e2978cae22a6adc41c0577e5c21355e9db7c8f5
50 lines
1.4 KiB
C++
50 lines
1.4 KiB
C++
// 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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namespace base_internal {
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int64_t PeriodicSamplerBase::GetExponentialBiased(int period) noexcept {
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return rng_.Get(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_ = -1 - GetExponentialBiased(current_period);
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if (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_ = -1 - GetExponentialBiased(current_period);
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return true;
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}
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} // namespace base_internal
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} // namespace absl
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