From 3df7b52a6ada51a72a23796b844549a7b282f1b8 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Fri, 15 Nov 2019 08:07:12 -0800 Subject: Export of internal Abseil changes -- 3a871e2cd854a46770a9416189953b2b38980bcf by Andy Getzendanner : Import of CCTZ from GitHub. PiperOrigin-RevId: 280660534 -- f5a155fb056dcf68b089c21aebb5bf5159dc0eb3 by Tom Manshreck : Nit: fix format of algorithm.h comments PiperOrigin-RevId: 280474139 -- 08b117a18353c0daf51b33b45100e5a007e5ab0c by Abseil Team : Allow absl::Notification::HasBeenNotified to be inlined. PiperOrigin-RevId: 280453271 -- 26d33dd2bad72945f1987f7b2669dbec3a6247e6 by Derek Mauro : Fix unused variable warnings on Windows PiperOrigin-RevId: 280324417 -- 907e9b23029be683af3b443bafd6a577a595922f by Abseil Team : PeriodicSampler implementation (for internal-use only) PiperOrigin-RevId: 280257168 GitOrigin-RevId: 3a871e2cd854a46770a9416189953b2b38980bcf Change-Id: I6e2978cae22a6adc41c0577e5c21355e9db7c8f5 --- absl/base/internal/periodic_sampler.cc | 50 ++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 absl/base/internal/periodic_sampler.cc (limited to 'absl/base/internal/periodic_sampler.cc') diff --git a/absl/base/internal/periodic_sampler.cc b/absl/base/internal/periodic_sampler.cc new file mode 100644 index 000000000000..439745d0c514 --- /dev/null +++ b/absl/base/internal/periodic_sampler.cc @@ -0,0 +1,50 @@ +// Copyright 2019 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/base/internal/periodic_sampler.h" + +#include + +#include "absl/base/internal/exponential_biased.h" + +namespace absl { +namespace base_internal { + +int64_t PeriodicSamplerBase::GetExponentialBiased(int period) noexcept { + return rng_.Get(period); +} + +bool PeriodicSamplerBase::SubtleConfirmSample() noexcept { + int current_period = period(); + + // Deal with period case 0 (always off) and 1 (always on) + if (ABSL_PREDICT_FALSE(current_period < 2)) { + stride_ = 0; + return current_period == 1; + } + + // Check if this is the first call to Sample() + if (ABSL_PREDICT_FALSE(stride_ == 1)) { + stride_ = -1 - GetExponentialBiased(current_period); + if (stride_ < -1) { + ++stride_; + return false; + } + } + stride_ = -1 - GetExponentialBiased(current_period); + return true; +} + +} // namespace base_internal +} // namespace absl -- cgit 1.4.1