94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
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/*
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* MetricSample.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project 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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*/
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#ifndef METRIC_SAMPLE_H
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#define METRIC_SAMPLE_H
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#pragma once
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template <class T>
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struct MetricSample {
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IndexedSet<T, int64_t> sample;
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int64_t metricUnitsPerSample = 0;
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explicit MetricSample(int64_t metricUnitsPerSample) : metricUnitsPerSample(metricUnitsPerSample) {}
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int64_t getMetric(const T& Key) {
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auto i = sample.find(Key);
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if (i == sample.end())
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return 0;
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else
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return sample.getMetric(i);
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}
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};
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template <class T>
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struct TransientMetricSample : MetricSample<T> {
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Deque< std::pair<double, std::pair<T, int64_t>> > queue;
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explicit TransientMetricSample(int64_t metricUnitsPerSample) : MetricSample<T>(metricUnitsPerSample) { }
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bool roll(int64_t metric) {
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return g_random->random01() < (double)metric / this->metricUnitsPerSample; //< SOMEDAY: Better randomInt64?
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}
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// Returns the sampled metric value (possibly 0, possibly increased by the sampling factor)
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int64_t addAndExpire(const T& key, int64_t metric, double expiration) {
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int64_t x = add(key, metric);
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if (x)
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queue.push_back(std::make_pair(expiration, std::make_pair(*this->sample.find(key), -x)));
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return x;
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}
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void poll() {
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double now = ::now();
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while (queue.size() &&
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queue.front().first <= now)
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{
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const T& key = queue.front().second.first;
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int64_t delta = queue.front().second.second;
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ASSERT(delta != 0);
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if (this->sample.addMetric(T(key), delta) == 0)
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this->sample.erase(key);
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queue.pop_front();
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}
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}
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private:
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int64_t add(const T& key, int64_t metric) {
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if (!metric) return 0;
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int64_t mag = metric<0 ? -metric : metric;
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if (mag < this->metricUnitsPerSample) {
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if (!roll(mag))
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return 0;
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metric = metric<0 ? -this->metricUnitsPerSample : this->metricUnitsPerSample;
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}
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if (this->sample.addMetric(T(key), metric) == 0)
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this->sample.erase(key);
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return metric;
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}
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};
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#endif
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