96 lines
2.6 KiB
C++
96 lines
2.6 KiB
C++
/*
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* Notified.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 FDBCLIENT_NOTIFIED_H
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#define FDBCLIENT_NOTIFIED_H
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#pragma once
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#include "fdbclient/FDBTypes.h"
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#include "flow/TDMetric.actor.h"
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template <class T>
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struct IsMetricHandle : std::false_type {};
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template <class T>
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struct IsMetricHandle<MetricHandle<T>> : std::true_type {};
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template <class T, class ValueType = T>
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struct Notified {
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explicit Notified(ValueType v = 0) { val = v; }
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[[nodiscard]] Future<Void> whenAtLeast(const ValueType& limit) {
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if (val >= limit)
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return Void();
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Promise<Void> p;
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waiting.emplace(limit, p);
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return p.getFuture();
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}
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[[nodiscard]] ValueType get() const { return val; }
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void initMetric(const StringRef& name, const StringRef& id) {
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if constexpr (IsMetricHandle<T>::value) {
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ValueType v = val;
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val.init(name, id);
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val = v;
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} else {
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TraceEvent(SevError, "InvalidNotifiedOperation")
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.detail("Reason", "Notified<T> where T is not a metric: Can't use initMetric");
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}
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}
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void set(const ValueType& v) {
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ASSERT(v >= val);
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if (v != val) {
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val = v;
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std::vector<Promise<Void>> toSend;
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while (waiting.size() && v >= waiting.top().first) {
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Promise<Void> p = std::move(waiting.top().second);
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waiting.pop();
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toSend.push_back(p);
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}
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for (auto& p : toSend) {
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p.send(Void());
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}
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}
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}
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void operator=(const ValueType& v) { set(v); }
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Notified(Notified&& r) noexcept : waiting(std::move(r.waiting)), val(std::move(r.val)) {}
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void operator=(Notified&& r) noexcept {
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waiting = std::move(r.waiting);
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val = std::move(r.val);
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}
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private:
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using Item = std::pair<ValueType, Promise<Void>>;
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struct ItemCompare {
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bool operator()(const Item& a, const Item& b) { return a.first > b.first; }
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};
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std::priority_queue<Item, std::vector<Item>, ItemCompare> waiting;
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T val;
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};
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using NotifiedVersion = Notified<VersionMetricHandle, VersionMetricHandle::ValueType>;
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using NotifiedDouble = Notified<double>;
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#endif
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