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117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of clio: https://github.com/XRPLF/clio
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Copyright (c) 2025, the clio developers.
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#pragma once
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#include "util/async/AnyStrand.hpp"
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#include <cstddef>
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#include <functional>
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#include <optional>
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#include <queue>
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#include <type_traits>
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#include <utility>
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#include <vector>
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namespace util {
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/**
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* @brief A wrapper for std::priority_queue that serialises operations using a strand
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* @note This may be a candidate for future improvements if performance proves to be poor (e.g. use a lock free queue)
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*/
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template <typename T, typename Compare = std::less<T>>
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class StrandedPriorityQueue {
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util::async::AnyStrand strand_;
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std::size_t limit_;
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std::priority_queue<T, std::vector<T>, Compare> queue_;
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public:
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/**
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* @brief Construct a new priority queue on a strand
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* @param strand The strand to use
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* @param limit The limit of items allowed simultaniously in the queue
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*/
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StrandedPriorityQueue(util::async::AnyStrand&& strand, std::optional<std::size_t> limit = std::nullopt)
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: strand_(std::move(strand)), limit_(limit.value_or(0uz))
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{
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}
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/**
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* @brief Enqueue a new item onto the queue if space is available
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* @note This function blocks until the item is attempted to be added to the queue
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*
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* @tparam I Type of the item to add
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* @param item The item to add
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* @return true if item added to the queue; false otherwise
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*/
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template <typename I>
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[[nodiscard]] bool
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enqueue(I&& item)
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requires std::is_same_v<std::decay_t<I>, T>
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{
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return strand_
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.execute([&item, this] {
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if (limit_ == 0uz or queue_.size() < limit_) {
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queue_.push(std::forward<I>(item));
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return true;
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}
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return false;
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})
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.get()
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.value_or(false); // if some exception happens - failed to add
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}
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/**
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* @brief Dequeue the next available item out of the queue
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* @note This function blocks until the item is taken off the queue
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* @return An item if available; nullopt otherwise
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*/
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[[nodiscard]] std::optional<T>
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dequeue()
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{
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return strand_
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.execute([this] -> std::optional<T> {
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std::optional<T> out;
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if (not queue_.empty()) {
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out.emplace(queue_.top());
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queue_.pop();
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}
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return out;
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})
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.get()
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.value_or(std::nullopt);
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}
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/**
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* @brief Check if the queue is empty
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* @note This function blocks until the queue is checked
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*
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* @return true if the queue is empty; false otherwise
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*/
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[[nodiscard]] bool
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empty()
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{
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return strand_.execute([this] { return queue_.empty(); }).get().value();
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}
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};
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} // namespace util
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