116 lines
2.9 KiB
C++
116 lines
2.9 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2022
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#pragma once
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#include "td/utils/common.h"
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#include "td/utils/FlatHashSet.h"
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#include "td/utils/HashTableUtils.h"
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#include <functional>
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namespace td {
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template <class KeyT, class HashT = std::hash<KeyT>, class EqT = std::equal_to<KeyT>>
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class WaitFreeHashSet {
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using Storage = FlatHashSet<KeyT, HashT, EqT>;
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static constexpr size_t MAX_STORAGE_COUNT = 1 << 11;
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static_assert((MAX_STORAGE_COUNT & (MAX_STORAGE_COUNT - 1)) == 0, "");
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static constexpr size_t MAX_STORAGE_SIZE = 1 << 16;
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static_assert((MAX_STORAGE_SIZE & (MAX_STORAGE_SIZE - 1)) == 0, "");
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Storage default_set_;
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struct WaitFreeStorage {
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Storage sets_[MAX_STORAGE_COUNT];
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};
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unique_ptr<WaitFreeStorage> wait_free_storage_;
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Storage &get_wait_free_storage(const KeyT &key) {
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return wait_free_storage_->sets_[randomize_hash(HashT()(key)) & (MAX_STORAGE_COUNT - 1)];
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}
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Storage &get_storage(const KeyT &key) {
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if (wait_free_storage_ == nullptr) {
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return default_set_;
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}
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return get_wait_free_storage(key);
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}
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const Storage &get_storage(const KeyT &key) const {
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return const_cast<WaitFreeHashSet *>(this)->get_storage(key);
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}
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void split_storage() {
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CHECK(wait_free_storage_ == nullptr);
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wait_free_storage_ = make_unique<WaitFreeStorage>();
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for (auto &it : default_set_) {
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get_wait_free_storage(it).insert(it);
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}
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default_set_.clear();
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}
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public:
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void insert(const KeyT &key) {
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auto &storage = get_storage(key);
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storage.insert(key);
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if (default_set_.size() == MAX_STORAGE_SIZE) {
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split_storage();
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}
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}
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size_t count(const KeyT &key) const {
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const auto &storage = get_storage(key);
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return storage.count(key);
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}
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size_t erase(const KeyT &key) {
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return get_storage(key).erase(key);
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}
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void foreach(std::function<void(const KeyT &key)> callback) const {
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if (wait_free_storage_ == nullptr) {
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for (auto &it : default_set_) {
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callback(it);
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}
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return;
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}
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for (size_t i = 0; i < MAX_STORAGE_COUNT; i++) {
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for (auto &it : wait_free_storage_->sets_[i]) {
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callback(it);
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}
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}
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}
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size_t size() const {
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if (wait_free_storage_ == nullptr) {
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return default_set_.size();
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}
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size_t result = 0;
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for (size_t i = 0; i < MAX_STORAGE_COUNT; i++) {
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result += wait_free_storage_->sets_[i].size();
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}
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return result;
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}
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bool empty() const {
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if (wait_free_storage_ == nullptr) {
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return default_set_.empty();
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}
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for (size_t i = 0; i < MAX_STORAGE_COUNT; i++) {
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if (!wait_free_storage_->sets_[i].empty()) {
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return false;
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}
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}
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return true;
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}
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};
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} // namespace td
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