552 lines
13 KiB
C++
552 lines
13 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/HashTableUtils.h"
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#include <cstddef>
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#include <initializer_list>
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#include <iterator>
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#include <utility>
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namespace td {
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namespace detail {
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uint32 normalize_flat_hash_table_size(uint32 size);
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uint32 get_random_flat_hash_table_bucket(uint32 bucket_count_mask);
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} // namespace detail
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template <class NodeT, class HashT, class EqT>
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class FlatHashTable {
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static constexpr uint32 INVALID_BUCKET = 0xFFFFFFFF;
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void allocate_nodes(uint32 size) {
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DCHECK(size >= 8);
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DCHECK((size & (size - 1)) == 0);
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CHECK(size <= min(static_cast<uint32>(1) << 29, static_cast<uint32>(0x7FFFFFFF / sizeof(NodeT))));
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nodes_ = new NodeT[size];
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// used_node_count_ = 0;
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bucket_count_mask_ = size - 1;
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bucket_count_ = size;
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begin_bucket_ = INVALID_BUCKET;
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}
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static void clear_nodes(NodeT *nodes) {
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delete[] nodes;
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}
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public:
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using KeyT = typename NodeT::public_key_type;
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using key_type = typename NodeT::public_key_type;
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using value_type = typename NodeT::public_type;
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// TODO use EndSentinel for end() after switching to C++17
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// struct EndSentinel {};
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struct Iterator {
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using iterator_category = std::forward_iterator_tag;
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using difference_type = std::ptrdiff_t;
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using value_type = FlatHashTable::value_type;
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using pointer = value_type *;
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using reference = value_type &;
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Iterator &operator++() {
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DCHECK(it_ != nullptr);
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do {
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if (unlikely(++it_ == end_)) {
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it_ = begin_;
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}
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if (unlikely(it_ == start_)) {
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it_ = nullptr;
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break;
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}
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} while (it_->empty());
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return *this;
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}
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reference operator*() {
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return it_->get_public();
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}
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const value_type &operator*() const {
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return it_->get_public();
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}
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pointer operator->() {
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return &it_->get_public();
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}
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const value_type *operator->() const {
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return &it_->get_public();
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}
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NodeT *get() {
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return it_;
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}
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bool operator==(const Iterator &other) const {
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DCHECK(other.it_ == nullptr);
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return it_ == nullptr;
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}
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bool operator!=(const Iterator &other) const {
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DCHECK(other.it_ == nullptr);
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return it_ != nullptr;
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}
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Iterator() = default;
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Iterator(NodeT *it, NodeT *begin, NodeT *end) : it_(it), begin_(begin), start_(it), end_(end) {
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}
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private:
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NodeT *it_ = nullptr;
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NodeT *begin_ = nullptr;
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NodeT *start_ = nullptr;
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NodeT *end_ = nullptr;
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};
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struct ConstIterator {
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using iterator_category = std::forward_iterator_tag;
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using difference_type = std::ptrdiff_t;
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using value_type = FlatHashTable::value_type;
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using pointer = const value_type *;
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using reference = const value_type &;
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ConstIterator &operator++() {
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++it_;
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return *this;
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}
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reference operator*() const {
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return *it_;
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}
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pointer operator->() const {
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return &*it_;
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}
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bool operator==(const ConstIterator &other) const {
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return it_ == other.it_;
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}
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bool operator!=(const ConstIterator &other) const {
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return it_ != other.it_;
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}
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ConstIterator() = default;
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ConstIterator(Iterator it) : it_(std::move(it)) {
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}
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private:
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Iterator it_;
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};
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using iterator = Iterator;
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using const_iterator = ConstIterator;
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struct NodePointer {
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value_type &operator*() {
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return it_->get_public();
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}
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const value_type &operator*() const {
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return it_->get_public();
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}
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value_type *operator->() {
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return &it_->get_public();
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}
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const value_type *operator->() const {
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return &it_->get_public();
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}
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NodeT *get() {
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return it_;
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}
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bool operator==(const Iterator &) const {
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return it_ == nullptr;
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}
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bool operator!=(const Iterator &) const {
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return it_ != nullptr;
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}
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explicit NodePointer(NodeT *it) : it_(it) {
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}
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private:
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NodeT *it_ = nullptr;
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};
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struct ConstNodePointer {
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const value_type &operator*() const {
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return it_->get_public();
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}
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const value_type *operator->() const {
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return &it_->get_public();
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}
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bool operator==(const ConstIterator &) const {
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return it_ == nullptr;
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}
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bool operator!=(const ConstIterator &) const {
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return it_ != nullptr;
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}
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const NodeT *get() const {
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return it_;
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}
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explicit ConstNodePointer(const NodeT *it) : it_(it) {
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}
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private:
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const NodeT *it_ = nullptr;
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};
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FlatHashTable() = default;
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FlatHashTable(const FlatHashTable &other) = delete;
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FlatHashTable &operator=(const FlatHashTable &other) = delete;
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FlatHashTable(std::initializer_list<NodeT> nodes) {
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if (nodes.size() == 0) {
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return;
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}
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reserve(nodes.size());
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uint32 used_nodes = 0;
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for (auto &new_node : nodes) {
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CHECK(!new_node.empty());
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auto bucket = calc_bucket(new_node.key());
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while (true) {
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auto &node = nodes_[bucket];
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if (node.empty()) {
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node.copy_from(new_node);
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used_nodes++;
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break;
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}
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if (EqT()(node.key(), new_node.key())) {
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break;
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}
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next_bucket(bucket);
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}
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}
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used_node_count_ = used_nodes;
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}
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FlatHashTable(FlatHashTable &&other) noexcept
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: nodes_(other.nodes_)
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, used_node_count_(other.used_node_count_)
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, bucket_count_mask_(other.bucket_count_mask_)
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, bucket_count_(other.bucket_count_)
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, begin_bucket_(other.begin_bucket_) {
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other.drop();
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}
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void operator=(FlatHashTable &&other) noexcept {
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clear();
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nodes_ = other.nodes_;
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used_node_count_ = other.used_node_count_;
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bucket_count_mask_ = other.bucket_count_mask_;
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bucket_count_ = other.bucket_count_;
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begin_bucket_ = other.begin_bucket_;
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other.drop();
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}
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~FlatHashTable() {
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clear_nodes(nodes_);
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}
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void swap(FlatHashTable &other) noexcept {
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std::swap(nodes_, other.nodes_);
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std::swap(used_node_count_, other.used_node_count_);
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std::swap(bucket_count_mask_, other.bucket_count_mask_);
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std::swap(bucket_count_, other.bucket_count_);
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std::swap(begin_bucket_, other.begin_bucket_);
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}
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uint32 bucket_count() const {
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return bucket_count_;
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}
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NodePointer find(const KeyT &key) {
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return NodePointer(find_impl(key));
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}
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ConstNodePointer find(const KeyT &key) const {
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return ConstNodePointer(const_cast<FlatHashTable *>(this)->find_impl(key));
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}
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size_t size() const {
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return used_node_count_;
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}
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bool empty() const {
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return used_node_count_ == 0;
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}
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Iterator begin() {
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return create_iterator(begin_impl());
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}
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Iterator end() {
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return Iterator();
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}
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ConstIterator begin() const {
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return ConstIterator(const_cast<FlatHashTable *>(this)->begin());
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}
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ConstIterator end() const {
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return ConstIterator();
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}
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void reserve(size_t size) {
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if (size == 0) {
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return;
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}
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CHECK(size <= (1u << 29));
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uint32 want_size = detail::normalize_flat_hash_table_size(static_cast<uint32>(size) * 5 / 3 + 1);
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if (want_size > bucket_count()) {
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resize(want_size);
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}
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}
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template <class... ArgsT>
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std::pair<NodePointer, bool> emplace(KeyT key, ArgsT &&...args) {
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CHECK(!is_hash_table_key_empty(key));
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if (unlikely(bucket_count_mask_ == 0)) {
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CHECK(used_node_count_ == 0);
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resize(8);
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}
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auto bucket = calc_bucket(key);
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while (true) {
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auto &node = nodes_[bucket];
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if (node.empty()) {
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if (unlikely(used_node_count_ * 5 >= bucket_count_mask_ * 3)) {
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resize(2 * bucket_count_);
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CHECK(used_node_count_ * 5 < bucket_count_mask_ * 3);
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return emplace(std::move(key), std::forward<ArgsT>(args)...);
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}
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invalidate_iterators();
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node.emplace(std::move(key), std::forward<ArgsT>(args)...);
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used_node_count_++;
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return {NodePointer(&node), true};
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}
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if (EqT()(node.key(), key)) {
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return {NodePointer(&node), false};
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}
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next_bucket(bucket);
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}
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}
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std::pair<NodePointer, bool> insert(KeyT key) {
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return emplace(std::move(key));
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}
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template <class ItT>
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void insert(ItT begin, ItT end) {
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for (; begin != end; ++begin) {
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emplace(*begin);
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}
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}
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template <class T = typename NodeT::second_type>
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T &operator[](const KeyT &key) {
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return emplace(key).first->second;
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}
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size_t erase(const KeyT &key) {
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auto *node = find_impl(key);
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if (node == nullptr) {
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return 0;
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}
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erase_node(node);
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try_shrink();
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return 1;
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}
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size_t count(const KeyT &key) const {
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return const_cast<FlatHashTable *>(this)->find_impl(key) != nullptr;
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}
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void clear() {
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if (nodes_ != nullptr) {
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clear_nodes(nodes_);
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drop();
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}
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}
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void erase(Iterator it) {
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DCHECK(it != end());
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erase_node(it.get());
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try_shrink();
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}
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void erase(NodePointer it) {
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DCHECK(it != end());
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erase_node(it.get());
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try_shrink();
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}
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template <class F>
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void remove_if(F &&f) {
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if (empty()) {
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return;
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}
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auto it = begin_impl();
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auto end = nodes_ + bucket_count();
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while (it != end && !it->empty()) {
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++it;
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}
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if (it == end) {
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do {
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--it;
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} while (!it->empty());
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}
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auto first_empty = it;
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while (it != end) {
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if (!it->empty() && f(it->get_public())) {
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erase_node(it);
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} else {
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++it;
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}
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}
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for (it = nodes_; it != first_empty;) {
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if (!it->empty() && f(it->get_public())) {
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erase_node(it);
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} else {
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++it;
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}
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}
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try_shrink();
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}
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private:
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NodeT *nodes_ = nullptr;
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uint32 used_node_count_ = 0;
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uint32 bucket_count_mask_ = 0;
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uint32 bucket_count_ = 0;
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uint32 begin_bucket_ = 0;
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void drop() {
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nodes_ = nullptr;
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used_node_count_ = 0;
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bucket_count_mask_ = 0;
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bucket_count_ = 0;
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begin_bucket_ = 0;
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}
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NodeT *begin_impl() {
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if (empty()) {
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return nullptr;
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}
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if (begin_bucket_ == INVALID_BUCKET) {
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begin_bucket_ = detail::get_random_flat_hash_table_bucket(bucket_count_mask_);
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while (nodes_[begin_bucket_].empty()) {
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next_bucket(begin_bucket_);
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}
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}
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return nodes_ + begin_bucket_;
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}
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NodeT *find_impl(const KeyT &key) {
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if (unlikely(nodes_ == nullptr) || is_hash_table_key_empty(key)) {
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return nullptr;
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}
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auto bucket = calc_bucket(key);
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while (true) {
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auto &node = nodes_[bucket];
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if (node.empty()) {
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return nullptr;
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}
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if (EqT()(node.key(), key)) {
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return &node;
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}
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next_bucket(bucket);
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}
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}
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void try_shrink() {
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DCHECK(nodes_ != nullptr);
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if (unlikely(used_node_count_ * 10 < bucket_count_mask_ && bucket_count_mask_ > 7)) {
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resize(detail::normalize_flat_hash_table_size((used_node_count_ + 1) * 5 / 3 + 1));
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}
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invalidate_iterators();
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}
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uint32 calc_bucket(const KeyT &key) const {
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return randomize_hash(HashT()(key)) & bucket_count_mask_;
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}
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inline void next_bucket(uint32 &bucket) const {
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bucket = (bucket + 1) & bucket_count_mask_;
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}
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void resize(uint32 new_size) {
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if (unlikely(nodes_ == nullptr)) {
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allocate_nodes(new_size);
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used_node_count_ = 0;
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return;
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}
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auto old_nodes = nodes_;
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uint32 old_size = used_node_count_;
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uint32 old_bucket_count = bucket_count_;
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allocate_nodes(new_size);
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used_node_count_ = old_size;
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auto old_nodes_end = old_nodes + old_bucket_count;
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for (NodeT *old_node = old_nodes; old_node != old_nodes_end; ++old_node) {
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if (old_node->empty()) {
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continue;
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}
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auto bucket = calc_bucket(old_node->key());
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while (!nodes_[bucket].empty()) {
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next_bucket(bucket);
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}
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nodes_[bucket] = std::move(*old_node);
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}
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clear_nodes(old_nodes);
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}
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void erase_node(NodeT *it) {
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DCHECK(nodes_ <= it && static_cast<size_t>(it - nodes_) < bucket_count());
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it->clear();
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used_node_count_--;
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const auto bucket_count = bucket_count_;
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const auto *end = nodes_ + bucket_count;
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for (auto *test_node = it + 1; test_node != end; test_node++) {
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if (likely(test_node->empty())) {
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return;
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}
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auto want_node = nodes_ + calc_bucket(test_node->key());
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if (want_node <= it || want_node > test_node) {
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*it = std::move(*test_node);
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it = test_node;
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}
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}
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auto empty_i = static_cast<uint32>(it - nodes_);
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auto empty_bucket = empty_i;
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for (uint32 test_i = bucket_count;; test_i++) {
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auto test_bucket = test_i - bucket_count_;
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if (nodes_[test_bucket].empty()) {
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return;
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}
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auto want_i = calc_bucket(nodes_[test_bucket].key());
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if (want_i < empty_i) {
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want_i += bucket_count;
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}
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if (want_i <= empty_i || want_i > test_i) {
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nodes_[empty_bucket] = std::move(nodes_[test_bucket]);
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empty_i = test_i;
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empty_bucket = test_bucket;
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}
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}
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}
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Iterator create_iterator(NodeT *node) {
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return Iterator(node, nodes_, nodes_ + bucket_count());
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}
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void invalidate_iterators() {
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begin_bucket_ = INVALID_BUCKET;
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}
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};
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} // namespace td
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