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art_internal_impl.hpp
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art_internal_impl.hpp
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// Copyright 2019-2023 Laurynas Biveinis
#ifndef UNODB_DETAIL_ART_INTERNAL_IMPL_HPP
#define UNODB_DETAIL_ART_INTERNAL_IMPL_HPP
#include "global.hpp"
#include <algorithm>
#include <array>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <limits>
#include <memory>
#include <stdexcept>
#include <type_traits>
#include <utility>
#ifdef UNODB_DETAIL_X86_64
#include <emmintrin.h>
#ifdef UNODB_DETAIL_AVX2
#include <immintrin.h>
#elif defined(UNODB_DETAIL_SSE4_2)
#include <smmintrin.h>
#endif
#elif defined(__aarch64__)
#include <arm_neon.h>
#endif
#include <gsl/util>
#include "art_common.hpp"
#include "art_internal.hpp"
#include "assert.hpp"
#include "heap.hpp"
#include "node_type.hpp"
#include "portability_builtins.hpp"
namespace unodb {
class db;
class olc_db;
} // namespace unodb
namespace unodb::detail {
template <>
[[nodiscard, gnu::const]] UNODB_DETAIL_CONSTEXPR_NOT_MSVC std::uint64_t
basic_art_key<std::uint64_t>::make_binary_comparable(std::uint64_t k) noexcept {
#ifdef UNODB_DETAIL_LITTLE_ENDIAN
return bswap(k);
#else
#error Needs implementing
#endif
}
#ifdef UNODB_DETAIL_X86_64
// Idea from https://stackoverflow.com/a/32945715/80458
[[nodiscard, gnu::const]] inline auto _mm_cmple_epu8(__m128i x,
__m128i y) noexcept {
return _mm_cmpeq_epi8(_mm_max_epu8(y, x), y);
}
#elif !defined(__aarch64__)
// From public domain
// https://graphics.stanford.edu/~seander/bithacks.html
[[nodiscard, gnu::const]] constexpr std::uint32_t has_zero_byte(
std::uint32_t v) noexcept {
return ((v - 0x01010101UL) & ~v & 0x80808080UL);
}
[[nodiscard, gnu::const]] constexpr std::uint32_t contains_byte(
std::uint32_t v, std::byte b) noexcept {
return has_zero_byte(v ^ (~0U / 255 * static_cast<std::uint8_t>(b)));
}
#endif // #ifdef UNODB_DETAIL_X86_64
template <class Header>
class [[nodiscard]] basic_leaf final : public Header {
public:
using value_size_type = std::uint32_t;
UNODB_DETAIL_DISABLE_MSVC_WARNING(26495)
constexpr basic_leaf(art_key k, value_view v) noexcept
: key{k}, value_size{gsl::narrow_cast<value_size_type>(v.size())} {
UNODB_DETAIL_ASSERT(v.size() <= max_value_size);
if (!v.empty()) std::memcpy(&value_start[0], v.data(), value_size);
}
UNODB_DETAIL_RESTORE_MSVC_WARNINGS()
[[nodiscard, gnu::pure]] constexpr auto get_key() const noexcept {
return key;
}
[[nodiscard, gnu::pure]] constexpr auto matches(art_key k) const noexcept {
return k == get_key();
}
[[nodiscard, gnu::pure]] constexpr auto get_value_view() const noexcept {
return value_view{&value_start[0], value_size};
}
[[nodiscard, gnu::pure]] constexpr auto get_size() const noexcept {
return compute_size(value_size);
}
[[gnu::cold]] UNODB_DETAIL_NOINLINE void dump(std::ostream &os) const {
os << ", " << get_key() << ", value size: " << value_size << '\n';
}
[[nodiscard, gnu::const]] static constexpr auto compute_size(
value_size_type val_size) noexcept {
return sizeof(basic_leaf<Header>) + val_size - 1;
}
static constexpr std::size_t max_value_size =
std::numeric_limits<value_size_type>::max();
private:
const art_key key;
const value_size_type value_size;
// NOLINTNEXTLINE(modernize-avoid-c-arrays)
std::byte value_start[1];
};
template <class Header, class Db>
[[nodiscard]] auto make_db_leaf_ptr(art_key k, value_view v,
Db &db UNODB_DETAIL_LIFETIMEBOUND) {
using leaf_type = basic_leaf<Header>;
if (UNODB_DETAIL_UNLIKELY(v.size() > leaf_type::max_value_size)) {
throw std::length_error("Value length must fit in std::uint32_t");
}
const auto size = leaf_type::compute_size(
gsl::narrow_cast<typename leaf_type::value_size_type>(v.size()));
auto *const leaf_mem = static_cast<std::byte *>(
allocate_aligned(size, alignment_for_new<leaf_type>()));
db.increment_leaf_count(size);
return basic_db_leaf_unique_ptr<Header, Db>{
new (leaf_mem) leaf_type{k, v}, basic_db_leaf_deleter<Header, Db>{db}};
}
template <class INode, class Node4, class Node16, class Node48, class Node256>
struct basic_inode_def final {
using inode = INode;
using n4 = Node4;
using n16 = Node16;
using n48 = Node48;
using n256 = Node256;
template <class Node>
[[nodiscard]] static constexpr bool is_inode() noexcept {
return std::is_same_v<Node, n4> || std::is_same_v<Node, n16> ||
std::is_same_v<Node, n48> || std::is_same_v<Node, n256>;
}
basic_inode_def() = delete;
};
// Implementation of things declared in art_internal.hpp
template <class Header, class Db>
inline void basic_db_leaf_deleter<Header, Db>::operator()(
leaf_type *to_delete) const noexcept {
const auto leaf_size = to_delete->get_size();
free_aligned(to_delete);
db.decrement_leaf_count(leaf_size);
}
template <class INode, class Db>
inline void basic_db_inode_deleter<INode, Db>::operator()(
INode *inode_ptr) noexcept {
static_assert(std::is_trivially_destructible_v<INode>);
free_aligned(inode_ptr);
db.template decrement_inode_count<INode>();
}
template <class Db, template <class> class CriticalSectionPolicy, class NodePtr,
class INodeDefs, template <class> class INodeReclamator,
template <class, class> class LeafReclamator>
struct basic_art_policy final {
using node_ptr = NodePtr;
using header_type = typename NodePtr::header_type;
using inode_defs = INodeDefs;
using inode = typename inode_defs::inode;
using inode4_type = typename inode_defs::n4;
using inode16_type = typename inode_defs::n16;
using inode48_type = typename inode_defs::n48;
using inode256_type = typename inode_defs::n256;
using leaf_type = basic_leaf<header_type>;
using db = Db;
private:
template <class INode>
using db_inode_deleter = basic_db_inode_deleter<INode, Db>;
using leaf_reclaimable_ptr =
std::unique_ptr<leaf_type, LeafReclamator<header_type, Db>>;
public:
template <typename T>
using critical_section_policy = CriticalSectionPolicy<T>;
template <class INode>
using db_inode_unique_ptr = std::unique_ptr<INode, db_inode_deleter<INode>>;
using db_inode4_unique_ptr = db_inode_unique_ptr<inode4_type>;
using db_inode16_unique_ptr = db_inode_unique_ptr<inode16_type>;
using db_inode48_unique_ptr = db_inode_unique_ptr<inode48_type>;
using db_inode256_unique_ptr = db_inode_unique_ptr<inode256_type>;
template <class INode>
using db_inode_reclaimable_ptr =
std::unique_ptr<INode, INodeReclamator<INode>>;
using db_leaf_unique_ptr = basic_db_leaf_unique_ptr<header_type, Db>;
[[nodiscard]] static auto make_db_leaf_ptr(
art_key k, value_view v, Db &db_instance UNODB_DETAIL_LIFETIMEBOUND) {
return ::unodb::detail::make_db_leaf_ptr<header_type, Db>(k, v,
db_instance);
}
[[nodiscard]] static auto reclaim_leaf_on_scope_exit(
leaf_type *leaf UNODB_DETAIL_LIFETIMEBOUND,
Db &db_instance UNODB_DETAIL_LIFETIMEBOUND) noexcept {
return leaf_reclaimable_ptr{leaf,
LeafReclamator<header_type, Db>{db_instance}};
}
UNODB_DETAIL_DISABLE_GCC_11_WARNING("-Wmismatched-new-delete")
UNODB_DETAIL_DISABLE_MSVC_WARNING(26409)
template <class INode, class... Args>
[[nodiscard]] static auto make_db_inode_unique_ptr(
Db &db_instance UNODB_DETAIL_LIFETIMEBOUND, Args &&...args) {
auto *const inode_mem = static_cast<std::byte *>(
allocate_aligned(sizeof(INode), alignment_for_new<INode>()));
db_instance.template increment_inode_count<INode>();
return db_inode_unique_ptr<INode>{
new (inode_mem) INode{db_instance, std::forward<Args>(args)...},
db_inode_deleter<INode>{db_instance}};
}
UNODB_DETAIL_RESTORE_MSVC_WARNINGS()
UNODB_DETAIL_RESTORE_GCC_11_WARNINGS()
template <class INode>
[[nodiscard]] static auto make_db_inode_unique_ptr(
INode *inode_ptr UNODB_DETAIL_LIFETIMEBOUND,
Db &db_instance UNODB_DETAIL_LIFETIMEBOUND) noexcept {
return db_inode_unique_ptr<INode>{inode_ptr,
db_inode_deleter<INode>{db_instance}};
}
template <class INode>
[[nodiscard]] static auto make_db_inode_reclaimable_ptr(
INode *inode_ptr UNODB_DETAIL_LIFETIMEBOUND,
Db &db_instance UNODB_DETAIL_LIFETIMEBOUND) noexcept {
return db_inode_reclaimable_ptr<INode>{inode_ptr,
INodeReclamator<INode>{db_instance}};
}
private:
[[nodiscard]] static auto make_db_leaf_ptr(
leaf_type *leaf UNODB_DETAIL_LIFETIMEBOUND,
Db &db_instance UNODB_DETAIL_LIFETIMEBOUND) noexcept {
return basic_db_leaf_unique_ptr<header_type, Db>{
leaf, basic_db_leaf_deleter<header_type, Db>{db_instance}};
}
struct delete_db_node_ptr_at_scope_exit final {
constexpr explicit delete_db_node_ptr_at_scope_exit(
NodePtr node_ptr_ UNODB_DETAIL_LIFETIMEBOUND,
Db &db_ UNODB_DETAIL_LIFETIMEBOUND) noexcept
: node_ptr{node_ptr_}, db{db_} {}
~delete_db_node_ptr_at_scope_exit() noexcept {
switch (node_ptr.type()) {
case node_type::LEAF: {
const auto r{
make_db_leaf_ptr(node_ptr.template ptr<leaf_type *>(), db)};
return;
}
case node_type::I4: {
const auto r{make_db_inode_unique_ptr(
node_ptr.template ptr<inode4_type *>(), db)};
return;
}
case node_type::I16: {
const auto r{make_db_inode_unique_ptr(
node_ptr.template ptr<inode16_type *>(), db)};
return;
}
case node_type::I48: {
const auto r{make_db_inode_unique_ptr(
node_ptr.template ptr<inode48_type *>(), db)};
return;
}
case node_type::I256: {
const auto r{make_db_inode_unique_ptr(
node_ptr.template ptr<inode256_type *>(), db)};
return;
}
}
UNODB_DETAIL_CANNOT_HAPPEN(); // LCOV_EXCL_LINE
}
delete_db_node_ptr_at_scope_exit(const delete_db_node_ptr_at_scope_exit &) =
delete;
delete_db_node_ptr_at_scope_exit(delete_db_node_ptr_at_scope_exit &&) =
delete;
auto &operator=(const delete_db_node_ptr_at_scope_exit &) = delete;
auto &operator=(delete_db_node_ptr_at_scope_exit &&) = delete;
private:
const NodePtr node_ptr;
Db &db;
};
public:
static void delete_subtree(NodePtr node, Db &db_instance) noexcept {
delete_db_node_ptr_at_scope_exit delete_on_scope_exit{node, db_instance};
switch (node.type()) {
case node_type::LEAF:
return;
case node_type::I4: {
auto *const subtree_ptr{node.template ptr<inode4_type *>()};
subtree_ptr->delete_subtree(db_instance);
return;
}
case node_type::I16: {
auto *const subtree_ptr{node.template ptr<inode16_type *>()};
subtree_ptr->delete_subtree(db_instance);
return;
}
case node_type::I48: {
auto *const subtree_ptr{node.template ptr<inode48_type *>()};
subtree_ptr->delete_subtree(db_instance);
return;
}
case node_type::I256: {
auto *const subtree_ptr{node.template ptr<inode256_type *>()};
subtree_ptr->delete_subtree(db_instance);
return;
}
}
}
[[gnu::cold]] UNODB_DETAIL_NOINLINE static void dump_node(
std::ostream &os, const NodePtr &node) {
os << "node at: " << node.template ptr<void *>() << ", tagged ptr = 0x"
<< std::hex << node.raw_val() << std::dec;
if (node == nullptr) {
os << '\n';
return;
}
os << ", type = ";
switch (node.type()) {
case node_type::LEAF:
os << "LEAF";
node.template ptr<leaf_type *>()->dump(os);
break;
case node_type::I4:
os << "I4";
node.template ptr<inode4_type *>()->dump(os);
break;
case node_type::I16:
os << "I16";
node.template ptr<inode16_type *>()->dump(os);
break;
case node_type::I48:
os << "I48";
node.template ptr<inode48_type *>()->dump(os);
break;
case node_type::I256:
os << "I256";
node.template ptr<inode256_type *>()->dump(os);
break;
}
}
basic_art_policy() = delete;
};
template <template <class> class CriticalSectionPolicy>
union [[nodiscard]] key_prefix {
private:
template <typename T>
using critical_section_policy = CriticalSectionPolicy<T>;
using key_prefix_size = std::uint8_t;
static constexpr key_prefix_size key_prefix_capacity = 7;
using key_prefix_data =
std::array<critical_section_policy<std::byte>, key_prefix_capacity>;
struct [[nodiscard]] inode_fields {
key_prefix_data key_prefix;
critical_section_policy<key_prefix_size> key_prefix_length;
} f;
critical_section_policy<std::uint64_t> u64;
public:
key_prefix(art_key k1, art_key shifted_k2, tree_depth depth) noexcept
: u64{make_u64(k1, shifted_k2, depth)} {}
key_prefix(unsigned key_prefix_len,
const key_prefix &source_key_prefix) noexcept
: u64{(source_key_prefix.u64 & key_bytes_mask) |
length_to_word(key_prefix_len)} {
UNODB_DETAIL_ASSERT(key_prefix_len <= key_prefix_capacity);
}
key_prefix(const key_prefix &other) noexcept : u64{other.u64.load()} {}
~key_prefix() noexcept = default;
[[nodiscard]] constexpr auto get_shared_length(
unodb::detail::art_key shifted_key) const noexcept {
return shared_len(static_cast<std::uint64_t>(shifted_key), u64, length());
}
[[nodiscard]] constexpr unsigned length() const noexcept {
const auto result = f.key_prefix_length.load();
UNODB_DETAIL_ASSERT(result <= key_prefix_capacity);
return result;
}
constexpr void cut(unsigned cut_len) noexcept {
UNODB_DETAIL_ASSERT(cut_len > 0);
UNODB_DETAIL_ASSERT(cut_len <= length());
u64 = ((u64 >> (cut_len * 8)) & key_bytes_mask) |
length_to_word(length() - cut_len);
UNODB_DETAIL_ASSERT(f.key_prefix_length.load() <= key_prefix_capacity);
}
constexpr void prepend(const key_prefix &prefix1,
std::byte prefix2) noexcept {
UNODB_DETAIL_ASSERT(length() + prefix1.length() < key_prefix_capacity);
const auto prefix1_bit_length = prefix1.length() * 8U;
const auto prefix1_mask = (1ULL << prefix1_bit_length) - 1;
const auto prefix3_bit_length = length() * 8U;
const auto prefix3_mask = (1ULL << prefix3_bit_length) - 1;
const auto prefix3 = u64 & prefix3_mask;
const auto shifted_prefix3 = prefix3 << (prefix1_bit_length + 8U);
const auto shifted_prefix2 = static_cast<std::uint64_t>(prefix2)
<< prefix1_bit_length;
const auto masked_prefix1 = prefix1.u64 & prefix1_mask;
u64 = shifted_prefix3 | shifted_prefix2 | masked_prefix1 |
length_to_word(length() + prefix1.length() + 1);
UNODB_DETAIL_ASSERT(f.key_prefix_length.load() <= key_prefix_capacity);
}
[[nodiscard]] constexpr auto byte_at(std::size_t i) const noexcept {
UNODB_DETAIL_ASSERT(i < length());
return f.key_prefix[i].load();
}
[[gnu::cold]] UNODB_DETAIL_NOINLINE void dump(std::ostream &os) const {
const auto len = length();
os << ", key prefix len = " << len;
if (len > 0) {
os << ", key prefix =";
for (std::size_t i = 0; i < len; ++i) dump_byte(os, f.key_prefix[i]);
}
}
key_prefix(key_prefix &&) = delete;
key_prefix &operator=(const key_prefix &) = delete;
key_prefix &operator=(key_prefix &&) = delete;
private:
static constexpr auto key_bytes_mask = 0x00FF'FFFF'FFFF'FFFFULL;
[[nodiscard, gnu::const]] static constexpr std::uint64_t length_to_word(
unsigned length) {
UNODB_DETAIL_ASSERT(length <= key_prefix_capacity);
return static_cast<std::uint64_t>(length) << 56U;
}
[[nodiscard, gnu::const]] static constexpr unsigned shared_len(
std::uint64_t k1, std::uint64_t k2, unsigned clamp_byte_pos) noexcept {
UNODB_DETAIL_ASSERT(clamp_byte_pos < 8);
const auto diff = k1 ^ k2;
const auto clamped = diff | (1ULL << (clamp_byte_pos * 8U));
return static_cast<unsigned>(detail::ctz(clamped) >> 3U);
}
[[nodiscard, gnu::const]] static constexpr std::uint64_t make_u64(
art_key k1, art_key shifted_k2, tree_depth depth) noexcept {
k1.shift_right(depth);
const auto k1_u64 = static_cast<std::uint64_t>(k1) & key_bytes_mask;
return k1_u64 | length_to_word(shared_len(
k1_u64, static_cast<std::uint64_t>(shifted_k2),
key_prefix_capacity));
}
};
// A class used as a sentinel for basic_inode template args: the
// larger node type for the largest node type and the smaller node type for
// the smallest node type.
class fake_inode final {
public:
fake_inode() = delete;
};
template <class ArtPolicy>
class basic_inode_impl : public ArtPolicy::header_type {
public:
using node_ptr = typename ArtPolicy::node_ptr;
template <typename T>
using critical_section_policy =
typename ArtPolicy::template critical_section_policy<T>;
using db_leaf_unique_ptr = typename ArtPolicy::db_leaf_unique_ptr;
using db = typename ArtPolicy::db;
// The first element is the child index in the node, the 2nd is pointer
// to the child. If not present, the pointer is nullptr, and the index
// is undefined
using find_result =
std::pair<std::uint8_t, critical_section_policy<node_ptr> *>;
protected:
using inode_type = typename ArtPolicy::inode;
using db_inode4_unique_ptr = typename ArtPolicy::db_inode4_unique_ptr;
using db_inode16_unique_ptr = typename ArtPolicy::db_inode16_unique_ptr;
using db_inode48_unique_ptr = typename ArtPolicy::db_inode48_unique_ptr;
private:
using header_type = typename ArtPolicy::header_type;
using inode4_type = typename ArtPolicy::inode4_type;
using inode16_type = typename ArtPolicy::inode16_type;
using inode48_type = typename ArtPolicy::inode48_type;
using inode256_type = typename ArtPolicy::inode256_type;
public:
[[nodiscard]] constexpr const auto &get_key_prefix() const noexcept {
return k_prefix;
}
[[nodiscard]] constexpr auto &get_key_prefix() noexcept { return k_prefix; }
// Only for unodb::detail use.
[[nodiscard]] constexpr auto get_children_count() const noexcept {
return children_count.load();
}
UNODB_DETAIL_DISABLE_MSVC_WARNING(26491)
template <typename ReturnType, typename... Args>
[[nodiscard]] ReturnType add_or_choose_subtree(node_type type,
Args &&...args) {
switch (type) {
case node_type::I4:
return static_cast<inode4_type *>(this)->add_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I16:
return static_cast<inode16_type *>(this)->add_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I48:
return static_cast<inode48_type *>(this)->add_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I256:
return static_cast<inode256_type *>(this)->add_or_choose_subtree(
std::forward<Args>(args)...);
// LCOV_EXCL_START
case node_type::LEAF:
UNODB_DETAIL_CANNOT_HAPPEN();
}
UNODB_DETAIL_CANNOT_HAPPEN();
// LCOV_EXCL_STOP
}
template <typename ReturnType, typename... Args>
[[nodiscard]] ReturnType remove_or_choose_subtree(node_type type,
Args &&...args) {
switch (type) {
case node_type::I4:
return static_cast<inode4_type *>(this)->remove_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I16:
return static_cast<inode16_type *>(this)->remove_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I48:
return static_cast<inode48_type *>(this)->remove_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::I256:
return static_cast<inode256_type *>(this)->remove_or_choose_subtree(
std::forward<Args>(args)...);
case node_type::LEAF:
// LCOV_EXCL_START
UNODB_DETAIL_CANNOT_HAPPEN();
}
UNODB_DETAIL_CANNOT_HAPPEN();
// LCOV_EXCL_STOP
}
[[nodiscard]] constexpr find_result find_child(node_type type,
std::byte key_byte) noexcept {
UNODB_DETAIL_ASSERT(type != node_type::LEAF);
// Because of the parallel updates, the callees below may work on
// inconsistent nodes and must not assert, just produce results, which are
// OK to be incorrect/inconsistent as the node state will be checked before
// acting on them.
switch (type) {
case node_type::I4:
return static_cast<inode4_type *>(this)->find_child(key_byte);
case node_type::I16:
return static_cast<inode16_type *>(this)->find_child(key_byte);
case node_type::I48:
return static_cast<inode48_type *>(this)->find_child(key_byte);
case node_type::I256:
return static_cast<inode256_type *>(this)->find_child(key_byte);
// LCOV_EXCL_START
case node_type::LEAF:
UNODB_DETAIL_CANNOT_HAPPEN();
}
UNODB_DETAIL_CANNOT_HAPPEN();
// LCOV_EXCL_STOP
}
UNODB_DETAIL_RESTORE_MSVC_WARNINGS()
constexpr basic_inode_impl(unsigned children_count_, art_key k1,
art_key shifted_k2, tree_depth depth) noexcept
: k_prefix{k1, shifted_k2, depth},
children_count{gsl::narrow_cast<std::uint8_t>(children_count_)} {}
constexpr basic_inode_impl(unsigned children_count_, unsigned key_prefix_len,
const inode_type &key_prefix_source_node) noexcept
: k_prefix{key_prefix_len, key_prefix_source_node.get_key_prefix()},
children_count{gsl::narrow_cast<std::uint8_t>(children_count_)} {}
constexpr basic_inode_impl(unsigned children_count_,
const basic_inode_impl &other) noexcept
: k_prefix{other.k_prefix},
children_count{gsl::narrow_cast<std::uint8_t>(children_count_)} {}
protected:
[[gnu::cold]] UNODB_DETAIL_NOINLINE void dump(std::ostream &os) const {
k_prefix.dump(os);
const auto children_count_ = this->children_count.load();
os << ", # children = "
<< (children_count_ == 0 ? 256 : static_cast<unsigned>(children_count_));
}
private:
key_prefix<critical_section_policy> k_prefix;
static_assert(sizeof(k_prefix) == 8);
critical_section_policy<std::uint8_t> children_count;
static constexpr std::uint8_t child_not_found_i = 0xFFU;
protected:
static constexpr find_result child_not_found{child_not_found_i, nullptr};
using leaf_type = basic_leaf<header_type>;
friend class unodb::db;
friend class unodb::olc_db;
friend struct olc_inode_immediate_deleter;
template <class, unsigned, unsigned, node_type, class, class, class>
friend class basic_inode;
template <class>
friend class basic_inode_4;
template <class>
friend class basic_inode_16;
template <class>
friend class basic_inode_48;
template <class>
friend class basic_inode_256;
};
template <class ArtPolicy, unsigned MinSize, unsigned Capacity,
node_type NodeType, class SmallerDerived, class LargerDerived,
class Derived>
class [[nodiscard]] basic_inode : public basic_inode_impl<ArtPolicy> {
static_assert(NodeType != node_type::LEAF);
static_assert(!std::is_same_v<Derived, LargerDerived>);
static_assert(!std::is_same_v<SmallerDerived, Derived>);
static_assert(!std::is_same_v<SmallerDerived, LargerDerived>);
static_assert(MinSize < Capacity);
public:
using typename basic_inode_impl<ArtPolicy>::db_leaf_unique_ptr;
using typename basic_inode_impl<ArtPolicy>::db;
using typename basic_inode_impl<ArtPolicy>::node_ptr;
template <typename... Args>
[[nodiscard]] static constexpr auto create(db &db_instance, Args &&...args) {
return ArtPolicy::template make_db_inode_unique_ptr<Derived>(
db_instance, std::forward<Args>(args)...);
}
#ifndef NDEBUG
[[nodiscard]] constexpr bool is_full_for_add() const noexcept {
return this->children_count == capacity;
}
#endif
[[nodiscard]] constexpr bool is_min_size() const noexcept {
return this->children_count == min_size;
}
static constexpr auto min_size = MinSize;
static constexpr auto capacity = Capacity;
static constexpr auto type = NodeType;
using larger_derived_type = LargerDerived;
using smaller_derived_type = SmallerDerived;
using inode_type = typename basic_inode_impl<ArtPolicy>::inode_type;
protected:
constexpr basic_inode(art_key k1, art_key shifted_k2,
tree_depth depth) noexcept
: basic_inode_impl<ArtPolicy>{MinSize, k1, shifted_k2, depth} {
UNODB_DETAIL_ASSERT(is_min_size());
}
constexpr basic_inode(unsigned key_prefix_len,
const inode_type &key_prefix_source_node) noexcept
: basic_inode_impl<ArtPolicy>{MinSize, key_prefix_len,
key_prefix_source_node} {
UNODB_DETAIL_ASSERT(is_min_size());
}
explicit constexpr basic_inode(const SmallerDerived &source_node) noexcept
: basic_inode_impl<ArtPolicy>{MinSize, source_node} {
// Cannot assert that source_node.is_full_for_add because we are creating
// this node optimistically in the case of OLC.
UNODB_DETAIL_ASSERT(is_min_size());
}
explicit constexpr basic_inode(const LargerDerived &source_node) noexcept
: basic_inode_impl<ArtPolicy>{Capacity, source_node} {
// Cannot assert that source_node.is_min_size because we are creating this
// node optimistically in the case of OLC.
UNODB_DETAIL_ASSERT(is_full_for_add());
}
};
template <class ArtPolicy>
using basic_inode_4_parent =
basic_inode<ArtPolicy, 2, 4, node_type::I4, fake_inode,
typename ArtPolicy::inode16_type,
typename ArtPolicy::inode4_type>;
template <class ArtPolicy>
class basic_inode_4 : public basic_inode_4_parent<ArtPolicy> {
using parent_class = basic_inode_4_parent<ArtPolicy>;
using typename parent_class::inode16_type;
using typename parent_class::inode4_type;
using typename parent_class::inode_type;
template <typename T>
using critical_section_policy =
typename ArtPolicy::template critical_section_policy<T>;
public:
using typename parent_class::db;
using typename parent_class::db_inode4_unique_ptr;
using typename parent_class::db_leaf_unique_ptr;
using typename parent_class::find_result;
using typename parent_class::larger_derived_type;
using typename parent_class::leaf_type;
using typename parent_class::node_ptr;
UNODB_DETAIL_DISABLE_MSVC_WARNING(26434)
constexpr basic_inode_4(db &, art_key k1, art_key shifted_k2,
tree_depth depth) noexcept
: parent_class{k1, shifted_k2, depth} {}
constexpr basic_inode_4(db &, art_key k1, art_key shifted_k2,
tree_depth depth, leaf_type *child1,
db_leaf_unique_ptr &&child2) noexcept
: parent_class{k1, shifted_k2, depth} {
init(k1, shifted_k2, depth, child1, std::move(child2));
}
constexpr basic_inode_4(db &, node_ptr source_node, unsigned len) noexcept
: parent_class{len, *source_node.template ptr<inode_type *>()} {}
constexpr basic_inode_4(db &, node_ptr source_node, unsigned len,
tree_depth depth,
db_leaf_unique_ptr &&child1) noexcept
: parent_class{len, *source_node.template ptr<inode_type *>()} {
init(source_node, len, depth, std::move(child1));
}
constexpr basic_inode_4(db &, const inode16_type &source_node) noexcept
: parent_class{source_node} {}
constexpr basic_inode_4(db &db_instance, inode16_type &source_node,
std::uint8_t child_to_delete)
: parent_class{source_node} {
init(db_instance, source_node, child_to_delete);
}
UNODB_DETAIL_RESTORE_MSVC_WARNINGS()
constexpr void init(node_ptr source_node, unsigned len, tree_depth depth,
db_leaf_unique_ptr &&child1) {
auto *const source_inode{source_node.template ptr<inode_type *>()};
auto &source_key_prefix = source_inode->get_key_prefix();
UNODB_DETAIL_ASSERT(len < source_key_prefix.length());
const auto diff_key_byte_i =
static_cast<std::remove_cv_t<decltype(art_key::size)>>(depth) + len;
UNODB_DETAIL_ASSERT(diff_key_byte_i < art_key::size);
const auto source_node_key_byte = source_key_prefix.byte_at(len);
source_key_prefix.cut(len + 1);
const auto new_key_byte = child1->get_key()[diff_key_byte_i];
add_two_to_empty(source_node_key_byte, source_node, new_key_byte,
std::move(child1));
}
constexpr void init(db &db_instance, inode16_type &source_node,
std::uint8_t child_to_delete) {
const auto reclaim_source_node{
ArtPolicy::template make_db_inode_reclaimable_ptr(&source_node,
db_instance)};
auto source_keys_itr = source_node.keys.byte_array.cbegin();
auto keys_itr = keys.byte_array.begin();
auto source_children_itr = source_node.children.cbegin();
auto children_itr = children.begin();
while (source_keys_itr !=
source_node.keys.byte_array.cbegin() + child_to_delete) {
*keys_itr++ = *source_keys_itr++;
*children_itr++ = *source_children_itr++;
}
const auto r{ArtPolicy::reclaim_leaf_on_scope_exit(
source_children_itr->load().template ptr<leaf_type *>(), db_instance)};
++source_keys_itr;
++source_children_itr;
while (source_keys_itr !=
source_node.keys.byte_array.cbegin() + inode16_type::min_size) {
*keys_itr++ = *source_keys_itr++;
*children_itr++ = *source_children_itr++;
}
UNODB_DETAIL_ASSERT(this->children_count == basic_inode_4::capacity);
UNODB_DETAIL_ASSERT(
std::is_sorted(keys.byte_array.cbegin(),
keys.byte_array.cbegin() + basic_inode_4::capacity));
}
constexpr void init(art_key k1, art_key shifted_k2, tree_depth depth,
leaf_type *child1, db_leaf_unique_ptr &&child2) noexcept {
const auto k2_next_byte_depth = this->get_key_prefix().length();
const auto k1_next_byte_depth = k2_next_byte_depth + depth;
add_two_to_empty(k1[k1_next_byte_depth], node_ptr{child1, node_type::LEAF},
shifted_k2[k2_next_byte_depth], std::move(child2));
}
constexpr void add_to_nonfull(db_leaf_unique_ptr &&child, tree_depth depth,
std::uint8_t children_count_) noexcept {
UNODB_DETAIL_ASSERT(children_count_ == this->children_count);
UNODB_DETAIL_ASSERT(children_count_ < parent_class::capacity);
UNODB_DETAIL_ASSERT(std::is_sorted(
keys.byte_array.cbegin(), keys.byte_array.cbegin() + children_count_));
const auto key_byte = static_cast<std::uint8_t>(child->get_key()[depth]);
#ifdef UNODB_DETAIL_X86_64
const auto mask = (1U << children_count_) - 1;
const auto insert_pos_index = get_insert_pos(key_byte, mask);
#else
// This is also currently the best ARM implementation.
const auto first_lt = ((keys.integer & 0xFFU) < key_byte) ? 1 : 0;
const auto second_lt = (((keys.integer >> 8U) & 0xFFU) < key_byte) ? 1 : 0;
const auto third_lt = ((keys.integer >> 16U) & 0xFFU) < key_byte ? 1 : 0;
const auto insert_pos_index =
static_cast<unsigned>(first_lt + second_lt + third_lt);
#endif
for (typename decltype(keys.byte_array)::size_type i = children_count_;
i > insert_pos_index; --i) {
keys.byte_array[i] = keys.byte_array[i - 1];
children[i] = children[i - 1];
}
keys.byte_array[insert_pos_index] = static_cast<std::byte>(key_byte);
children[insert_pos_index] = node_ptr{child.release(), node_type::LEAF};
++children_count_;
this->children_count = children_count_;
UNODB_DETAIL_ASSERT(std::is_sorted(
keys.byte_array.cbegin(), keys.byte_array.cbegin() + children_count_));
}
constexpr void remove(std::uint8_t child_index, db &db_instance) noexcept {
auto children_count_ = this->children_count.load();
UNODB_DETAIL_ASSERT(child_index < children_count_);
UNODB_DETAIL_ASSERT(std::is_sorted(
keys.byte_array.cbegin(), keys.byte_array.cbegin() + children_count_));
const auto r{ArtPolicy::reclaim_leaf_on_scope_exit(
children[child_index].load().template ptr<leaf_type *>(), db_instance)};
typename decltype(keys.byte_array)::size_type i = child_index;
for (; i < static_cast<unsigned>(children_count_ - 1); ++i) {
keys.byte_array[i] = keys.byte_array[i + 1];
children[i] = children[i + 1];
}
#ifndef UNODB_DETAIL_X86_64
keys.byte_array[i] = unused_key_byte;
#endif
--children_count_;
this->children_count = children_count_;
UNODB_DETAIL_ASSERT(std::is_sorted(
keys.byte_array.cbegin(), keys.byte_array.cbegin() + children_count_));
}
[[nodiscard]] constexpr auto leave_last_child(std::uint8_t child_to_delete,
db &db_instance) noexcept {
UNODB_DETAIL_ASSERT(this->is_min_size());
// NOLINTNEXTLINE(readability-simplify-boolean-expr)
UNODB_DETAIL_ASSERT(child_to_delete == 0 || child_to_delete == 1);
auto *const child_to_delete_ptr{
children[child_to_delete].load().template ptr<leaf_type *>()};
const auto r{ArtPolicy::reclaim_leaf_on_scope_exit(child_to_delete_ptr,
db_instance)};
const std::uint8_t child_to_leave = (child_to_delete == 0) ? 1U : 0U;
const auto child_to_leave_ptr = children[child_to_leave].load();
if (child_to_leave_ptr.type() != node_type::LEAF) {
auto *const inode_to_leave_ptr{
child_to_leave_ptr.template ptr<inode_type *>()};
inode_to_leave_ptr->get_key_prefix().prepend(
this->get_key_prefix(), keys.byte_array[child_to_leave]);
}
return child_to_leave_ptr;
}
UNODB_DETAIL_DISABLE_MSVC_WARNING(26434)
[[nodiscard]] find_result find_child(std::byte key_byte) noexcept {
#ifdef UNODB_DETAIL_X86_64
const auto replicated_search_key =
_mm_set1_epi8(static_cast<char>(key_byte));
const auto keys_in_sse_reg =
_mm_cvtsi32_si128(static_cast<std::int32_t>(keys.integer.load()));
const auto matching_key_positions =
_mm_cmpeq_epi8(replicated_search_key, keys_in_sse_reg);
const auto mask = (1U << this->children_count.load()) - 1;
const auto bit_field =
static_cast<unsigned>(_mm_movemask_epi8(matching_key_positions)) & mask;
if (bit_field != 0) {
const auto i = detail::ctz(bit_field);
return std::make_pair(
i, static_cast<critical_section_policy<node_ptr> *>(&children[i]));
}
return parent_class::child_not_found;
#elif defined(__aarch64__)
const auto replicated_search_key =