Skip to content

Instantly share code, notes, and snippets.

@Kronuz

Kronuz/allocators.h

Created May 28, 2019 20:43
Show Gist options
  • Save Kronuz/f6a30adae8c88b289d501e9abb38ca33 to your computer and use it in GitHub Desktop.
Save Kronuz/f6a30adae8c88b289d501e9abb38ca33 to your computer and use it in GitHub Desktop.
Download ZIP
Benchmarking map for Xapian
Raw
allocators.h
/*
* Copyright (c) 2015-2019 Dubalu LLC
* Copyright (c) 2017 moya-lang.org
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <cstddef> // for std::size_t
#include <deque> // for std::deque
#include <limits> // for std::numeric_limits
#include <new> // for std::bad_alloc, std::nothrow_t, std::new_handler
// __ __ ____ _
// | \/ | ___ _ __ ___ ___ _ __ _ _ | _ \ ___ ___ | |
// | |\/| |/ _ \ '_ ` _ \ / _ \| '__| | | | | |_) / _ \ / _ \| |
// | | | | __/ | | | | | (_) | | | |_| | | __/ (_) | (_) | |
// |_| |_|\___|_| |_| |_|\___/|_| \__, | |_| \___/ \___/|_|
// |___/
namespace allocators {
template <typename _Tp>
class memory_pool_allocator {
public:
// type definitions
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
typedef _Tp* pointer;
typedef const _Tp* const_pointer;
typedef _Tp& reference;
typedef const _Tp& const_reference;
typedef _Tp value_type;
private:
union alignas(alignof(std::max_align_t)) memory_pool_block {
char value[sizeof(value_type)];
memory_pool_block* next;
};
std::deque<memory_pool_block> buffer;
memory_pool_block* next_free_block = nullptr;
public:
// constructors and destructor - deleted copy
memory_pool_allocator() = default;
template<typename _Tp1>
memory_pool_allocator(const memory_pool_allocator<_Tp1>&) throw() { }
// rebind allocator to type _Tp1
template <typename _Tp1>
struct rebind {
using other = memory_pool_allocator<_Tp1>;
};
// allocate but don't initialize n elements
pointer allocate(size_type __n, const void* __hint = static_cast<const void*>(0)) {
if (__n != 1 || __hint) {
throw std::bad_alloc();
}
if (next_free_block) {
memory_pool_block* block = next_free_block;
next_free_block = block->next;
return reinterpret_cast<pointer>(&block->value);
}
buffer.emplace_back();
return reinterpret_cast<pointer>(&buffer.back().value);
}
// deallocate storage __p of deleted elements
void deallocate(pointer __p, size_type) {
auto block = reinterpret_cast<memory_pool_block*>(__p);
block->next = next_free_block;
next_free_block = block;
}
// initialize elements of allocated storage __p with value value
void construct(pointer __p, const_reference __val) {
::new(__p) value_type(__val);
}
// destroy elements of initialized storage __p
void destroy(pointer __p) {
__p->~value_type();
}
};
template <typename _Tp>
inline bool operator==(const memory_pool_allocator<_Tp>& a, const memory_pool_allocator<_Tp>& b) noexcept { return &a == &b; }
template <typename _Tp>
inline bool operator!=(const memory_pool_allocator<_Tp>& a, const memory_pool_allocator<_Tp>& b) noexcept { return &a != &b; }
}
Raw
benchmark-maps.cc
/*
c++ -std=c++1z -pedantic -Wall -Wextra -O3 -lbenchmark -lbenchmark_main -I. -I./src -I../src -I.. -o benchmark-maps ./benchmark-maps.cc && ./benchmark-maps
*/
#include <benchmark/benchmark.h>
#include <map>
#include <unordered_map>
#include "btree.h"
#include "allocators.h"
static void BM_unordered_map(benchmark::State& state) {
for (auto _ : state) {
std::unordered_map<int, int> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace(i, i);
}
}
}
BENCHMARK(BM_unordered_map);
static void BM_map(benchmark::State& state) {
for (auto _ : state) {
std::map<int, int> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace(i, i);
}
}
}
BENCHMARK(BM_map);
static void BM_map_hint(benchmark::State& state) {
for (auto _ : state) {
std::map<int, int> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace_hint(map.end(), i, i);
}
}
}
BENCHMARK(BM_map_hint);
static void BM_map_allocator(benchmark::State& state) {
for (auto _ : state) {
std::map<int, int, std::less<int>, allocators::memory_pool_allocator<std::pair<const int, int>>> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace(i, i);
}
}
}
BENCHMARK(BM_map_allocator);
static void BM_map_hint_allocator(benchmark::State& state) {
for (auto _ : state) {
std::map<int, int, std::less<int>, allocators::memory_pool_allocator<std::pair<const int, int>>> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace_hint(map.end(), i, i);
}
}
}
BENCHMARK(BM_map_hint_allocator);
static void BM_btree_map(benchmark::State& state) {
for (auto _ : state) {
btree::map<int, int> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace(i, i);
}
}
}
BENCHMARK(BM_btree_map);
static void BM_btree_map_hint(benchmark::State& state) {
for (auto _ : state) {
btree::map<int, int> map;
for (int i = 0; i < 10000000; ++i) {
map.emplace_hint(map.end(), i, i);
}
}
}
BENCHMARK(BM_btree_map_hint);
Raw
btree.h
// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// A btree implementation of the STL set and map interfaces. A btree is both
// smaller and faster than STL set/map. The red-black tree implementation of
// STL set/map has an overhead of 3 pointers (left, right and parent) plus the
// node color information for each stored value. So a set<int32> consumes 20
// bytes for each value stored. This btree implementation stores multiple
// values on fixed size nodes (usually 256 bytes) and doesn't store child
// pointers for leaf nodes. The result is that a btree_set<int32> may use much
// less memory per stored value. For the random insertion benchmark in
// btree_test.cc, a btree_set<int32> with node-size of 256 uses 4.9 bytes per
// stored value.
//
// The packing of multiple values on to each node of a btree has another effect
// besides better space utilization: better cache locality due to fewer cache
// lines being accessed. Better cache locality translates into faster
// operations.
//
// CAVEATS
//
// Insertions and deletions on a btree can cause splitting, merging or
// rebalancing of btree nodes. And even without these operations, insertions
// and deletions on a btree will move values around within a node. In both
// cases, the result is that insertions and deletions can invalidate iterators
// pointing to values other than the one being inserted/deleted. This is
// notably different from STL set/map which takes care to not invalidate
// iterators on insert/erase except, of course, for iterators pointing to the
// value being erased. A partial workaround when erasing is available:
// erase() returns an iterator pointing to the item just after the one that was
// erased (or end() if none exists). See also safe_btree.
// PERFORMANCE
//
// btree_bench --benchmarks=. 2>&1 | ./benchmarks.awk
//
// Run on pmattis-warp.nyc (4 X 2200 MHz CPUs); 2010/03/04-15:23:06
// Benchmark STL(ns) B-Tree(ns) @ <size>
// --------------------------------------------------------
// BM_set_int32_insert 1516 608 +59.89% <256> [40.0, 5.2]
// BM_set_int32_lookup 1160 414 +64.31% <256> [40.0, 5.2]
// BM_set_int32_fulllookup 960 410 +57.29% <256> [40.0, 4.4]
// BM_set_int32_delete 1741 528 +69.67% <256> [40.0, 5.2]
// BM_set_int32_queueaddrem 3078 1046 +66.02% <256> [40.0, 5.5]
// BM_set_int32_mixedaddrem 3600 1384 +61.56% <256> [40.0, 5.3]
// BM_set_int32_fifo 227 113 +50.22% <256> [40.0, 4.4]
// BM_set_int32_fwditer 158 26 +83.54% <256> [40.0, 5.2]
// BM_map_int32_insert 1551 636 +58.99% <256> [48.0, 10.5]
// BM_map_int32_lookup 1200 508 +57.67% <256> [48.0, 10.5]
// BM_map_int32_fulllookup 989 487 +50.76% <256> [48.0, 8.8]
// BM_map_int32_delete 1794 628 +64.99% <256> [48.0, 10.5]
// BM_map_int32_queueaddrem 3189 1266 +60.30% <256> [48.0, 11.6]
// BM_map_int32_mixedaddrem 3822 1623 +57.54% <256> [48.0, 10.9]
// BM_map_int32_fifo 151 134 +11.26% <256> [48.0, 8.8]
// BM_map_int32_fwditer 161 32 +80.12% <256> [48.0, 10.5]
// BM_set_int64_insert 1546 636 +58.86% <256> [40.0, 10.5]
// BM_set_int64_lookup 1200 512 +57.33% <256> [40.0, 10.5]
// BM_set_int64_fulllookup 971 487 +49.85% <256> [40.0, 8.8]
// BM_set_int64_delete 1745 616 +64.70% <256> [40.0, 10.5]
// BM_set_int64_queueaddrem 3163 1195 +62.22% <256> [40.0, 11.6]
// BM_set_int64_mixedaddrem 3760 1564 +58.40% <256> [40.0, 10.9]
// BM_set_int64_fifo 146 103 +29.45% <256> [40.0, 8.8]
// BM_set_int64_fwditer 162 31 +80.86% <256> [40.0, 10.5]
// BM_map_int64_insert 1551 720 +53.58% <256> [48.0, 20.7]
// BM_map_int64_lookup 1214 612 +49.59% <256> [48.0, 20.7]
// BM_map_int64_fulllookup 994 592 +40.44% <256> [48.0, 17.2]
// BM_map_int64_delete 1778 764 +57.03% <256> [48.0, 20.7]
// BM_map_int64_queueaddrem 3189 1547 +51.49% <256> [48.0, 20.9]
// BM_map_int64_mixedaddrem 3779 1887 +50.07% <256> [48.0, 21.6]
// BM_map_int64_fifo 147 145 +1.36% <256> [48.0, 17.2]
// BM_map_int64_fwditer 162 41 +74.69% <256> [48.0, 20.7]
// BM_set_string_insert 1989 1966 +1.16% <256> [64.0, 44.5]
// BM_set_string_lookup 1709 1600 +6.38% <256> [64.0, 44.5]
// BM_set_string_fulllookup 1573 1529 +2.80% <256> [64.0, 35.4]
// BM_set_string_delete 2520 1920 +23.81% <256> [64.0, 44.5]
// BM_set_string_queueaddrem 4706 4309 +8.44% <256> [64.0, 48.3]
// BM_set_string_mixedaddrem 5080 4654 +8.39% <256> [64.0, 46.7]
// BM_set_string_fifo 318 512 -61.01% <256> [64.0, 35.4]
// BM_set_string_fwditer 182 93 +48.90% <256> [64.0, 44.5]
// BM_map_string_insert 2600 2227 +14.35% <256> [72.0, 55.8]
// BM_map_string_lookup 2068 1730 +16.34% <256> [72.0, 55.8]
// BM_map_string_fulllookup 1859 1618 +12.96% <256> [72.0, 44.0]
// BM_map_string_delete 3168 2080 +34.34% <256> [72.0, 55.8]
// BM_map_string_queueaddrem 5840 4701 +19.50% <256> [72.0, 59.4]
// BM_map_string_mixedaddrem 6400 5200 +18.75% <256> [72.0, 57.8]
// BM_map_string_fifo 398 596 -49.75% <256> [72.0, 44.0]
// BM_map_string_fwditer 243 113 +53.50% <256> [72.0, 55.8]
#ifndef UTIL_BTREE_BTREE_H__
#define UTIL_BTREE_BTREE_H__
#include <assert.h>
#include <stddef.h>
#include <string.h>
#include <sys/types.h>
#include <algorithm>
#include <functional>
#include <iosfwd>
#include <iostream>
#include <iterator>
#include <limits>
#include <memory>
#include <new>
#include <ostream>
#include <string>
#include <type_traits>
#include <utility>
#ifndef NDEBUG
#define NDEBUG 1
#endif
namespace btree {
// Inside a btree method, if we just call swap(), it will choose the
// btree::swap method, which we don't want. And we can't say ::swap
// because then MSVC won't pickup any std::swap() implementations. We
// can't just use std::swap() directly because then we don't get the
// specialization for types outside the std namespace. So the solution
// is to have a special swap helper function whose name doesn't
// collide with other swap functions defined by the btree classes.
template <typename T>
inline void btree_swap_helper(T &a, T &b) {
using std::swap;
swap(a, b);
}
// A template helper used to select A or B based on a condition.
template<bool cond, typename A, typename B>
struct if_{
typedef A type;
};
template<typename A, typename B>
struct if_<false, A, B> {
typedef B type;
};
// Types small_ and big_ are promise that sizeof(small_) < sizeof(big_)
typedef char small_;
struct big_ {
char dummy[2];
};
// A compile-time assertion.
template <bool>
struct CompileAssert {
};
#define COMPILE_ASSERT(expr, msg) \
typedef CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
// A helper type used to indicate that a key-compare-to functor has been
// provided. A user can specify a key-compare-to functor by doing:
//
// struct MyStringComparer
// : public util::btree::btree_key_compare_to_tag {
// int operator()(const string &a, const string &b) const {
// return a.compare(b);
// }
// };
//
// Note that the return type is an int and not a bool. There is a
// COMPILE_ASSERT which enforces this return type.
struct btree_key_compare_to_tag {
};
// A helper class that indicates if the Compare parameter is derived from
// btree_key_compare_to_tag.
template <typename Compare>
struct btree_is_key_compare_to
: public std::is_convertible<Compare, btree_key_compare_to_tag> {
};
// A helper class to convert a boolean comparison into a three-way
// "compare-to" comparison that returns a negative value to indicate
// less-than, zero to indicate equality and a positive value to
// indicate greater-than. This helper class is specialized for
// less<string> and greater<string>. The btree_key_compare_to_adapter
// class is provided so that btree users automatically get the more
// efficient compare-to code when using common google string types
// with common comparison functors.
template <typename Compare>
struct btree_key_compare_to_adapter : Compare {
btree_key_compare_to_adapter() { }
btree_key_compare_to_adapter(const Compare &c) : Compare(c) { }
btree_key_compare_to_adapter(const btree_key_compare_to_adapter<Compare> &c)
: Compare(c) {
}
};
template <>
struct btree_key_compare_to_adapter<std::less<std::string> >
: public btree_key_compare_to_tag {
btree_key_compare_to_adapter() {}
btree_key_compare_to_adapter(const std::less<std::string>&) {}
btree_key_compare_to_adapter(
const btree_key_compare_to_adapter<std::less<std::string> >&) {}
int operator()(const std::string &a, const std::string &b) const {
return a.compare(b);
}
};
template <>
struct btree_key_compare_to_adapter<std::greater<std::string> >
: public btree_key_compare_to_tag {
btree_key_compare_to_adapter() {}
btree_key_compare_to_adapter(const std::greater<std::string>&) {}
btree_key_compare_to_adapter(
const btree_key_compare_to_adapter<std::greater<std::string> >&) {}
int operator()(const std::string &a, const std::string &b) const {
return b.compare(a);
}
};
// A helper class that allows a compare-to functor to behave like a plain
// compare functor. This specialization is used when we do not have a
// compare-to functor.
template <typename Key, typename Compare, bool HaveCompareTo>
struct btree_key_comparer {
btree_key_comparer() {}
btree_key_comparer(Compare c) : comp(c) {}
static bool bool_compare(const Compare &comp, const Key &x, const Key &y) {
return comp(x, y);
}
bool operator()(const Key &x, const Key &y) const {
return bool_compare(comp, x, y);
}
Compare comp;
};
// A specialization of btree_key_comparer when a compare-to functor is
// present. We need a plain (boolean) comparison in some parts of the btree
// code, such as insert-with-hint.
template <typename Key, typename Compare>
struct btree_key_comparer<Key, Compare, true> {
btree_key_comparer() {}
btree_key_comparer(Compare c) : comp(c) {}
static bool bool_compare(const Compare &comp, const Key &x, const Key &y) {
return comp(x, y) < 0;
}
bool operator()(const Key &x, const Key &y) const {
return bool_compare(comp, x, y);
}
Compare comp;
};
// A helper function to compare to keys using the specified compare
// functor. This dispatches to the appropriate btree_key_comparer comparison,
// depending on whether we have a compare-to functor or not (which depends on
// whether Compare is derived from btree_key_compare_to_tag).
template <typename Key, typename Compare>
static bool btree_compare_keys(
const Compare &comp, const Key &x, const Key &y) {
typedef btree_key_comparer<Key, Compare,
btree_is_key_compare_to<Compare>::value> key_comparer;
return key_comparer::bool_compare(comp, x, y);
}
template <typename Key, typename Compare,
typename Alloc, int TargetNodeSize, int ValueSize>
struct btree_common_params {
// If Compare is derived from btree_key_compare_to_tag then use it as the
// key_compare type. Otherwise, use btree_key_compare_to_adapter<> which will
// fall-back to Compare if we don't have an appropriate specialization.
typedef typename if_<
btree_is_key_compare_to<Compare>::value,
Compare, btree_key_compare_to_adapter<Compare> >::type key_compare;
// A type which indicates if we have a key-compare-to functor or a plain old
// key-compare functor.
typedef btree_is_key_compare_to<key_compare> is_key_compare_to;
typedef Alloc allocator_type;
typedef Key key_type;
typedef ssize_t size_type;
typedef ptrdiff_t difference_type;
enum {
kTargetNodeSize = TargetNodeSize,
// Available space for values. This is largest for leaf nodes,
// which has overhead no fewer than two pointers.
kNodeValueSpace = TargetNodeSize - 2 * sizeof(void*),
};
// This is an integral type large enough to hold as many
// ValueSize-values as will fit a node of TargetNodeSize bytes.
typedef typename if_<
(kNodeValueSpace / ValueSize) >= 256,
uint16_t,
uint8_t>::type node_count_type;
};
// A parameters structure for holding the type parameters for a map.
template <typename Key, typename Data, typename Compare,
typename Alloc, int TargetNodeSize>
struct map_params
: public btree_common_params<Key, Compare, Alloc, TargetNodeSize,
sizeof(Key) + sizeof(Data)> {
typedef Data data_type;
typedef Data mapped_type;
typedef std::pair<const Key, data_type> value_type;
typedef value_type* pointer;
typedef const value_type* const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
enum {
kValueSize = sizeof(Key) + sizeof(data_type),
};
static const Key& key(const value_type &x) { return x.first; }
// static const Key& key(const value_type &x) { return x.first; }
static void swap(value_type *a, value_type *b) {
btree_swap_helper(const_cast<Key&>(a->first), const_cast<Key&>(b->first));
btree_swap_helper(a->second, b->second);
}
};
// An adapter class that converts a lower-bound compare into an upper-bound
// compare.
template <typename Key, typename Compare>
struct btree_upper_bound_adapter : public Compare {
btree_upper_bound_adapter(Compare c) : Compare(c) {}
bool operator()(const Key &a, const Key &b) const {
return !static_cast<const Compare&>(*this)(b, a);
}
};
template <typename Key, typename CompareTo>
struct btree_upper_bound_compare_to_adapter : public CompareTo {
btree_upper_bound_compare_to_adapter(CompareTo c) : CompareTo(c) {}
int operator()(const Key &a, const Key &b) const {
return static_cast<const CompareTo&>(*this)(b, a);
}
};
// Dispatch helper class for using linear search with plain compare.
template <typename K, typename N, typename Compare>
struct btree_linear_search_plain_compare {
static int lower_bound(const K &k, const N &n, Compare comp) {
return n.linear_search_plain_compare(k, 0, n.count(), comp);
}
static int upper_bound(const K &k, const N &n, Compare comp) {
typedef btree_upper_bound_adapter<K, Compare> upper_compare;
return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
}
};
// Dispatch helper class for using linear search with compare-to
template <typename K, typename N, typename CompareTo>
struct btree_linear_search_compare_to {
static int lower_bound(const K &k, const N &n, CompareTo comp) {
return n.linear_search_compare_to(k, 0, n.count(), comp);
}
static int upper_bound(const K &k, const N &n, CompareTo comp) {
typedef btree_upper_bound_adapter<K,
btree_key_comparer<K, CompareTo, true> > upper_compare;
return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
}
};
// Dispatch helper class for using binary search with plain compare.
template <typename K, typename N, typename Compare>
struct btree_binary_search_plain_compare {
static int lower_bound(const K &k, const N &n, Compare comp) {
return n.binary_search_plain_compare(k, 0, n.count(), comp);
}
static int upper_bound(const K &k, const N &n, Compare comp) {
typedef btree_upper_bound_adapter<K, Compare> upper_compare;
return n.binary_search_plain_compare(k, 0, n.count(), upper_compare(comp));
}
};
// Dispatch helper class for using binary search with compare-to.
template <typename K, typename N, typename CompareTo>
struct btree_binary_search_compare_to {
static int lower_bound(const K &k, const N &n, CompareTo /*comp*/) {
return n.binary_search_compare_to(k, 0, n.count(), CompareTo());
}
static int upper_bound(const K &k, const N &n, CompareTo comp) {
typedef btree_upper_bound_adapter<K,
btree_key_comparer<K, CompareTo, true> > upper_compare;
return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
}
};
// A node in the btree holding. The same node type is used for both internal
// and leaf nodes in the btree, though the nodes are allocated in such a way
// that the children array is only valid in internal nodes.
template <typename Params>
class btree_node {
public:
typedef Params params_type;
typedef btree_node<Params> self_type;
typedef typename Params::key_type key_type;
typedef typename Params::data_type data_type;
typedef typename Params::value_type value_type;
typedef typename Params::pointer pointer;
typedef typename Params::const_pointer const_pointer;
typedef typename Params::reference reference;
typedef typename Params::const_reference const_reference;
typedef typename Params::key_compare key_compare;
typedef typename Params::size_type size_type;
typedef typename Params::difference_type difference_type;
// Typedefs for the various types of node searches.
typedef btree_linear_search_plain_compare<
key_type, self_type, key_compare> linear_search_plain_compare_type;
typedef btree_linear_search_compare_to<
key_type, self_type, key_compare> linear_search_compare_to_type;
typedef btree_binary_search_plain_compare<
key_type, self_type, key_compare> binary_search_plain_compare_type;
typedef btree_binary_search_compare_to<
key_type, self_type, key_compare> binary_search_compare_to_type;
// If we have a valid key-compare-to type, use linear_search_compare_to,
// otherwise use linear_search_plain_compare.
typedef typename if_<
Params::is_key_compare_to::value,
linear_search_compare_to_type,
linear_search_plain_compare_type>::type linear_search_type;
// If we have a valid key-compare-to type, use binary_search_compare_to,
// otherwise use binary_search_plain_compare.
typedef typename if_<
Params::is_key_compare_to::value,
binary_search_compare_to_type,
binary_search_plain_compare_type>::type binary_search_type;
// If the key is an integral or floating point type, use linear search which
// is faster than binary search for such types. Might be wise to also
// configure linear search based on node-size.
typedef typename if_<
std::is_integral<key_type>::value ||
std::is_floating_point<key_type>::value,
linear_search_type, binary_search_type>::type search_type;
struct base_fields {
typedef typename Params::node_count_type field_type;
// A boolean indicating whether the node is a leaf or not.
bool leaf;
// The position of the node in the node's parent.
field_type position;
// The maximum number of values the node can hold.
field_type max_count;
// The count of the number of values in the node.
field_type count;
// A pointer to the node's parent.
btree_node *parent;
};
enum {
kValueSize = params_type::kValueSize,
kTargetNodeSize = params_type::kTargetNodeSize,
// Compute how many values we can fit onto a leaf node.
kNodeTargetValues = (kTargetNodeSize - sizeof(base_fields)) / kValueSize,
// We need a minimum of 3 values per internal node in order to perform
// splitting (1 value for the two nodes involved in the split and 1 value
// propagated to the parent as the delimiter for the split).
kNodeValues = kNodeTargetValues >= 3 ? kNodeTargetValues : 3,
kExactMatch = 1 << 30,
kMatchMask = kExactMatch - 1,
};
struct leaf_fields : public base_fields {
// The array of values. Only the first count of these values have been
// constructed and are valid.
value_type values[kNodeValues];
};
struct internal_fields : public leaf_fields {
// The array of child pointers. The keys in children_[i] are all less than
// key(i). The keys in children_[i + 1] are all greater than key(i). There
// are always count + 1 children.
btree_node *children[kNodeValues + 1];
};
struct root_fields : public internal_fields {
btree_node *rightmost;
size_type size;
};
public:
// Getter/setter for whether this is a leaf node or not. This value doesn't
// change after the node is created.
bool leaf() const { return fields_.leaf; }
// Getter for the position of this node in its parent.
int position() const { return fields_.position; }
void set_position(int v) { fields_.position = v; }
// Getter/setter for the number of values stored in this node.
int count() const { return fields_.count; }
void set_count(int v) { fields_.count = v; }
int max_count() const { return fields_.max_count; }
// Getter for the parent of this node.
btree_node* parent() const { return fields_.parent; }
// Getter for whether the node is the root of the tree. The parent of the
// root of the tree is the leftmost node in the tree which is guaranteed to
// be a leaf.
bool is_root() const { return parent()->leaf(); }
void make_root() {
assert(parent()->is_root());
fields_.parent = fields_.parent->parent();
}
// Getter for the rightmost root node field. Only valid on the root node.
btree_node* rightmost() const { return fields_.rightmost; }
btree_node** mutable_rightmost() { return &fields_.rightmost; }
// Getter for the size root node field. Only valid on the root node.
size_type size() const { return fields_.size; }
size_type* mutable_size() { return &fields_.size; }
// Getters for the key/value at position i in the node.
const key_type& key(int i) const {
return params_type::key(fields_.values[i]);
}
reference value(int i) {
return reinterpret_cast<reference>(fields_.values[i]);
}
const_reference value(int i) const {
return reinterpret_cast<const_reference>(fields_.values[i]);
}
// Swap value i in this node with value j in node x.
void value_swap(int i, btree_node *x, int j) {
params_type::swap(&value(i), &x->value(j));
}
// Getters/setter for the child at position i in the node.
btree_node* child(int i) const { return fields_.children[i]; }
btree_node** mutable_child(int i) { return &fields_.children[i]; }
void set_child(int i, btree_node *c) {
*mutable_child(i) = c;
c->fields_.parent = this;
c->fields_.position = i;
}
// Returns the position of the first value whose key is not less than k.
template <typename Compare>
int lower_bound(const key_type &k, const Compare &comp) const {
return search_type::lower_bound(k, *this, comp);
}
// Returns the position of the first value whose key is greater than k.
template <typename Compare>
int upper_bound(const key_type &k, const Compare &comp) const {
return search_type::upper_bound(k, *this, comp);
}
// Returns the position of the first value whose key is not less than k using
// linear search performed using plain compare.
template <typename Compare>
int linear_search_plain_compare(
const key_type &k, int s, int e, const Compare &comp) const {
while (s < e) {
if (!btree_compare_keys(comp, key(s), k)) {
break;
}
++s;
}
return s;
}
// Returns the position of the first value whose key is not less than k using
// linear search performed using compare-to.
template <typename Compare>
int linear_search_compare_to(
const key_type &k, int s, int e, const Compare &comp) const {
while (s < e) {
int c = comp(key(s), k);
if (c == 0) {
return s | kExactMatch;
} else if (c > 0) {
break;
}
++s;
}
return s;
}
// Returns the position of the first value whose key is not less than k using
// binary search performed using plain compare.
template <typename Compare>
int binary_search_plain_compare(
const key_type &k, int s, int e, const Compare &comp) const {
while (s != e) {
int mid = (s + e) / 2;
if (btree_compare_keys(comp, key(mid), k)) {
s = mid + 1;
} else {
e = mid;
}
}
return s;
}
// Returns the position of the first value whose key is not less than k using
// binary search performed using compare-to.
template <typename CompareTo>
int binary_search_compare_to(
const key_type &k, int s, int e, const CompareTo &comp) const {
while (s != e) {
int mid = (s + e) / 2;
int c = comp(key(mid), k);
if (c < 0) {
s = mid + 1;
} else if (c > 0) {
e = mid;
} else {
// Need to return the first value whose key is not less than k, which
// requires continuing the binary search. Note that we are guaranteed
// that the result is an exact match because if "key(mid-1) < k" the
// call to binary_search_compare_to() will return "mid".
s = binary_search_compare_to(k, s, mid, comp);
return s | kExactMatch;
}
}
return s;
}
// Inserts the value x at position i, shifting all existing values and
// children at positions >= i to the right by 1.
template <typename ValueType>
void insert_value(int i, ValueType &&x);
// Removes the value at position i, shifting all existing values and children
// at positions > i to the left by 1.
void remove_value(int i);
// Rebalances a node with its right sibling.
void rebalance_right_to_left(btree_node *sibling, int to_move);
void rebalance_left_to_right(btree_node *sibling, int to_move);
// Splits a node, moving a portion of the node's values to its right sibling.
void split(btree_node *sibling, int insert_position);
// Merges a node with its right sibling, moving all of the values and the
// delimiting key in the parent node onto itself.
void merge(btree_node *sibling);
// Swap the contents of "this" and "src".
void swap(btree_node *src);
// Node allocation/deletion routines.
static btree_node* init_leaf(
leaf_fields *f, btree_node *parent, int max_count) {
btree_node *n = reinterpret_cast<btree_node*>(f);
f->leaf = 1;
f->position = 0;
f->max_count = max_count;
f->count = 0;
f->parent = parent;
if (!NDEBUG) {
memset(&f->values, 0, max_count * sizeof(value_type));
}
return n;
}
static btree_node* init_internal(internal_fields *f, btree_node *parent) {
btree_node *n = init_leaf(f, parent, kNodeValues);
f->leaf = 0;
if (!NDEBUG) {
memset(f->children, 0, sizeof(f->children));
}
return n;
}
static btree_node* init_root(root_fields *f, btree_node *parent) {
btree_node *n = init_internal(f, parent);
f->rightmost = parent;
f->size = parent->count();
return n;
}
void destroy() {
for (int i = 0; i < count(); ++i) {
value_destroy(i);
}
}
private:
void value_init(int i) {
new (&fields_.values[i]) value_type;
}
template <typename ValueType>
void value_init(int i, ValueType &&x) {
new (&fields_.values[i]) value_type(std::forward<ValueType>(x));
}
void value_destroy(int i) {
fields_.values[i].~value_type();
}
private:
root_fields fields_;
private:
btree_node(const btree_node&);
void operator=(const btree_node&);
};
template <typename Node, typename Reference, typename Pointer>
struct btree_iterator {
typedef typename Node::key_type key_type;
typedef typename Node::size_type size_type;
typedef typename Node::difference_type difference_type;
typedef typename Node::params_type params_type;
typedef Node node_type;
typedef typename std::remove_const<Node>::type normal_node;
typedef const Node const_node;
typedef typename params_type::value_type value_type;
typedef typename params_type::pointer normal_pointer;
typedef typename params_type::reference normal_reference;
typedef typename params_type::const_pointer const_pointer;
typedef typename params_type::const_reference const_reference;
typedef Pointer pointer;
typedef Reference reference;
typedef std::bidirectional_iterator_tag iterator_category;
typedef btree_iterator<
normal_node, normal_reference, normal_pointer> iterator;
typedef btree_iterator<
const_node, const_reference, const_pointer> const_iterator;
typedef btree_iterator<Node, Reference, Pointer> self_type;
btree_iterator()
: node(NULL),
position(-1) {
}
btree_iterator(Node *n, int p)
: node(n),
position(p) {
}
btree_iterator(const iterator &x)
: node(x.node),
position(x.position) {
}
// Increment/decrement the iterator.
void increment() {
if (node->leaf() && ++position < node->count()) {
return;
}
increment_slow();
}
void increment_by(int count);
void increment_slow();
void decrement() {
if (node->leaf() && --position >= 0) {
return;
}
decrement_slow();
}
void decrement_slow();
bool operator==(const const_iterator &x) const {
return node == x.node && position == x.position;
}
bool operator!=(const const_iterator &x) const {
return node != x.node || position != x.position;
}
// Accessors for the key/value the iterator is pointing at.
const key_type& key() const {
return node->key(position);
}
reference operator*() const {
return node->value(position);
}
pointer operator->() const {
return &node->value(position);
}
self_type& operator++() {
increment();
return *this;
}
self_type& operator--() {
decrement();
return *this;
}
self_type operator++(int) {
self_type tmp = *this;
++*this;
return tmp;
}
self_type operator--(int) {
self_type tmp = *this;
--*this;
return tmp;
}
// The node in the tree the iterator is pointing at.
Node *node;
// The position within the node of the tree the iterator is pointing at.
int position;
};
// Dispatch helper class for using btree::internal_locate with plain compare.
struct btree_internal_locate_plain_compare {
template <typename K, typename T, typename Iter>
static std::pair<Iter, int> dispatch(const K &k, const T &t, Iter iter) {
return t.internal_locate_plain_compare(k, iter);
}
};
// Dispatch helper class for using btree::internal_locate with compare-to.
struct btree_internal_locate_compare_to {
template <typename K, typename T, typename Iter>
static std::pair<Iter, int> dispatch(const K &k, const T &t, Iter iter) {
return t.internal_locate_compare_to(k, iter);
}
};
template <typename Params>
class btree : public Params::key_compare {
typedef btree<Params> self_type;
typedef btree_node<Params> node_type;
typedef typename node_type::base_fields base_fields;
typedef typename node_type::leaf_fields leaf_fields;
typedef typename node_type::internal_fields internal_fields;
typedef typename node_type::root_fields root_fields;
typedef typename Params::is_key_compare_to is_key_compare_to;
friend struct btree_internal_locate_plain_compare;
friend struct btree_internal_locate_compare_to;
typedef typename if_<
is_key_compare_to::value,
btree_internal_locate_compare_to,
btree_internal_locate_plain_compare>::type internal_locate_type;
enum {
kNodeValues = node_type::kNodeValues,
kMinNodeValues = kNodeValues / 2,
kValueSize = node_type::kValueSize,
kExactMatch = node_type::kExactMatch,
kMatchMask = node_type::kMatchMask,
};
// A helper class to get the empty base class optimization for 0-size
// allocators. Base is internal_allocator_type.
// (e.g. empty_base_handle<internal_allocator_type, node_type*>). If Base is
// 0-size, the compiler doesn't have to reserve any space for it and
// sizeof(empty_base_handle) will simply be sizeof(Data). Google [empty base
// class optimization] for more details.
template <typename Base, typename Data>
struct empty_base_handle : public Base {
empty_base_handle(const Base &b, const Data &d)
: Base(b),
data(d) {
}
Data data;
};
struct node_stats {
node_stats(ssize_t l, ssize_t i)
: leaf_nodes(l),
internal_nodes(i) {
}
node_stats& operator+=(const node_stats &x) {
leaf_nodes += x.leaf_nodes;
internal_nodes += x.internal_nodes;
return *this;
}
ssize_t leaf_nodes;
ssize_t internal_nodes;
};
public:
typedef Params params_type;
typedef typename Params::key_type key_type;
typedef typename Params::data_type data_type;
typedef typename Params::mapped_type mapped_type;
typedef typename Params::value_type value_type;
typedef typename Params::key_compare key_compare;
typedef typename Params::pointer pointer;
typedef typename Params::const_pointer const_pointer;
typedef typename Params::reference reference;
typedef typename Params::const_reference const_reference;
typedef typename Params::size_type size_type;
typedef typename Params::difference_type difference_type;
typedef btree_iterator<node_type, reference, pointer> iterator;
typedef typename iterator::const_iterator const_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef typename Params::allocator_type allocator_type;
typedef typename allocator_type::template rebind<char>::other
internal_allocator_type;
public:
// Default constructor.
btree(const key_compare &comp, const allocator_type &alloc);
// Copy constructor.
btree(const self_type &x);
// Destructor.
~btree() {
clear();
}
// Iterator routines.
iterator begin() {
return iterator(leftmost(), 0);
}
const_iterator begin() const {
return const_iterator(leftmost(), 0);
}
iterator end() {
return iterator(rightmost(), rightmost() ? rightmost()->count() : 0);
}
const_iterator end() const {
return const_iterator(rightmost(), rightmost() ? rightmost()->count() : 0);
}
reverse_iterator rbegin() {
return reverse_iterator(end());
}
const_reverse_iterator rbegin() const {
return const_reverse_iterator(end());
}
reverse_iterator rend() {
return reverse_iterator(begin());
}
const_reverse_iterator rend() const {
return const_reverse_iterator(begin());
}
// Finds the first element whose key is not less than key.
iterator lower_bound(const key_type &key) {
return internal_end(
internal_lower_bound(key, iterator(root(), 0)));
}
const_iterator lower_bound(const key_type &key) const {
return internal_end(
internal_lower_bound(key, const_iterator(root(), 0)));
}
// Finds the first element whose key is greater than key.
iterator upper_bound(const key_type &key) {
return internal_end(
internal_upper_bound(key, iterator(root(), 0)));
}
const_iterator upper_bound(const key_type &key) const {
return internal_end(
internal_upper_bound(key, const_iterator(root(), 0)));
}
// Finds the range of values which compare equal to key. The first member of
// the returned pair is equal to lower_bound(key). The second member pair of
// the pair is equal to upper_bound(key).
std::pair<iterator,iterator> equal_range(const key_type &key) {
return std::make_pair(lower_bound(key), upper_bound(key));
}
std::pair<const_iterator,const_iterator> equal_range(const key_type &key) const {
return std::make_pair(lower_bound(key), upper_bound(key));
}
// Inserts a value into the btree only if it does not already exist. The
// boolean return value indicates whether insertion succeeded or failed.
template <typename ValueType>
std::pair<iterator, bool> insert_unique(const key_type &key, ValueType &&value);
// Inserts a value into the btree only if it does not already exist. The
// boolean return value indicates whether insertion succeeded or failed.
template <typename ValueType>
std::pair<iterator, bool> insert_unique(ValueType &&v) {
return insert_unique(params_type::key(v), std::forward<ValueType>(v));
}
// Insert with hint. Check to see if the value should be placed immediately
// before position in the tree. If it does, then the insertion will take
// amortized constant time. If not, the insertion will take amortized
// logarithmic time as if a call to insert_unique(v) were made.
template <typename ValueType>
iterator insert_unique(iterator position, ValueType &&v);
// Insert a range of values into the btree.
template <typename InputIterator>
void insert_unique(InputIterator b, InputIterator e);
// Inserts a value into the btree.
template <typename ValueType>
iterator insert_multi(const key_type &key, ValueType &&value);
// Inserts a value into the btree.
template <typename ValueType>
iterator insert_multi(ValueType &&v) {
return insert_multi(params_type::key(v), std::forward<ValueType>(v));
}
// Insert with hint. Check to see if the value should be placed immediately
// before position in the tree. If it does, then the insertion will take
// amortized constant time. If not, the insertion will take amortized
// logarithmic time as if a call to insert_multi(v) were made.
template <typename ValueType>
iterator insert_multi(iterator position, ValueType &&v);
// Insert a range of values into the btree.
template <typename InputIterator>
void insert_multi(InputIterator b, InputIterator e);
void assign(const self_type &x);
// Erase the specified iterator from the btree. The iterator must be valid
// (i.e. not equal to end()). Return an iterator pointing to the node after
// the one that was erased (or end() if none exists).
iterator erase(iterator iter);
// Erases range. Returns the number of keys erased.
int erase(iterator begin, iterator end);
// Erases the specified key from the btree. Returns 1 if an element was
// erased and 0 otherwise.
int erase_unique(const key_type &key);
// Erases all of the entries matching the specified key from the
// btree. Returns the number of elements erased.
int erase_multi(const key_type &key);
// Finds the iterator corresponding to a key or returns end() if the key is
// not present.
iterator find_unique(const key_type &key) {
return internal_end(
internal_find_unique(key, iterator(root(), 0)));
}
const_iterator find_unique(const key_type &key) const {
return internal_end(
internal_find_unique(key, const_iterator(root(), 0)));
}
iterator find_multi(const key_type &key) {
return internal_end(
internal_find_multi(key, iterator(root(), 0)));
}
const_iterator find_multi(const key_type &key) const {
return internal_end(
internal_find_multi(key, const_iterator(root(), 0)));
}
// Returns a count of the number of times the key appears in the btree.
size_type count_unique(const key_type &key) const {
const_iterator begin = internal_find_unique(
key, const_iterator(root(), 0));
if (!begin.node) {
// The key doesn't exist in the tree.
return 0;
}
return 1;
}
// Returns a count of the number of times the key appears in the btree.
size_type count_multi(const key_type &key) const {
return distance(lower_bound(key), upper_bound(key));
}
// Clear the btree, deleting all of the values it contains.
void clear();
// Swap the contents of *this and x.
void swap(self_type &x);
// Assign the contents of x to *this.
self_type& operator=(const self_type &x) {
if (&x == this) {
// Don't copy onto ourselves.
return *this;
}
assign(x);
return *this;
}
key_compare* mutable_key_comp() {
return this;
}
const key_compare& key_comp() const {
return *this;
}
bool compare_keys(const key_type &x, const key_type &y) const {
return btree_compare_keys(key_comp(), x, y);
}
// Dump the btree to the specified ostream. Requires that operator<< is
// defined for Key and Value.
void dump(std::ostream &os) const {
if (root() != NULL) {
internal_dump(os, root(), 0);
}
}
// Verifies the structure of the btree.
void verify() const;
// Size routines. Note that empty() is slightly faster than doing size()==0.
size_type size() const {
if (empty()) return 0;
if (root()->leaf()) return root()->count();
return root()->size();
}
size_type max_size() const { return std::numeric_limits<size_type>::max(); }
bool empty() const { return root() == NULL; }
// The height of the btree. An empty tree will have height 0.
size_type height() const {
size_type h = 0;
if (root()) {
// Count the length of the chain from the leftmost node up to the
// root. We actually count from the root back around to the level below
// the root, but the calculation is the same because of the circularity
// of that traversal.
const node_type *n = root();
do {
++h;
n = n->parent();
} while (n != root());
}
return h;
}
// The number of internal, leaf and total nodes used by the btree.
size_type leaf_nodes() const {
return internal_stats(root()).leaf_nodes;
}
size_type internal_nodes() const {
return internal_stats(root()).internal_nodes;
}
size_type nodes() const {
node_stats stats = internal_stats(root());
return stats.leaf_nodes + stats.internal_nodes;
}
// The total number of bytes used by the btree.
size_type bytes_used() const {
node_stats stats = internal_stats(root());
if (stats.leaf_nodes == 1 && stats.internal_nodes == 0) {
return sizeof(*this) +
sizeof(base_fields) + root()->max_count() * sizeof(value_type);
} else {
return sizeof(*this) +
sizeof(root_fields) - sizeof(internal_fields) +
stats.leaf_nodes * sizeof(leaf_fields) +
stats.internal_nodes * sizeof(internal_fields);
}
}
// The average number of bytes used per value stored in the btree.
static double average_bytes_per_value() {
// Returns the number of bytes per value on a leaf node that is 75%
// full. Experimentally, this matches up nicely with the computed number of
// bytes per value in trees that had their values inserted in random order.
return sizeof(leaf_fields) / (kNodeValues * 0.75);
}
// The fullness of the btree. Computed as the number of elements in the btree
// divided by the maximum number of elements a tree with the current number
// of nodes could hold. A value of 1 indicates perfect space
// utilization. Smaller values indicate space wastage.
double fullness() const {
return double(size()) / (nodes() * kNodeValues);
}
// The overhead of the btree structure in bytes per node. Computed as the
// total number of bytes used by the btree minus the number of bytes used for
// storing elements divided by the number of elements.
double overhead() const {
if (empty()) {
return 0.0;
}
return (bytes_used() - size() * kValueSize) / double(size());
}
private:
// Internal accessor routines.
node_type* root() { return root_.data; }
const node_type* root() const { return root_.data; }
node_type** mutable_root() { return &root_.data; }
// The rightmost node is stored in the root node.
node_type* rightmost() {
return (!root() || root()->leaf()) ? root() : root()->rightmost();
}
const node_type* rightmost() const {
return (!root() || root()->leaf()) ? root() : root()->rightmost();
}
node_type** mutable_rightmost() { return root()->mutable_rightmost(); }
// The leftmost node is stored as the parent of the root node.
node_type* leftmost() { return root() ? root()->parent() : NULL; }
const node_type* leftmost() const { return root() ? root()->parent() : NULL; }
// The size of the tree is stored in the root node.
size_type* mutable_size() { return root()->mutable_size(); }
// Allocator routines.
internal_allocator_type* mutable_internal_allocator() {
return static_cast<internal_allocator_type*>(&root_);
}
const internal_allocator_type& internal_allocator() const {
return *static_cast<const internal_allocator_type*>(&root_);
}
// Node creation/deletion routines.
node_type* new_internal_node(node_type *parent) {
internal_fields *p = reinterpret_cast<internal_fields*>(
mutable_internal_allocator()->allocate(sizeof(internal_fields)));
return node_type::init_internal(p, parent);
}
node_type* new_internal_root_node() {
root_fields *p = reinterpret_cast<root_fields*>(
mutable_internal_allocator()->allocate(sizeof(root_fields)));
return node_type::init_root(p, root()->parent());
}
node_type* new_leaf_node(node_type *parent) {
leaf_fields *p = reinterpret_cast<leaf_fields*>(
mutable_internal_allocator()->allocate(sizeof(leaf_fields)));
return node_type::init_leaf(p, parent, kNodeValues);
}
node_type* new_leaf_root_node(int max_count) {
leaf_fields *p = reinterpret_cast<leaf_fields*>(
mutable_internal_allocator()->allocate(
sizeof(base_fields) + max_count * sizeof(value_type)));
return node_type::init_leaf(p, reinterpret_cast<node_type*>(p), max_count);
}
void delete_internal_node(node_type *node) {
node->destroy();
assert(node != root());
mutable_internal_allocator()->deallocate(
reinterpret_cast<char*>(node), sizeof(internal_fields));
}
void delete_internal_root_node() {
root()->destroy();
mutable_internal_allocator()->deallocate(
reinterpret_cast<char*>(root()), sizeof(root_fields));
}
void delete_leaf_node(node_type *node) {
node->destroy();
mutable_internal_allocator()->deallocate(
reinterpret_cast<char*>(node),
sizeof(base_fields) + node->max_count() * sizeof(value_type));
}
// Rebalances or splits the node iter points to.
void rebalance_or_split(iterator *iter);
// Merges the values of left, right and the delimiting key on their parent
// onto left, removing the delimiting key and deleting right.
void merge_nodes(node_type *left, node_type *right);
// Tries to merge node with its left or right sibling, and failing that,
// rebalance with its left or right sibling. Returns true if a merge
// occurred, at which point it is no longer valid to access node. Returns
// false if no merging took place.
bool try_merge_or_rebalance(iterator *iter);
// Tries to shrink the height of the tree by 1.
void try_shrink();
iterator internal_end(iterator iter) {
return iter.node ? iter : end();
}
const_iterator internal_end(const_iterator iter) const {
return iter.node ? iter : end();
}
// Inserts a value into the btree immediately before iter. Requires that
// key(v) <= iter.key() and (--iter).key() <= key(v).
template <typename ValueType>
iterator internal_insert(iterator iter, ValueType &&v);
// Returns an iterator pointing to the first value >= the value "iter" is
// pointing at. Note that "iter" might be pointing to an invalid location as
// iter.position == iter.node->count(). This routine simply moves iter up in
// the tree to a valid location.
template <typename IterType>
static IterType internal_last(IterType iter);
// Returns an iterator pointing to the leaf position at which key would
// reside in the tree. We provide 2 versions of internal_locate. The first
// version (internal_locate_plain_compare) always returns 0 for the second
// field of the pair. The second version (internal_locate_compare_to) is for
// the key-compare-to specialization and returns either kExactMatch (if the
// key was found in the tree) or -kExactMatch (if it wasn't) in the second
// field of the pair. The compare_to specialization allows the caller to
// avoid a subsequent comparison to determine if an exact match was made,
// speeding up string keys.
template <typename IterType>
std::pair<IterType, int> internal_locate(
const key_type &key, IterType iter) const;
template <typename IterType>
std::pair<IterType, int> internal_locate_plain_compare(
const key_type &key, IterType iter) const;
template <typename IterType>
std::pair<IterType, int> internal_locate_compare_to(
const key_type &key, IterType iter) const;
// Internal routine which implements lower_bound().
template <typename IterType>
IterType internal_lower_bound(
const key_type &key, IterType iter) const;
// Internal routine which implements upper_bound().
template <typename IterType>
IterType internal_upper_bound(
const key_type &key, IterType iter) const;
// Internal routine which implements find_unique().
template <typename IterType>
IterType internal_find_unique(
const key_type &key, IterType iter) const;
// Internal routine which implements find_multi().
template <typename IterType>
IterType internal_find_multi(
const key_type &key, IterType iter) const;
// Deletes a node and all of its children.
void internal_clear(node_type *node);
// Dumps a node and all of its children to the specified ostream.
void internal_dump(std::ostream &os, const node_type *node, int level) const;
// Verifies the tree structure of node.
int internal_verify(const node_type *node,
const key_type *lo, const key_type *hi) const;
node_stats internal_stats(const node_type *node) const {
if (!node) {
return node_stats(0, 0);
}
if (node->leaf()) {
return node_stats(1, 0);
}
node_stats res(0, 1);
for (int i = 0; i <= node->count(); ++i) {
res += internal_stats(node->child(i));
}
return res;
}
private:
empty_base_handle<internal_allocator_type, node_type*> root_;
private:
// A never instantiated helper function that returns big_ if we have a
// key-compare-to functor or if R is bool and small_ otherwise.
template <typename R>
static typename if_<
if_<is_key_compare_to::value,
std::is_same<R, int>,
std::is_same<R, bool> >::type::value,
big_, small_>::type key_compare_checker(R);
// A never instantiated helper function that returns the key comparison
// functor.
static key_compare key_compare_helper();
// Verify that key_compare returns a bool. This is similar to the way
// is_convertible in base/type_traits.h works. Note that key_compare_checker
// is never actually invoked. The compiler will select which
// key_compare_checker() to instantiate and then figure out the size of the
// return type of key_compare_checker() at compile time which we then check
// against the sizeof of big_.
COMPILE_ASSERT(
sizeof(key_compare_checker(key_compare_helper()(key_type(), key_type()))) ==
sizeof(big_),
key_comparison_function_must_return_bool);
// Note: We insist on kTargetValues, which is computed from
// Params::kTargetNodeSize, must fit the base_fields::field_type.
COMPILE_ASSERT(kNodeValues <
(1 << (8 * sizeof(typename base_fields::field_type))),
target_node_size_too_large);
// Test the assumption made in setting kNodeValueSpace.
COMPILE_ASSERT(sizeof(base_fields) >= 2 * sizeof(void*),
node_space_assumption_incorrect);
};
////
// btree_node methods
template <typename P> template <typename ValueType>
inline void btree_node<P>::insert_value(int i, ValueType &&x) {
assert(i <= count());
value_init(count(), std::forward<ValueType>(x));
for (int j = count(); j > i; --j) {
value_swap(j, this, j - 1);
}
set_count(count() + 1);
if (!leaf()) {
++i;
for (int j = count(); j > i; --j) {
*mutable_child(j) = child(j - 1);
child(j)->set_position(j);
}
*mutable_child(i) = NULL;
}
}
template <typename P>
inline void btree_node<P>::remove_value(int i) {
if (!leaf()) {
assert(child(i + 1)->count() == 0);
for (int j = i + 1; j < count(); ++j) {
*mutable_child(j) = child(j + 1);
child(j)->set_position(j);
}
*mutable_child(count()) = NULL;
}
set_count(count() - 1);
for (; i < count(); ++i) {
value_swap(i, this, i + 1);
}
value_destroy(i);
}
template <typename P>
void btree_node<P>::rebalance_right_to_left(btree_node *src, int to_move) {
assert(parent() == src->parent());
assert(position() + 1 == src->position());
assert(src->count() >= count());
assert(to_move >= 1);
assert(to_move <= src->count());
// Make room in the left node for the new values.
for (int i = 0; i < to_move; ++i) {
value_init(i + count());
}
// Move the delimiting value to the left node and the new delimiting value
// from the right node.
value_swap(count(), parent(), position());
parent()->value_swap(position(), src, to_move - 1);
// Move the values from the right to the left node.
for (int i = 1; i < to_move; ++i) {
value_swap(count() + i, src, i - 1);
}
// Shift the values in the right node to their correct position.
for (int i = to_move; i < src->count(); ++i) {
src->value_swap(i - to_move, src, i);
}
for (int i = 1; i <= to_move; ++i) {
src->value_destroy(src->count() - i);
}
if (!leaf()) {
// Move the child pointers from the right to the left node.
for (int i = 0; i < to_move; ++i) {
set_child(1 + count() + i, src->child(i));
}
for (int i = 0; i <= src->count() - to_move; ++i) {
assert(i + to_move <= src->max_count());
src->set_child(i, src->child(i + to_move));
*src->mutable_child(i + to_move) = NULL;
}
}
// Fixup the counts on the src and dest nodes.
set_count(count() + to_move);
src->set_count(src->count() - to_move);
}
template <typename P>
void btree_node<P>::rebalance_left_to_right(btree_node *dest, int to_move) {
assert(parent() == dest->parent());
assert(position() + 1 == dest->position());
assert(count() >= dest->count());
assert(to_move >= 1);
assert(to_move <= count());
// Make room in the right node for the new values.
for (int i = 0; i < to_move; ++i) {
dest->value_init(i + dest->count());
}
for (int i = dest->count() - 1; i >= 0; --i) {
dest->value_swap(i, dest, i + to_move);
}
// Move the delimiting value to the right node and the new delimiting value
// from the left node.
dest->value_swap(to_move - 1, parent(), position());
parent()->value_swap(position(), this, count() - to_move);
value_destroy(count() - to_move);
// Move the values from the left to the right node.
for (int i = 1; i < to_move; ++i) {
value_swap(count() - to_move + i, dest, i - 1);
value_destroy(count() - to_move + i);
}
if (!leaf()) {
// Move the child pointers from the left to the right node.
for (int i = dest->count(); i >= 0; --i) {
dest->set_child(i + to_move, dest->child(i));
*dest->mutable_child(i) = NULL;
}
for (int i = 1; i <= to_move; ++i) {
dest->set_child(i - 1, child(count() - to_move + i));
*mutable_child(count() - to_move + i) = NULL;
}
}
// Fixup the counts on the src and dest nodes.
set_count(count() - to_move);
dest->set_count(dest->count() + to_move);
}
template <typename P>
void btree_node<P>::split(btree_node *dest, int insert_position) {
assert(dest->count() == 0);
// We bias the split based on the position being inserted. If we're
// inserting at the beginning of the left node then bias the split to put
// more values on the right node. If we're inserting at the end of the
// right node then bias the split to put more values on the left node.
if (insert_position == 0) {
dest->set_count(count() - 1);
} else if (insert_position == max_count()) {
dest->set_count(0);
} else {
dest->set_count(count() / 2);
}
set_count(count() - dest->count());
assert(count() >= 1);
// Move values from the left sibling to the right sibling.
for (int i = 0; i < dest->count(); ++i) {
dest->value_init(i);
value_swap(count() + i, dest, i);
value_destroy(count() + i);
}
// The split key is the largest value in the left sibling.
set_count(count() - 1);
parent()->insert_value(position(), value_type());
value_swap(count(), parent(), position());
value_destroy(count());
parent()->set_child(position() + 1, dest);
if (!leaf()) {
for (int i = 0; i <= dest->count(); ++i) {
assert(child(count() + i + 1) != NULL);
dest->set_child(i, child(count() + i + 1));
*mutable_child(count() + i + 1) = NULL;
}
}
}
template <typename P>
void btree_node<P>::merge(btree_node *src) {
assert(parent() == src->parent());
assert(position() + 1 == src->position());
// Move the delimiting value to the left node.
value_init(count());
value_swap(count(), parent(), position());
// Move the values from the right to the left node.
for (int i = 0; i < src->count(); ++i) {
value_init(1 + count() + i);
value_swap(1 + count() + i, src, i);
src->value_destroy(i);
}
if (!leaf()) {
// Move the child pointers from the right to the left node.
for (int i = 0; i <= src->count(); ++i) {
set_child(1 + count() + i, src->child(i));
*src->mutable_child(i) = NULL;
}
}
// Fixup the counts on the src and dest nodes.
set_count(1 + count() + src->count());
src->set_count(0);
// Remove the value on the parent node.
parent()->remove_value(position());
}
template <typename P>
void btree_node<P>::swap(btree_node *x) {
assert(leaf() == x->leaf());
// Swap the values.
for (int i = count(); i < x->count(); ++i) {
value_init(i);
}
for (int i = x->count(); i < count(); ++i) {
x->value_init(i);
}
int n = std::max(count(), x->count());
for (int i = 0; i < n; ++i) {
value_swap(i, x, i);
}
for (int i = count(); i < x->count(); ++i) {
x->value_destroy(i);
}
for (int i = x->count(); i < count(); ++i) {
value_destroy(i);
}
if (!leaf()) {
// Swap the child pointers.
for (int i = 0; i <= n; ++i) {
btree_swap_helper(*mutable_child(i), *x->mutable_child(i));
}
for (int i = 0; i <= count(); ++i) {
x->child(i)->fields_.parent = x;
}
for (int i = 0; i <= x->count(); ++i) {
child(i)->fields_.parent = this;
}
}
// Swap the counts.
btree_swap_helper(fields_.count, x->fields_.count);
}
////
// btree_iterator methods
template <typename N, typename R, typename P>
void btree_iterator<N, R, P>::increment_slow() {
if (node->leaf()) {
assert(position >= node->count());
self_type save(*this);
while (position == node->count() && !node->is_root()) {
assert(node->parent()->child(node->position()) == node);
position = node->position();
node = node->parent();
}
if (position == node->count()) {
*this = save;
}
} else {
assert(position < node->count());
node = node->child(position + 1);
while (!node->leaf()) {
node = node->child(0);
}
position = 0;
}
}
template <typename N, typename R, typename P>
void btree_iterator<N, R, P>::increment_by(int count) {
while (count > 0) {
if (node->leaf()) {
int rest = node->count() - position;
position += std::min(rest, count);
count = count - rest;
if (position < node->count()) {
return;
}
} else {
--count;
}
increment_slow();
}
}
template <typename N, typename R, typename P>
void btree_iterator<N, R, P>::decrement_slow() {
if (node->leaf()) {
assert(position <= -1);
self_type save(*this);
while (position < 0 && !node->is_root()) {
assert(node->parent()->child(node->position()) == node);
position = node->position() - 1;
node = node->parent();
}
if (position < 0) {
*this = save;
}
} else {
assert(position >= 0);
node = node->child(position);
while (!node->leaf()) {
node = node->child(node->count());
}
position = node->count() - 1;
}
}
////
// btree methods
template <typename P>
btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
: key_compare(comp),
root_(alloc, NULL) {
}
template <typename P>
btree<P>::btree(const self_type &x)
: key_compare(x.key_comp()),
root_(x.internal_allocator(), NULL) {
assign(x);
}
template <typename P> template <typename ValueType>
std::pair<typename btree<P>::iterator, bool>
btree<P>::insert_unique(const key_type &key, ValueType &&value) {
if (empty()) {
*mutable_root() = new_leaf_root_node(1);
}
std::pair<iterator, int> res = internal_locate(key, iterator(root(), 0));
iterator &iter = res.first;
if (res.second == kExactMatch) {
// The key already exists in the tree, do nothing.
return std::make_pair(internal_last(iter), false);
} else if (!res.second) {
iterator last = internal_last(iter);
if (last.node && !compare_keys(key, last.key())) {
// The key already exists in the tree, do nothing.
return std::make_pair(last, false);
}
}
return std::make_pair(internal_insert(iter, std::forward<ValueType>(value)), true);
}
template <typename P> template <typename ValueType>
inline typename btree<P>::iterator
btree<P>::insert_unique(iterator position, ValueType &&v) {
if (!empty()) {
const key_type &key = params_type::key(v);
if (position == end() || compare_keys(key, position.key())) {
iterator prev = position;
if (position == begin() || compare_keys((--prev).key(), key)) {
// prev.key() < key < position.key()
return internal_insert(position, std::forward<ValueType>(v));
}
} else if (compare_keys(position.key(), key)) {
iterator next = position;
++next;
if (next == end() || compare_keys(key, next.key())) {
// position.key() < key < next.key()
return internal_insert(next, std::forward<ValueType>(v));
}
} else {
// position.key() == key
return position;
}
}
return insert_unique(std::forward<ValueType>(v)).first;
}
template <typename P> template <typename InputIterator>
void btree<P>::insert_unique(InputIterator b, InputIterator e) {
for (; b != e; ++b) {
insert_unique(end(), *b);
}
}
template <typename P> template <typename ValueType>
typename btree<P>::iterator
btree<P>::insert_multi(const key_type &key, ValueType &&value) {
if (empty()) {
*mutable_root() = new_leaf_root_node(1);
}
iterator iter = internal_upper_bound(key, iterator(root(), 0));
if (!iter.node) {
iter = end();
}
return internal_insert(iter, std::forward<ValueType>(value));
}
template <typename P> template <typename ValueType>
typename btree<P>::iterator
btree<P>::insert_multi(iterator position, ValueType &&v) {
if (!empty()) {
const key_type &key = params_type::key(v);
if (position == end() || !compare_keys(position.key(), key)) {
iterator prev = position;
if (position == begin() || !compare_keys(key, (--prev).key())) {
// prev.key() <= key <= position.key()
return internal_insert(position, std::forward<ValueType>(v));
}
} else {
iterator next = position;
++next;
if (next == end() || !compare_keys(next.key(), key)) {
// position.key() < key <= next.key()
return internal_insert(next, std::forward<ValueType>(v));
}
}
}
return insert_multi(std::forward<ValueType>(v));
}
template <typename P> template <typename InputIterator>
void btree<P>::insert_multi(InputIterator b, InputIterator e) {
for (; b != e; ++b) {
insert_multi(end(), *b);
}
}
template <typename P>
void btree<P>::assign(const self_type &x) {
clear();
*mutable_key_comp() = x.key_comp();
*mutable_internal_allocator() = x.internal_allocator();
// Assignment can avoid key comparisons because we know the order of the
// values is the same order we'll store them in.
for (const_iterator iter = x.begin(); iter != x.end(); ++iter) {
if (empty()) {
insert_multi(*iter);
} else {
// If the btree is not empty, we can just insert the new value at the end
// of the tree!
internal_insert(end(), *iter);
}
}
}
template <typename P>
typename btree<P>::iterator btree<P>::erase(iterator iter) {
bool internal_delete = false;
if (!iter.node->leaf()) {
// Deletion of a value on an internal node. Swap the key with the largest
// value of our left child. This is easy, we just decrement iter.
iterator tmp_iter(iter--);
assert(iter.node->leaf());
assert(!compare_keys(tmp_iter.key(), iter.key()));
iter.node->value_swap(iter.position, tmp_iter.node, tmp_iter.position);
internal_delete = true;
--*mutable_size();
} else if (!root()->leaf()) {
--*mutable_size();
}
// Delete the key from the leaf.
iter.node->remove_value(iter.position);
// We want to return the next value after the one we just erased. If we
// erased from an internal node (internal_delete == true), then the next
// value is ++(++iter). If we erased from a leaf node (internal_delete ==
// false) then the next value is ++iter. Note that ++iter may point to an
// internal node and the value in the internal node may move to a leaf node
// (iter.node) when rebalancing is performed at the leaf level.
// Merge/rebalance as we walk back up the tree.
iterator res(iter);
for (;;) {
if (iter.node == root()) {
try_shrink();
if (empty()) {
return end();
}
break;
}
if (iter.node->count() >= kMinNodeValues) {
break;
}
bool merged = try_merge_or_rebalance(&iter);
if (iter.node->leaf()) {
res = iter;
}
if (!merged) {
break;
}
iter.node = iter.node->parent();
}
// Adjust our return value. If we're pointing at the end of a node, advance
// the iterator.
if (res.position == res.node->count()) {
res.position = res.node->count() - 1;
++res;
}
// If we erased from an internal node, advance the iterator.
if (internal_delete) {
++res;
}
return res;
}
template <typename P>
int btree<P>::erase(iterator begin, iterator end) {
int count = distance(begin, end);
for (int i = 0; i < count; i++) {
begin = erase(begin);
}
return count;
}
template <typename P>
int btree<P>::erase_unique(const key_type &key) {
iterator iter = internal_find_unique(key, iterator(root(), 0));
if (!iter.node) {
// The key doesn't exist in the tree, return nothing done.
return 0;
}
erase(iter);
return 1;
}
template <typename P>
int btree<P>::erase_multi(const key_type &key) {
iterator begin = internal_lower_bound(key, iterator(root(), 0));
if (!begin.node) {
// The key doesn't exist in the tree, return nothing done.
return 0;
}
// Delete all of the keys between begin and upper_bound(key).
iterator end = internal_end(
internal_upper_bound(key, iterator(root(), 0)));
return erase(begin, end);
}
template <typename P>
void btree<P>::clear() {
if (root() != NULL) {
internal_clear(root());
}
*mutable_root() = NULL;
}
template <typename P>
void btree<P>::swap(self_type &x) {
std::swap(static_cast<key_compare&>(*this), static_cast<key_compare&>(x));
std::swap(root_, x.root_);
}
template <typename P>
void btree<P>::verify() const {
if (root() != NULL) {
assert(size() == internal_verify(root(), NULL, NULL));
assert(leftmost() == (++const_iterator(root(), -1)).node);
assert(rightmost() == (--const_iterator(root(), root()->count())).node);
assert(leftmost()->leaf());
assert(rightmost()->leaf());
} else {
assert(size() == 0);
assert(leftmost() == NULL);
assert(rightmost() == NULL);
}
}
template <typename P>
void btree<P>::rebalance_or_split(iterator *iter) {
node_type *&node = iter->node;
int &insert_position = iter->position;
assert(node->count() == node->max_count());
// First try to make room on the node by rebalancing.
node_type *parent = node->parent();
if (node != root()) {
if (node->position() > 0) {
// Try rebalancing with our left sibling.
node_type *left = parent->child(node->position() - 1);
if (left->count() < left->max_count()) {
// We bias rebalancing based on the position being inserted. If we're
// inserting at the end of the right node then we bias rebalancing to
// fill up the left node.
int to_move = (left->max_count() - left->count()) /
(1 + (insert_position < left->max_count()));
to_move = std::max(1, to_move);
if (((insert_position - to_move) >= 0) ||
((left->count() + to_move) < left->max_count())) {
left->rebalance_right_to_left(node, to_move);
assert(node->max_count() - node->count() == to_move);
insert_position = insert_position - to_move;
if (insert_position < 0) {
insert_position = insert_position + left->count() + 1;
node = left;
}
assert(node->count() < node->max_count());
return;
}
}
}
if (node->position() < parent->count()) {
// Try rebalancing with our right sibling.
node_type *right = parent->child(node->position() + 1);
if (right->count() < right->max_count()) {
// We bias rebalancing based on the position being inserted. If we're
// inserting at the beginning of the left node then we bias rebalancing
// to fill up the right node.
int to_move = (right->max_count() - right->count()) /
(1 + (insert_position > 0));
to_move = std::max(1, to_move);
if ((insert_position <= (node->count() - to_move)) ||
((right->count() + to_move) < right->max_count())) {
node->rebalance_left_to_right(right, to_move);
if (insert_position > node->count()) {
insert_position = insert_position - node->count() - 1;
node = right;
}
assert(node->count() < node->max_count());
return;
}
}
}
// Rebalancing failed, make sure there is room on the parent node for a new
// value.
if (parent->count() == parent->max_count()) {
iterator parent_iter(node->parent(), node->position());
rebalance_or_split(&parent_iter);
}
} else {
// Rebalancing not possible because this is the root node.
if (root()->leaf()) {
// The root node is currently a leaf node: create a new root node and set
// the current root node as the child of the new root.
parent = new_internal_root_node();
parent->set_child(0, root());
*mutable_root() = parent;
assert(*mutable_rightmost() == parent->child(0));
} else {
// The root node is an internal node. We do not want to create a new root
// node because the root node is special and holds the size of the tree
// and a pointer to the rightmost node. So we create a new internal node
// and move all of the items on the current root into the new node.
parent = new_internal_node(parent);
parent->set_child(0, parent);
parent->swap(root());
node = parent;
}
}
// Split the node.
node_type *split_node;
if (node->leaf()) {
split_node = new_leaf_node(parent);
node->split(split_node, insert_position);
if (rightmost() == node) {
*mutable_rightmost() = split_node;
}
} else {
split_node = new_internal_node(parent);
node->split(split_node, insert_position);
}
if (insert_position > node->count()) {
insert_position = insert_position - node->count() - 1;
node = split_node;
}
}
template <typename P>
void btree<P>::merge_nodes(node_type *left, node_type *right) {
left->merge(right);
if (right->leaf()) {
if (rightmost() == right) {
*mutable_rightmost() = left;
}
delete_leaf_node(right);
} else {
delete_internal_node(right);
}
}
template <typename P>
bool btree<P>::try_merge_or_rebalance(iterator *iter) {
node_type *parent = iter->node->parent();
if (iter->node->position() > 0) {
// Try merging with our left sibling.
node_type *left = parent->child(iter->node->position() - 1);
if ((1 + left->count() + iter->node->count()) <= left->max_count()) {
iter->position += 1 + left->count();
merge_nodes(left, iter->node);
iter->node = left;
return true;
}
}
if (iter->node->position() < parent->count()) {
// Try merging with our right sibling.
node_type *right = parent->child(iter->node->position() + 1);
if ((1 + iter->node->count() + right->count()) <= right->max_count()) {
merge_nodes(iter->node, right);
return true;
}
// Try rebalancing with our right sibling. We don't perform rebalancing if
// we deleted the first element from iter->node and the node is not
// empty. This is a small optimization for the common pattern of deleting
// from the front of the tree.
if ((right->count() > kMinNodeValues) &&
((iter->node->count() == 0) ||
(iter->position > 0))) {
int to_move = (right->count() - iter->node->count()) / 2;
to_move = std::min(to_move, right->count() - 1);
iter->node->rebalance_right_to_left(right, to_move);
return false;
}
}
if (iter->node->position() > 0) {
// Try rebalancing with our left sibling. We don't perform rebalancing if
// we deleted the last element from iter->node and the node is not
// empty. This is a small optimization for the common pattern of deleting
// from the back of the tree.
node_type *left = parent->child(iter->node->position() - 1);
if ((left->count() > kMinNodeValues) &&
((iter->node->count() == 0) ||
(iter->position < iter->node->count()))) {
int to_move = (left->count() - iter->node->count()) / 2;
to_move = std::min(to_move, left->count() - 1);
left->rebalance_left_to_right(iter->node, to_move);
iter->position += to_move;
return false;
}
}
return false;
}
template <typename P>
void btree<P>::try_shrink() {
if (root()->count() > 0) {
return;
}
// Deleted the last item on the root node, shrink the height of the tree.
if (root()->leaf()) {
assert(size() == 0);
delete_leaf_node(root());
*mutable_root() = NULL;
} else {
node_type *child = root()->child(0);
if (child->leaf()) {
// The child is a leaf node so simply make it the root node in the tree.
child->make_root();
delete_internal_root_node();
*mutable_root() = child;
} else {
// The child is an internal node. We want to keep the existing root node
// so we move all of the values from the child node into the existing
// (empty) root node.
child->swap(root());
delete_internal_node(child);
}
}
}
template <typename P> template <typename IterType>
inline IterType btree<P>::internal_last(IterType iter) {
while (iter.node && iter.position == iter.node->count()) {
iter.position = iter.node->position();
iter.node = iter.node->parent();
if (iter.node->leaf()) {
iter.node = NULL;
}
}
return iter;
}
template <typename P> template <typename ValueType>
inline typename btree<P>::iterator
btree<P>::internal_insert(iterator iter, ValueType &&v) {
if (!iter.node->leaf()) {
// We can't insert on an internal node. Instead, we'll insert after the
// previous value which is guaranteed to be on a leaf node.
--iter;
++iter.position;
}
if (iter.node->count() == iter.node->max_count()) {
// Make room in the leaf for the new item.
if (iter.node->max_count() < kNodeValues) {
// Insertion into the root where the root is smaller that the full node
// size. Simply grow the size of the root node.
assert(iter.node == root());
iter.node = new_leaf_root_node(
std::min<int>(kNodeValues, 2 * iter.node->max_count()));
iter.node->swap(root());
delete_leaf_node(root());
*mutable_root() = iter.node;
} else {
rebalance_or_split(&iter);
++*mutable_size();
}
} else if (!root()->leaf()) {
++*mutable_size();
}
iter.node->insert_value(iter.position, std::forward<ValueType>(v));
return iter;
}
template <typename P> template <typename IterType>
inline std::pair<IterType, int> btree<P>::internal_locate(
const key_type &key, IterType iter) const {
return internal_locate_type::dispatch(key, *this, iter);
}
template <typename P> template <typename IterType>
inline std::pair<IterType, int> btree<P>::internal_locate_plain_compare(
const key_type &key, IterType iter) const {
for (;;) {
iter.position = iter.node->lower_bound(key, key_comp());
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
return std::make_pair(iter, 0);
}
template <typename P> template <typename IterType>
inline std::pair<IterType, int> btree<P>::internal_locate_compare_to(
const key_type &key, IterType iter) const {
for (;;) {
int res = iter.node->lower_bound(key, key_comp());
iter.position = res & kMatchMask;
if (res & kExactMatch) {
return std::make_pair(iter, static_cast<int>(kExactMatch));
}
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
return std::make_pair(iter, -kExactMatch);
}
template <typename P> template <typename IterType>
IterType btree<P>::internal_lower_bound(
const key_type &key, IterType iter) const {
if (iter.node) {
for (;;) {
iter.position =
iter.node->lower_bound(key, key_comp()) & kMatchMask;
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
iter = internal_last(iter);
}
return iter;
}
template <typename P> template <typename IterType>
IterType btree<P>::internal_upper_bound(
const key_type &key, IterType iter) const {
if (iter.node) {
for (;;) {
iter.position = iter.node->upper_bound(key, key_comp());
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
iter = internal_last(iter);
}
return iter;
}
template <typename P> template <typename IterType>
IterType btree<P>::internal_find_unique(
const key_type &key, IterType iter) const {
if (iter.node) {
std::pair<IterType, int> res = internal_locate(key, iter);
if (res.second == kExactMatch) {
return res.first;
}
if (!res.second) {
iter = internal_last(res.first);
if (iter.node && !compare_keys(key, iter.key())) {
return iter;
}
}
}
return IterType(NULL, 0);
}
template <typename P> template <typename IterType>
IterType btree<P>::internal_find_multi(
const key_type &key, IterType iter) const {
if (iter.node) {
iter = internal_lower_bound(key, iter);
if (iter.node) {
iter = internal_last(iter);
if (iter.node && !compare_keys(key, iter.key())) {
return iter;
}
}
}
return IterType(NULL, 0);
}
template <typename P>
void btree<P>::internal_clear(node_type *node) {
if (!node->leaf()) {
for (int i = 0; i <= node->count(); ++i) {
internal_clear(node->child(i));
}
if (node == root()) {
delete_internal_root_node();
} else {
delete_internal_node(node);
}
} else {
delete_leaf_node(node);
}
}
template <typename P>
void btree<P>::internal_dump(
std::ostream &os, const node_type *node, int level) const {
for (int i = 0; i < node->count(); ++i) {
if (!node->leaf()) {
internal_dump(os, node->child(i), level + 1);
}
for (int j = 0; j < level; ++j) {
os << " ";
}
os << node->key(i) << " [" << level << "]\n";
}
if (!node->leaf()) {
internal_dump(os, node->child(node->count()), level + 1);
}
}
template <typename P>
int btree<P>::internal_verify(
const node_type *node, const key_type *lo, const key_type *hi) const {
assert(node->count() > 0);
assert(node->count() <= node->max_count());
if (lo) {
assert(!compare_keys(node->key(0), *lo));
}
if (hi) {
assert(!compare_keys(*hi, node->key(node->count() - 1)));
}
for (int i = 1; i < node->count(); ++i) {
assert(!compare_keys(node->key(i), node->key(i - 1)));
}
int count = node->count();
if (!node->leaf()) {
for (int i = 0; i <= node->count(); ++i) {
assert(node->child(i) != NULL);
assert(node->child(i)->parent() == node);
assert(node->child(i)->position() == i);
count += internal_verify(
node->child(i),
(i == 0) ? lo : &node->key(i - 1),
(i == node->count()) ? hi : &node->key(i));
}
}
return count;
}
// A common base class for btree_set, map, btree_multiset and
// btree_multimap.
template <typename Tree>
class btree_container {
typedef btree_container<Tree> self_type;
public:
typedef typename Tree::params_type params_type;
typedef typename Tree::key_type key_type;
typedef typename Tree::value_type value_type;
typedef typename Tree::key_compare key_compare;
typedef typename Tree::allocator_type allocator_type;
typedef typename Tree::pointer pointer;
typedef typename Tree::const_pointer const_pointer;
typedef typename Tree::reference reference;
typedef typename Tree::const_reference const_reference;
typedef typename Tree::size_type size_type;
typedef typename Tree::difference_type difference_type;
typedef typename Tree::iterator iterator;
typedef typename Tree::const_iterator const_iterator;
typedef typename Tree::reverse_iterator reverse_iterator;
typedef typename Tree::const_reverse_iterator const_reverse_iterator;
public:
// Default constructor.
btree_container(const key_compare &comp, const allocator_type &alloc)
: tree_(comp, alloc) {
}
// Copy constructor.
btree_container(const self_type &x)
: tree_(x.tree_) {
}
// Iterator routines.
iterator begin() { return tree_.begin(); }
const_iterator begin() const { return tree_.begin(); }
iterator end() { return tree_.end(); }
const_iterator end() const { return tree_.end(); }
reverse_iterator rbegin() { return tree_.rbegin(); }
const_reverse_iterator rbegin() const { return tree_.rbegin(); }
reverse_iterator rend() { return tree_.rend(); }
const_reverse_iterator rend() const { return tree_.rend(); }
// Lookup routines.
iterator lower_bound(const key_type &key) {
return tree_.lower_bound(key);
}
const_iterator lower_bound(const key_type &key) const {
return tree_.lower_bound(key);
}
iterator upper_bound(const key_type &key) {
return tree_.upper_bound(key);
}
const_iterator upper_bound(const key_type &key) const {
return tree_.upper_bound(key);
}
std::pair<iterator,iterator> equal_range(const key_type &key) {
return tree_.equal_range(key);
}
std::pair<const_iterator,const_iterator> equal_range(const key_type &key) const {
return tree_.equal_range(key);
}
// Utility routines.
void clear() {
tree_.clear();
}
void swap(self_type &x) {
tree_.swap(x.tree_);
}
void dump(std::ostream &os) const {
tree_.dump(os);
}
void verify() const {
tree_.verify();
}
// Size routines.
size_type size() const { return tree_.size(); }
size_type max_size() const { return tree_.max_size(); }
bool empty() const { return tree_.empty(); }
size_type height() const { return tree_.height(); }
size_type internal_nodes() const { return tree_.internal_nodes(); }
size_type leaf_nodes() const { return tree_.leaf_nodes(); }
size_type nodes() const { return tree_.nodes(); }
size_type bytes_used() const { return tree_.bytes_used(); }
static double average_bytes_per_value() {
return Tree::average_bytes_per_value();
}
double fullness() const { return tree_.fullness(); }
double overhead() const { return tree_.overhead(); }
bool operator==(const self_type& x) const {
if (size() != x.size()) {
return false;
}
for (const_iterator i = begin(), xi = x.begin(); i != end(); ++i, ++xi) {
if (*i != *xi) {
return false;
}
}
return true;
}
bool operator!=(const self_type& other) const {
return !operator==(other);
}
protected:
Tree tree_;
};
template <typename T>
inline std::ostream& operator<<(std::ostream &os, const btree_container<T> &b) {
b.dump(os);
return os;
}
// A common base class for btree_set and safe_btree_set.
template <typename Tree>
class btree_unique_container : public btree_container<Tree> {
typedef btree_unique_container<Tree> self_type;
typedef btree_container<Tree> super_type;
public:
typedef typename Tree::key_type key_type;
typedef typename Tree::value_type value_type;
typedef typename Tree::size_type size_type;
typedef typename Tree::key_compare key_compare;
typedef typename Tree::allocator_type allocator_type;
typedef typename Tree::iterator iterator;
typedef typename Tree::const_iterator const_iterator;
public:
// Default constructor.
btree_unique_container(const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
}
// Copy constructor.
btree_unique_container(const self_type &x)
: super_type(x) {
}
// Range constructor.
template <class InputIterator>
btree_unique_container(InputIterator b, InputIterator e,
const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
insert(b, e);
}
// Lookup routines.
iterator find(const key_type &key) {
return this->tree_.find_unique(key);
}
const_iterator find(const key_type &key) const {
return this->tree_.find_unique(key);
}
size_type count(const key_type &key) const {
return this->tree_.count_unique(key);
}
// Insertion routines.
std::pair<iterator, bool> insert(const value_type &x) {
return this->tree_.insert_unique(x);
}
template <typename P>
std::pair<iterator, bool> insert(P&& x) {
return this->tree_.insert_unique(std::forward<P>(x));
}
std::pair<iterator, bool> insert(value_type &&x) {
return this->tree_.insert_unique(std::move(x));
}
iterator insert(iterator position, const value_type &x) {
return this->tree_.insert_unique(position, x);
}
template <typename P>
std::pair<iterator, bool> insert(iterator position, P&& x) {
return this->tree_.insert_unique(position, std::forward<P>(x));
}
iterator insert(iterator position, value_type &&x) {
return this->tree_.insert_unique(position, std::move(x));
}
template <typename InputIterator>
void insert(InputIterator b, InputIterator e) {
this->tree_.insert_unique(b, e);
}
template <typename... Args>
std::pair<iterator, bool> emplace(Args&&... args) {
return insert(value_type(std::forward<Args>(args)...));
}
template <typename... Args>
iterator emplace_hint(iterator position, Args&&... args) {
return insert(position, value_type(std::forward<Args>(args)...));
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(const key_type& k, Args&&... args) {
auto it = find(k);
if (it == this->end()) {
return insert(value_type(
std::piecewise_construct,
std::forward_as_tuple(k),
std::forward_as_tuple(std::forward<Args>(args)...)));
}
return std::make_pair(it, false);
}
template <typename... Args>
std::pair<iterator, bool> try_emplace(key_type&& k, Args&&... args) {
auto it = find(k);
if (it == this->end()) {
return insert(value_type(
std::piecewise_construct,
std::forward_as_tuple(std::move(k)),
std::forward_as_tuple(std::forward<Args>(args)...)));
}
return std::make_pair(it, false);
}
template <typename... Args>
iterator try_emplace(iterator position, const key_type& k, Args&&... args) {
auto it = find(k);
if (it == this->end()) {
return insert(position, value_type(
std::piecewise_construct,
std::forward_as_tuple(k),
std::forward_as_tuple(std::forward<Args>(args)...)));
}
return std::make_pair(it, false);
}
template <typename... Args>
iterator try_emplace(iterator position, key_type&& k, Args&&... args) {
auto it = find(k);
if (it == this->end()) {
return insert(position, value_type(
std::piecewise_construct,
std::forward_as_tuple(std::move(k)),
std::forward_as_tuple(std::forward<Args>(args)...)));
}
return std::make_pair(it, false);
}
// Deletion routines.
int erase(const key_type &key) {
return this->tree_.erase_unique(key);
}
// Erase the specified iterator from the btree. The iterator must be valid
// (i.e. not equal to end()). Return an iterator pointing to the node after
// the one that was erased (or end() if none exists).
iterator erase(const iterator &iter) {
return this->tree_.erase(iter);
}
void erase(const iterator &first, const iterator &last) {
this->tree_.erase(first, last);
}
};
// A common base class for map and safe_map.
template <typename Tree>
class map_container : public btree_unique_container<Tree> {
typedef map_container<Tree> self_type;
typedef btree_unique_container<Tree> super_type;
public:
typedef typename Tree::key_type key_type;
typedef typename Tree::data_type data_type;
typedef typename Tree::value_type value_type;
typedef typename Tree::mapped_type mapped_type;
typedef typename Tree::key_compare key_compare;
typedef typename Tree::allocator_type allocator_type;
public:
// Default constructor.
map_container(const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
}
// Copy constructor.
map_container(const self_type &x)
: super_type(x) {
}
// Range constructor.
template <class InputIterator>
map_container(InputIterator b, InputIterator e,
const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(b, e, comp, alloc) {
}
// Insertion routines.
data_type& operator[](const key_type &key) {
return this->try_emplace(key).first->second;
}
data_type& operator[](key_type&& key) {
return this->try_emplace(std::move(key)).first->second;
}
};
// The map class is needed mainly for its constructors.
template <typename Key, typename Value,
typename Compare = std::less<Key>,
typename Alloc = std::allocator<std::pair<const Key, Value> >,
int TargetNodeSize = 256>
class map : public map_container<
btree<map_params<Key, Value, Compare, Alloc, TargetNodeSize> > > {
typedef map<Key, Value, Compare, Alloc, TargetNodeSize> self_type;
typedef map_params<
Key, Value, Compare, Alloc, TargetNodeSize> params_type;
typedef btree<params_type> btree_type;
typedef map_container<btree_type> super_type;
public:
typedef typename btree_type::key_compare key_compare;
typedef typename btree_type::allocator_type allocator_type;
public:
// Default constructor.
map(const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
}
// Copy constructor.
map(const self_type &x)
: super_type(x) {
}
// Range constructor.
template <class InputIterator>
map(InputIterator b, InputIterator e,
const key_compare &comp = key_compare(),
const allocator_type &alloc = allocator_type())
: super_type(b, e, comp, alloc) {
}
};
template <typename K, typename V, typename C, typename A, int N>
inline void swap(map<K, V, C, A, N> &x,
map<K, V, C, A, N> &y) {
x.swap(y);
}
} // namespace btree
#endif // UTIL_BTREE_BTREE_H__
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment