X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Finclude%2Fcpp-btree%2Fbtree.h;fp=src%2Fceph%2Fsrc%2Finclude%2Fcpp-btree%2Fbtree.h;h=0000000000000000000000000000000000000000;hb=7da45d65be36d36b880cc55c5036e96c24b53f00;hp=49310a2e441d34391fdf9f4277051fe02baaccb9;hpb=691462d09d0987b47e112d6ee8740375df3c51b2;p=stor4nfv.git diff --git a/src/ceph/src/include/cpp-btree/btree.h b/src/ceph/src/include/cpp-btree/btree.h deleted file mode 100644 index 49310a2..0000000 --- a/src/ceph/src/include/cpp-btree/btree.h +++ /dev/null @@ -1,2394 +0,0 @@ -// 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 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 may use much -// less memory per stored value. For the random insertion benchmark in -// btree_test.cc, a btree_set 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) @ -// -------------------------------------------------------- -// 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 -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#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 -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 -struct if_{ - typedef A type; -}; - -template -struct if_ { - 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 -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 -struct btree_is_key_compare_to - : public std::is_convertible { -}; - -// 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 and greater. 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 -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 &c) - : Compare(c) { - } -}; - -template <> -struct btree_key_compare_to_adapter > - : public btree_key_compare_to_tag { - btree_key_compare_to_adapter() {} - btree_key_compare_to_adapter(const std::less&) {} - btree_key_compare_to_adapter( - const btree_key_compare_to_adapter >&) {} - int operator()(const std::string &a, const std::string &b) const { - return a.compare(b); - } -}; - -template <> -struct btree_key_compare_to_adapter > - : public btree_key_compare_to_tag { - btree_key_compare_to_adapter() {} - btree_key_compare_to_adapter(const std::greater&) {} - btree_key_compare_to_adapter( - const btree_key_compare_to_adapter >&) {} - 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 -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 -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) < 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 -static bool btree_compare_keys( - const Compare &comp, const Key &x, const Key &y) { - typedef btree_key_comparer::value> key_comparer; - return key_comparer::bool_compare(comp, x, y); -} - -template -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::value, - Compare, btree_key_compare_to_adapter >::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 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 btree_map. -template -struct btree_map_params - : public btree_common_params { - typedef Data data_type; - typedef Data mapped_type; - typedef std::pair value_type; - typedef std::pair mutable_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 mutable_value_type &x) { return x.first; } - static void swap(mutable_value_type *a, mutable_value_type *b) { - btree_swap_helper(a->first, b->first); - btree_swap_helper(a->second, b->second); - } -}; - -// A parameters structure for holding the type parameters for a btree_set. -template -struct btree_set_params - : public btree_common_params { - typedef std::false_type data_type; - typedef std::false_type mapped_type; - typedef Key value_type; - typedef value_type mutable_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), - }; - - static const Key& key(const value_type &x) { return x; } - static void swap(mutable_value_type *a, mutable_value_type *b) { - btree_swap_helper(*a, *b); - } -}; - -// An adapter class that converts a lower-bound compare into an upper-bound -// compare. -template -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(*this)(b, a); - } -}; - -template -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(*this)(b, a); - } -}; - -// Dispatch helper class for using linear search with plain compare. -template -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 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 -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 > 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 -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 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 -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 > 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 -class btree_node { - public: - typedef Params params_type; - typedef btree_node 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::mutable_value_type mutable_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::value || - std::is_floating_point::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. - mutable_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(fields_.values[i]); - } - const_reference value(int i) const { - return reinterpret_cast(fields_.values[i]); - } - mutable_value_type* mutable_value(int i) { - return &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(mutable_value(i), x->mutable_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 - 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 - 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 - 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 - 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 - 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 - 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. - void insert_value(int i, const value_type &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(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]) mutable_value_type; - } - void value_init(int i, const value_type &x) { - new (&fields_.values[i]) mutable_value_type(x); - } - void value_destroy(int i) { - fields_.values[i].~mutable_value_type(); - } - - private: - root_fields fields_; - - private: - btree_node(const btree_node&); - void operator=(const btree_node&); -}; - -template -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::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 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 - static std::pair 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 - static std::pair dispatch(const K &k, const T &t, Iter iter) { - return t.internal_locate_compare_to(k, iter); - } -}; - -template -class btree : public Params::key_compare { - typedef btree self_type; - typedef btree_node 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 class btree_internal_locate_plain_compare; - friend class 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). 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 - 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 iterator; - typedef typename iterator::const_iterator const_iterator; - typedef std::reverse_iterator const_reverse_iterator; - typedef std::reverse_iterator reverse_iterator; - - typedef typename Params::allocator_type allocator_type; - typedef typename allocator_type::template rebind::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 equal_range(const key_type &key) { - return std::make_pair(lower_bound(key), upper_bound(key)); - } - std::pair 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. The - // ValuePointer type is used to avoid instatiating the value unless the key - // is being inserted. Value is not dereferenced if the key already exists in - // the btree. See btree_map::operator[]. - template - std::pair insert_unique(const key_type &key, ValuePointer value); - - // Inserts a value into the btree only if it does not already exist. The - // boolean return value indicates whether insertion succeeded or failed. - std::pair insert_unique(const value_type &v) { - return insert_unique(params_type::key(v), &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. - iterator insert_unique(iterator position, const value_type &v); - - // Insert a range of values into the btree. - template - void insert_unique(InputIterator b, InputIterator e); - - // Inserts a value into the btree. The ValuePointer type is used to avoid - // instatiating the value unless the key is being inserted. Value is not - // dereferenced if the key already exists in the btree. See - // btree_map::operator[]. - template - iterator insert_multi(const key_type &key, ValuePointer value); - - // Inserts a value into the btree. - iterator insert_multi(const value_type &v) { - return insert_multi(params_type::key(v), &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. - iterator insert_multi(iterator position, const value_type &v); - - // Insert a range of values into the btree. - template - 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::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(&root_); - } - const internal_allocator_type& internal_allocator() const { - return *static_cast(&root_); - } - - // Node creation/deletion routines. - node_type* new_internal_node(node_type *parent) { - internal_fields *p = reinterpret_cast( - 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( - 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( - 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( - mutable_internal_allocator()->allocate( - sizeof(base_fields) + max_count * sizeof(value_type))); - return node_type::init_leaf(p, reinterpret_cast(p), max_count); - } - void delete_internal_node(node_type *node) { - node->destroy(); - assert(node != root()); - mutable_internal_allocator()->deallocate( - reinterpret_cast(node), sizeof(internal_fields)); - } - void delete_internal_root_node() { - root()->destroy(); - mutable_internal_allocator()->deallocate( - reinterpret_cast(root()), sizeof(root_fields)); - } - void delete_leaf_node(node_type *node) { - node->destroy(); - mutable_internal_allocator()->deallocate( - reinterpret_cast(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). - iterator internal_insert(iterator iter, const value_type &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 - 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 - std::pair internal_locate( - const key_type &key, IterType iter) const; - template - std::pair internal_locate_plain_compare( - const key_type &key, IterType iter) const; - template - std::pair internal_locate_compare_to( - const key_type &key, IterType iter) const; - - // Internal routine which implements lower_bound(). - template - IterType internal_lower_bound( - const key_type &key, IterType iter) const; - - // Internal routine which implements upper_bound(). - template - IterType internal_upper_bound( - const key_type &key, IterType iter) const; - - // Internal routine which implements find_unique(). - template - IterType internal_find_unique( - const key_type &key, IterType iter) const; - - // Internal routine which implements find_multi(). - template - 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 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 - static typename if_< - if_, - std::is_same >::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 -inline void btree_node

::insert_value(int i, const value_type &x) { - assert(i <= count()); - value_init(count(), 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 -inline void btree_node

::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 -void btree_node

::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 -void btree_node

::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 -void btree_node

::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 -void btree_node

::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 -void btree_node

::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 -void btree_iterator::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 -void btree_iterator::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 -void btree_iterator::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 -btree

::btree(const key_compare &comp, const allocator_type &alloc) - : key_compare(comp), - root_(alloc, NULL) { -} - -template -btree

::btree(const self_type &x) - : key_compare(x.key_comp()), - root_(x.internal_allocator(), NULL) { - assign(x); -} - -template template -std::pair::iterator, bool> -btree

::insert_unique(const key_type &key, ValuePointer value) { - if (empty()) { - *mutable_root() = new_leaf_root_node(1); - } - - std::pair 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, *value), true); -} - -template -inline typename btree

::iterator -btree

::insert_unique(iterator position, const value_type &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, 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, v); - } - } else { - // position.key() == key - return position; - } - } - return insert_unique(v).first; -} - -template template -void btree

::insert_unique(InputIterator b, InputIterator e) { - for (; b != e; ++b) { - insert_unique(end(), *b); - } -} - -template template -typename btree

::iterator -btree

::insert_multi(const key_type &key, ValuePointer 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, *value); -} - -template -typename btree

::iterator -btree

::insert_multi(iterator position, const value_type &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, v); - } - } else { - iterator next = position; - ++next; - if (next == end() || !compare_keys(next.key(), key)) { - // position.key() < key <= next.key() - return internal_insert(next, v); - } - } - } - return insert_multi(v); -} - -template template -void btree

::insert_multi(InputIterator b, InputIterator e) { - for (; b != e; ++b) { - insert_multi(end(), *b); - } -} - -template -void btree

::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 btree

::iterator btree

::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 -int btree

::erase(iterator begin, iterator end) { - int count = distance(begin, end); - for (int i = 0; i < count; i++) { - begin = erase(begin); - } - return count; -} - -template -int btree

::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 -int btree

::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 -void btree

::clear() { - if (root() != NULL) { - internal_clear(root()); - } - *mutable_root() = NULL; -} - -template -void btree

::swap(self_type &x) { - std::swap(static_cast(*this), static_cast(x)); - std::swap(root_, x.root_); -} - -template -void btree

::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 -void btree

::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 -void btree

::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 -bool btree

::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 -void btree

::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 template -inline IterType btree

::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 -inline typename btree

::iterator -btree

::internal_insert(iterator iter, const value_type &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(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, v); - return iter; -} - -template template -inline std::pair btree

::internal_locate( - const key_type &key, IterType iter) const { - return internal_locate_type::dispatch(key, *this, iter); -} - -template template -inline std::pair btree

::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 template -inline std::pair btree

::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(kExactMatch)); - } - if (iter.node->leaf()) { - break; - } - iter.node = iter.node->child(iter.position); - } - return std::make_pair(iter, -kExactMatch); -} - -template template -IterType btree

::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 template -IterType btree

::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 template -IterType btree

::internal_find_unique( - const key_type &key, IterType iter) const { - if (iter.node) { - std::pair 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 template -IterType btree

::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 -void btree

::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 -void btree

::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 -int btree

::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; -} - -} // namespace btree - -#endif // UTIL_BTREE_BTREE_H__