526 lines
14 KiB
C++
526 lines
14 KiB
C++
// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
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//
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// This file is part of the thin-provisioning-tools source.
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//
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// thin-provisioning-tools is free software: you can redistribute it
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// and/or modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation, either version 3 of
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// the License, or (at your option) any later version.
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//
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// thin-provisioning-tools is distributed in the hope that it will be
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// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with thin-provisioning-tools. If not, see
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// <http://www.gnu.org/licenses/>.
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#ifndef BTREE_H
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#define BTREE_H
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#include "base/endian_utils.h"
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#include "persistent-data/transaction_manager.h"
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#include "persistent-data/data-structures/ref_counter.h"
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#include "persistent-data/data-structures/btree_disk_structures.h"
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#include <boost/noncopyable.hpp>
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#include <boost/optional.hpp>
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#include <list>
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#include <deque>
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//----------------------------------------------------------------
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namespace persistent_data {
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class block_ref_counter : public ref_counter<block_address> {
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public:
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block_ref_counter(space_map::ptr sm);
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virtual void set(block_address const &v, uint32_t rc);
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virtual void inc(block_address const &v);
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virtual void dec(block_address const &v);
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private:
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space_map::ptr sm_;
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};
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struct block_traits {
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typedef base::le64 disk_type;
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typedef block_address value_type;
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typedef block_ref_counter ref_counter;
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static void unpack(disk_type const &disk, value_type &value) {
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value = base::to_cpu<uint64_t>(disk);
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}
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static void pack(value_type const &value, disk_type &disk) {
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disk = base::to_disk<base::le64>(value);
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}
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};
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namespace btree_detail {
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using namespace base;
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using namespace std;
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//------------------------------------------------
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// Class that acts as an interface over the raw little endian btree
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// node data.
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template <typename ValueTraits>
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class node_ref {
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public:
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explicit node_ref(block_address b, disk_node *raw);
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uint32_t get_checksum() const;
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block_address get_location() const {
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return location_;
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}
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block_address get_block_nr() const;
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node_type get_type() const;
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void set_type(node_type t);
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unsigned get_nr_entries() const;
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void set_nr_entries(unsigned n);
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unsigned get_max_entries() const;
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void set_max_entries(unsigned n);
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// FIXME: remove this, and get the constructor to do it.
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void set_max_entries(); // calculates the max for you.
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size_t get_value_size() const;
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void set_value_size(size_t);
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uint64_t key_at(unsigned i) const;
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void set_key(unsigned i, uint64_t k);
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typename ValueTraits::value_type value_at(unsigned i) const;
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void set_value(unsigned i,
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typename ValueTraits::value_type const &v);
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// Increments the nr_entries field
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void insert_at(unsigned i,
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uint64_t key,
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typename ValueTraits::value_type const &v);
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// Does not increment nr_entries
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void overwrite_at(unsigned i,
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uint64_t key,
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typename ValueTraits::value_type const &v);
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// Decrements the nr_entries field
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void delete_at(unsigned i);
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// Copies entries from another node, appends them
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// to the back of this node. Adjusts nr_entries.
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void copy_entries(node_ref const &rhs,
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unsigned begin,
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unsigned end);
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// Moves entries between the sibling node,
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// and maintains the key ordering.
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// The nr_entreis of both nodes are adjusted.
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void move_entries(node_ref &rhs,
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int count);
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// Copies entries from the beginning of rhs to the end of lhs,
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// or copies entries from the end of lhs to the beginning of rhs.
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// The nr_entries is not adjusted.
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void copy_entries_to_left(node_ref const &rhs, unsigned count);
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void copy_entries_to_right(node_ref &rhs, unsigned count) const;
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// Shifts entries to left or right.
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// The nr_entries is not adjusted.
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void shift_entries_left(unsigned shift);
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void shift_entries_right(unsigned shift);
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unsigned merge_threshold() const;
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// Various searches
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int bsearch(uint64_t key, int want_hi) const;
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boost::optional<unsigned> exact_search(uint64_t key) const;
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int lower_bound(uint64_t key) const;
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template <typename RefCounter>
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void inc_children(RefCounter &rc);
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template <typename RefCounter>
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void dec_children(RefCounter &rc);
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disk_node *raw() {
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return raw_;
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}
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disk_node const *raw() const {
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return raw_;
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}
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bool value_sizes_match() const;
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std::string value_mismatch_string() const;
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private:
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static unsigned calc_max_entries(void);
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void check_fits_within_block() const;
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void *key_ptr(unsigned i) const;
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void *value_ptr(unsigned i) const;
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block_address location_;
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disk_node *raw_;
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mutable bool checked_; // flag indicating we've checked the data fits in the block
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};
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//------------------------------------------------
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//
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template <typename ValueTraits>
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node_ref<ValueTraits>
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to_node(typename block_manager::read_ref &b)
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{
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// FIXME: this should return a const read_ref somehow.
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return node_ref<ValueTraits>(
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b.get_location(),
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reinterpret_cast<disk_node *>(
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const_cast<void *>(b.data())));
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}
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template <typename ValueTraits>
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node_ref<ValueTraits>
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to_node(typename block_manager::write_ref &b)
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{
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return node_ref<ValueTraits>(
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b.get_location(),
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reinterpret_cast<disk_node *>(b.data()));
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}
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class ro_spine : private boost::noncopyable {
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public:
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ro_spine(transaction_manager &tm,
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bcache::validator::ptr v)
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: tm_(tm),
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validator_(v) {
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}
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void step(block_address b);
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template <typename ValueTraits>
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node_ref<ValueTraits> get_node() {
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return to_node<ValueTraits>(spine_.back());
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}
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private:
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transaction_manager &tm_;
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bcache::validator::ptr validator_;
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std::list<block_manager::read_ref> spine_;
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};
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class shadow_spine : private boost::noncopyable {
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public:
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typedef transaction_manager::read_ref read_ref;
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typedef transaction_manager::write_ref write_ref;
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typedef boost::optional<block_address> maybe_block;
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shadow_spine(transaction_manager &tm,
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bcache::validator::ptr v)
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: tm_(tm),
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validator_(v) {
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}
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// true if the children of the shadow need incrementing
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bool step(block_address b);
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void step(transaction_manager::write_ref b) {
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spine_.push_back(b);
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if (spine_.size() == 1)
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root_ = spine_.front().get_location();
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else if (spine_.size() > 2)
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spine_.pop_front();
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}
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void pop() {
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spine_.pop_back();
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}
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template <typename ValueTraits>
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node_ref<ValueTraits> get_node() {
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return to_node<ValueTraits>(spine_.back());
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}
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block_address get_block() const {
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return spine_.back().get_location();
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}
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bool has_parent() const {
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return spine_.size() > 1;
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}
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node_ref<block_traits> get_parent() {
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if (spine_.size() < 2)
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throw std::runtime_error("no parent");
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return to_node<block_traits>(spine_.front());
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}
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block_address get_parent_location() const {
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return spine_.front().get_location();
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}
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block_address get_root() const {
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if (root_)
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return *root_;
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throw std::runtime_error("shadow spine has no root");
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}
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private:
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transaction_manager &tm_;
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bcache::validator::ptr validator_;
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std::list<block_manager::write_ref> spine_;
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maybe_block root_;
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};
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class shadow_child {
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public:
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shadow_child(block_manager::write_ref &wr, node_type type)
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: wr_(wr), type_(type) {
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}
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node_type get_type() const {
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return type_;
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}
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template <typename ValueTraits>
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node_ref<ValueTraits> get_node() {
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return to_node<ValueTraits>(wr_);
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}
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private:
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block_manager::write_ref wr_;
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node_type type_;
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};
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// Used to keep a record of a nested btree's position.
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typedef std::vector<uint64_t> btree_path;
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// Used when visiting the nodes that make up a btree.
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struct node_location {
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node_location()
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: depth(0) {
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}
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void inc_depth() {
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depth++;
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}
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void push_key(uint64_t k) {
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path.push_back(k);
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depth = 0;
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}
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bool is_sub_root() const {
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return depth == 0; // && path.size();
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}
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unsigned level() const {
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return path.size();
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}
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// Keys used to access this sub tree
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btree_path path;
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// in this sub tree
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unsigned depth;
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// This is the key from the parent node to this
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// node. If this node is a root then there will be
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// no parent, and hence no key.
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boost::optional<uint64_t> key;
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};
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}
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template <unsigned Levels, typename ValueTraits>
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class btree {
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public:
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typedef std::shared_ptr<btree<Levels, ValueTraits> > ptr;
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typedef uint64_t key[Levels];
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typedef typename ValueTraits::value_type value_type;
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typedef boost::optional<value_type> maybe_value;
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typedef boost::optional<std::pair<unsigned, value_type> > maybe_pair;
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typedef typename block_manager::read_ref read_ref;
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typedef typename block_manager::write_ref write_ref;
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typedef typename btree_detail::node_ref<ValueTraits> leaf_node;
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typedef typename btree_detail::node_ref<block_traits> internal_node;
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btree(transaction_manager &tm,
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typename ValueTraits::ref_counter rc);
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btree(transaction_manager &tm,
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block_address root,
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typename ValueTraits::ref_counter rc);
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~btree();
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maybe_value lookup(key const &key) const;
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maybe_pair lookup_le(key const &key) const;
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maybe_pair lookup_ge(key const &key) const;
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bool insert(key const &key, typename ValueTraits::value_type const &value);
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void remove(key const &key);
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void set_root(block_address root);
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block_address get_root() const;
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ptr clone() const;
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// free the on disk btree when the destructor is called
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void destroy();
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// Derive a class from this base class if you need to
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// inspect the individual nodes that make up a btree.
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class visitor {
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public:
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typedef std::shared_ptr<visitor> ptr;
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typedef btree_detail::node_location node_location;
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virtual ~visitor() {}
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// The bool return values indicate whether the walk
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// should be continued into sub trees of the node (true == continue).
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virtual bool visit_internal(node_location const &l,
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internal_node const &n) = 0;
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virtual bool visit_internal_leaf(node_location const &l,
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internal_node const &n) = 0;
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virtual bool visit_leaf(node_location const &l,
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leaf_node const &n) = 0;
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virtual void visit_complete() {}
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enum error_outcome {
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EXCEPTION_HANDLED,
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RETHROW_EXCEPTION
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};
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virtual error_outcome error_accessing_node(node_location const &l, block_address b,
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std::string const &what) {
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return RETHROW_EXCEPTION;
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}
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};
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// Walks the tree in depth first order
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void visit_depth_first(visitor &visitor) const;
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private:
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template <typename ValueTraits2, typename Search>
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boost::optional<typename ValueTraits2::value_type>
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lookup_raw(btree_detail::ro_spine &spine, block_address block, uint64_t key) const;
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template <typename ValueTraits2>
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void split_node(btree_detail::shadow_spine &spine,
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block_address parent_index,
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uint64_t key,
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bool top);
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template <typename ValueTraits2>
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void split_beneath(btree_detail::shadow_spine &spine, uint64_t key);
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template <typename ValueTraits2>
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void split_sibling(btree_detail::shadow_spine &spine,
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block_address parent_index,
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uint64_t key);
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template <typename ValueTraits2, typename RC>
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bool
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insert_location(btree_detail::shadow_spine &spine,
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block_address block,
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uint64_t key,
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int *index,
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RC &leaf_rc);
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template <typename ValueTraits2, typename RC>
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bool
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remove_location(btree_detail::shadow_spine &spine,
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block_address block,
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uint64_t key,
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unsigned *index,
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RC &leaf_rc);
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void walk_tree(visitor &visitor,
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btree_detail::node_location const &loc,
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block_address b) const;
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void walk_tree_internal(visitor &visitor,
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btree_detail::node_location const &loc,
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block_address b) const;
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template <typename ValueTraits2, typename RefCounter>
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void inc_children(btree_detail::shadow_spine &spine,
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RefCounter &leaf_rc);
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btree_detail::shadow_child
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create_shadow_child(internal_node &parent,
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unsigned index);
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template <typename ValueTraits2>
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bool rebalance_children(btree_detail::shadow_spine &spine,
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uint64_t key);
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template <typename ValueTraits2>
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void rebalance2(btree_detail::shadow_spine &spine,
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unsigned left_index);
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template <typename ValueTraits2>
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void rebalance3(btree_detail::shadow_spine &spine,
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unsigned left_index);
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template <typename ValueTraits2>
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void
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__rebalance2(internal_node &parent,
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btree_detail::node_ref<ValueTraits2> &left,
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btree_detail::node_ref<ValueTraits2> &right,
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unsigned left_index);
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template <typename ValueTraits2>
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void
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__rebalance3(internal_node &parent,
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btree_detail::node_ref<ValueTraits2> &left,
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btree_detail::node_ref<ValueTraits2> ¢er,
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btree_detail::node_ref<ValueTraits2> &right,
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unsigned left_index);
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template <typename ValueTraits2>
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void
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delete_center_node(internal_node &parent,
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btree_detail::node_ref<ValueTraits2> &left,
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btree_detail::node_ref<ValueTraits2> ¢er,
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btree_detail::node_ref<ValueTraits2> &right,
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unsigned left_index);
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template <typename ValueTraits2>
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void
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redistribute3(internal_node &parent,
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btree_detail::node_ref<ValueTraits2> &left,
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btree_detail::node_ref<ValueTraits2> ¢er,
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btree_detail::node_ref<ValueTraits2> &right,
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unsigned left_index);
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transaction_manager &tm_;
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bool destroy_;
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block_address root_;
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block_ref_counter internal_rc_;
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typename ValueTraits::ref_counter rc_;
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typename bcache::validator::ptr validator_;
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};
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};
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#include "btree.tcc"
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#include "btree-remove.tcc"
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//----------------------------------------------------------------
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#endif
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