98236fb10e
Summary: To be used for implementing Range Locking. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7753 Reviewed By: zhichao-cao Differential Revision: D25378980 Pulled By: cheng-chang fbshipit-source-id: 801a9c5cd92a84654ca2586b73e8f69001e89320
141 lines
5.3 KiB
C++
141 lines
5.3 KiB
C++
/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
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// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
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#ident "$Id$"
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/*======
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This file is part of PerconaFT.
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Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
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PerconaFT is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2,
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as published by the Free Software Foundation.
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PerconaFT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
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----------------------------------------
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PerconaFT is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License, version 3,
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as published by the Free Software Foundation.
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PerconaFT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
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----------------------------------------
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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======= */
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#ident \
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"Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
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#pragma once
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#include "../ft/comparator.h"
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namespace toku {
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// A keyrange has a left and right key as endpoints.
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//
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// When a keyrange is created it owns no memory, but when it copies
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// or extends another keyrange, it copies memory as necessary. This
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// means it is cheap in the common case.
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class keyrange {
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public:
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// effect: constructor that borrows left and right key pointers.
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// no memory is allocated or copied.
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void create(const DBT *left_key, const DBT *right_key);
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// effect: constructor that allocates and copies another keyrange's points.
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void create_copy(const keyrange &range);
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// effect: destroys the keyrange, freeing any allocated memory
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void destroy(void);
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// effect: extends the keyrange by choosing the leftmost and rightmost
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// endpoints from this range and the given range.
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// replaced keys in this range are freed, new keys are copied.
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void extend(const comparator &cmp, const keyrange &range);
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// returns: the amount of memory this keyrange takes. does not account
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// for point optimizations or malloc overhead.
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uint64_t get_memory_size(void) const;
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// returns: pointer to the left key of this range
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const DBT *get_left_key(void) const;
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// returns: pointer to the right key of this range
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const DBT *get_right_key(void) const;
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// two ranges are either equal, lt, gt, or overlapping
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enum comparison { EQUALS, LESS_THAN, GREATER_THAN, OVERLAPS };
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// effect: compares this range to the given range
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// returns: LESS_THAN if given range is strictly to the left
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// GREATER_THAN if given range is strictly to the right
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// EQUALS if given range has the same left and right endpoints
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// OVERLAPS if at least one of the given range's endpoints falls
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// between this range's endpoints
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comparison compare(const comparator &cmp, const keyrange &range) const;
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// returns: true if the range and the given range are equal or overlapping
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bool overlaps(const comparator &cmp, const keyrange &range) const;
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// returns: a keyrange representing -inf, +inf
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static keyrange get_infinite_range(void);
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private:
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// some keys should be copied, some keys should not be.
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//
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// to support both, we use two DBTs for copies and two pointers
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// for temporaries. the access rule is:
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// - if a pointer is non-null, then it reprsents the key.
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// - otherwise the pointer is null, and the key is in the copy.
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DBT m_left_key_copy;
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DBT m_right_key_copy;
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const DBT *m_left_key;
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const DBT *m_right_key;
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// if this range is a point range, then m_left_key == m_right_key
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// and the actual data is stored exactly once in m_left_key_copy.
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bool m_point_range;
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// effect: initializes a keyrange to be empty
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void init_empty(void);
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// effect: copies the given key once into the left key copy
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// and sets the right key copy to share the left.
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// rationale: optimization for point ranges to only do one malloc
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void set_both_keys(const DBT *key);
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// effect: destroys the current left key. sets and copies the new one.
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void replace_left_key(const DBT *key);
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// effect: destroys the current right key. sets and copies the new one.
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void replace_right_key(const DBT *key);
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};
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} /* namespace toku */
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