ceph/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.h

   1 /* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
   2 // vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
   3 #ident "$Id$"
   4 /*======
   5 This file is part of PerconaFT.
   6
   7
   8 Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
   9
  10     PerconaFT is free software: you can redistribute it and/or modify
  11     it under the terms of the GNU General Public License, version 2,
  12     as published by the Free Software Foundation.
  13
  14     PerconaFT is distributed in the hope that it will be useful,
  15     but WITHOUT ANY WARRANTY; without even the implied warranty of
  16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17     GNU General Public License for more details.
  18
  19     You should have received a copy of the GNU General Public License
  20     along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
  21
  22 ----------------------------------------
  23
  24     PerconaFT is free software: you can redistribute it and/or modify
  25     it under the terms of the GNU Affero General Public License, version 3,
  26     as published by the Free Software Foundation.
  27
  28     PerconaFT is distributed in the hope that it will be useful,
  29     but WITHOUT ANY WARRANTY; without even the implied warranty of
  30     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  31     GNU Affero General Public License for more details.
  32
  33     You should have received a copy of the GNU Affero General Public License
  34     along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
  35
  36 ----------------------------------------
  37
  38    Licensed under the Apache License, Version 2.0 (the "License");
  39    you may not use this file except in compliance with the License.
  40    You may obtain a copy of the License at
  41
  42        http://www.apache.org/licenses/LICENSE-2.0
  43
  44    Unless required by applicable law or agreed to in writing, software
  45    distributed under the License is distributed on an "AS IS" BASIS,
  46    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  47    See the License for the specific language governing permissions and
  48    limitations under the License.
  49 ======= */
  50
  51 #ident \
  52     "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
  53
  54 #pragma once
  55
  56 #include "../ft/comparator.h"
  57
  58 namespace toku {
  59
  60 // A keyrange has a left and right key as endpoints.
  61 //
  62 // When a keyrange is created it owns no memory, but when it copies
  63 // or extends another keyrange, it copies memory as necessary. This
  64 // means it is cheap in the common case.
  65
  66 class keyrange {
  67  public:
  68   // effect: constructor that borrows left and right key pointers.
  69   //         no memory is allocated or copied.
  70   void create(const DBT *left_key, const DBT *right_key);
  71
  72   // effect: constructor that allocates and copies another keyrange's points.
  73   void create_copy(const keyrange &range);
  74
  75   // effect: destroys the keyrange, freeing any allocated memory
  76   void destroy(void);
  77
  78   // effect: extends the keyrange by choosing the leftmost and rightmost
  79   //         endpoints from this range and the given range.
  80   //         replaced keys in this range are freed, new keys are copied.
  81   void extend(const comparator &cmp, const keyrange &range);
  82
  83   // returns: the amount of memory this keyrange takes. does not account
  84   //          for point optimizations or malloc overhead.
  85   uint64_t get_memory_size(void) const;
  86
  87   // returns: pointer to the left key of this range
  88   const DBT *get_left_key(void) const;
  89
  90   // returns: pointer to the right key of this range
  91   const DBT *get_right_key(void) const;
  92
  93   // two ranges are either equal, lt, gt, or overlapping
  94   enum comparison { EQUALS, LESS_THAN, GREATER_THAN, OVERLAPS };
  95
  96   // effect: compares this range to the given range
  97   // returns: LESS_THAN    if given range is strictly to the left
  98   //          GREATER_THAN if given range is strictly to the right
  99   //          EQUALS       if given range has the same left and right endpoints
 100   //          OVERLAPS     if at least one of the given range's endpoints falls
 101   //                       between this range's endpoints
 102   comparison compare(const comparator &cmp, const keyrange &range) const;
 103
 104   // returns: true if the range and the given range are equal or overlapping
 105   bool overlaps(const comparator &cmp, const keyrange &range) const;
 106
 107   // returns: a keyrange representing -inf, +inf
 108   static keyrange get_infinite_range(void);
 109
 110  private:
 111   // some keys should be copied, some keys should not be.
 112   //
 113   // to support both, we use two DBTs for copies and two pointers
 114   // for temporaries. the access rule is:
 115   // - if a pointer is non-null, then it reprsents the key.
 116   // - otherwise the pointer is null, and the key is in the copy.
 117   DBT m_left_key_copy;
 118   DBT m_right_key_copy;
 119   const DBT *m_left_key;
 120   const DBT *m_right_key;
 121
 122   // if this range is a point range, then m_left_key == m_right_key
 123   // and the actual data is stored exactly once in m_left_key_copy.
 124   bool m_point_range;
 125
 126   // effect: initializes a keyrange to be empty
 127   void init_empty(void);
 128
 129   // effect: copies the given key once into the left key copy
 130   //         and sets the right key copy to share the left.
 131   // rationale: optimization for point ranges to only do one malloc
 132   void set_both_keys(const DBT *key);
 133
 134   // effect: destroys the current left key. sets and copies the new one.
 135   void replace_left_key(const DBT *key);
 136
 137   // effect: destroys the current right key. sets and copies the new one.
 138   void replace_right_key(const DBT *key);
 139 };
 140
 141 } /* namespace toku */