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/*======
5This file is part of PerconaFT.
6
7
8Copyright (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#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
38
39#pragma once
40
41#include <ft/comparator.h>
42
43namespace toku {
44
45// A keyrange has a left and right key as endpoints.
46//
47// When a keyrange is created it owns no memory, but when it copies
48// or extends another keyrange, it copies memory as necessary. This
49// means it is cheap in the common case.
50
51class keyrange {
52public:
53
54 // effect: constructor that borrows left and right key pointers.
55 // no memory is allocated or copied.
56 void create(const DBT *left_key, const DBT *right_key);
57
58 // effect: constructor that allocates and copies another keyrange's points.
59 void create_copy(const keyrange &range);
60
61 // effect: destroys the keyrange, freeing any allocated memory
62 void destroy(void);
63
64 // effect: extends the keyrange by choosing the leftmost and rightmost
65 // endpoints from this range and the given range.
66 // replaced keys in this range are freed, new keys are copied.
67 void extend(const comparator &cmp, const keyrange &range);
68
69 // returns: the amount of memory this keyrange takes. does not account
70 // for point optimizations or malloc overhead.
71 uint64_t get_memory_size(void) const;
72
73 // returns: pointer to the left key of this range
74 const DBT *get_left_key(void) const;
75
76 // returns: pointer to the right key of this range
77 const DBT *get_right_key(void) const;
78
79 // two ranges are either equal, lt, gt, or overlapping
80 enum comparison {
81 EQUALS,
82 LESS_THAN,
83 GREATER_THAN,
84 OVERLAPS
85 };
86
87 // effect: compares this range to the given range
88 // returns: LESS_THAN if given range is strictly to the left
89 // GREATER_THAN if given range is strictly to the right
90 // EQUALS if given range has the same left and right endpoints
91 // OVERLAPS if at least one of the given range's endpoints falls
92 // between this range's endpoints
93 comparison compare(const comparator &cmp, const keyrange &range) const;
94
95 // returns: true if the range and the given range are equal or overlapping
96 bool overlaps(const comparator &cmp, const keyrange &range) const;
97
98 // returns: a keyrange representing -inf, +inf
99 static keyrange get_infinite_range(void);
100
101private:
102 // some keys should be copied, some keys should not be.
103 //
104 // to support both, we use two DBTs for copies and two pointers
105 // for temporaries. the access rule is:
106 // - if a pointer is non-null, then it reprsents the key.
107 // - otherwise the pointer is null, and the key is in the copy.
108 DBT m_left_key_copy;
109 DBT m_right_key_copy;
110 const DBT *m_left_key;
111 const DBT *m_right_key;
112
113 // if this range is a point range, then m_left_key == m_right_key
114 // and the actual data is stored exactly once in m_left_key_copy.
115 bool m_point_range;
116
117 // effect: initializes a keyrange to be empty
118 void init_empty(void);
119
120 // effect: copies the given key once into the left key copy
121 // and sets the right key copy to share the left.
122 // rationale: optimization for point ranges to only do one malloc
123 void set_both_keys(const DBT *key);
124
125 // effect: destroys the current left key. sets and copies the new one.
126 void replace_left_key(const DBT *key);
127
128 // effect: destroys the current right key. sets and copies the new one.
129 void replace_right_key(const DBT *key);
130};
131
132} /* namespace toku */
133