ceph/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/comparator.h

   1 /* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
   2 // vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
   3 /*======
   4 This file is part of PerconaFT.
   5
   6
   7 Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
   8
   9     PerconaFT is free software: you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License, version 2,
  11     as published by the Free Software Foundation.
  12
  13     PerconaFT is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 ----------------------------------------
  22
  23     PerconaFT is free software: you can redistribute it and/or modify
  24     it under the terms of the GNU Affero General Public License, version 3,
  25     as published by the Free Software Foundation.
  26
  27     PerconaFT is distributed in the hope that it will be useful,
  28     but WITHOUT ANY WARRANTY; without even the implied warranty of
  29     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30     GNU Affero General Public License for more details.
  31
  32     You should have received a copy of the GNU Affero General Public License
  33     along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
  34
  35 ----------------------------------------
  36
  37    Licensed under the Apache License, Version 2.0 (the "License");
  38    you may not use this file except in compliance with the License.
  39    You may obtain a copy of the License at
  40
  41        http://www.apache.org/licenses/LICENSE-2.0
  42
  43    Unless required by applicable law or agreed to in writing, software
  44    distributed under the License is distributed on an "AS IS" BASIS,
  45    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  46    See the License for the specific language governing permissions and
  47    limitations under the License.
  48 ======= */
  49
  50 #ident \
  51     "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
  52
  53 #pragma once
  54
  55 #include <string.h>
  56
  57 #include "../db.h"
  58 #include "../portability/memory.h"
  59 #include "../util/dbt.h"
  60
  61 typedef int (*ft_compare_func)(void *arg, const DBT *a, const DBT *b);
  62
  63 int toku_keycompare(const void *key1, size_t key1len, const void *key2,
  64                     size_t key2len);
  65
  66 int toku_builtin_compare_fun(const DBT *, const DBT *)
  67     __attribute__((__visibility__("default")));
  68
  69 namespace toku {
  70
  71 // a comparator object encapsulates the data necessary for
  72 // comparing two keys in a fractal tree. it further understands
  73 // that points may be positive or negative infinity.
  74
  75 class comparator {
  76   void init(ft_compare_func cmp, void *cmp_arg, uint8_t memcmp_magic) {
  77     _cmp = cmp;
  78     _cmp_arg = cmp_arg;
  79     _memcmp_magic = memcmp_magic;
  80   }
  81
  82  public:
  83   // This magic value is reserved to mean that the magic has not been set.
  84   static const uint8_t MEMCMP_MAGIC_NONE = 0;
  85
  86   void create(ft_compare_func cmp, void *cmp_arg,
  87               uint8_t memcmp_magic = MEMCMP_MAGIC_NONE) {
  88     init(cmp, cmp_arg, memcmp_magic);
  89   }
  90
  91   // inherit the attributes of another comparator, but keep our own
  92   // copy of fake_db that is owned separately from the one given.
  93   void inherit(const comparator &cmp) {
  94     invariant_notnull(cmp._cmp);
  95     init(cmp._cmp, cmp._cmp_arg, cmp._memcmp_magic);
  96   }
  97
  98   // like inherit, but doesn't require that the this comparator
  99   // was already created
 100   void create_from(const comparator &cmp) { inherit(cmp); }
 101
 102   void destroy() {}
 103
 104   ft_compare_func get_compare_func() const { return _cmp; }
 105
 106   uint8_t get_memcmp_magic() const { return _memcmp_magic; }
 107
 108   bool valid() const { return _cmp != nullptr; }
 109
 110   inline bool dbt_has_memcmp_magic(const DBT *dbt) const {
 111     return *reinterpret_cast<const char *>(dbt->data) == _memcmp_magic;
 112   }
 113
 114   int operator()(const DBT *a, const DBT *b) const {
 115     if (__builtin_expect(toku_dbt_is_infinite(a) || toku_dbt_is_infinite(b),
 116                          0)) {
 117       return toku_dbt_infinite_compare(a, b);
 118     } else if (_memcmp_magic != MEMCMP_MAGIC_NONE
 119                // If `a' has the memcmp magic..
 120                && dbt_has_memcmp_magic(a)
 121                // ..then we expect `b' to also have the memcmp magic
 122                && __builtin_expect(dbt_has_memcmp_magic(b), 1)) {
 123       assert(0);  // psergey: this branch should not be taken.
 124       return toku_builtin_compare_fun(a, b);
 125     } else {
 126       // yikes, const sadness here
 127       return _cmp(_cmp_arg, a, b);
 128     }
 129   }
 130
 131  private:
 132   ft_compare_func _cmp;
 133   void *_cmp_arg;
 134
 135   uint8_t _memcmp_magic;
 136 };
 137
 138 } /* namespace toku */