gprofng/src/DbeCacheMap.h

   1 /* Copyright (C) 2021 Free Software Foundation, Inc.
   2    Contributed by Oracle.
   3
   4    This file is part of GNU Binutils.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, 51 Franklin Street - Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 /*
  22  *      Dbe Cache Map implementation.
  23  *
  24  *    Simple Cache Map makes the following assumptions:
  25  *    - Cache Map is used for very fast but not guaranteed mapping;
  26  *    - No Relations can be used;
  27  *    - all objects used as keys or values has to be managed
  28  *      outside CacheMap (f.e. deletion);
  29  */
  30
  31 #ifndef _DbeCacheMap_h
  32 #define _DbeCacheMap_h
  33
  34 #include <Map.h>
  35
  36 template <typename Key_t, class ITEM>
  37 class DbeCacheMap : public Map<Key_t, ITEM *>
  38 {
  39 public:
  40
  41   DbeCacheMap (int _size = DefaultSize)
  42   { // _size should be 2 ** N
  43     size = _size;
  44     table = new DbeCache_T[size];
  45     memset (table, 0, size * sizeof (DbeCache_T));
  46   };
  47
  48   ~DbeCacheMap ()
  49   {
  50     delete[] table;
  51   };
  52
  53   void
  54   put (Key_t key, ITEM *val)
  55   {
  56     int ind = get_hash (key);
  57     table[ind].key = key;
  58     table[ind].value = val;
  59   };
  60
  61   ITEM *
  62   get (Key_t key)
  63   {
  64     int ind = get_hash (key);
  65     if (table[ind].key == key)
  66       return table[ind].value;
  67     return (ITEM *) NULL;
  68   };
  69
  70   ITEM *
  71   remove (Key_t key)
  72   {
  73     int ind = get_hash (key);
  74     ITEM *v = table[ind].value;
  75     table[ind].value = (ITEM *) NULL;
  76     return v;
  77   };
  78
  79   ITEM *
  80   get (Key_t /* key */, typename Map<Key_t, ITEM *>::Relation /* rel */)
  81   {
  82     return (ITEM *) NULL;
  83   };
  84
  85 private:
  86
  87   enum
  88   {
  89     DefaultSize     = (1 << 13)
  90   };
  91
  92   typedef struct DbeCache_S
  93   {
  94     Key_t key;
  95     ITEM *value;
  96   } DbeCache_T;
  97   DbeCache_T *table;
  98   int size;
  99
 100   int
 101   get_hash (Key_t key)
 102   {
 103     unsigned long long h = (unsigned long long) key;
 104     h ^= (h >> 20) ^ (h >> 12);
 105     return (h ^ (h >> 7) ^ (h >> 4)) & (size - 1);
 106   }
 107 };
 108
 109 #endif