Modules/_sqlite/cache.h

   1 /* cache.h - definitions for the LRU cache
   2  *
   3  * Copyright (C) 2004-2006 Gerhard Häring <gh@ghaering.de>
   4  *
   5  * This file is part of pysqlite.
   6  *
   7  * This software is provided 'as-is', without any express or implied
   8  * warranty.  In no event will the authors be held liable for any damages
   9  * arising from the use of this software.
  10  *
  11  * Permission is granted to anyone to use this software for any purpose,
  12  * including commercial applications, and to alter it and redistribute it
  13  * freely, subject to the following restrictions:
  14  *
  15  * 1. The origin of this software must not be misrepresented; you must not
  16  *    claim that you wrote the original software. If you use this software
  17  *    in a product, an acknowledgment in the product documentation would be
  18  *    appreciated but is not required.
  19  * 2. Altered source versions must be plainly marked as such, and must not be
  20  *    misrepresented as being the original software.
  21  * 3. This notice may not be removed or altered from any source distribution.
  22  */
  23
  24 #ifndef PYSQLITE_CACHE_H
  25 #define PYSQLITE_CACHE_H
  26 #include "Python.h"
  27
  28 /* The LRU cache is implemented as a combination of a doubly-linked with a
  29  * dictionary. The list items are of type 'Node' and the dictionary has the
  30  * nodes as values. */
  31
  32 typedef struct _Node
  33 {
  34     PyObject_HEAD
  35     PyObject* key;
  36     PyObject* data;
  37     long count;
  38     struct _Node* prev;
  39     struct _Node* next;
  40 } Node;
  41
  42 typedef struct
  43 {
  44     PyObject_HEAD
  45     int size;
  46
  47     /* a dictionary mapping keys to Node entries */
  48     PyObject* mapping;
  49
  50     /* the factory callable */
  51     PyObject* factory;
  52
  53     Node* first;
  54     Node* last;
  55
  56     /* if set, decrement the factory function when the Cache is deallocated.
  57      * this is almost always desirable, but not in the pysqlite context */
  58     int decref_factory;
  59 } Cache;
  60
  61 extern PyTypeObject NodeType;
  62 extern PyTypeObject CacheType;
  63
  64 int node_init(Node* self, PyObject* args, PyObject* kwargs);
  65 void node_dealloc(Node* self);
  66
  67 int cache_init(Cache* self, PyObject* args, PyObject* kwargs);
  68 void cache_dealloc(Cache* self);
  69 PyObject* cache_get(Cache* self, PyObject* args);
  70
  71 int cache_setup_types(void);
  72
  73 #endif