1/* cache.h - definitions for the LRU cache
2 *
3 * Copyright (C) 2004-2010 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
32typedef struct _pysqlite_Node
33{
34    PyObject_HEAD
35    PyObject* key;
36    PyObject* data;
37    long count;
38    struct _pysqlite_Node* prev;
39    struct _pysqlite_Node* next;
40} pysqlite_Node;
41
42typedef 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    pysqlite_Node* first;
54    pysqlite_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} pysqlite_Cache;
60
61extern PyTypeObject pysqlite_NodeType;
62extern PyTypeObject pysqlite_CacheType;
63
64int pysqlite_node_init(pysqlite_Node* self, PyObject* args, PyObject* kwargs);
65void pysqlite_node_dealloc(pysqlite_Node* self);
66
67int pysqlite_cache_init(pysqlite_Cache* self, PyObject* args, PyObject* kwargs);
68void pysqlite_cache_dealloc(pysqlite_Cache* self);
69PyObject* pysqlite_cache_get(pysqlite_Cache* self, PyObject* args);
70
71int pysqlite_cache_setup_types(void);
72
73#endif
74