1 /* cache.h - definitions for the LRU cache
2  *
3  * Copyright (C) 2004-2010 Gerhard H�ring <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 _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 
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     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 
61 extern PyTypeObject pysqlite_NodeType;
62 extern PyTypeObject pysqlite_CacheType;
63 
64 int pysqlite_node_init(pysqlite_Node* self, PyObject* args, PyObject* kwargs);
65 void pysqlite_node_dealloc(pysqlite_Node* self);
66 
67 int pysqlite_cache_init(pysqlite_Cache* self, PyObject* args, PyObject* kwargs);
68 void pysqlite_cache_dealloc(pysqlite_Cache* self);
69 PyObject* pysqlite_cache_get(pysqlite_Cache* self, PyObject* args);
70 
71 int pysqlite_cache_setup_types(void);
72 
73 #endif
74