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 #define PY_SSIZE_T_CLEAN
27 #include "Python.h"
28 
29 /* The LRU cache is implemented as a combination of a doubly-linked with a
30  * dictionary. The list items are of type 'Node' and the dictionary has the
31  * nodes as values. */
32 
33 typedef struct _pysqlite_Node
34 {
35     PyObject_HEAD
36     PyObject* key;
37     PyObject* data;
38     long count;
39     struct _pysqlite_Node* prev;
40     struct _pysqlite_Node* next;
41 } pysqlite_Node;
42 
43 typedef struct
44 {
45     PyObject_HEAD
46     int size;
47 
48     /* a dictionary mapping keys to Node entries */
49     PyObject* mapping;
50 
51     /* the factory callable */
52     PyObject* factory;
53 
54     pysqlite_Node* first;
55     pysqlite_Node* last;
56 
57     /* if set, decrement the factory function when the Cache is deallocated.
58      * this is almost always desirable, but not in the pysqlite context */
59     int decref_factory;
60 } pysqlite_Cache;
61 
62 extern PyTypeObject pysqlite_NodeType;
63 extern PyTypeObject pysqlite_CacheType;
64 
65 int pysqlite_node_init(pysqlite_Node* self, PyObject* args, PyObject* kwargs);
66 void pysqlite_node_dealloc(pysqlite_Node* self);
67 
68 int pysqlite_cache_init(pysqlite_Cache* self, PyObject* args, PyObject* kwargs);
69 void pysqlite_cache_dealloc(pysqlite_Cache* self);
70 PyObject* pysqlite_cache_get(pysqlite_Cache* self, PyObject* args);
71 
72 int pysqlite_cache_setup_types(void);
73 
74 #endif
75