xref: /titanic_41/usr/src/lib/libsqlite/src/pager.h (revision c5c4113dfcabb1eed3d4bdf7609de5170027a794)
1 
2 #pragma ident	"%Z%%M%	%I%	%E% SMI"
3 
4 /*
5 ** 2001 September 15
6 **
7 ** The author disclaims copyright to this source code.  In place of
8 ** a legal notice, here is a blessing:
9 **
10 **    May you do good and not evil.
11 **    May you find forgiveness for yourself and forgive others.
12 **    May you share freely, never taking more than you give.
13 **
14 *************************************************************************
15 ** This header file defines the interface that the sqlite page cache
16 ** subsystem.  The page cache subsystem reads and writes a file a page
17 ** at a time and provides a journal for rollback.
18 **
19 ** @(#) $Id: pager.h,v 1.26 2004/02/11 02:18:07 drh Exp $
20 */
21 
22 /*
23 ** The size of one page
24 **
25 ** You can change this value to another (reasonable) value you want.
26 ** It need not be a power of two, though the interface to the disk
27 ** will likely be faster if it is.
28 **
29 ** Experiments show that a page size of 1024 gives the best speed
30 ** for common usages.  The speed differences for different sizes
31 ** such as 512, 2048, 4096, an so forth, is minimal.  Note, however,
32 ** that changing the page size results in a completely imcompatible
33 ** file format.
34 */
35 #ifndef SQLITE_PAGE_SIZE
36 #define SQLITE_PAGE_SIZE 1024
37 #endif
38 
39 /*
40 ** Number of extra bytes of data allocated at the end of each page and
41 ** stored on disk but not used by the higher level btree layer.  Changing
42 ** this value results in a completely incompatible file format.
43 */
44 #ifndef SQLITE_PAGE_RESERVE
45 #define SQLITE_PAGE_RESERVE 0
46 #endif
47 
48 /*
49 ** The total number of usable bytes stored on disk for each page.
50 ** The usable bytes come at the beginning of the page and the reserve
51 ** bytes come at the end.
52 */
53 #define SQLITE_USABLE_SIZE (SQLITE_PAGE_SIZE-SQLITE_PAGE_RESERVE)
54 
55 /*
56 ** Maximum number of pages in one database.  (This is a limitation of
57 ** imposed by 4GB files size limits.)
58 */
59 #define SQLITE_MAX_PAGE 1073741823
60 
61 /*
62 ** The type used to represent a page number.  The first page in a file
63 ** is called page 1.  0 is used to represent "not a page".
64 */
65 typedef unsigned int Pgno;
66 
67 /*
68 ** Each open file is managed by a separate instance of the "Pager" structure.
69 */
70 typedef struct Pager Pager;
71 
72 /*
73 ** See source code comments for a detailed description of the following
74 ** routines:
75 */
76 int sqlitepager_open(Pager **ppPager, const char *zFilename,
77                      int nPage, int nExtra, int useJournal);
78 void sqlitepager_set_destructor(Pager*, void(*)(void*));
79 void sqlitepager_set_cachesize(Pager*, int);
80 int sqlitepager_close(Pager *pPager);
81 int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage);
82 void *sqlitepager_lookup(Pager *pPager, Pgno pgno);
83 int sqlitepager_ref(void*);
84 int sqlitepager_unref(void*);
85 Pgno sqlitepager_pagenumber(void*);
86 int sqlitepager_write(void*);
87 int sqlitepager_iswriteable(void*);
88 int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void*);
89 int sqlitepager_pagecount(Pager*);
90 int sqlitepager_truncate(Pager*,Pgno);
91 int sqlitepager_begin(void*);
92 int sqlitepager_commit(Pager*);
93 int sqlitepager_rollback(Pager*);
94 int sqlitepager_isreadonly(Pager*);
95 int sqlitepager_ckpt_begin(Pager*);
96 int sqlitepager_ckpt_commit(Pager*);
97 int sqlitepager_ckpt_rollback(Pager*);
98 void sqlitepager_dont_rollback(void*);
99 void sqlitepager_dont_write(Pager*, Pgno);
100 int *sqlitepager_stats(Pager*);
101 void sqlitepager_set_safety_level(Pager*,int);
102 const char *sqlitepager_filename(Pager*);
103 int sqlitepager_rename(Pager*, const char *zNewName);
104 void sqlitepager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*);
105 
106 #ifdef SQLITE_TEST
107 void sqlitepager_refdump(Pager*);
108 int pager_refinfo_enable;
109 int journal_format;
110 #endif
111