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