1*c5c4113dSnw141292 2*c5c4113dSnw141292 #pragma ident "%Z%%M% %I% %E% SMI" 3*c5c4113dSnw141292 4*c5c4113dSnw141292 /* 5*c5c4113dSnw141292 ** 2001 September 15 6*c5c4113dSnw141292 ** 7*c5c4113dSnw141292 ** The author disclaims copyright to this source code. In place of 8*c5c4113dSnw141292 ** a legal notice, here is a blessing: 9*c5c4113dSnw141292 ** 10*c5c4113dSnw141292 ** May you do good and not evil. 11*c5c4113dSnw141292 ** May you find forgiveness for yourself and forgive others. 12*c5c4113dSnw141292 ** May you share freely, never taking more than you give. 13*c5c4113dSnw141292 ** 14*c5c4113dSnw141292 ************************************************************************* 15*c5c4113dSnw141292 ** This header file defines the interface that the sqlite page cache 16*c5c4113dSnw141292 ** subsystem. The page cache subsystem reads and writes a file a page 17*c5c4113dSnw141292 ** at a time and provides a journal for rollback. 18*c5c4113dSnw141292 ** 19*c5c4113dSnw141292 ** @(#) $Id: pager.h,v 1.26 2004/02/11 02:18:07 drh Exp $ 20*c5c4113dSnw141292 */ 21*c5c4113dSnw141292 22*c5c4113dSnw141292 /* 23*c5c4113dSnw141292 ** The size of one page 24*c5c4113dSnw141292 ** 25*c5c4113dSnw141292 ** You can change this value to another (reasonable) value you want. 26*c5c4113dSnw141292 ** It need not be a power of two, though the interface to the disk 27*c5c4113dSnw141292 ** will likely be faster if it is. 28*c5c4113dSnw141292 ** 29*c5c4113dSnw141292 ** Experiments show that a page size of 1024 gives the best speed 30*c5c4113dSnw141292 ** for common usages. The speed differences for different sizes 31*c5c4113dSnw141292 ** such as 512, 2048, 4096, an so forth, is minimal. Note, however, 32*c5c4113dSnw141292 ** that changing the page size results in a completely imcompatible 33*c5c4113dSnw141292 ** file format. 34*c5c4113dSnw141292 */ 35*c5c4113dSnw141292 #ifndef SQLITE_PAGE_SIZE 36*c5c4113dSnw141292 #define SQLITE_PAGE_SIZE 1024 37*c5c4113dSnw141292 #endif 38*c5c4113dSnw141292 39*c5c4113dSnw141292 /* 40*c5c4113dSnw141292 ** Number of extra bytes of data allocated at the end of each page and 41*c5c4113dSnw141292 ** stored on disk but not used by the higher level btree layer. Changing 42*c5c4113dSnw141292 ** this value results in a completely incompatible file format. 43*c5c4113dSnw141292 */ 44*c5c4113dSnw141292 #ifndef SQLITE_PAGE_RESERVE 45*c5c4113dSnw141292 #define SQLITE_PAGE_RESERVE 0 46*c5c4113dSnw141292 #endif 47*c5c4113dSnw141292 48*c5c4113dSnw141292 /* 49*c5c4113dSnw141292 ** The total number of usable bytes stored on disk for each page. 50*c5c4113dSnw141292 ** The usable bytes come at the beginning of the page and the reserve 51*c5c4113dSnw141292 ** bytes come at the end. 52*c5c4113dSnw141292 */ 53*c5c4113dSnw141292 #define SQLITE_USABLE_SIZE (SQLITE_PAGE_SIZE-SQLITE_PAGE_RESERVE) 54*c5c4113dSnw141292 55*c5c4113dSnw141292 /* 56*c5c4113dSnw141292 ** Maximum number of pages in one database. (This is a limitation of 57*c5c4113dSnw141292 ** imposed by 4GB files size limits.) 58*c5c4113dSnw141292 */ 59*c5c4113dSnw141292 #define SQLITE_MAX_PAGE 1073741823 60*c5c4113dSnw141292 61*c5c4113dSnw141292 /* 62*c5c4113dSnw141292 ** The type used to represent a page number. The first page in a file 63*c5c4113dSnw141292 ** is called page 1. 0 is used to represent "not a page". 64*c5c4113dSnw141292 */ 65*c5c4113dSnw141292 typedef unsigned int Pgno; 66*c5c4113dSnw141292 67*c5c4113dSnw141292 /* 68*c5c4113dSnw141292 ** Each open file is managed by a separate instance of the "Pager" structure. 69*c5c4113dSnw141292 */ 70*c5c4113dSnw141292 typedef struct Pager Pager; 71*c5c4113dSnw141292 72*c5c4113dSnw141292 /* 73*c5c4113dSnw141292 ** See source code comments for a detailed description of the following 74*c5c4113dSnw141292 ** routines: 75*c5c4113dSnw141292 */ 76*c5c4113dSnw141292 int sqlitepager_open(Pager **ppPager, const char *zFilename, 77*c5c4113dSnw141292 int nPage, int nExtra, int useJournal); 78*c5c4113dSnw141292 void sqlitepager_set_destructor(Pager*, void(*)(void*)); 79*c5c4113dSnw141292 void sqlitepager_set_cachesize(Pager*, int); 80*c5c4113dSnw141292 int sqlitepager_close(Pager *pPager); 81*c5c4113dSnw141292 int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage); 82*c5c4113dSnw141292 void *sqlitepager_lookup(Pager *pPager, Pgno pgno); 83*c5c4113dSnw141292 int sqlitepager_ref(void*); 84*c5c4113dSnw141292 int sqlitepager_unref(void*); 85*c5c4113dSnw141292 Pgno sqlitepager_pagenumber(void*); 86*c5c4113dSnw141292 int sqlitepager_write(void*); 87*c5c4113dSnw141292 int sqlitepager_iswriteable(void*); 88*c5c4113dSnw141292 int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void*); 89*c5c4113dSnw141292 int sqlitepager_pagecount(Pager*); 90*c5c4113dSnw141292 int sqlitepager_truncate(Pager*,Pgno); 91*c5c4113dSnw141292 int sqlitepager_begin(void*); 92*c5c4113dSnw141292 int sqlitepager_commit(Pager*); 93*c5c4113dSnw141292 int sqlitepager_rollback(Pager*); 94*c5c4113dSnw141292 int sqlitepager_isreadonly(Pager*); 95*c5c4113dSnw141292 int sqlitepager_ckpt_begin(Pager*); 96*c5c4113dSnw141292 int sqlitepager_ckpt_commit(Pager*); 97*c5c4113dSnw141292 int sqlitepager_ckpt_rollback(Pager*); 98*c5c4113dSnw141292 void sqlitepager_dont_rollback(void*); 99*c5c4113dSnw141292 void sqlitepager_dont_write(Pager*, Pgno); 100*c5c4113dSnw141292 int *sqlitepager_stats(Pager*); 101*c5c4113dSnw141292 void sqlitepager_set_safety_level(Pager*,int); 102*c5c4113dSnw141292 const char *sqlitepager_filename(Pager*); 103*c5c4113dSnw141292 int sqlitepager_rename(Pager*, const char *zNewName); 104*c5c4113dSnw141292 void sqlitepager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*); 105*c5c4113dSnw141292 106*c5c4113dSnw141292 #ifdef SQLITE_TEST 107*c5c4113dSnw141292 void sqlitepager_refdump(Pager*); 108*c5c4113dSnw141292 int pager_refinfo_enable; 109*c5c4113dSnw141292 int journal_format; 110*c5c4113dSnw141292 #endif 111