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: pager.h,v 1.44 2005/05/20 20:01:56 drh Exp $ 17 */ 18 19 /* 20 ** The default size of a database page. 21 */ 22 #ifndef SQLITE_DEFAULT_PAGE_SIZE 23 # define SQLITE_DEFAULT_PAGE_SIZE 1024 24 #endif 25 26 /* Maximum page size. The upper bound on this value is 32768. This a limit 27 ** imposed by necessity of storing the value in a 2-byte unsigned integer 28 ** and the fact that the page size must be a power of 2. 29 ** 30 ** This value is used to initialize certain arrays on the stack at 31 ** various places in the code. On embedded machines where stack space 32 ** is limited and the flexibility of having large pages is not needed, 33 ** it makes good sense to reduce the maximum page size to something more 34 ** reasonable, like 1024. 35 */ 36 #ifndef SQLITE_MAX_PAGE_SIZE 37 # define SQLITE_MAX_PAGE_SIZE 8192 38 #endif 39 40 /* 41 ** Maximum number of pages in one database. 42 */ 43 #define SQLITE_MAX_PAGE 1073741823 44 45 /* 46 ** The type used to represent a page number. The first page in a file 47 ** is called page 1. 0 is used to represent "not a page". 48 */ 49 typedef unsigned int Pgno; 50 51 /* 52 ** Each open file is managed by a separate instance of the "Pager" structure. 53 */ 54 typedef struct Pager Pager; 55 56 /* 57 ** Allowed values for the flags parameter to sqlite3pager_open(). 58 ** 59 ** NOTE: This values must match the corresponding BTREE_ values in btree.h. 60 */ 61 #define PAGER_OMIT_JOURNAL 0x0001 /* Do not use a rollback journal */ 62 #define PAGER_NO_READLOCK 0x0002 /* Omit readlocks on readonly files */ 63 64 65 /* 66 ** See source code comments for a detailed description of the following 67 ** routines: 68 */ 69 int sqlite3pager_open(Pager **ppPager, const char *zFilename, 70 int nExtra, int flags); 71 void sqlite3pager_set_busyhandler(Pager*, BusyHandler *pBusyHandler); 72 void sqlite3pager_set_destructor(Pager*, void(*)(void*,int)); 73 void sqlite3pager_set_reiniter(Pager*, void(*)(void*,int)); 74 int sqlite3pager_set_pagesize(Pager*, int); 75 void sqlite3pager_read_fileheader(Pager*, int, unsigned char*); 76 void sqlite3pager_set_cachesize(Pager*, int); 77 int sqlite3pager_close(Pager *pPager); 78 int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage); 79 void *sqlite3pager_lookup(Pager *pPager, Pgno pgno); 80 int sqlite3pager_ref(void*); 81 int sqlite3pager_unref(void*); 82 Pgno sqlite3pager_pagenumber(void*); 83 int sqlite3pager_write(void*); 84 int sqlite3pager_iswriteable(void*); 85 int sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void*); 86 int sqlite3pager_pagecount(Pager*); 87 int sqlite3pager_truncate(Pager*,Pgno); 88 int sqlite3pager_begin(void*, int exFlag); 89 int sqlite3pager_commit(Pager*); 90 int sqlite3pager_sync(Pager*,const char *zMaster, Pgno); 91 int sqlite3pager_rollback(Pager*); 92 int sqlite3pager_isreadonly(Pager*); 93 int sqlite3pager_stmt_begin(Pager*); 94 int sqlite3pager_stmt_commit(Pager*); 95 int sqlite3pager_stmt_rollback(Pager*); 96 void sqlite3pager_dont_rollback(void*); 97 void sqlite3pager_dont_write(Pager*, Pgno); 98 int *sqlite3pager_stats(Pager*); 99 void sqlite3pager_set_safety_level(Pager*,int); 100 const char *sqlite3pager_filename(Pager*); 101 const char *sqlite3pager_dirname(Pager*); 102 const char *sqlite3pager_journalname(Pager*); 103 int sqlite3pager_rename(Pager*, const char *zNewName); 104 void sqlite3pager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*); 105 int sqlite3pager_movepage(Pager*,void*,Pgno); 106 int sqlite3pager_reset(Pager*); 107 108 #if defined(SQLITE_DEBUG) || defined(SQLITE_TEST) 109 int sqlite3pager_lockstate(Pager*); 110 #endif 111 112 #ifdef SQLITE_TEST 113 void sqlite3pager_refdump(Pager*); 114 int pager3_refinfo_enable; 115 #endif 116