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 1.51 2006/08/08 13:51:43 drh Exp $

    17 */

    18 

    19 #ifndef _PAGER_H_

    20 #define _PAGER_H_

    21 

    22 /*

    23 ** The default size of a database page.

    24 */

    25 #ifndef SQLITE_DEFAULT_PAGE_SIZE

    26 # define SQLITE_DEFAULT_PAGE_SIZE 1024

    27 #endif

    28 

    29 /* Maximum page size.  The upper bound on this value is 32768.  This a limit

    30 ** imposed by necessity of storing the value in a 2-byte unsigned integer

    31 ** and the fact that the page size must be a power of 2.

    32 **

    33 ** This value is used to initialize certain arrays on the stack at

    34 ** various places in the code.  On embedded machines where stack space

    35 ** is limited and the flexibility of having large pages is not needed,

    36 ** it makes good sense to reduce the maximum page size to something more

    37 ** reasonable, like 1024.

    38 */

    39 #ifndef SQLITE_MAX_PAGE_SIZE

    40 # define SQLITE_MAX_PAGE_SIZE 32768

    41 #endif

    42 

    43 /*

    44 ** Maximum number of pages in one database.

    45 */

    46 #define SQLITE_MAX_PAGE 1073741823

    47 

    48 /*

    49 ** The type used to represent a page number.  The first page in a file

    50 ** is called page 1.  0 is used to represent "not a page".

    51 */

    52 typedef unsigned int Pgno;

    53 

    54 /*

    55 ** Each open file is managed by a separate instance of the "Pager" structure.

    56 */

    57 typedef struct Pager Pager;

    58 

    59 /*

    60 ** Allowed values for the flags parameter to sqlite3pager_open().

    61 **

    62 ** NOTE: This values must match the corresponding BTREE_ values in btree.h.

    63 */

    64 #define PAGER_OMIT_JOURNAL  0x0001    /* Do not use a rollback journal */

    65 #define PAGER_NO_READLOCK   0x0002    /* Omit readlocks on readonly files */

    66 

    67 

    68 /*

    69 ** See source code comments for a detailed description of the following

    70 ** routines:

    71 */

    72 int sqlite3pager_open(Pager **ppPager, const char *zFilename,

    73                      int nExtra, int flags);

    74 void sqlite3pager_set_busyhandler(Pager*, BusyHandler *pBusyHandler);

    75 void sqlite3pager_set_destructor(Pager*, void(*)(void*,int));

    76 void sqlite3pager_set_reiniter(Pager*, void(*)(void*,int));

    77 int sqlite3pager_set_pagesize(Pager*, int);

    78 void sqlite3pager_read_fileheader(Pager*, int, unsigned char*);

    79 void sqlite3pager_set_cachesize(Pager*, int);

    80 int sqlite3pager_close(Pager *pPager);

    81 int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage);

    82 void *sqlite3pager_lookup(Pager *pPager, Pgno pgno);

    83 int sqlite3pager_ref(void*);

    84 int sqlite3pager_unref(void*);

    85 Pgno sqlite3pager_pagenumber(void*);

    86 int sqlite3pager_write(void*);

    87 int sqlite3pager_iswriteable(void*);

    88 int sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void*);

    89 int sqlite3pager_pagecount(Pager*);

    90 int sqlite3pager_truncate(Pager*,Pgno);

    91 int sqlite3pager_begin(void*, int exFlag);

    92 int sqlite3pager_commit(Pager*);

    93 int sqlite3pager_sync(Pager*,const char *zMaster, Pgno);

    94 int sqlite3pager_rollback(Pager*);

    95 int sqlite3pager_isreadonly(Pager*);

    96 int sqlite3pager_stmt_begin(Pager*);

    97 int sqlite3pager_stmt_commit(Pager*);

    98 int sqlite3pager_stmt_rollback(Pager*);

    99 void sqlite3pager_dont_rollback(void*);

   100 void sqlite3pager_dont_write(Pager*, Pgno);

   101 int sqlite3pager_refcount(Pager*);

   102 int *sqlite3pager_stats(Pager*);

   103 void sqlite3pager_set_safety_level(Pager*,int,int);

   104 const char *sqlite3pager_filename(Pager*);

   105 const char *sqlite3pager_dirname(Pager*);

   106 const char *sqlite3pager_journalname(Pager*);

   107 int sqlite3pager_nosync(Pager*);

   108 int sqlite3pager_rename(Pager*, const char *zNewName);

   109 void sqlite3pager_set_codec(Pager*,void*(*)(void*,void*,Pgno,int),void*);

   110 int sqlite3pager_movepage(Pager*,void*,Pgno);

   111 int sqlite3pager_reset(Pager*);

   112 int sqlite3pager_release_memory(int);

   113 

   114 #if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)

   115 int sqlite3pager_lockstate(Pager*);

   116 #endif

   117 

   118 #ifdef SQLITE_TEST

   119 void sqlite3pager_refdump(Pager*);

   120 int pager3_refinfo_enable;

   121 #endif

   122 

   123 #endif /* _PAGER_H_ */