/*

 ** 2001 September 15

 **

 ** The author disclaims copyright to this source code.  In place of

 ** a legal notice, here is a blessing:

 **

 **    May you do good and not evil.

 **    May you find forgiveness for yourself and forgive others.

 **    May you share freely, never taking more than you give.

 **

 *************************************************************************

 ** This header file defines the interface that the sqlite page cache

 ** subsystem.  The page cache subsystem reads and writes a file a page

 ** at a time and provides a journal for rollback.

 **

 ** @(#) $Id$

 */

 #ifndef _PAGER_H_

 #define _PAGER_H_

 /*

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

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

 */

 typedef unsigned int Pgno;

 /*

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

 */

 typedef struct Pager Pager;

 /*

 ** Handle type for pages.

 */

 typedef struct PgHdr DbPage;

 /*

 ** Allowed values for the flags parameter to sqlite3PagerOpen().

 **

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

 */

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

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

 /*

 ** Valid values for the second argument to sqlite3PagerLockingMode().

 */

 #define PAGER_LOCKINGMODE_QUERY      -1

 #define PAGER_LOCKINGMODE_NORMAL      0

 #define PAGER_LOCKINGMODE_EXCLUSIVE   1

 /*

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

 ** routines:

 */

 int sqlite3PagerOpen(sqlite3_vfs *, Pager **ppPager, const char*, int,int,int);

 void sqlite3PagerSetBusyhandler(Pager*, BusyHandler *pBusyHandler);

 void sqlite3PagerSetDestructor(Pager*, void(*)(DbPage*,int));

 void sqlite3PagerSetReiniter(Pager*, void(*)(DbPage*,int));

 int sqlite3PagerSetPagesize(Pager*, u16*);

 int sqlite3PagerMaxPageCount(Pager*, int);

 int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);

 void sqlite3PagerSetCachesize(Pager*, int);

 int sqlite3PagerClose(Pager *pPager);

 int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);

 #define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0)

 DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);

 int sqlite3PagerRef(DbPage*);

 int sqlite3PagerUnref(DbPage*);

 int sqlite3PagerWrite(DbPage*);

 int sqlite3PagerOverwrite(Pager *pPager, Pgno pgno, void*);

 int sqlite3PagerPagecount(Pager*);

 int sqlite3PagerTruncate(Pager*,Pgno);

 int sqlite3PagerBegin(DbPage*, int exFlag);

 int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, Pgno);

 int sqlite3PagerCommitPhaseTwo(Pager*);

 int sqlite3PagerRollback(Pager*);

 int sqlite3PagerIsreadonly(Pager*);

 int sqlite3PagerStmtBegin(Pager*);

 int sqlite3PagerStmtCommit(Pager*);

 int sqlite3PagerStmtRollback(Pager*);

 void sqlite3PagerDontRollback(DbPage*);

 void sqlite3PagerDontWrite(DbPage*);

 int sqlite3PagerRefcount(Pager*);

 void sqlite3PagerSetSafetyLevel(Pager*,int,int);

 const char *sqlite3PagerFilename(Pager*);

 const sqlite3_vfs *sqlite3PagerVfs(Pager*);

 sqlite3_file *sqlite3PagerFile(Pager*);

 const char *sqlite3PagerDirname(Pager*);

 const char *sqlite3PagerJournalname(Pager*);

 int sqlite3PagerNosync(Pager*);

 int sqlite3PagerMovepage(Pager*,DbPage*,Pgno);

 void *sqlite3PagerGetData(DbPage *); 

 void *sqlite3PagerGetExtra(DbPage *); 

 int sqlite3PagerLockingMode(Pager *, int);

 #if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) && !defined(SQLITE_OMIT_DISKIO)

   int sqlite3PagerReleaseMemory(int);

 #endif

 #ifdef SQLITE_HAS_CODEC

   void sqlite3PagerSetCodec(Pager*,void*(*)(void*,void*,Pgno,int),void*);

 #endif

 #if !defined(NDEBUG) || defined(SQLITE_TEST)

   Pgno sqlite3PagerPagenumber(DbPage*);

   int sqlite3PagerIswriteable(DbPage*);

 #endif

 #ifdef SQLITE_TEST

   int *sqlite3PagerStats(Pager*);

   void sqlite3PagerRefdump(Pager*);

   int pager3_refinfo_enable;

 #endif

 #ifdef SQLITE_TEST

 void disable_simulated_io_errors(void);

 void enable_simulated_io_errors(void);

 #else

 # define disable_simulated_io_errors()

 # define enable_simulated_io_errors()

 #endif

 #endif /* _PAGER_H_ */