/*

** 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_ */