** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.402 2008/01/18 13:42:55 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*
................................................................................
** means that the pager does not have to record the given page in the
** rollback journal.
**
** If we have not yet actually read the content of this page (if
** the PgHdr.needRead flag is set) then this routine acts as a promise
** that we will never need to read the page content in the future.
** so the needRead flag can be cleared at this point.













*/
void sqlite3PagerDontRollback(DbPage *pPg){
  Pager *pPager = pPg->pPager;

  pagerEnter(pPager);
  assert( pPager->state>=PAGER_RESERVED );





  if( pPager->journalOpen==0 || pPg->alwaysRollback 
   || pPager->alwaysRollback || MEMDB ){
    pagerLeave(pPager);
    return;
  }





  if( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ){

    assert( pPager->aInJournal!=0 );
    pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
    pPg->inJournal = 1;
    pPg->needRead = 0;
    if( pPager->stmtInUse ){

      pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
    }
    PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
    IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))
  }
  if( pPager->stmtInUse 
   && !pageInStatement(pPg) 
   && (int)pPg->pgno<=pPager->stmtSize 
  ){
    assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize );
    assert( pPager->aInStmt!=0 );
    pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
  }
  pagerLeave(pPager);
}


/*
** This routine is called to increment the database file change-counter,
** stored at byte 24 of the pager file.

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.403 2008/01/21 13:04:35 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*
................................................................................
** means that the pager does not have to record the given page in the
** rollback journal.
**
** If we have not yet actually read the content of this page (if
** the PgHdr.needRead flag is set) then this routine acts as a promise
** that we will never need to read the page content in the future.
** so the needRead flag can be cleared at this point.
**
** This routine is only called from a single place in the sqlite btree
** code (when a leaf is removed from the free-list). This allows the
** following assumptions to be made about pPg:
**
**   1. PagerDontWrite() has been called on the page, OR 
**      PagerWrite() has not yet been called on the page.
**
**   2. The page existed when the transaction was started.
**
** Details: DontRollback() (this routine) is only called when a leaf is
** removed from the free list. DontWrite() is called whenever a page 
** becomes a free-list leaf.
*/
void sqlite3PagerDontRollback(DbPage *pPg){
  Pager *pPager = pPg->pPager;

  pagerEnter(pPager);
  assert( pPager->state>=PAGER_RESERVED );

  /* If the journal file is not open, or DontWrite() has been called on
  ** this page (DontWrite() sets the alwaysRollback flag), then this
  ** function is a no-op.
  */
  if( pPager->journalOpen==0 || pPg->alwaysRollback || pPager->alwaysRollback ){

    pagerLeave(pPager);
    return;
  }
  assert( !MEMDB );    /* For a memdb, pPager->journalOpen is always 0 */

  /* Check that PagerWrite() has not yet been called on this page, and
  ** that the page existed when the transaction started.
  */
  assert( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize );

  assert( pPager->aInJournal!=0 );
  pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
  pPg->inJournal = 1;
  pPg->needRead = 0;
  if( pPager->stmtInUse ){
    assert( pPager->stmtSize <= pPager->origDbSize );
    pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
  }
  PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
  IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))









  pagerLeave(pPager);
}


/*
** This routine is called to increment the database file change-counter,
** stored at byte 24 of the pager file.