SQLite

/*
** 2004 April 6
**
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.457 2008/05/07 19:11:03 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

    ** present in pTo before the copy operation, journal page i from pTo.
    */
    if( i!=iSkip && i<=nToPage ){
      DbPage *pDbPage = 0;
      rc = sqlite3PagerGet(pBtTo->pPager, i, &pDbPage);
      if( rc==SQLITE_OK ){
        rc = sqlite3PagerWrite(pDbPage);

        if( rc==SQLITE_OK && i>nFromPage ){
          /* Yeah.  It seems wierd to call DontWrite() right after Write(). But
          ** that is because the names of those procedures do not exactly 
          ** represent what they do.  Write() really means "put this page in the
          ** rollback journal and mark it as dirty so that it will be written
          ** to the database file later."  DontWrite() undoes the second part of
          ** that and prevents the page from being written to the database. The
          ** page is still on the rollback journal, though.  And that is the 
          ** whole point of this block: to put pages on the rollback journal. 
          */
          sqlite3PagerDontWrite(pDbPage);
        }
        sqlite3PagerUnref(pDbPage);
      }
    }

    /* Overwrite the data in page i of the target database */
    if( rc==SQLITE_OK && i!=iSkip && i<=nNewPage ){

      DbPage *pToPage = 0;
      sqlite3_int64 iOff;

** 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 1.443 2008/05/07 19:11:03 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*

}

/*
** Write zeros over the header of the journal file.  This has the
** effect of invalidating the journal file and committing the
** transaction.
*/
static int zeroJournalHdr(Pager *pPager, int doTruncate){
  int rc = SQLITE_OK;
  static const char zeroHdr[28];

  if( pPager->journalOff ){
    IOTRACE(("JZEROHDR %p\n", pPager))
    if( doTruncate ){
      rc = sqlite3OsTruncate(pPager->jfd, 0);
    }else{
      rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
    }
    if( rc==SQLITE_OK ){
      rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->sync_flags);
    }
  }
  return rc;
}

/*
** The journal file must be open when this routine is called. A journal
** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the

** this call is a no-op.
*/
static int writeMasterJournal(Pager *pPager, const char *zMaster){
  int rc;
  int len; 
  int i; 
  i64 jrnlOff;
  i64 jrnlSize;
  u32 cksum = 0;
  char zBuf[sizeof(aJournalMagic)+2*4];

  if( !zMaster || pPager->setMaster) return SQLITE_OK;
  pPager->setMaster = 1;

  len = strlen(zMaster);

  if( rc!=SQLITE_OK ) return rc;
  jrnlOff += len;

  put32bits(zBuf, len);
  put32bits(&zBuf[4], cksum);
  memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic));
  rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic), jrnlOff);
  jrnlOff += 8+sizeof(aJournalMagic);
  pPager->needSync = !pPager->noSync;

  /* If the pager is in peristent-journal mode, then the physical 
  ** journal-file may extend past the end of the master-journal name
  ** and 8 bytes of magic data just written to the file. This is 
  ** dangerous because the code to rollback a hot-journal file
  ** will not be able to find the master-journal name to determine 
  ** whether or not the journal is hot. 
  **
  ** Easiest thing to do in this scenario is to truncate the journal 
  ** file to the required size.
  */ 
  if( (rc==SQLITE_OK)
   && (rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))==SQLITE_OK
   && jrnlSize>jrnlOff
  ){
    rc = sqlite3OsTruncate(pPager->jfd, jrnlOff);
  }
  return rc;
}

/*
** Add or remove a page from the list of all pages that are in the
** statement journal.
**

**
** The journal file is either deleted or truncated.
**
** TODO: Consider keeping the journal file open for temporary databases.
** This might give a performance improvement on windows where opening
** a file is an expensive operation.
*/
static int pager_end_transaction(Pager *pPager, int hasMaster){
  PgHdr *pPg;
  int rc = SQLITE_OK;
  int rc2 = SQLITE_OK;
  assert( !MEMDB );
  if( pPager->state<PAGER_RESERVED ){
    return SQLITE_OK;
  }
  sqlite3PagerStmtCommit(pPager);
  if( pPager->stmtOpen && !pPager->exclusiveMode ){
    sqlite3OsClose(pPager->stfd);
    pPager->stmtOpen = 0;
  }
  if( pPager->journalOpen ){
    if( (pPager->exclusiveMode ||
         pPager->journalMode==PAGER_JOURNALMODE_PERSIST) 
       && (rc = zeroJournalHdr(pPager, hasMaster))==SQLITE_OK ){
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      sqlite3OsClose(pPager->jfd);
      pPager->journalOpen = 0;
      if( rc==SQLITE_OK ){
        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);

end_playback:
  if( rc==SQLITE_OK ){
    zMaster = pPager->pTmpSpace;
    rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
  }
  if( rc==SQLITE_OK ){
    rc = pager_end_transaction(pPager, zMaster[0]!='\0');
  }
  if( rc==SQLITE_OK && zMaster[0] ){
    /* If there was a master journal and this routine will return success,
    ** see if it is possible to delete the master journal.
    */
    rc = pager_delmaster(pPager, zMaster);
  }

  rc = writeJournalHdr(pPager);

  if( pPager->stmtAutoopen && rc==SQLITE_OK ){
    rc = sqlite3PagerStmtBegin(pPager);
  }
  if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && rc!=SQLITE_IOERR_NOMEM ){
    rc = pager_end_transaction(pPager, 0);
    if( rc==SQLITE_OK ){
      rc = SQLITE_FULL;
    }
  }
  return rc;

failed_to_open_journal:

#endif
    pPager->pStmt = 0;
    pPager->state = PAGER_SHARED;
    pagerLeave(pPager);
    return SQLITE_OK;
  }
  assert( pPager->state==PAGER_SYNCED || !pPager->dirtyCache );
  rc = pager_end_transaction(pPager, pPager->setMaster);
  rc = pager_error(pPager, rc);
  pagerLeave(pPager);
  return rc;
}

/*
** Rollback all changes.  The database falls back to PAGER_SHARED mode.

    pPager->stmtInUse = 0;
    pPager->state = PAGER_SHARED;
    return SQLITE_OK;
  }

  pagerEnter(pPager);
  if( !pPager->dirtyCache || !pPager->journalOpen ){
    rc = pager_end_transaction(pPager, pPager->setMaster);
    pagerLeave(pPager);
    return rc;
  }

  if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
    if( pPager->state>=PAGER_EXCLUSIVE ){
      pager_playback(pPager, 0);
    }
    pagerLeave(pPager);
    return pPager->errCode;
  }
  if( pPager->state==PAGER_RESERVED ){
    int rc2;
    rc = pager_playback(pPager, 0);
    rc2 = pager_end_transaction(pPager, pPager->setMaster);
    if( rc==SQLITE_OK ){
      rc = rc2;
    }
  }else{
    rc = pager_playback(pPager, 0);
  }
  /* pager_reset(pPager); */

# 2008 April 17
#
# 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 file implements regression tests for SQLite library. The focus
# of these tests is the journal mode pragma.
#
# $Id: jrnlmode.test,v 1.2 2008/05/07 19:11:03 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

ifcapable {!pager_pragmas} {
  finish_test
  return

    execsql {
      DETACH aux1;
      DETACH aux2;
      DETACH aux3;
    }
  } {}
}

ifcapable attach {
  file delete -force test2.db
  do_test jrnlmode-2.1 {
    execsql {
      ATTACH 'test2.db' AS aux;
      PRAGMA main.journal_mode = persist;
      PRAGMA aux.journal_mode = persist;
      CREATE TABLE abc(a, b, c);
      CREATE TABLE aux.def(d, e, f);
    }
    execsql {
      BEGIN;
      INSERT INTO abc VALUES(1, 2, 3);
      INSERT INTO def VALUES(4, 5, 6);
      COMMIT;
    }
    list [file exists test.db-journal] [file exists test2.db-journal]
  } {1 1}

  do_test jrnlmode-2.2 {
    file size test.db-journal
  } {0}

  do_test jrnlmode-2.3 {
    execsql {
      SELECT * FROM abc;
    }
  } {1 2 3}

  do_test jrnlmode-2.4 {
    file size test.db-journal
  } {0}

  do_test jrnlmode-2.5 {
    execsql {
      SELECT * FROM def;
    }
  } {4 5 6}

}




finish_test