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 1.265 2005/08/27 16:36:49 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

*/
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
int sqlite3BtreeSetSafetyLevel(Btree *pBt, int level){
  sqlite3pager_set_safety_level(pBt->pPager, level);
  return SQLITE_OK;
}
#endif

/*
** Return TRUE if the given btree is set to safety level 1.  In other
** words, return TRUE if no sync() occurs on the disk files.
*/
int sqlite3BtreeSyncDisabled(Btree *pBt){
  assert( pBt && pBt->pPager );
  return sqlite3pager_nosync(pBt->pPager);
}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Change the default pages size and the number of reserved bytes per page.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
** size supplied does not meet this constraint then the page size is not

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.64 2005/08/27 16:36:49 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/

#define BTREE_NO_READLOCK   2  /* Omit readlocks on readonly files */
#define BTREE_MEMORY        4  /* In-memory DB.  No argument */

int sqlite3BtreeClose(Btree*);
int sqlite3BtreeSetBusyHandler(Btree*,BusyHandler*);
int sqlite3BtreeSetCacheSize(Btree*,int);
int sqlite3BtreeSetSafetyLevel(Btree*,int);
int sqlite3BtreeSyncDisabled(Btree*);
int sqlite3BtreeSetPageSize(Btree*,int,int);
int sqlite3BtreeGetPageSize(Btree*);
int sqlite3BtreeGetReserve(Btree*);
int sqlite3BtreeSetAutoVacuum(Btree *, int);
int sqlite3BtreeGetAutoVacuum(Btree *);
int sqlite3BtreeBeginTrans(Btree*,int);
int sqlite3BtreeCommit(Btree*);

** 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 1.210 2005/08/27 16:36:49 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

  rc = write32bits(&pPager->jfd, len);
  if( rc!=SQLITE_OK ) return rc;

  rc = write32bits(&pPager->jfd, cksum);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3OsWrite(&pPager->jfd, aJournalMagic, sizeof(aJournalMagic));
  pPager->needSync = !pPager->noSync;
  return rc;
}

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

/*
** Return the full pathname of the journal file.
*/
const char *sqlite3pager_journalname(Pager *pPager){
  return pPager->zJournal;
}

/*
** Return true if fsync() calls are disabled for this pager.  Return FALSE
** if fsync()s are executed normally.
*/
int sqlite3pager_nosync(Pager *pPager){
  return pPager->noSync;
}

/*
** Set the codec for this pager
*/
void sqlite3pager_set_codec(
  Pager *pPager,
  void (*xCodec)(void*,void*,Pgno,int),

**    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: pager.h,v 1.45 2005/08/27 16:36:49 drh Exp $
*/

/*
** The default size of a database page.
*/
#ifndef SQLITE_DEFAULT_PAGE_SIZE
# define SQLITE_DEFAULT_PAGE_SIZE 1024

void sqlite3pager_dont_rollback(void*);
void sqlite3pager_dont_write(Pager*, Pgno);
int *sqlite3pager_stats(Pager*);
void sqlite3pager_set_safety_level(Pager*,int);
const char *sqlite3pager_filename(Pager*);
const char *sqlite3pager_dirname(Pager*);
const char *sqlite3pager_journalname(Pager*);
int sqlite3pager_nosync(Pager*);
int sqlite3pager_rename(Pager*, const char *zNewName);
void sqlite3pager_set_codec(Pager*,void(*)(void*,void*,Pgno,int),void*);
int sqlite3pager_movepage(Pager*,void*,Pgno);
int sqlite3pager_reset(Pager*);

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
int sqlite3pager_lockstate(Pager*);
#endif

#ifdef SQLITE_TEST
void sqlite3pager_refdump(Pager*);
int pager3_refinfo_enable;
#endif

  /* The complex case - There is a multi-file write-transaction active.
  ** This requires a master journal file to ensure the transaction is
  ** committed atomicly.
  */
#ifndef SQLITE_OMIT_DISKIO
  else{
    int needSync = 0;
    char *zMaster = 0;   /* File-name for the master journal */
    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
    OsFile master;

    /* Select a master journal file name */
    do {
      u32 random;

    */
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( i==1 ) continue;   /* Ignore the TEMP database */
      if( pBt && sqlite3BtreeIsInTrans(pBt) ){
        char const *zFile = sqlite3BtreeGetJournalname(pBt);
        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
          needSync = 1;
        }
        rc = sqlite3OsWrite(&master, zFile, strlen(zFile)+1);
        if( rc!=SQLITE_OK ){
          sqlite3OsClose(&master);
          sqlite3OsDelete(zMaster);
          sqliteFree(zMaster);
          return rc;
        }
      }
    }


    /* Sync the master journal file. Before doing this, open the directory
    ** the master journal file is store in so that it gets synced too.
    */
    zMainFile = sqlite3BtreeGetDirname(db->aDb[0].pBt);
    rc = sqlite3OsOpenDirectory(zMainFile, &master);
    if( rc!=SQLITE_OK || (needSync && (rc=sqlite3OsSync(&master))!=SQLITE_OK) ){
      sqlite3OsClose(&master);
      sqlite3OsDelete(zMaster);
      sqliteFree(zMaster);
      return rc;
    }

    /* Sync all the db files involved in the transaction. The same call

# 2005 August 28
#
# 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.
#
# This file implements tests to verify that fsync is disabled when
# pragma synchronous=off even for multi-database commits.
#
# $Id: sync.test,v 1.1 2005/08/27 16:36:49 drh Exp $

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

#
# These tests are only applicable on unix when pager pragma are
# enabled.
#
if {$::tcl_platform(platform)!="unix"} {
  finish_test
}
ifcapable !pager_pragmas {
  finish_test
}

do_test sync-1.1 {
  set sqlite_sync_count 0
  file delete -force test2.db
  file delete -force test2.db-journal
  execsql {
    CREATE TABLE t1(a,b);
    ATTACH DATABASE 'test2.db' AS db2;
    CREATE TABLE db2.t2(x,y);
  }
  set sqlite_sync_count
} 8
do_test sync-1.2 {
  set sqlite_sync_count 0
  execsql {
    PRAGMA main.synchronous=on;
    PRAGMA db2.synchronous=on;
    BEGIN;
    INSERT INTO t1 VALUES(1,2);
    INSERT INTO t2 VALUES(3,4);
    COMMIT;
  }
  set sqlite_sync_count
} 8
do_test sync-1.3 {
  set sqlite_sync_count 0
  execsql {
    PRAGMA main.synchronous=full;
    PRAGMA db2.synchronous=full;
    BEGIN;
    INSERT INTO t1 VALUES(3,4);
    INSERT INTO t2 VALUES(5,6);
    COMMIT;
  }
  set sqlite_sync_count
} 10
do_test sync-1.4 {
  set sqlite_sync_count 0
  execsql {
    PRAGMA main.synchronous=off;
    PRAGMA db2.synchronous=off;
    BEGIN;
    INSERT INTO t1 VALUES(5,6);
    INSERT INTO t2 VALUES(7,8);
    COMMIT;
  }
  set sqlite_sync_count
} 0


finish_test