SQLite

Check-in [9a06660037]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:If after obtaining an exclusive lock to rollback a hot-journal file it is found that the journal file has been deleted, do not return an SQLITE_BUSY error. Just downgrade the lock and continue with the current operation. This eliminates a spurious SQLITE_BUSY error caused by a race condition. (CVS 6792)
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 9a0666003764774b0bf861687002f8db9fd314b1
User & Date: danielk1977 2009-06-20 11:54:39.000
Context
2009-06-20
18:52
When recovering from the error-state in pagerSharedLock(), do not search for a hot-journal in the file-system if the pager is configured to use an anonymous temp file as the journal. (CVS 6793) (check-in: 4b46805cbc user: danielk1977 tags: trunk)
11:54
If after obtaining an exclusive lock to rollback a hot-journal file it is found that the journal file has been deleted, do not return an SQLITE_BUSY error. Just downgrade the lock and continue with the current operation. This eliminates a spurious SQLITE_BUSY error caused by a race condition. (CVS 6792) (check-in: 9a06660037 user: danielk1977 tags: trunk)
2009-06-19
22:50
Improved documentation on the VFS methods. Ticket #3925. (CVS 6791) (check-in: f66fc7713e user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/pager.c.
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
** 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 1.598 2009/06/19 17:50:02 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/







|







14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
** 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 1.599 2009/06/20 11:54:39 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
** IO error occurs while locking the database, checking for a hot-journal
** file or rolling back a journal file, the IO error code is returned.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;                /* Return code */
  int isErrorReset = 0;              /* True if recovering from error state */

  /* If this database is opened for exclusive access, has no outstanding 
  ** page references and is in an error-state, this is a chance to clear
  ** the error. Discard the contents of the pager-cache and treat any
  ** open journal file as a hot-journal.
  */
  if( !MEMDB 
   && sqlite3PcacheRefCount(pPager->pPCache)==0 && pPager->errCode 
  ){
    if( isOpen(pPager->jfd) ){
      isErrorReset = 1;
    }
    pPager->errCode = SQLITE_OK;
    pager_reset(pPager);
  }

  /* If the pager is still in an error state, do not proceed. The error 
  ** state will be cleared at some point in the future when all page 
  ** references are dropped and the cache can be discarded.







|
|
|
|

<
|
<
<
|
<







3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578

3579


3580

3581
3582
3583
3584
3585
3586
3587
** IO error occurs while locking the database, checking for a hot-journal
** file or rolling back a journal file, the IO error code is returned.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;                /* Return code */
  int isErrorReset = 0;              /* True if recovering from error state */

  /* If this database has no outstanding page references and is in an 
  ** error-state, this is a chance to clear the error. Discard the 
  ** contents of the pager-cache and rollback any hot journal in the
  ** file-system.
  */

  if( !MEMDB && sqlite3PcacheRefCount(pPager->pPCache)==0 && pPager->errCode ){


    isErrorReset = 1;

    pPager->errCode = SQLITE_OK;
    pager_reset(pPager);
  }

  /* If the pager is still in an error state, do not proceed. The error 
  ** state will be cleared at some point in the future when all page 
  ** references are dropped and the cache can be discarded.
3658
3659
3660
3661
3662
3663
3664
3665
3666



3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685

3686
3687
3688
3689

3690
3691
3692
3693
3694
3695
3696
            rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
            assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
            if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
              rc = SQLITE_CANTOPEN;
              sqlite3OsClose(pPager->jfd);
            }
          }else{
            /* If the journal does not exist, that means some other process
            ** has already rolled it back */



            rc = SQLITE_BUSY;
          }
        }
      }
      if( rc!=SQLITE_OK ){
        goto failed;
      }

      /* TODO: Why are these cleared here? Is it necessary? */
      pPager->journalStarted = 0;
      pPager->journalOff = 0;
      pPager->setMaster = 0;
      pPager->journalHdr = 0;
 
      /* Playback and delete the journal.  Drop the database write
      ** lock and reacquire the read lock. Purge the cache before
      ** playing back the hot-journal so that we don't end up with
      ** an inconsistent cache.
      */

      rc = pager_playback(pPager, 1);
      if( rc!=SQLITE_OK ){
        rc = pager_error(pPager, rc);
        goto failed;

      }
      assert( (pPager->state==PAGER_SHARED)
           || (pPager->exclusiveMode && pPager->state>PAGER_SHARED)
      );
    }

    if( pPager->pBackup || sqlite3PcachePagecount(pPager->pPCache)>0 ){







|
|
>
>
>
|


















>
|
|
|
|
>







3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
            rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
            assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
            if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
              rc = SQLITE_CANTOPEN;
              sqlite3OsClose(pPager->jfd);
            }
          }else{
            /* If the journal does not exist, it usually means that some 
            ** other connection managed to get in and roll it back before 
            ** this connection obtained the exclusive lock above. Or, it 
            ** may mean that the pager was in the error-state when this
            ** function was called and the journal file does not exist.  */
            rc = pager_end_transaction(pPager, 0);
          }
        }
      }
      if( rc!=SQLITE_OK ){
        goto failed;
      }

      /* TODO: Why are these cleared here? Is it necessary? */
      pPager->journalStarted = 0;
      pPager->journalOff = 0;
      pPager->setMaster = 0;
      pPager->journalHdr = 0;
 
      /* Playback and delete the journal.  Drop the database write
      ** lock and reacquire the read lock. Purge the cache before
      ** playing back the hot-journal so that we don't end up with
      ** an inconsistent cache.
      */
      if( isOpen(pPager->jfd) ){
        rc = pager_playback(pPager, 1);
        if( rc!=SQLITE_OK ){
          rc = pager_error(pPager, rc);
          goto failed;
        }
      }
      assert( (pPager->state==PAGER_SHARED)
           || (pPager->exclusiveMode && pPager->state>PAGER_SHARED)
      );
    }

    if( pPager->pBackup || sqlite3PcachePagecount(pPager->pPCache)>0 ){