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Overview
Comment:Fix a problem causing corruption when an UNLOCKED transaction is rolled back.
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SHA1: 7c36147846484c96023939864417b5624f3bc5f8
User & Date: dan 2015-08-20 20:25:56
Wiki:begin-concurrent
Context
2015-08-21
14:21
Add extra tests and a fix for rollbacks of UNLOCKED transactions. check-in: 82cd837e user: dan tags: begin-concurrent
2015-08-20
20:25
Fix a problem causing corruption when an UNLOCKED transaction is rolled back. check-in: 7c361478 user: dan tags: begin-concurrent
2015-08-19
20:27
When committing an unlocked transaction, relocate newly allocated database pages within the file to avoid conflicting with committed transactions. There are lots of things still to fix in this code. check-in: 3bbc31d5 user: dan tags: begin-concurrent
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/pager.c.

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/*
** This function is called to rollback a transaction on a WAL database.
*/
static int pagerRollbackWal(Pager *pPager){
  int rc;                         /* Return Code */
  PgHdr *pList;                   /* List of dirty pages to revert */


  /* For all pages in the cache that are currently dirty or have already
  ** been written (but not committed) to the log file, do one of the 
  ** following:
  **
  **   + Discard the cached page (if refcount==0), or
  **   + Reload page content from the database (if refcount>0).
  */
  pPager->dbSize = pPager->dbOrigSize;
  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
  pList = sqlite3PcacheDirtyList(pPager->pPCache);
  while( pList && rc==SQLITE_OK ){
    PgHdr *pNext = pList->pDirty;

    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }








  return rc;
}

/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),







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/*
** This function is called to rollback a transaction on a WAL database.
*/
static int pagerRollbackWal(Pager *pPager){
  int rc;                         /* Return Code */
  PgHdr *pList;                   /* List of dirty pages to revert */
  int bPage1 = 0;                 /* True if page 1 has been undone */

  /* For all pages in the cache that are currently dirty or have already
  ** been written (but not committed) to the log file, do one of the 
  ** following:
  **
  **   + Discard the cached page (if refcount==0), or
  **   + Reload page content from the database (if refcount>0).
  */
  pPager->dbSize = pPager->dbOrigSize;
  rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
  pList = sqlite3PcacheDirtyList(pPager->pPCache);
  while( pList && rc==SQLITE_OK ){
    PgHdr *pNext = pList->pDirty;
    if( pList->pgno==1 ) bPage1 = 1;
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }

  /* If this is an UNLOCKED transaction, then page 1 must be reread from the
  ** db file, even if it is not dirty. This is because the b-tree layer may
  ** have already zeroed the nFree and iTrunk header fields.  */
  if( rc==SQLITE_OK && bPage1==0 && pPager->pAllRead ){
    rc = pagerUndoCallback((void*)pPager, 1);
  }

  return rc;
}

/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),

Changes to test/unlocked2.test.

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    sql1 { 
      BEGIN UNLOCKED;
        INSERT INTO t1 VALUES(randomblob(1500));
    }
    sql2 {
      INSERT INTO t2 VALUES(randomblob(1500));
    }






    sql1 {






      COMMIT;

    }




















  } {}

  do_test 2.$tn.3 { sql3 { PRAGMA integrity_check } } {ok}
}



























finish_test








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    sql1 { 
      BEGIN UNLOCKED;
        INSERT INTO t1 VALUES(randomblob(1500));
    }
    sql2 {
      INSERT INTO t2 VALUES(randomblob(1500));
    }
    sql1 COMMIT
  } {}

  do_test 2.$tn.3 { sql3 { PRAGMA integrity_check } } {ok}

  do_test 2.$tn.4  {
    sql1 { 
      BEGIN UNLOCKED;
        DELETE FROM t1;
    }
    sql2 {
      DELETE FROM t2;
    }
    sql1 COMMIT
  } {}

  do_test 2.$tn.5 { sql3 { PRAGMA integrity_check } } {ok}

  do_test 2.$tn.6 {
    sql1 {
      INSERT INTO t1 VALUES(randomblob(1500));
      INSERT INTO t1 VALUES(randomblob(1500));
      INSERT INTO t2 VALUES(randomblob(1500));
      DELETE FROM t1 WHERE rowid=1;
    }

    sql1 {
      BEGIN UNLOCKED;
        DELETE FROM t1 WHERE rowid=2;
    }

    sql2 {
      DELETE FROM t2;
    }

    sql1 COMMIT
  } {}

  do_test 2.$tn.7 { sql3 { PRAGMA integrity_check } } {ok}
}

reset_db
do_execsql_test 3.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(x, y);
  INSERT INTO t1 VALUES(randomblob(1500), randomblob(1500));
  DELETE FROM t1;
} {wal}

db close
sqlite3 db test.db
breakpoint

do_execsql_test 3.1 {
  BEGIN UNLOCKED;
    INSERT INTO t1 VALUES(1, 2);
  ROLLBACK;
}

do_execsql_test 3.2 {
  PRAGMA integrity_check;
} {ok}

do_execsql_test 3.3 {
  PRAGMA freelist_count;
} {2}

finish_test