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Overview
Comment:Fix a problem allowing a conflicting transaction to be committed in the case where more than one 32KB shared-memory page has been written to since the transaction was started.
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Timelines: family | ancestors | descendants | both | begin-concurrent
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SHA3-256: 38dd9b50fe260d853cbc2551bc1bb60ddf5752f0456e0da3afe4cbf728c891d8
User & Date: dan 2017-08-11 21:16:23.047
Context
2017-08-15
01:07
Fix a problem allowing a conflicting transaction to be committed in the case where more than one 32KB shared-memory page has been written to since the transaction was started. (check-in: 346a710da4 user: drh tags: begin-concurrent-branch-3.19)
2017-08-12
14:06
Add a more rigorous test case for the bug fixed by the previous commit on this branch. (check-in: 4256072399 user: dan tags: begin-concurrent)
2017-08-11
21:16
Fix a problem allowing a conflicting transaction to be committed in the case where more than one 32KB shared-memory page has been written to since the transaction was started. (check-in: 38dd9b50fe user: dan tags: begin-concurrent)
20:22
Add another PAGERTRACE() macro to show when pages are added to Pager.pAllRead. No impact on production builds. (check-in: 11054cf5e8 user: drh tags: begin-concurrent)
Changes
Side-by-Side Diff Ignore Whitespace Patch
Changes to src/wal.c.
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        volatile ht_slot *aHash;
        volatile u32 *aPgno;
        u32 iZero;

        rc = walHashGet(pWal, iHash, &aHash, &aPgno, &iZero);
        if( rc==SQLITE_OK ){
          u32 i, iMin, iMax;
          assert( iFirst >= iZero );
          iMin = (iFirst - iZero);
          assert( head.mxFrame>=iZero );
          iMin = (iZero >= iFirst) ? 1 : (iFirst - iZero);
          iMax = (iHash==0) ? HASHTABLE_NPAGE_ONE : HASHTABLE_NPAGE;
          if( iMin<1 ) iMin = 1;
          if( iMax>head.mxFrame ) iMax = head.mxFrame;
          if( iMax>(head.mxFrame-iZero) ) iMax = (head.mxFrame-iZero);
          for(i=iMin; rc==SQLITE_OK && i<=iMax; i++){
            PgHdr *pPg;
            if( aPgno[i]==1 ){
              /* Check that the schema cookie has not been modified. If
              ** it has not, the commit can proceed. */
              u8 aNew[4];
              u8 *aOld = &((u8*)pPage1->pData)[40];
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Changes to test/concurrent.test.
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      INSERT INTO t2 VALUES(3, 'three');
    }
  } {}

  do_test 6.$tn.2 {
    list [catch { sql2 { COMMIT } } msg] $msg
  } {1 {database is locked}}
}

do_multiclient_test tn {
  do_test 7.$tn.1 {
    sql1 {
      PRAGMA journal_mode = wal;
      CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100) 
      INSERT INTO t1 SELECT NULL, randomblob(400) FROM s;

      CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<50000) 
      INSERT INTO t2 SELECT NULL, randomblob(400) FROM s;

      CREATE TABLE t3(a INTEGER PRIMARY KEY, b);
      WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100) 
      INSERT INTO t3 SELECT NULL, randomblob(400) FROM s;

      CREATE TABLE t4(a INTEGER PRIMARY KEY, b);

      PRAGMA wal_checkpoint;
    }
    set {} {}
  } {}

  do_test 7.$tn.2 {
    sql2 {
      BEGIN CONCURRENT;
        SELECT * FROM t1;
        INSERT INTO t4 VALUES(1, 2);
    }
    set {} {}
  } {}

  do_test 7.$tn.3 {
    sql3 {
      BEGIN CONCURRENT;
        SELECT * FROM t3;
        INSERT INTO t4 VALUES(1, 2);
    }
    set {} {}
  } {}

  do_test 7.$tn.4 {
    sql1 {
      UPDATE t1 SET b=randomblob(400);
      UPDATE t2 SET b=randomblob(400);
      UPDATE t3 SET b=randomblob(400);
    }
  } {}

  do_test 7.$tn.5 {
    csql2 { COMMIT } 
  } {1 {database is locked}}

  do_test 7.$tn.6 {
    csql3 { COMMIT } 
  } {1 {database is locked}}

}

finish_test