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Changes to src/wal.c.

  2490   2490     }
  2491   2491   
  2492   2492     assert( pWal->nWiData>0 );
  2493   2493     assert( pWal->apWiData[0]!=0 );
  2494   2494     pInfo = walCkptInfo(pWal);
  2495   2495     if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame
  2496   2496   #ifdef SQLITE_ENABLE_SNAPSHOT
  2497         -   && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0
  2498         -     || 0==memcmp(&pWal->hdr, pWal->pSnapshot, sizeof(WalIndexHdr)))
         2497  +   && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0)
  2499   2498   #endif
  2500   2499     ){
  2501   2500       /* The WAL has been completely backfilled (or it is empty).
  2502   2501       ** and can be safely ignored.
  2503   2502       */
  2504   2503       rc = walLockShared(pWal, WAL_READ_LOCK(0));
  2505   2504       walShmBarrier(pWal);

Added test/snapshot3.test.

            1  +# 2016 September 23
            2  +#
            3  +# The author disclaims copyright to this source code.  In place of
            4  +# a legal notice, here is a blessing:
            5  +#
            6  +#    May you do good and not evil.
            7  +#    May you find forgiveness for yourself and forgive others.
            8  +#    May you share freely, never taking more than you give.
            9  +#
           10  +#***********************************************************************
           11  +# This file implements regression tests for SQLite library. The focus
           12  +# of this file is the sqlite3_snapshot_xxx() APIs.
           13  +#
           14  +
           15  +set testdir [file dirname $argv0]
           16  +source $testdir/tester.tcl
           17  +ifcapable !snapshot {finish_test; return}
           18  +set testprefix snapshot3
           19  +
           20  +# This test does not work with the inmemory_journal permutation. The reason
           21  +# is that each connection opened as part of this permutation executes
           22  +# "PRAGMA journal_mode=memory", which fails if the database is in wal mode
           23  +# and there are one or more existing connections.
           24  +if {[permutation]=="inmemory_journal"} {
           25  +  finish_test
           26  +  return
           27  +}
           28  +
           29  +#-------------------------------------------------------------------------
           30  +# This block of tests verifies that it is not possible to wrap the wal
           31  +# file - using a writer or a "PRAGMA wal_checkpoint = TRUNCATE" - while
           32  +# there is an open snapshot transaction (transaction opened using
           33  +# sqlite3_snapshot_open()).
           34  +#
           35  +do_execsql_test 1.0 {
           36  +  CREATE TABLE t1(y);
           37  +  PRAGMA journal_mode = wal;
           38  +  INSERT INTO t1 VALUES(1);
           39  +  INSERT INTO t1 VALUES(2);
           40  +  INSERT INTO t1 VALUES(3);
           41  +  INSERT INTO t1 VALUES(4);
           42  +} {wal}
           43  +
           44  +do_test 1.1 {
           45  +  sqlite3 db2 test.db
           46  +  sqlite3 db3 test.db
           47  +
           48  +  execsql {SELECT * FROM sqlite_master} db2
           49  +  execsql {SELECT * FROM sqlite_master} db3
           50  +
           51  +  db2 trans { set snap [sqlite3_snapshot_get_blob db2 main] }
           52  +  db2 eval { SELECT * FROM t1 }
           53  +} {1 2 3 4}
           54  +
           55  +do_test 1.2 {
           56  +  execsql BEGIN db2
           57  +  sqlite3_snapshot_open_blob db2 main $snap
           58  +  db2 eval { SELECT * FROM t1 }
           59  +} {1 2 3 4}
           60  +
           61  +do_test 1.2 {
           62  +  execsql END db2
           63  +  execsql { PRAGMA wal_checkpoint }
           64  +
           65  +  execsql BEGIN db2
           66  +  sqlite3_snapshot_open_blob db2 main $snap
           67  +  db2 eval { SELECT * FROM t1 }
           68  +} {1 2 3 4}
           69  +
           70  +set sz [file size test.db-wal]
           71  +do_test 1.3 {
           72  +  execsql { PRAGMA wal_checkpoint = truncate }
           73  +  file size test.db-wal
           74  +} $sz
           75  +
           76  +do_test 1.4 {
           77  +  execsql BEGIN db3
           78  +  list [catch { sqlite3_snapshot_open_blob db3 main $snap } msg] $msg
           79  +} {0 {}}
           80  +
           81  +do_test 1.5 {
           82  +  db3 eval { SELECT * FROM t1; END }
           83  +} {1 2 3 4}
           84  +
           85  +do_test 1.6 {
           86  +  db2 eval { SELECT * FROM t1; END }
           87  +} {1 2 3 4}
           88  +
           89  +do_test 1.7 {
           90  +  execsql { PRAGMA wal_checkpoint = truncate }
           91  +  file size test.db-wal
           92  +} 0
           93  +
           94  +do_test 1.8 {
           95  +  execsql BEGIN db3
           96  +  list [catch { sqlite3_snapshot_open_blob db3 main $snap } msg] $msg
           97  +} {1 SQLITE_BUSY_SNAPSHOT}
           98  +
           99  +finish_test
          100  +