SQLite

  rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
  if( rc==SQLITE_OK && changed ){
    pager_reset(pPager);
  }

  return rc;
}
#endif

/*
** This function is called as part of the transition from PAGER_OPEN
** to PAGER_READER state to determine the size of the database file
** in pages (assuming the page size currently stored in Pager.pageSize).
**
** If no error occurs, SQLITE_OK is returned and the size of the database

  ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
  ** if the database size is not available. The database size is not
  ** available from the WAL sub-system if the log file is empty or
  ** contains no valid committed transactions.
  */
  assert( pPager->eState==PAGER_OPEN );
  assert( pPager->eLock>=SHARED_LOCK || pPager->noReadlock );
#ifndef SQLITE_OMIT_WAL
  nPage = sqlite3WalDbsize(pPager->pWal);
#else
  nPage = 0;
#endif

  /* If the database size was not available from the WAL sub-system,
  ** determine it based on the size of the database file. If the size
  ** of the database file is not an integer multiple of the page-size,
  ** round down to the nearest page. Except, any file larger than 0
  ** bytes in size is considered to contain at least one page.
  */

    pPager->mxPgno = (Pgno)nPage;
  }

  *pnPage = nPage;
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_WAL
/*
** Check if the *-wal file that corresponds to the database opened by pPager
** exists if the database is not empy, or verify that the *-wal file does
** not exist (by deleting it) if the database file is empty.
**
** If the database is not empty and the *-wal file exists, open the pager
** in WAL mode.  If the database is empty or if no *-wal file exists and

      }
    }

    /* If there is a WAL file in the file-system, open this database in WAL
    ** mode. Otherwise, the following function call is a no-op.
    */
    rc = pagerOpenWalIfPresent(pPager);
#ifndef SQLITE_OMIT_WAL
    assert( pPager->pWal==0 || rc==SQLITE_OK );
#endif
  }

  if( pagerUseWal(pPager) ){
    assert( rc==SQLITE_OK );
    rc = pagerBeginReadTransaction(pPager);
  }

do_test pager1-20.2.2 {
  execsql {
    BEGIN EXCLUSIVE;
    COMMIT;
  }
} {}

ifcapable wal {
  do_test pager1-20.3.1 {
    faultsim_delete_and_reopen
    db func a_string a_string
    execsql {
      PRAGMA cache_size = 10;
      PRAGMA journal_mode = wal;
      BEGIN;
        CREATE TABLE t1(x);
        CREATE TABLE t2(y);
        INSERT INTO t1 VALUES(a_string(800));
        INSERT INTO t1 SELECT a_string(800) FROM t1;         /*   2 */
        INSERT INTO t1 SELECT a_string(800) FROM t1;         /*   4 */
        INSERT INTO t1 SELECT a_string(800) FROM t1;         /*   8 */
        INSERT INTO t1 SELECT a_string(800) FROM t1;         /*  16 */
        INSERT INTO t1 SELECT a_string(800) FROM t1;         /*  32 */
      COMMIT;
    }
  } {wal}
  do_test pager1-20.3.2 {
    execsql {
      BEGIN;
      INSERT INTO t2 VALUES('xxxx');
    }
    recursive_select 32 t1
    execsql COMMIT
  } {}
}

#-------------------------------------------------------------------------
# Test that a WAL database may not be opened if:
#
#   pager1-21.1.*: The VFS has an iVersion less than 2, or
#   pager1-21.2.*: The VFS does not provide xShmXXX() methods.
#
ifcapable wal {
  do_test pager1-21.0 {
    faultsim_delete_and_reopen
    execsql {
      PRAGMA journal_mode = WAL;
      CREATE TABLE ko(c DEFAULT 'abc', b DEFAULT 'def');
      INSERT INTO ko DEFAULT VALUES;
    }
  } {wal}
  do_test pager1-21.1 {
    testvfs tv -noshm 1
    sqlite3 db2 test.db -vfs tv
    catchsql { SELECT * FROM ko } db2
  } {1 {unable to open database file}}
  db2 close
  tv delete
  do_test pager1-21.2 {
    testvfs tv -iversion 1
    sqlite3 db2 test.db -vfs tv
    catchsql { SELECT * FROM ko } db2
  } {1 {unable to open database file}}
  db2 close
  tv delete
}

#-------------------------------------------------------------------------
# Test that a "PRAGMA wal_checkpoint":
#
#   pager1-22.1.*: is a no-op on a non-WAL db, and
#   pager1-22.2.*: does not cause xSync calls with a synchronous=off db.
#

#-------------------------------------------------------------------------
# Test that attempting to open a write-transaction with 
# locking_mode=exclusive in WAL mode fails if there are other clients on 
# the same database.
#
catch { db close }
ifcapable wal {
  do_multiclient_test tn {
    do_test pager1-28.$tn.1 {
      sql1 { 
        PRAGMA journal_mode = WAL;
        CREATE TABLE t1(a, b);
        INSERT INTO t1 VALUES('a', 'b');
      }
    } {wal}
    do_test pager1-28.$tn.2 { sql2 { SELECT * FROM t1 } } {a b}

    do_test pager1-28.$tn.3 { sql1 { PRAGMA locking_mode=exclusive } } {exclusive}
    do_test pager1-28.$tn.4 { 
      csql1 { BEGIN; INSERT INTO t1 VALUES('c', 'd'); }
    } {1 {database is locked}}
    code2 { db2 close ; sqlite3 db2 test.db }
    do_test pager1-28.$tn.4 { 
      sql1 { INSERT INTO t1 VALUES('c', 'd'); COMMIT }
    } {}
  }
}

#-------------------------------------------------------------------------
# Normally, when changing from journal_mode=PERSIST to DELETE the pager
# attempts to delete the journal file. However, if it cannot obtain a
# RESERVED lock on the database file, this step is skipped.
#

db func a_string a_string

register_dbstat_vtab db
do_execsql_test stat-0.0 {
  CREATE VIRTUAL TABLE temp.stat USING dbstat;
  SELECT * FROM stat;
} {}

ifcapable wal {
  do_execsql_test stat-0.1 {
    PRAGMA journal_mode = WAL;
    PRAGMA journal_mode = delete;
    SELECT * FROM stat;
  } {wal delete sqlite_master / 1 leaf 0 0 916 0}
}

do_test stat-1.0 {
  execsql {
    CREATE TABLE t1(a, b);
    CREATE INDEX i1 ON t1(b);
    INSERT INTO t1(rowid, a, b) VALUES(2, 2, 3);
    INSERT INTO t1(rowid, a, b) VALUES(3, 4, 5);

# This file implements regression tests for SQLite library.  The
# focus of this file is testing the operation of the library in
# "PRAGMA journal_mode=WAL" mode with shared-cache turned on.
#

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

ifcapable !wal {finish_test ; return }

db close
set ::enable_shared_cache [sqlite3_enable_shared_cache 1]

sqlite3 db  test.db
sqlite3 db2 test.db

do_test walshared-1.0 {