/ Artifact Content
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact 1f841d2048080d32f552942e333fd99ce541dada:


# 2010 May 5
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# 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.
#

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

set testprefix wal2

ifcapable !wal {finish_test ; return }

set sqlite_sync_count 0
proc cond_incr_sync_count {adj} {
  global sqlite_sync_count
  if {$::tcl_platform(platform) == "windows"} {
    incr sqlite_sync_count $adj
  } {
    ifcapable !dirsync {
      incr sqlite_sync_count $adj
    }
  }
}

proc set_tvfs_hdr {file args} {

  # Set $nHdr to the number of bytes in the wal-index header:
  set nHdr 48
  set nInt [expr {$nHdr/4}]

  if {[llength $args]>2} {
    error {wrong # args: should be "set_tvfs_hdr fileName ?val1? ?val2?"}
  }

  set blob [tvfs shm $file]
  if {$::tcl_platform(byteOrder)=="bigEndian"} {set fmt I} {set fmt i}

  if {[llength $args]} {
    set ia [lindex $args 0]
    set ib $ia
    if {[llength $args]==2} {
      set ib [lindex $args 1]
    }
    binary scan $blob a[expr $nHdr*2]a* dummy tail
    set blob [binary format ${fmt}${nInt}${fmt}${nInt}a* $ia $ib $tail]
    tvfs shm $file $blob
  }

  binary scan $blob ${fmt}${nInt} ints
  return $ints
}

proc incr_tvfs_hdr {file idx incrval} {
  set ints [set_tvfs_hdr $file]
  set v [lindex $ints $idx]
  incr v $incrval
  lset ints $idx $v
  set_tvfs_hdr $file $ints
}


#-------------------------------------------------------------------------
# Test case wal2-1.*:
#
# Set up a small database containing a single table. The database is not
# checkpointed during the test - all content resides in the log file.
#
# Two connections are established to the database file - a writer ([db])
# and a reader ([db2]). For each of the 8 integer fields in the wal-index
# header (6 fields and 2 checksum values), do the following:
#
#   1. Modify the database using the writer.
#
#   2. Attempt to read the database using the reader. Before the reader
#      has a chance to snapshot the wal-index header, increment one
#      of the integer fields (so that the reader ends up with a corrupted
#      header).
#
#   3. Check that the reader recovers the wal-index and reads the correct
#      database content.
#
do_test wal2-1.0 {
  proc tvfs_cb {method filename args} { 
    set ::filename $filename
    return SQLITE_OK 
  }

  testvfs tvfs
  tvfs script tvfs_cb
  tvfs filter xShmOpen

  sqlite3 db  test.db -vfs tvfs
  sqlite3 db2 test.db -vfs tvfs

  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a);
  } db2
  execsql {
    INSERT INTO t1 VALUES(1);
    INSERT INTO t1 VALUES(2);
    INSERT INTO t1 VALUES(3);
    INSERT INTO t1 VALUES(4);
    SELECT count(a), sum(a) FROM t1;
  }
} {4 10}
do_test wal2-1.1 {
  execsql { SELECT count(a), sum(a) FROM t1 } db2
} {4 10}

set RECOVER [list                                      \
  {0 1 lock exclusive}   {1 7 lock exclusive}          \
  {1 7 unlock exclusive} {0 1 unlock exclusive}        \
]
set READ [list                                         \
  {4 1 lock shared}    {4 1 unlock shared}             \
]
set INITSLOT [list                                     \
  {4 1 lock exclusive} {4 1 unlock exclusive}          \
]

foreach {tn iInsert res wal_index_hdr_mod wal_locks} "
         2    5   {5 15}    0             {$RECOVER $READ}
         3    6   {6 21}    1             {$RECOVER $READ}
         4    7   {7 28}    2             {$RECOVER $READ}
         5    8   {8 36}    3             {$RECOVER $READ}
         6    9   {9 45}    4             {$RECOVER $READ}
         7   10   {10 55}   5             {$RECOVER $READ}
         8   11   {11 66}   6             {$RECOVER $READ}
         9   12   {12 78}   7             {$RECOVER $READ}
        10   13   {13 91}   8             {$RECOVER $READ}
        11   14   {14 105}  9             {$RECOVER $READ}
        12   15   {15 120}  -1            {$INITSLOT $READ}
" {

  do_test wal2-1.$tn.1 {
    execsql { INSERT INTO t1 VALUES($iInsert) }
    set ::locks [list]
    proc tvfs_cb {method args} {
      lappend ::locks [lindex $args 2]
      return SQLITE_OK
    }
    tvfs filter xShmLock
    if {$::wal_index_hdr_mod >= 0} {
      incr_tvfs_hdr $::filename $::wal_index_hdr_mod 1
    }
    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res

  do_test wal2-1.$tn.2 {
    set ::locks
  } $wal_locks
}
db close
db2 close
tvfs delete
forcedelete test.db test.db-wal test.db-journal

#-------------------------------------------------------------------------
# This test case is very similar to the previous one, except, after
# the reader reads the corrupt wal-index header, but before it has
# a chance to re-read it under the cover of the RECOVER lock, the
# wal-index header is replaced with a valid, but out-of-date, header.
#
# Because the header checksum looks Ok, the reader does not run recovery,
# it simply drops back to a READ lock and proceeds. But because the
# header is out-of-date, the reader reads the out-of-date snapshot.
#
# After this, the header is corrupted again and the reader is allowed
# to run recovery. This time, it sees an up-to-date snapshot of the
# database file.
#
set WRITER [list 0 1 lock exclusive]
set LOCKS  [list \
  {0 1 lock exclusive} {0 1 unlock exclusive} \
  {4 1 lock exclusive} {4 1 unlock exclusive} \
  {4 1 lock shared}    {4 1 unlock shared}    \
]
do_test wal2-2.0 {

  testvfs tvfs
  tvfs script tvfs_cb
  tvfs filter xShmOpen
  proc tvfs_cb {method args} {
    set ::filename [lindex $args 0]
    return SQLITE_OK
  }

  sqlite3 db  test.db -vfs tvfs
  sqlite3 db2 test.db -vfs tvfs

  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a);
  } db2
  execsql {
    INSERT INTO t1 VALUES(1);
    INSERT INTO t1 VALUES(2);
    INSERT INTO t1 VALUES(3);
    INSERT INTO t1 VALUES(4);
    SELECT count(a), sum(a) FROM t1;
  }
} {4 10}
do_test wal2-2.1 {
  execsql { SELECT count(a), sum(a) FROM t1 } db2
} {4 10}

foreach {tn iInsert res0 res1 wal_index_hdr_mod} {
         2    5   {4 10}   {5 15}    0
         3    6   {5 15}   {6 21}    1
         4    7   {6 21}   {7 28}    2
         5    8   {7 28}   {8 36}    3
         6    9   {8 36}   {9 45}    4
         7   10   {9 45}   {10 55}   5
         8   11   {10 55}  {11 66}   6
         9   12   {11 66}  {12 78}   7
} {
  tvfs filter xShmLock

  do_test wal2-2.$tn.1 {
    set oldhdr [set_tvfs_hdr $::filename]
    execsql { INSERT INTO t1 VALUES($iInsert) }
    execsql { SELECT count(a), sum(a) FROM t1 }
  } $res1

  do_test wal2-2.$tn.2 {
    set ::locks [list]
    proc tvfs_cb {method args} {
      set lock [lindex $args 2]
      lappend ::locks $lock
      if {$lock == $::WRITER} {
        set_tvfs_hdr $::filename $::oldhdr
      }
      return SQLITE_OK
    }

    if {$::wal_index_hdr_mod >= 0} {
      incr_tvfs_hdr $::filename $::wal_index_hdr_mod 1
    }
    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res0

  do_test wal2-2.$tn.3 {
    set ::locks
  } $LOCKS

  do_test wal2-2.$tn.4 {
    set ::locks [list]
    proc tvfs_cb {method args} {
      set lock [lindex $args 2]
      lappend ::locks $lock
      return SQLITE_OK
    }

    if {$::wal_index_hdr_mod >= 0} {
      incr_tvfs_hdr $::filename $::wal_index_hdr_mod 1
    }
    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res1
}
db close
db2 close
tvfs delete
forcedelete test.db test.db-wal test.db-journal


if 0 {
#-------------------------------------------------------------------------
# This test case - wal2-3.* - tests the response of the library to an
# SQLITE_BUSY when attempting to obtain a READ or RECOVER lock.
#
#   wal2-3.0 - 2: SQLITE_BUSY when obtaining a READ lock
#   wal2-3.3 - 6: SQLITE_BUSY when obtaining a RECOVER lock
#
do_test wal2-3.0 {
  proc tvfs_cb {method args} {
    if {$method == "xShmLock"} {
      if {[info exists ::locked]} { return SQLITE_BUSY }
    }
    return SQLITE_OK
  }

  proc busyhandler x {
    if {$x>3} { unset -nocomplain ::locked }
    return 0
  }

  testvfs tvfs
  tvfs script tvfs_cb
  sqlite3 db test.db -vfs tvfs
  db busy busyhandler

  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a);
    INSERT INTO t1 VALUES(1);
    INSERT INTO t1 VALUES(2);
    INSERT INTO t1 VALUES(3);
    INSERT INTO t1 VALUES(4);
  } 

  set ::locked 1
  info exists ::locked
} {1}
do_test wal2-3.1 {
  execsql { SELECT count(a), sum(a) FROM t1 }
} {4 10}
do_test wal2-3.2 {
  info exists ::locked
} {0}

do_test wal2-3.3 {
  proc tvfs_cb {method args} {
    if {$method == "xShmLock"} {
      if {[info exists ::sabotage]} {
        unset -nocomplain ::sabotage
        incr_tvfs_hdr [lindex $args 0] 1 1
      }
      if {[info exists ::locked] && [lindex $args 2] == "RECOVER"} {
        return SQLITE_BUSY
      }
    }
    return SQLITE_OK
  }
  set ::sabotage 1
  set ::locked 1
  list [info exists ::sabotage] [info exists ::locked]
} {1 1}
do_test wal2-3.4 {
  execsql { SELECT count(a), sum(a) FROM t1 }
} {4 10}
do_test wal2-3.5 {
  list [info exists ::sabotage] [info exists ::locked]
} {0 0}
db close
tvfs delete
forcedelete test.db test.db-wal test.db-journal

}

#-------------------------------------------------------------------------
# Test that a database connection using a VFS that does not support the
# xShmXXX interfaces cannot open a WAL database.
#
do_test wal2-4.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA auto_vacuum = 0;
    PRAGMA journal_mode = WAL;
    CREATE TABLE data(x);
    INSERT INTO data VALUES('need xShmOpen to see this');
    PRAGMA wal_checkpoint;
  }
  # Three pages in the WAL file at this point: One copy of page 1 and two
  # of the root page for table "data".
} {wal 0 3 3}
do_test wal2-4.2 {
  db close
  testvfs tvfs -noshm 1
  sqlite3 db test.db -vfs tvfs
  catchsql { SELECT * FROM data }
} {1 {unable to open database file}}
do_test wal2-4.3 {
  db close
  testvfs tvfs
  sqlite3 db test.db -vfs tvfs
  catchsql { SELECT * FROM data }
} {0 {{need xShmOpen to see this}}}
db close
tvfs delete

#-------------------------------------------------------------------------
# Test that if a database connection is forced to run recovery before it
# can perform a checkpoint, it does not transition into RECOVER state.
#
# UPDATE: This has now changed. When running a checkpoint, if recovery is
# required the client grabs all exclusive locks (just as it would for a
# recovery performed as a pre-cursor to a normal database transaction).
#
set expected_locks [list]
lappend expected_locks {1 1 lock exclusive}   ;# Lock checkpoint
lappend expected_locks {0 1 lock exclusive}   ;# Lock writer
lappend expected_locks {2 6 lock exclusive}   ;# Lock recovery & all aReadMark[]
lappend expected_locks {2 6 unlock exclusive} ;# Unlock recovery & aReadMark[]
lappend expected_locks {0 1 unlock exclusive} ;# Unlock writer
lappend expected_locks {3 1 lock exclusive}   ;# Lock aReadMark[0]
lappend expected_locks {3 1 unlock exclusive} ;# Unlock aReadMark[0]
lappend expected_locks {1 1 unlock exclusive} ;# Unlock checkpoint
do_test wal2-5.1 {
  proc tvfs_cb {method args} {
    set ::shm_file [lindex $args 0]
    if {$method == "xShmLock"} { lappend ::locks [lindex $args 2] }
    return $::tvfs_cb_return
  }
  set tvfs_cb_return SQLITE_OK

  testvfs tvfs
  tvfs script tvfs_cb

  sqlite3 db test.db -vfs tvfs
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE x(y);
    INSERT INTO x VALUES(1);
  }

  incr_tvfs_hdr $::shm_file 1 1
  set ::locks [list]
  execsql { PRAGMA wal_checkpoint }
  set ::locks
} $expected_locks
db close
tvfs delete

#-------------------------------------------------------------------------
# This block, test cases wal2-6.*, tests the operation of WAL with
# "PRAGMA locking_mode=EXCLUSIVE" set.
#
#   wal2-6.1.*: Changing to WAL mode before setting locking_mode=exclusive.
#
#   wal2-6.2.*: Changing to WAL mode after setting locking_mode=exclusive.
#
#   wal2-6.3.*: Changing back to rollback mode from WAL mode after setting 
#               locking_mode=exclusive.
#
#   wal2-6.4.*: Check that xShmLock calls are omitted in exclusive locking
#               mode.
#
#   wal2-6.5.*: 
#
#   wal2-6.6.*: Check that if the xShmLock() to reaquire a WAL read-lock when
#               exiting exclusive mode fails (i.e. SQLITE_IOERR), then the
#               connection silently remains in exclusive mode.
#
do_test wal2-6.1.1 {
  forcedelete test.db test.db-wal test.db-journal
  sqlite3 db test.db
  execsql {
    Pragma Journal_Mode = Wal;
  }
} {wal}
do_test wal2-6.1.2 {
  execsql { PRAGMA lock_status }
} {main unlocked temp closed}
do_test wal2-6.1.3 {
  execsql {
    SELECT * FROM sqlite_master;
    Pragma Locking_Mode = Exclusive;
  }
  execsql {
    BEGIN;
      CREATE TABLE t1(a, b);
      INSERT INTO t1 VALUES(1, 2);
    COMMIT;
    PRAGMA lock_status;
  }
} {main exclusive temp closed}
do_test wal2-6.1.4 {
  execsql { 
    PRAGMA locking_mode = normal; 
    PRAGMA lock_status;
  }
} {normal main exclusive temp closed}
do_test wal2-6.1.5 {
  execsql { 
    SELECT * FROM t1;
    PRAGMA lock_status;
  }
} {1 2 main shared temp closed}
do_test wal2-6.1.6 {
  execsql {
    INSERT INTO t1 VALUES(3, 4);
    PRAGMA lock_status;
  }
} {main shared temp closed}
db close

do_test wal2-6.2.1 {
  forcedelete test.db test.db-wal test.db-journal
  sqlite3 db test.db
  execsql {
    Pragma Locking_Mode = Exclusive;
    Pragma Journal_Mode = Wal;
    Pragma Lock_Status;
  }
} {exclusive wal main exclusive temp closed}
do_test wal2-6.2.2 {
  execsql {
    BEGIN;
      CREATE TABLE t1(a, b);
      INSERT INTO t1 VALUES(1, 2);
    COMMIT;
    Pragma loCK_STATus;
  }
} {main exclusive temp closed}
do_test wal2-6.2.3 {
  db close
  sqlite3 db test.db
  execsql { SELECT * FROM sqlite_master }
  execsql { PRAGMA LOCKING_MODE = EXCLUSIVE }
} {exclusive}
do_test wal2-6.2.4 {
  execsql {
    SELECT * FROM t1;
    pragma lock_status;
  }
} {1 2 main shared temp closed}
do_test wal2-6.2.5 {
  execsql {
    INSERT INTO t1 VALUES(3, 4);
    pragma lock_status;
  }
} {main exclusive temp closed}
do_test wal2-6.2.6 {
  execsql {
    PRAGMA locking_mode = NORMAL;
    pragma lock_status;
  }
} {normal main exclusive temp closed}
do_test wal2-6.2.7 {
  execsql {
    BEGIN IMMEDIATE; COMMIT;
    pragma lock_status;
  }
} {main shared temp closed}
do_test wal2-6.2.8 {
  execsql {
    PRAGMA locking_mode = EXCLUSIVE;
    BEGIN IMMEDIATE; COMMIT;
    PRAGMA locking_mode = NORMAL;
  }
  execsql {
    SELECT * FROM t1;
    pragma lock_status;
  }
} {1 2 3 4 main shared temp closed}
do_test wal2-6.2.9 {
  execsql {
    INSERT INTO t1 VALUES(5, 6);
    SELECT * FROM t1;
    pragma lock_status;
  }
} {1 2 3 4 5 6 main shared temp closed}
db close

do_test wal2-6.3.1 {
  forcedelete test.db test.db-wal test.db-journal
  sqlite3 db test.db
  execsql {
    PRAGMA journal_mode = WAL;
    PRAGMA locking_mode = exclusive;
    BEGIN;
      CREATE TABLE t1(x);
      INSERT INTO t1 VALUES('Chico');
      INSERT INTO t1 VALUES('Harpo');
    COMMIT;
  }
  list [file exists test.db-wal] [file exists test.db-journal]
} {1 0}
do_test wal2-6.3.2 {
  execsql { PRAGMA journal_mode = DELETE }
  file exists test.db-wal
} {0}
do_test wal2-6.3.3 {
  execsql { PRAGMA lock_status }
} {main exclusive temp closed}
do_test wal2-6.3.4 {
  execsql { 
    BEGIN;
      INSERT INTO t1 VALUES('Groucho');
  }
  list [file exists test.db-wal] [file exists test.db-journal]
} {0 1}
do_test wal2-6.3.5 {
  execsql { PRAGMA lock_status }
} {main exclusive temp closed}
do_test wal2-6.3.6 {
  execsql { COMMIT }
  list [file exists test.db-wal] [file exists test.db-journal]
} {0 1}
do_test wal2-6.3.7 {
  execsql { PRAGMA lock_status }
} {main exclusive temp closed}
db close


# This test - wal2-6.4.* - uses a single database connection and the
# [testvfs] instrumentation to test that xShmLock() is being called
# as expected when a WAL database is used with locking_mode=exclusive.
#
do_test wal2-6.4.1 {
  forcedelete test.db test.db-wal test.db-journal
  proc tvfs_cb {method args} {
    set ::shm_file [lindex $args 0]
    if {$method == "xShmLock"} { lappend ::locks [lindex $args 2] }
    return "SQLITE_OK"
  }
  testvfs tvfs
  tvfs script tvfs_cb
  sqlite3 db test.db -vfs tvfs
  set {} {}
} {}

set RECOVERY {
  {0 1 lock exclusive} {1 7 lock exclusive} 
  {1 7 unlock exclusive} {0 1 unlock exclusive}
}
set READMARK0_READ {
  {3 1 lock shared} {3 1 unlock shared}
}
set READMARK0_WRITE {
  {3 1 lock shared} 
  {0 1 lock exclusive} {3 1 unlock shared} 
  {4 1 lock exclusive} {4 1 unlock exclusive} {4 1 lock shared} 
  {0 1 unlock exclusive} {4 1 unlock shared}
}
set READMARK1_SET {
  {4 1 lock exclusive} {4 1 unlock exclusive}
}
set READMARK1_READ {
  {4 1 lock shared} {4 1 unlock shared}
}
set READMARK1_WRITE {
  {4 1 lock shared} 
    {0 1 lock exclusive} {0 1 unlock exclusive} 
  {4 1 unlock shared}
}

foreach {tn sql res expected_locks} {
  2 {
    PRAGMA auto_vacuum = 0;
    PRAGMA journal_mode = WAL;
    BEGIN;
      CREATE TABLE t1(x);
      INSERT INTO t1 VALUES('Leonard');
      INSERT INTO t1 VALUES('Arthur');
    COMMIT;
  } {wal} {
    $RECOVERY 
    $READMARK0_WRITE
  }

  3 {
    # This test should do the READMARK1_SET locking to populate the 
    # aReadMark[1] slot with the current mxFrame value. Followed by
    # READMARK1_READ to read the database.
    #
    SELECT * FROM t1
  } {Leonard Arthur} {
    $READMARK1_SET
    $READMARK1_READ
  }

  4 {
    # aReadMark[1] is already set to mxFrame. So just READMARK1_READ
    # this time, not READMARK1_SET.
    #
    SELECT * FROM t1 ORDER BY x
  } {Arthur Leonard} { 
    $READMARK1_READ 
  }

  5 {
    PRAGMA locking_mode = exclusive
  } {exclusive} { } 

  6 {
    INSERT INTO t1 VALUES('Julius Henry');
    SELECT * FROM t1;
  } {Leonard Arthur {Julius Henry}} {
    $READMARK1_READ
  }

  7 {
    INSERT INTO t1 VALUES('Karl');
    SELECT * FROM t1;
  } {Leonard Arthur {Julius Henry} Karl} { }

  8 {
    PRAGMA locking_mode = normal
  } {normal} { }

  9 {
    SELECT * FROM t1 ORDER BY x
  } {Arthur {Julius Henry} Karl Leonard} $READMARK1_READ

  10 { DELETE FROM t1 } {} $READMARK1_WRITE

  11 {
    SELECT * FROM t1
  } {} {
    $READMARK1_SET
    $READMARK1_READ
  }
} {

  set L [list]
  foreach el [subst $expected_locks] { lappend L $el }

  set S ""
  foreach sq [split $sql "\n"] { 
    set sq [string trim $sq]
    if {[string match {#*} $sq]==0} {append S "$sq\n"}
  }

  set ::locks [list]
  do_test wal2-6.4.$tn.1 { execsql $S } $res
  do_test wal2-6.4.$tn.2 { set ::locks  } $L
}

db close
tvfs delete

do_test wal2-6.5.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA auto_vacuum = 0;
    PRAGMA journal_mode = wal;
    PRAGMA locking_mode = exclusive;
    CREATE TABLE t2(a, b);
    PRAGMA wal_checkpoint;
    INSERT INTO t2 VALUES('I', 'II');
    PRAGMA journal_mode;
  }
} {wal exclusive 0 2 2 wal}
do_test wal2-6.5.2 {
  execsql {
    PRAGMA locking_mode = normal;
    INSERT INTO t2 VALUES('III', 'IV');
    PRAGMA locking_mode = exclusive;
    SELECT * FROM t2;
  }
} {normal exclusive I II III IV}
do_test wal2-6.5.3 {
  execsql { PRAGMA wal_checkpoint }
} {0 2 2}
db close

proc lock_control {method filename handle spec} {
  foreach {start n op type} $spec break
  if {$op == "lock"} { return SQLITE_IOERR }
  return SQLITE_OK
}
do_test wal2-6.6.1 {
  testvfs T
  T script lock_control
  T filter {}
  sqlite3 db test.db -vfs T
  execsql { SELECT * FROM sqlite_master }
  execsql { PRAGMA locking_mode = exclusive }
  execsql { INSERT INTO t2 VALUES('V', 'VI') }
} {}
do_test wal2-6.6.2 {
  execsql { PRAGMA locking_mode = normal }
  T filter xShmLock
  execsql { INSERT INTO t2 VALUES('VII', 'VIII') }
} {}
do_test wal2-6.6.3 {
  # At this point the connection should still be in exclusive-mode, even
  # though it tried to exit exclusive-mode when committing the INSERT
  # statement above. To exit exclusive mode, SQLite has to take a read-lock 
  # on the WAL file using xShmLock(). Since that call failed, it remains
  # in exclusive mode.
  #
  sqlite3 db2 test.db -vfs T
  catchsql { SELECT * FROM t2 } db2
} {1 {database is locked}}
do_test wal2-6.6.2 {
  db2 close
  T filter {}
  execsql { INSERT INTO t2 VALUES('IX', 'X') }
} {}
do_test wal2-6.6.4 {
  # This time, we have successfully exited exclusive mode. So the second
  # connection can read the database.
  sqlite3 db2 test.db -vfs T
  catchsql { SELECT * FROM t2 } db2
} {0 {I II III IV V VI VII VIII IX X}}

db close
db2 close
T delete

#-------------------------------------------------------------------------
# Test a theory about the checksum algorithm. Theory was false and this
# test did not provoke a bug.
#
forcedelete test.db test.db-wal test.db-journal
do_test wal2-7.1.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA page_size = 4096;
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b);
  }
  file size test.db
} {4096}
do_test wal2-7.1.2 {
  forcecopy test.db test2.db
  forcecopy test.db-wal test2.db-wal
  # The first 32 bytes of the WAL file contain the WAL header. Offset 48
  # is the first byte of the checksum for the first frame in the WAL. 
  # The following three lines replaces the contents of that byte with 
  # a different value.
  set newval FF
  if {$newval == [hexio_read test2.db-wal 48 1]} { set newval 00 }
  hexio_write test2.db-wal 48 $newval
} {1}
do_test wal2-7.1.3 {
  sqlite3 db2 test2.db
  execsql { PRAGMA wal_checkpoint } db2
  execsql { SELECT * FROM sqlite_master } db2
} {}
db close
db2 close
forcedelete test.db test.db-wal test.db-journal
do_test wal2-8.1.2 {
  sqlite3 db test.db
  execsql {
    PRAGMA auto_vacuum=OFF;
    PRAGMA page_size = 1024;
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(zeroblob(8188*1020));
    CREATE TABLE t2(y);
    PRAGMA wal_checkpoint;
  }
  execsql {
    SELECT rootpage>=8192 FROM sqlite_master WHERE tbl_name = 't2';
  }
} {1}
do_test wal2-8.1.3 {
  execsql {
    PRAGMA cache_size = 10;
    CREATE TABLE t3(z);
    BEGIN;
      INSERT INTO t3 VALUES(randomblob(900));
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t2 VALUES('hello');
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
    ROLLBACK;
  }
  execsql {
    INSERT INTO t2 VALUES('goodbye');
    INSERT INTO t3 SELECT randomblob(900) FROM t3;
    INSERT INTO t3 SELECT randomblob(900) FROM t3;
  }
} {}
do_test wal2-8.1.4 {
  sqlite3 db2 test.db
  execsql { SELECT * FROM t2 }
} {goodbye}
db2 close
db close

#-------------------------------------------------------------------------
# Test that even if the checksums for both are valid, if the two copies
# of the wal-index header in the wal-index do not match, the client
# runs (or at least tries to run) database recovery.
# 
#
proc get_name {method args} { set ::filename [lindex $args 0] ; tvfs filter {} }
testvfs tvfs
tvfs script get_name
tvfs filter xShmOpen

forcedelete test.db test.db-wal test.db-journal
do_test wal2-9.1 {
  sqlite3 db test.db -vfs tvfs
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE x(y);
    INSERT INTO x VALUES('Barton');
    INSERT INTO x VALUES('Deakin');
  }

  # Set $wih(1) to the contents of the wal-index header after
  # the frames associated with the first two rows in table 'x' have
  # been inserted. Then insert one more row and set $wih(2)
  # to the new value of the wal-index header.
  #
  # If the $wih(1) is written into the wal-index before running
  # a read operation, the client will see only the first two rows. If
  # $wih(2) is written into the wal-index, the client will see
  # three rows. If an invalid header is written into the wal-index, then
  # the client will run recovery and see three rows.
  #
  set wih(1) [set_tvfs_hdr $::filename]
  execsql { INSERT INTO x VALUES('Watson') }
  set wih(2) [set_tvfs_hdr $::filename]

  sqlite3 db2 test.db -vfs tvfs
  execsql { SELECT * FROM x } db2
} {Barton Deakin Watson}

foreach {tn hdr1 hdr2 res} [list                                            \
  3  $wih(1)                $wih(1)                {Barton Deakin}          \
  4  $wih(1)                $wih(2)                {Barton Deakin Watson}   \
  5  $wih(2)                $wih(1)                {Barton Deakin Watson}   \
  6  $wih(2)                $wih(2)                {Barton Deakin Watson}   \
  7  $wih(1)                $wih(1)                {Barton Deakin}          \
  8  {0 0 0 0 0 0 0 0 0 0 0 0} {0 0 0 0 0 0 0 0 0 0 0 0} {Barton Deakin Watson}
] {
  do_test wal2-9.$tn {
    set_tvfs_hdr $::filename $hdr1 $hdr2
    execsql { SELECT * FROM x } db2
  } $res
}

db2 close
db close

#-------------------------------------------------------------------------
# This block of tests - wal2-10.* - focus on the libraries response to
# new versions of the wal or wal-index formats. 
#
#   wal2-10.1.*: Test that the library refuses to "recover" a new WAL 
#                format.
#
#   wal2-10.2.*: Test that the library refuses to read or write a database
#                if the wal-index version is newer than it understands.
#
# At time of writing, the only versions of the wal and wal-index formats
# that exist are versions 3007000 (corresponding to SQLite version 3.7.0,
# the first version of SQLite to feature wal mode).
#
do_test wal2-10.1.1 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b);
    PRAGMA wal_checkpoint;
    INSERT INTO t1 VALUES(1, 2);
    INSERT INTO t1 VALUES(3, 4);
  }
  faultsim_save_and_close
} {}
do_test wal2-10.1.2 {
  faultsim_restore_and_reopen
  execsql { SELECT * FROM t1 }
} {1 2 3 4}
do_test wal2-10.1.3 {
  faultsim_restore_and_reopen
  set hdr [wal_set_walhdr test.db-wal]
  lindex $hdr 1
} {3007000}
do_test wal2-10.1.4 {
  lset hdr 1 3007001
  wal_set_walhdr test.db-wal $hdr
  catchsql { SELECT * FROM t1 }
} {1 {unable to open database file}}

testvfs tvfs -default 1
do_test wal2-10.2.1 {
  faultsim_restore_and_reopen
  execsql { SELECT * FROM t1 }
} {1 2 3 4}
do_test wal2-10.2.2 { 
  set hdr [set_tvfs_hdr $::filename] 
  lindex $hdr 0 
} {3007000}
do_test wal2-10.2.3 { 
  lset hdr 0 3007001
  wal_fix_walindex_cksum hdr 
  set_tvfs_hdr $::filename $hdr
  catchsql { SELECT * FROM t1 }
} {1 {unable to open database file}}
db close
tvfs delete

#-------------------------------------------------------------------------
# This block of tests - wal2-11.* - tests that it is not possible to put
# the library into an infinite loop by presenting it with a corrupt
# hash table (one that appears to contain a single chain of infinite 
# length).
#
#   wal2-11.1.*: While reading the hash-table.
#
#   wal2-11.2.*: While writing the hash-table.
#
testvfs tvfs -default 1
do_test wal2-11.0 {
  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b, c);
    INSERT INTO t1 VALUES(1, 2, 3);
    INSERT INTO t1 VALUES(4, 5, 6);
    INSERT INTO t1 VALUES(7, 8, 9);
    SELECT * FROM t1;
  }
} {wal 1 2 3 4 5 6 7 8 9}

do_test wal2-11.1.1 {
  sqlite3 db2 test.db
  execsql { SELECT name FROM sqlite_master } db2
} {t1}

if {$::tcl_version>=8.5} {
  # Set all zeroed slots in the first hash table to invalid values.
  #
  set blob [string range [tvfs shm $::filename] 0 16383]
  set I [string range [tvfs shm $::filename] 16384 end]
  binary scan $I t* L
  set I [list]
  foreach p $L {
    lappend I [expr $p ? $p : 400]
  }
  append blob [binary format t* $I]
  tvfs shm $::filename $blob
  do_test wal2-11.2 {
    catchsql { INSERT INTO t1 VALUES(10, 11, 12) }
  } {1 {database disk image is malformed}}
  
  # Fill up the hash table on the first page of shared memory with 0x55 bytes.
  #
  set blob [string range [tvfs shm $::filename] 0 16383]
  append blob [string repeat [binary format c 55] 16384]
  tvfs shm $::filename $blob
  do_test wal2-11.3 {
    catchsql { SELECT * FROM t1 } db2
  } {1 {database disk image is malformed}}
}

db close
db2 close
tvfs delete

#-------------------------------------------------------------------------
# If a connection is required to create a WAL or SHM file, it creates 
# the new files with the same file-system permissions as the database 
# file itself. Test this.
#
if {$::tcl_platform(platform) == "unix"} {
  faultsim_delete_and_reopen
  # Changed on 2012-02-13: umask is deliberately ignored for -wal files.
  #set umask [exec /bin/sh -c umask]
  set umask 0
  

  do_test wal2-12.1 {
    sqlite3 db test.db
    execsql { 
      CREATE TABLE tx(y, z);
      PRAGMA journal_mode = WAL;
    }
    db close
    list [file exists test.db-wal] [file exists test.db-shm]
  } {0 0}
  
  foreach {tn permissions} {
   1 00644
   2 00666
   3 00600
   4 00755
  } {
    set effective [format %.5o [expr $permissions & ~$umask]]
    do_test wal2-12.2.$tn.1 {
      file attributes test.db -permissions $permissions
      file attributes test.db -permissions
    } $permissions
    do_test wal2-12.2.$tn.2 {
      list [file exists test.db-wal] [file exists test.db-shm]
    } {0 0}
    do_test wal2-12.2.$tn.3 {
      sqlite3 db test.db
      execsql { INSERT INTO tx DEFAULT VALUES }
      list [file exists test.db-wal] [file exists test.db-shm]
    } {1 1}
    do_test wal2-12.2.$tn.4 {
      list [file attr test.db-wal -perm] [file attr test.db-shm -perm]
    } [list $effective $effective]
    do_test wal2-12.2.$tn.5 {
      db close
      list [file exists test.db-wal] [file exists test.db-shm]
    } {0 0}
  }
}

#-------------------------------------------------------------------------
# Test the libraries response to discovering that one or more of the
# database, wal or shm files cannot be opened, or can only be opened
# read-only.
#
if {$::tcl_platform(platform) == "unix"} {
  proc perm {} {
    set L [list]
    foreach f {test.db test.db-wal test.db-shm} {
      if {[file exists $f]} {
        lappend L [file attr $f -perm]
      } else {
        lappend L {}
      }
    }
    set L
  }

  faultsim_delete_and_reopen
  execsql {
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b);
    PRAGMA wal_checkpoint;
    INSERT INTO t1 VALUES('3.14', '2.72');
  }
  do_test wal2-13.1.1 {
    list [file exists test.db-shm] [file exists test.db-wal]
  } {1 1}
  faultsim_save_and_close

  foreach {tn db_perm wal_perm shm_perm can_open can_read can_write} {
    2   00644   00644   00644   1   1   1
    3   00644   00400   00644   1   1   0
    4   00644   00644   00400   1   0   0
    5   00400   00644   00644   1   1   0

    7   00644   00000   00644   1   0   0
    8   00644   00644   00000   1   0   0
    9   00000   00644   00644   0   0   0
  } {
    faultsim_restore
    do_test wal2-13.$tn.1 {
      file attr test.db     -perm $db_perm
      file attr test.db-wal -perm $wal_perm
      file attr test.db-shm -perm $shm_perm

      set     L [file attr test.db -perm]
      lappend L [file attr test.db-wal -perm]
      lappend L [file attr test.db-shm -perm]
    } [list $db_perm $wal_perm $shm_perm]

    # If $can_open is true, then it should be possible to open a database
    # handle. Otherwise, if $can_open is 0, attempting to open the db
    # handle throws an "unable to open database file" exception.
    #
    set r(1) {0 ok}
    set r(0) {1 {unable to open database file}}
    do_test wal2-13.$tn.2 {
      list [catch {sqlite3 db test.db ; set {} ok} msg] $msg
    } $r($can_open)

    if {$can_open} {

      # If $can_read is true, then the client should be able to read from
      # the database file. If $can_read is false, attempting to read should
      # throw the "unable to open database file" exception. 
      #
      set a(0) {1 {unable to open database file}}
      set a(1) {0 {3.14 2.72}}
      do_test wal2-13.$tn.3 {
        catchsql { SELECT * FROM t1 }
      } $a($can_read)
  
      # Now try to write to the db file. If the client can read but not
      # write, then it should throw the familiar "unable to open db file"
      # exception. If it can read but not write, the exception should
      # be "attempt to write a read only database".
      #
      # If the client can read and write, the operation should succeed.
      #
      set b(0,0) {1 {unable to open database file}}
      set b(1,0) {1 {attempt to write a readonly database}}
      set b(1,1) {0 {}}
      do_test wal2-13.$tn.4 {
        catchsql { INSERT INTO t1 DEFAULT VALUES }
      } $b($can_read,$can_write)
    }
    catch { db close }
  }
}

#-------------------------------------------------------------------------
# Test that "PRAGMA checkpoint_fullsync" appears to be working.
#
foreach {tn sql reslist} {
  1 { }                                 {10 0 4 0 6 0}
  2 { PRAGMA checkpoint_fullfsync = 1 } {10 4 4 2 6 2}
  3 { PRAGMA checkpoint_fullfsync = 0 } {10 0 4 0 6 0}
} {
  faultsim_delete_and_reopen

  execsql {PRAGMA auto_vacuum = 0}
  execsql $sql
  do_execsql_test wal2-14.$tn.0 { PRAGMA page_size = 4096 }   {}
  do_execsql_test wal2-14.$tn.1 { PRAGMA journal_mode = WAL } {wal}

  set sqlite_sync_count 0
  set sqlite_fullsync_count 0

  do_execsql_test wal2-14.$tn.2 {
    PRAGMA wal_autocheckpoint = 10;
    CREATE TABLE t1(a, b);                -- 2 wal syncs
    INSERT INTO t1 VALUES(1, 2);          -- 2 wal sync
    PRAGMA wal_checkpoint;                -- 1 wal sync, 1 db sync
    BEGIN;
      INSERT INTO t1 VALUES(3, 4);
      INSERT INTO t1 VALUES(5, 6);
    COMMIT;                               -- 2 wal sync
    PRAGMA wal_checkpoint;                -- 1 wal sync, 1 db sync
  } {10 0 3 3 0 1 1}

  do_test wal2-14.$tn.3 {
    cond_incr_sync_count 1
    list $sqlite_sync_count $sqlite_fullsync_count
  } [lrange $reslist 0 1]

  set sqlite_sync_count 0
  set sqlite_fullsync_count 0

  do_test wal2-14.$tn.4 {
    execsql { INSERT INTO t1 VALUES(7, zeroblob(12*4096)) }
    list $sqlite_sync_count $sqlite_fullsync_count
  } [lrange $reslist 2 3]

  set sqlite_sync_count 0
  set sqlite_fullsync_count 0

  do_test wal2-14.$tn.5 {
    execsql { PRAGMA wal_autocheckpoint = 1000 }
    execsql { INSERT INTO t1 VALUES(9, 10) }
    execsql { INSERT INTO t1 VALUES(11, 12) }
    execsql { INSERT INTO t1 VALUES(13, 14) }
    db close
    list $sqlite_sync_count $sqlite_fullsync_count
  } [lrange $reslist 4 5]
}

catch { db close }

# PRAGMA checkpoint_fullsync
# PRAGMA fullfsync
# PRAGMA synchronous
#
foreach {tn settings restart_sync commit_sync ckpt_sync} {
  1  {0 0 off}     {0 0}  {0 0}  {0 0}
  2  {0 0 normal}  {1 0}  {0 0}  {2 0}
  3  {0 0 full}    {2 0}  {1 0}  {2 0}

  4  {0 1 off}     {0 0}  {0 0}  {0 0}
  5  {0 1 normal}  {0 1}  {0 0}  {0 2}
  6  {0 1 full}    {0 2}  {0 1}  {0 2}

  7  {1 0 off}     {0 0}  {0 0}  {0 0}
  8  {1 0 normal}  {1 0}  {0 0}  {0 2}
  9  {1 0 full}    {2 0}  {1 0}  {0 2}

  10 {1 1 off}     {0 0}  {0 0}  {0 0}
  11 {1 1 normal}  {0 1}  {0 0}  {0 2}
  12 {1 1 full}    {0 2}  {0 1}  {0 2}
} {
  forcedelete test.db

  testvfs tvfs -default 1
  tvfs filter xSync
  tvfs script xSyncCb
  proc xSyncCb {method file fileid flags} {
    incr ::sync($flags)
  }

  sqlite3 db test.db
  do_execsql_test 15.$tn.1 "
    PRAGMA page_size = 4096;
    CREATE TABLE t1(x);
    PRAGMA wal_autocheckpoint = OFF;
    PRAGMA journal_mode = WAL;
    PRAGMA checkpoint_fullfsync = [lindex $settings 0];
    PRAGMA fullfsync = [lindex $settings 1];
    PRAGMA synchronous = [lindex $settings 2];
  " {0 wal}

  do_test 15.$tn.2 {
    set sync(normal) 0
    set sync(full) 0
    execsql { INSERT INTO t1 VALUES('abc') }
    list $::sync(normal) $::sync(full)
  } $restart_sync

  do_test 15.$tn.3 {
    set sync(normal) 0
    set sync(full) 0
    execsql { INSERT INTO t1 VALUES('abc') }
    list $::sync(normal) $::sync(full)
  } $commit_sync

  do_test 15.$tn.4 {
    set sync(normal) 0
    set sync(full) 0
    execsql { INSERT INTO t1 VALUES('def') }
    list $::sync(normal) $::sync(full)
  } $commit_sync

  do_test 15.$tn.5 {
    set sync(normal) 0
    set sync(full) 0
    execsql { PRAGMA wal_checkpoint }
    list $::sync(normal) $::sync(full)
  } $ckpt_sync
  
  db close
  tvfs delete
}



finish_test