SQLite

      INSERT INTO t1 SELECT randomblob(900) FROM t1;
      INSERT INTO t1 SELECT randomblob(900) FROM t1;
      INSERT INTO t1 SELECT randomblob(900) FROM t1;
      INSERT INTO t1 SELECT randomblob(900) FROM t1;          /* 64 rows */
      BEGIN;
        UPDATE t1 SET x = randomblob(900);
    }
    file delete -force testX.db testX.db-journal
    copy_file test.db testX.db
    copy_file test.db-journal testX.db-journal
    db close

    crashsql -file test.db -delay [expr ($::i%2) + 1] {
      SELECT * FROM sqlite_master;
      INSERT INTO t1 VALUES(randomblob(900));

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file contains code used by several different test scripts. The
# code in this file allows testfixture to control another process (or
# processes) to test locking.
#















































# Launch another testfixture process to be controlled by this one. A
# channel name is returned that may be passed as the first argument to proc
# 'testfixture' to execute a command. The child testfixture process is shut
# down by closing the channel.
proc launch_testfixture {} {
  set prg [info nameofexec]

#

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

foreach code [list {
  set ::code2_chan [launch_testfixture]
  set ::code3_chan [launch_testfixture]
  proc code2 {tcl} { testfixture $::code2_chan $tcl }
  proc code3 {tcl} { testfixture $::code3_chan $tcl }
  set tn 1
} {
  proc code2 {tcl} { uplevel #0 $tcl }
  proc code3 {tcl} { uplevel #0 $tcl }
  set tn 2
}] {

  faultsim_delete_and_reopen

  # Open connections [db2] and [db3]. Depending on which iteration this
  # is, the connections may be created in this interpreter, or in 
  # interpreters running in other OS processes. As such, the [db2] and [db3]
  # commands should only be accessed within [code2] and [code3] blocks,
  # respectively.
  #
  eval $code
  code2 { sqlite3 db2 test.db }
  code3 { sqlite3 db3 test.db }
  
  # Shorthand commands. Execute SQL using database connection [db2] or 
  # [db3]. Return the results.
  #
  proc sql1 {sql} { db eval $sql }
  proc sql2 {sql} { code2 [list db2 eval $sql] }
  proc sql3 {sql} { code3 [list db3 eval $sql] }

  proc csql1 {sql} { list [catch { sql1 $sql } msg] $msg }
  proc csql2 {sql} { list [catch { sql2 $sql } msg] $msg }
  proc csql3 {sql} { list [catch { sql3 $sql } msg] $msg }

  # Create and populate a database table using connection [db]. Check 
  # that connections [db2] and [db3] can see the schema and content.
  #
  do_test pager1-$tn.1 {
    sql1 {
      CREATE TABLE t1(a PRIMARY KEY, b);

  do_test pager1-$tn.4 {
    sql1 {
      BEGIN;
        INSERT INTO t1 VALUES(3, 'three');
    }
  } {}
  do_test pager1-$tn.5 { sql2 { SELECT * FROM t1 } } {1 one 2 two}
  do_test pager1-$tn.6 { sql3 { SELECT * FROM t1 } } {1 one 2 two}
  do_test pager1-$tn.7 { sql1 { SELECT * FROM t1 } } {1 one 2 two 3 three}

  # [db] still has an open write transaction. Check that this prevents
  # other connections (specifically [db2]) from writing to the database.
  #
  # Even if [db2] opens a transaction first, it may not write to the
  # database. After the attempt to write the db within a transaction, 

  # committed, all three connections can read the new content.
  #
  do_test pager1-$tn.25 { sql1 { UPDATE t1 SET a = a+10 } } {}
  do_test pager1-$tn.26 { sql1 { COMMIT } } {}
  do_test pager1-$tn.27 { sql1 { SELECT * FROM t1 } } {21 one 22 two 23 three}
  do_test pager1-$tn.27 { sql2 { SELECT * FROM t1 } } {21 one 22 two 23 three}
  do_test pager1-$tn.28 { sql3 { SELECT * FROM t1 } } {21 one 22 two 23 three}

  code2 { db2 close }
  code3 { db3 close }
  catch { close $::code2_chan }
  catch { close $::code3_chan }
}

finish_test

# 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


ifcapable !wal {finish_test ; return }

proc reopen_db {} {
  catch { db close }
  file delete -force test.db test.db-wal test.db-wal-summary
  sqlite3_wal db test.db

#-------------------------------------------------------------------------
# The following block of tests - wal-10.* - test that the WAL locking 
# scheme works in simple cases. This block of tests is run twice. Once
# using multiple connections in the address space of the current process,
# and once with all connections except one running in external processes.
#
foreach code [list {
  set ::code2_chan [launch_testfixture]
  set ::code3_chan [launch_testfixture]
  proc code2 {tcl} { testfixture $::code2_chan $tcl }
  proc code3 {tcl} { testfixture $::code3_chan $tcl }
  set tn 1
} {
  proc code2 {tcl} { uplevel #0 $tcl }
  proc code3 {tcl} { uplevel #0 $tcl }
  set tn 2
}] {

  eval $code
  reopen_db

  # Open connections [db2] and [db3]. Depending on which iteration this
  # is, the connections may be created in this interpreter, or in 
  # interpreters running in other OS processes. As such, the [db2] and [db3]
  # commands should only be accessed within [code2] and [code3] blocks,
  # respectively.
  #
  code2 { sqlite3 db2 test.db ; db2 eval { PRAGMA journal_mode = WAL } }
  code3 { sqlite3 db3 test.db ; db3 eval { PRAGMA journal_mode = WAL } }

  # Shorthand commands. Execute SQL using database connection [db2] or 
  # [db3]. Return the results.
  #
  proc sql2 {sql} { code2 [list db2 eval $sql] }
  proc sql3 {sql} { code3 [list db3 eval $sql] }

  # Initialize the database schema and contents.
  #
  do_test wal-10.$tn.1 {
    execsql {

      CREATE TABLE t1(a, b);
      INSERT INTO t1 VALUES(1, 2);
      SELECT * FROM t1;
    }
  } {1 2}

  # Open a transaction and write to the database using [db]. Check that [db2]
  # is still able to read the snapshot before the transaction was opened.
  #
  do_test wal-10.$tn.2 {
    execsql { BEGIN; INSERT INTO t1 VALUES(3, 4); }
    sql2 {SELECT * FROM t1}

    sql3 { INSERT INTO t1 VALUES('e', 'f') }
    sql2 { SELECT * FROM t1 }
  } {a b c d}
  do_test wal-10.$tn.37 {
    sql2 COMMIT
    execsql { PRAGMA wal_checkpoint }
  } {}

  catch { db close }
  catch { code2 { db2 close } }
  catch { code3 { db3 close } }
  catch { close $::code2_chan }
  catch { close $::code3_chan }
}

#-------------------------------------------------------------------------
# This block of tests, wal-11.*, test that nothing goes terribly wrong
# if frames must be written to the log file before a transaction is
# committed (in order to free up memory).
#

  }
  execsql { SELECT count(*) FROM t2 }
} [expr int(pow(2, 16))]
do_test wal-13.2.3 {
  expr [file size test.db-wal] > [log_file_size 33000 1024]
} 1

foreach code [list {
  set tn 3
  proc buddy {tcl} { uplevel #0 $tcl }
} {
  set tn 4
  set ::buddy [launch_testfixture]
  proc buddy {tcl} { testfixture $::buddy $tcl }
}] {

  eval $code
  reopen_db

  do_test wal-13.$tn.0 {
    buddy { sqlite3 db2 test.db }
    execsql {
      PRAGMA journal_mode = WAL;
      CREATE TABLE t1(x);
      INSERT INTO t1 SELECT randomblob(800);
    }
    execsql { SELECT count(*) FROM t1 }
  } {1}

  for {set ii 1} {$ii<16} {incr ii} {
    do_test wal-13.$tn.$ii.a {
      buddy { db2 eval { INSERT INTO t1 SELECT randomblob(800) FROM t1 } }
      buddy { db2 eval { SELECT count(*) FROM t1 } }
    } [expr (1<<$ii)]
    do_test wal-13.$tn.$ii.b {
      db eval { SELECT count(*) FROM t1 }
    } [expr (1<<$ii)]
    do_test wal-13.$tn.$ii.c {
      db eval { SELECT count(*) FROM t1 }
    } [expr (1<<$ii)]
    do_test wal-13.$tn.$ii.d {
      db eval { PRAGMA integrity_check }
    } {ok}
  }

  catch { db2 close }
  catch { close $::buddy }
  db close
}

#-------------------------------------------------------------------------
# Check a fun corruption case has been fixed.
#
# The problem was that after performing a checkpoint using a connection
# that had an out-of-date pager-cache, the next time the connection was

  } $str
  do_test wal3-1.$i.7 {
    execsql { PRAGMA integrity_check } db2
  } {ok}
  db2 close
}

db close
foreach code [list {
  proc code2 {tcl} { uplevel #0 $tcl }
  proc code3 {tcl} { uplevel #0 $tcl }
  set tn singleproc
} {
  set ::code2_chan [launch_testfixture]
  set ::code3_chan [launch_testfixture]
  proc code2 {tcl} { testfixture $::code2_chan $tcl }
  proc code3 {tcl} { testfixture $::code3_chan $tcl }
  set tn multiproc
}] {
  file delete -force test.db test.db-wal test.db-journal
  sqlite3 db test.db
  eval $code

  # Open connections [db2] and [db3]. Depending on which iteration this
  # is, the connections may be created in this interpreter, or in 
  # interpreters running in other OS processes. As such, the [db2] and [db3]
  # commands should only be accessed within [code2] and [code3] blocks,
  # respectively.
  #
  code2 { sqlite3 db2 test.db ; db2 eval { PRAGMA journal_mode = WAL } }
  code3 { sqlite3 db3 test.db ; db3 eval { PRAGMA journal_mode = WAL } }

  # Shorthand commands. Execute SQL using database connection [db], [db2] 
  # or [db3]. Return the results.
  #
  proc sql  {sql} { db eval $sql }
  proc sql2 {sql} { code2 [list db2 eval $sql] }
  proc sql3 {sql} { code3 [list db3 eval $sql] }

  do_test wal3-2.$tn.1 {
    sql { 
      PRAGMA page_size = 1024;
      PRAGMA auto_vacuum = OFF; 
      PRAGMA journal_mode = WAL;
    }
    sql {
      CREATE TABLE t1(a, b);
      INSERT INTO t1 VALUES(1, 'one');
      BEGIN;
        SELECT * FROM t1;
    }
  } {1 one}
  do_test wal3-2.$tn.2 {

  # these frames would clobber the snapshot currently being used by [db2]).
  #
  # After [db2] has committed, a checkpoint can copy the entire log to the
  # database file. Checkpointing after [db3] has committed is therefore a
  # no-op, as the entire log has already been backfilled.
  #
  do_test wal3-2.$tn.4 {
    sql {
      COMMIT;
      PRAGMA wal_checkpoint;
    }
    file size test.db
  } [expr $AUTOVACUUM ? 4*1024 : 3*1024]
  do_test wal3-2.$tn.5 {
    sql2 {
      COMMIT;
      PRAGMA wal_checkpoint;
    }
    file size test.db
  } [expr $AUTOVACUUM ? 5*1024 : 4*1024]
  do_test wal3-2.$tn.6 {
    sql3 {
      COMMIT;
      PRAGMA wal_checkpoint;
    }
    file size test.db
  } [expr $AUTOVACUUM ? 5*1024 : 4*1024]

  catch { db close }
  catch { code2 { db2 close } }
  catch { code3 { db3 close } }
  catch { close $::code2_chan }
  catch { close $::code3_chan }
}
catch {db close}

#-------------------------------------------------------------------------
# Test that that for the simple test:
#
#   CREATE TABLE x(y);