SQLite

# 2011 May 06
#
# 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.
#
#***********************************************************************
#

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

db close
testvfs oldvfs -iversion 1


# EVIDENCE-OF: R-58297-14483 WAL databases can be created, read, and
# written even if shared memory is unavailable as long as the
# locking_mode is set to EXCLUSIVE before the first attempted access.
#
# EVIDENCE-OF: R-00449-33772 This feature allows WAL databases to be
# created, read, and written by legacy VFSes that lack the "version 2"
# shared-memory methods xShmMap, xShmLock, xShmBarrier, and xShmUnmap on
# the sqlite3_io_methods object.
#
# 1.1: "create" tests.
# 1.2: "read" tests.
# 1.3: "write" tests.
#
# All three done with VFS "oldvfs", which has iVersion==1 and so does
# not support shared memory.
# 
sqlite3 db test.db -vfs oldvfs
do_execsql_test 1.1.1 {
  PRAGMA journal_mode = WAL;
} {delete}
do_execsql_test 1.1.2 {
  PRAGMA locking_mode = EXCLUSIVE;
  PRAGMA journal_mode = WAL;
} {exclusive wal}
do_execsql_test 1.1.3 {
  CREATE TABLE t1(x, y);
  INSERT INTO t1 VALUES(1, 2);
} {}
do_test 1.1.4 {
  list [file exists test.db-shm] [file exists test.db-wal]
} {0 1}

do_test 1.2.1 {
  db close
  sqlite3 db test.db -vfs oldvfs
  catchsql { SELECT * FROM t1 }
} {1 {unable to open database file}}
do_test 1.2.2 {
  execsql { PRAGMA locking_mode = EXCLUSIVE }
  execsql { SELECT * FROM t1 }
} {1 2}
do_test 1.2.3 {
  list [file exists test.db-shm] [file exists test.db-wal]
} {0 1}

do_test 1.3.1 {
  db close
  sqlite3 db test.db -vfs oldvfs
  catchsql { INSERT INTO t1 VALUES(3, 4) }
} {1 {unable to open database file}}
do_test 1.3.2 {
  execsql { PRAGMA locking_mode = EXCLUSIVE }
  execsql { INSERT INTO t1 VALUES(3, 4) }
  execsql { SELECT * FROM t1 }
} {1 2 3 4}
do_test 1.3.3 {
  list [file exists test.db-shm] [file exists test.db-wal]
} {0 1}

# EVIDENCE-OF: R-31969-57825 If EXCLUSIVE locking mode is set prior to
# the first WAL-mode database access, then SQLite never attempts to call
# any of the shared-memory methods and hence no shared-memory wal-index
# is ever created.
#
db close
sqlite3 db test.db
do_execsql_test 2.1.1 {
  PRAGMA locking_mode = EXCLUSIVE;
  SELECT * FROM t1;
} {exclusive 1 2 3 4}
do_test 2.1.2 {
  list [file exists test.db-shm] [file exists test.db-wal]
} {0 1}

# EVIDENCE-OF: R-36328-16367 In that case, the database connection
# remains in EXCLUSIVE mode as long as the journal mode is WAL; attempts
# to change the locking mode using "PRAGMA locking_mode=NORMAL;" are
# no-ops.
#
do_execsql_test 2.2.1 {
  PRAGMA locking_mode = NORMAL;
  SELECT * FROM t1;
} {exclusive 1 2 3 4}
do_test 2.2.2 {
  sqlite3 db2 test.db
  catchsql {SELECT * FROM t1} db2
} {1 {database is locked}}
db2 close

# EVIDENCE-OF: R-63522-46088 The only way to change out of EXCLUSIVE
# locking mode is to first change out of WAL journal mode.
#
do_execsql_test 2.3.1 {
  PRAGMA journal_mode = DELETE;
  SELECT * FROM t1;
} {delete 1 2 3 4}
do_test 2.3.2 {
  sqlite3 db2 test.db
  catchsql {SELECT * FROM t1} db2
} {1 {database is locked}}
do_execsql_test 2.3.3 {
  PRAGMA locking_mode = NORMAL;
  SELECT * FROM t1;
} {normal 1 2 3 4}
do_test 2.3.4 {
  sqlite3 db2 test.db
  catchsql {SELECT * FROM t1} db2
} {0 {1 2 3 4}}
db2 close
db close


# EVIDENCE-OF: R-57239-11845 If NORMAL locking mode is in effect for the
# first WAL-mode database access, then the shared-memory wal-index is
# created.
#
do_test 3.0 {
  sqlite3 db test.db
  execsql { PRAGMA journal_mode = WAL }
  db close
} {}
do_test 3.1 {
  sqlite3 db test.db
  execsql { SELECT * FROM t1 }
  list [file exists test.db-shm] [file exists test.db-wal]
} {1 1}

# EVIDENCE-OF: R-13779-07711 As long as exactly one connection is using
# a shared-memory wal-index, the locking mode can be changed freely
# between NORMAL and EXCLUSIVE.
#
do_execsql_test 3.2.1 {
  PRAGMA locking_mode = EXCLUSIVE;
  PRAGMA locking_mode = NORMAL;
  PRAGMA locking_mode = EXCLUSIVE;
  INSERT INTO t1 VALUES(5, 6);
} {exclusive normal exclusive}
do_test 3.2.2 {
  sqlite3 db2 test.db
  catchsql { SELECT * FROM t1 } db2
} {1 {database is locked}}

# EVIDENCE-OF: R-10993-11647 It is only when the shared-memory wal-index
# is omitted, when the locking mode is EXCLUSIVE prior to the first
# WAL-mode database access, that the locking mode is stuck in EXCLUSIVE.
#
do_execsql_test 3.2.3 {
  PRAGMA locking_mode = NORMAL;
  SELECT * FROM t1;
} {normal 1 2 3 4 5 6}
do_test 3.2.4 {
  catchsql { SELECT * FROM t1 } db2
} {0 {1 2 3 4 5 6}}

do_catchsql_test 3.2.5 {
  PRAGMA locking_mode = EXCLUSIVE;
  INSERT INTO t1 VALUES(7, 8);
} {1 {database is locked}}

db2 close

# EVIDENCE-OF: R-46197-42811 This means that the underlying VFS must
# support the "version 2" shared-memory.
#
# EVIDENCE-OF: R-55316-21772 If the VFS does not support shared-memory
# methods, then the attempt to open a database that is already in WAL
# mode, or the attempt convert a database into WAL mode, will fail.
#
db close
do_test 3.4.1 {
  sqlite3 db test.db -vfs oldvfs
  catchsql { SELECT * FROM t1 }
} {1 {unable to open database file}}
db close
do_test 3.4.2 {
  forcedelete test.db2
  sqlite3 db test.db2 -vfs oldvfs
  catchsql { PRAGMA journal_mode = WAL }
} {0 delete}
db close


# EVIDENCE-OF: R-22428-28959 To prevent older versions of SQLite from
# trying to recover a WAL-mode database (and making matters worse) the
# database file format version numbers (bytes 18 and 19 in the database
# header) are increased from 1 to 2 in WAL mode.
#
reset_db
do_execsql_test 4.1.1 { CREATE TABLE t1(x, y) }
do_test 4.1.2 { hexio_read test.db 18 2 } {0101}
do_execsql_test 4.1.3 { PRAGMA journal_mode = wAL } {wal}
do_test 4.1.4 { hexio_read test.db 18 2 } {0202}


# EVIDENCE-OF: R-02535-05811 One can explicitly change out of WAL mode
# using a pragma such as this: PRAGMA journal_mode=DELETE;
#
do_execsql_test 4.2.1 { INSERT INTO t1 VALUES(1, 1); } {}
do_test 4.2.2 { file exists test.db-wal } {1}
do_execsql_test 4.2.3 { PRAGMA journal_mode = delete } {delete}
do_test 4.2.4 { file exists test.db-wal } {0}

# EVIDENCE-OF: R-60175-02388 Deliberately changing out of WAL mode
# changes the database file format version numbers back to 1 so that
# older versions of SQLite can once again access the database file.
#
do_test 4.3 { hexio_read test.db 18 2 } {0101}

finish_test