sqlite/test/snapshot.test

# 2015 December 7
#
# 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 the sqlite3_snapshot_xxx() APIs.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
ifcapable !snapshot {finish_test; return}
set testprefix snapshot

# This test does not work with the inmemory_journal permutation. The reason
# is that each connection opened as part of this permutation executes
# "PRAGMA journal_mode=memory", which fails if the database is in wal mode
# and there are one or more existing connections.
if {[permutation]=="inmemory_journal"} {
  finish_test
  return
}

#-------------------------------------------------------------------------
# Check some error conditions in snapshot_get(). It is an error if:
#
#  1) snapshot_get() is called on a non-WAL database, or
#  2) there is an open write transaction on the database.
#
do_execsql_test 1.0 {
  CREATE TABLE t1(a, b);
  INSERT INTO t1 VALUES(1, 2);
  INSERT INTO t1 VALUES(3, 4);
}

do_test 1.1.1 {
  execsql { BEGIN; SELECT * FROM t1; }
  list [catch { sqlite3_snapshot_get db main } msg] $msg
} {1 SQLITE_ERROR}
do_execsql_test 1.1.2 COMMIT

do_test 1.2.1 {
  execsql {
    PRAGMA journal_mode = WAL;
    BEGIN;
      INSERT INTO t1 VALUES(5, 6);
      INSERT INTO t1 VALUES(7, 8);
  }
  list [catch { sqlite3_snapshot_get db main } msg] $msg
} {1 SQLITE_ERROR}
do_execsql_test 1.3.2 COMMIT

#-------------------------------------------------------------------------
# Check that a simple case works. Reuse the database created by the
# block of tests above.
#
do_execsql_test 2.1.0 {
  BEGIN;
    SELECT * FROM t1;
} {1 2 3 4 5 6 7 8}

do_test 2.1.1 {
  set snapshot [sqlite3_snapshot_get db main]
  execsql {
    COMMIT;
    INSERT INTO t1 VALUES(9, 10);
    SELECT * FROM t1;
  }
} {1 2 3 4 5 6 7 8 9 10}

do_test 2.1.2 {
  execsql BEGIN
  sqlite3_snapshot_open db main $snapshot
  execsql {
    SELECT * FROM t1;
  }
} {1 2 3 4 5 6 7 8}

do_test 2.1.3 {
  sqlite3_snapshot_free $snapshot
  execsql COMMIT
} {}

do_test 2.2.0 {
  sqlite3 db2 test.db
  execsql {
    BEGIN;
      SELECT * FROM t1;
  } db2
} {1 2 3 4 5 6 7 8 9 10}

do_test 2.2.1 {
  set snapshot [sqlite3_snapshot_get db2 main]
  execsql {
    INSERT INTO t1 VALUES(11, 12);
    SELECT * FROM t1;
  }
} {1 2 3 4 5 6 7 8 9 10 11 12}

do_test 2.2.2 {
  execsql BEGIN
  sqlite3_snapshot_open db main $snapshot
  execsql {
    SELECT * FROM t1;
  }
} {1 2 3 4 5 6 7 8 9 10}

do_test 2.2.3 {
  sqlite3_snapshot_free $snapshot
  execsql COMMIT
  execsql COMMIT db2
  db2 close
} {}

do_test 2.3.1 {
  execsql { DELETE FROM t1 WHERE a>6 }
  set snapshot [sqlite3_snapshot_get db main]
  execsql {
    INSERT INTO t1 VALUES('a', 'b');
    INSERT INTO t1 VALUES('c', 'd');
    SELECT * FROM t1;
  }
} {1 2 3 4 5 6 a b c d}
do_test 2.3.2 {
  execsql BEGIN
  sqlite3_snapshot_open db main $snapshot
  execsql { SELECT * FROM t1 }
} {1 2 3 4 5 6}

do_test 2.3.3 {
  catchsql {
    INSERT INTO t1 VALUES('x','y')
  }
} {1 {database is locked}}
do_test 2.3.4 {
  execsql COMMIT
  sqlite3_snapshot_free $snapshot
} {}

#-------------------------------------------------------------------------
# Check some errors in sqlite3_snapshot_open(). It is an error if:
#
#   1) the db is in auto-commit mode,
#   2) the db has an open (read or write) transaction,
#   3) the db is not a wal database,
#
# Reuse the database created by earlier tests.
#
do_execsql_test 3.0.0 {
  CREATE TABLE t2(x, y);
  INSERT INTO t2 VALUES('a', 'b');
  INSERT INTO t2 VALUES('c', 'd');
  BEGIN;
    SELECT * FROM t2;
} {a b c d}
do_test 3.0.1 {
  set snapshot [sqlite3_snapshot_get db main]
  execsql { COMMIT }
  execsql { INSERT INTO t2 VALUES('e', 'f'); }
} {}

do_test 3.1 {
  list [catch {sqlite3_snapshot_open db main $snapshot } msg] $msg
} {1 SQLITE_ERROR}

do_test 3.2.1 {
  execsql {
    BEGIN;
      SELECT * FROM t2;
  }
} {a b c d e f}
do_test 3.2.2 {
  list [catch {sqlite3_snapshot_open db main $snapshot } msg] $msg
} {1 SQLITE_ERROR}

do_test 3.2.3 {
  execsql {
    COMMIT;
    BEGIN;
      INSERT INTO t2 VALUES('g', 'h');
  }
  list [catch {sqlite3_snapshot_open db main $snapshot } msg] $msg
} {1 SQLITE_ERROR}
do_execsql_test 3.2.4 COMMIT

do_test 3.3.1 {
  execsql { PRAGMA journal_mode = DELETE }
  execsql { BEGIN }
  list [catch {sqlite3_snapshot_open db main $snapshot } msg] $msg
} {1 SQLITE_ERROR}

do_test 3.3.2 {
  sqlite3_snapshot_free $snapshot
  execsql COMMIT
} {}

#-------------------------------------------------------------------------
# Check that SQLITE_BUSY_SNAPSHOT is returned if the specified snapshot
# no longer exists because the wal file has been checkpointed.
#
#   1. Reading a snapshot from the middle of a wal file is not possible
#      after the wal file has been checkpointed.
#
#   2. That a snapshot from the end of a wal file can not be read once
#      the wal file has been wrapped.
#
do_execsql_test 4.1.0 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t3(i, j);
  INSERT INTO t3 VALUES('o', 't');
  INSERT INTO t3 VALUES('t', 'f');
  BEGIN;
    SELECT * FROM t3;
} {wal o t t f}

do_test 4.1.1 {
  set snapshot [sqlite3_snapshot_get db main]
  execsql COMMIT
} {}
do_test 4.1.2 {
  execsql { 
    INSERT INTO t3 VALUES('f', 's'); 
    BEGIN;
  }
  sqlite3_snapshot_open db main $snapshot
  execsql { SELECT * FROM t3 }
} {o t t f}

do_test 4.1.3 {
  execsql { 
    COMMIT;
    PRAGMA wal_checkpoint;
    BEGIN;
  }
  list [catch {sqlite3_snapshot_open db main $snapshot} msg] $msg
} {1 SQLITE_BUSY_SNAPSHOT}
do_test 4.1.4 {
  sqlite3_snapshot_free $snapshot
  execsql COMMIT
} {}

do_test 4.2.1 {
  execsql {
    INSERT INTO t3 VALUES('s', 'e');
    INSERT INTO t3 VALUES('n', 't');
    BEGIN;
      SELECT * FROM t3;
  }
} {o t t f f s s e n t}
do_test 4.2.2 {
  set snapshot [sqlite3_snapshot_get db main]
  execsql {
    COMMIT;
    PRAGMA wal_checkpoint;
    BEGIN;
  }
  sqlite3_snapshot_open db main $snapshot
  execsql { SELECT * FROM t3 }
} {o t t f f s s e n t}
do_test 4.2.3 {
  execsql {
    COMMIT;
    INSERT INTO t3 VALUES('e', 't');
    BEGIN;
  }
  list [catch {sqlite3_snapshot_open db main $snapshot} msg] $msg
} {1 SQLITE_BUSY_SNAPSHOT}
do_test 4.2.4 {
  sqlite3_snapshot_free $snapshot
} {}

#-------------------------------------------------------------------------
# Check that SQLITE_BUSY is returned if a checkpoint is running when
# sqlite3_snapshot_open() is called.
#
reset_db
db close
testvfs tvfs
sqlite3 db test.db -vfs tvfs

do_execsql_test 5.1 {
  PRAGMA journal_mode = wal;
  CREATE TABLE x1(x, xx, xxx);
  INSERT INTO x1 VALUES('z', 'zz', 'zzz');
  BEGIN;
    SELECT * FROM x1;
} {wal z zz zzz}

do_test 5.2 {
  set ::snapshot [sqlite3_snapshot_get db main]
  sqlite3 db2 test.db -vfs tvfs
  execsql {
    INSERT INTO x1 VALUES('a', 'aa', 'aaa');
    COMMIT;
  }
} {}

set t53 0
proc write_callback {args} {
  do_test 5.3.[incr ::t53] {
    execsql BEGIN
    list [catch { sqlite3_snapshot_open db main $::snapshot } msg] $msg
  } {1 SQLITE_BUSY}
  catchsql COMMIT
}

tvfs filter xWrite
tvfs script write_callback
db2 eval { PRAGMA wal_checkpoint }
db close
db2 close
tvfs delete
sqlite3_snapshot_free $snapshot

#-------------------------------------------------------------------------
# Test that sqlite3_snapshot_get() may be called immediately after
# "BEGIN; PRAGMA user_version;". And that sqlite3_snapshot_open() may
# be called after opening the db handle and running the script
# "PRAGMA user_version; BEGIN".
reset_db
do_execsql_test 6.1 {
  PRAGMA journal_mode = wal;
  CREATE TABLE x1(x, xx, xxx);
  INSERT INTO x1 VALUES('z', 'zz', 'zzz');
  BEGIN;
    PRAGMA user_version;
} {wal 0}
do_test 6.2 {
  set ::snapshot [sqlite3_snapshot_get db main]
  execsql {
    INSERT INTO x1 VALUES('a', 'aa', 'aaa');
    COMMIT;
  }
} {}
do_test 6.3 {
  sqlite3 db2 test.db 
  db2 eval "PRAGMA user_version ; BEGIN"
  sqlite3_snapshot_open db2 main $::snapshot
  db2 eval { SELECT * FROM x1 }
} {z zz zzz}
do_test 6.4 {
  db2 close
  sqlite3 db2 test.db 
  db2 eval "PRAGMA application_id"
  db2 eval "BEGIN"
  sqlite3_snapshot_open db2 main $::snapshot
  db2 eval { SELECT * FROM x1 }
} {z zz zzz}

# EVIDENCE-OF: R-55491-50411 A snapshot will fail to open if the
# database connection D has not previously completed at least one read
# operation against the database file.
#
do_test 6.5 {
  db2 close
  sqlite3 db2 test.db 
  db2 eval "BEGIN"
  list [catch {sqlite3_snapshot_open db2 main $::snapshot} msg] $msg
} {1 SQLITE_ERROR}

sqlite3_snapshot_free $snapshot

#-------------------------------------------------------------------------
# The following tests investigate the sqlite3_snapshot_cmp() API.
#

# Compare snapshots $p1 and $p2, checking that the result is $r.
#
proc do_snapshot_cmp_test {tn p1 p2 r} {
  uplevel [list do_test $tn.1 [list sqlite3_snapshot_cmp $p1 $p2] $r]
  uplevel [list do_test $tn.2 [list sqlite3_snapshot_cmp $p2 $p1] [expr $r*-1]]
  uplevel [list do_test $tn.3 [list sqlite3_snapshot_cmp $p1 $p1] 0]
  uplevel [list do_test $tn.4 [list sqlite3_snapshot_cmp $p2 $p2] 0]
}

catch { db2 close }
reset_db

do_execsql_test 7.1 {
  PRAGMA journal_mode = wal;
  CREATE TABLE t1(x);
} wal

do_test 7.1.2 {
  execsql { BEGIN ; PRAGMA application_id }
  set p1 [sqlite3_snapshot_get db main]
  execsql {
    INSERT INTO t1 VALUES(10);
    COMMIT;
  }
  execsql { BEGIN ; PRAGMA application_id }
  set p2 [sqlite3_snapshot_get db main]
  execsql COMMIT
} {}

do_snapshot_cmp_test 7.1.3 $p1 $p2 -1
sqlite3_snapshot_free $p1
sqlite3_snapshot_free $p2

do_execsql_test 7.2.1 {
  INSERT INTO t1 VALUES(11);
  INSERT INTO t1 VALUES(12);
  INSERT INTO t1 VALUES(13);
  BEGIN; 
    PRAGMA application_id;
} {0}
do_test 7.2.2 {
  set p1 [sqlite3_snapshot_get db main]
  execsql {
    COMMIT;
    INSERT INTO t1 VALUES(14);
    PRAGMA wal_checkpoint;
    BEGIN;
      PRAGMA application_id;
  }
  set p2 [sqlite3_snapshot_get db main]
  execsql COMMIT
} {}

do_snapshot_cmp_test 7.2.3 $p1 $p2 -1
sqlite3_snapshot_free $p2

do_test 7.3.1 {
  execsql {
    INSERT INTO t1 VALUES(14);
    BEGIN;
      PRAGMA application_id;
  }
  set p2 [sqlite3_snapshot_get db main]
  execsql COMMIT
} {}

do_snapshot_cmp_test 7.3.2 $p1 $p2 -1
sqlite3_snapshot_free $p1
sqlite3_snapshot_free $p2

finish_test