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

Artifact 866bb4982c45ce216c61ded5e8fde4e7e2f3ffa9:


# 2009 April 01
#
# 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.
#
#***********************************************************************
#
# $Id: shared6.test,v 1.4 2009/06/05 17:09:12 drh Exp $

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

do_test shared6-1.1.1 {
  execsql {
    CREATE TABLE t1(a, b);
    CREATE TABLE t2(c, d);
    CREATE TABLE t3(e, f);
  }
  db close
} {}
do_test shared6-1.1.2 {
  set ::enable_shared_cache [sqlite3_enable_shared_cache 1]
  sqlite3_enable_shared_cache
} {1}

do_test shared6-1.1.3 {
  sqlite3 db1 test.db
  sqlite3 db2 test.db
} {}

# Exclusive shared-cache locks. Test the following:
#
#   1.2.1: If [db1] has an exclusive lock, [db2] cannot read.
#   1.2.2: If [db1] has an exclusive lock, [db1] can read.
#   1.2.3: If [db1] has a non-exclusive write-lock, [db2] can read.
# 
do_test shared6-1.2.1 {
  execsql { SELECT * FROM t1 } db2    ;# Cache a compiled statement
  execsql { BEGIN EXCLUSIVE } db1
  catchsql { SELECT * FROM t1 } db2   ;# Execute the cached compiled statement
} {1 {database table is locked}}
do_test shared6-1.2.2 {
  execsql { SELECT * FROM t1 } db1
} {}
do_test shared6-1.2.3 {
  execsql {
    COMMIT;
    BEGIN;
    INSERT INTO t2 VALUES(3, 4);
  } db1
  execsql { SELECT * FROM t1 } db2
} {}
do_test shared6-1.2.X {
  execsql { COMMIT } db1
} {}

# Regular shared-cache locks. Verify the following:
#
#   1.3.1: If [db1] has a write-lock on t1, [db1] can read from t1.
#   1.3.2: If [db1] has a write-lock on t1, [db2] can read from t2.
#   1.3.3: If [db1] has a write-lock on t1, [db2] cannot read from t1.
#   1.3.4: If [db1] has a write-lock on t1, [db2] cannot write to t1.
#   1.3.5: If [db1] has a read-lock on t1, [db2] can read from t1.
#   1.3.6: If [db1] has a read-lock on t1, [db2] cannot write to t1.
#
do_test shared6-1.3.1 {
  execsql {
    BEGIN;
    INSERT INTO t1 VALUES(1, 2);
  } db1
  execsql { SELECT * FROM t1 } db1
} {1 2}
do_test shared6-1.3.2 {
  execsql { SELECT * FROM t2 } db2
} {3 4}
do_test shared6-1.3.3 {
  catchsql { SELECT * FROM t1 } db2
} {1 {database table is locked: t1}}
do_test shared6-1.3.4 {
  catchsql { INSERT INTO t2 VALUES(1, 2) } db2
} {1 {database table is locked}}
do_test shared6-1.3.5 {
  execsql {
    COMMIT;
    BEGIN;
    SELECT * FROM t1;
  } db1
  execsql { SELECT * FROM t1 } db2
} {1 2}
do_test shared6-1.3.5 {
  catchsql { INSERT INTO t1 VALUES(5, 6) } db2
} {1 {database table is locked: t1}}
do_test shared6-1.3.X {
  execsql { COMMIT } db1
} {}

# Read-uncommitted mode.
#
# For these tests, connection [db2] is in read-uncommitted mode.
#
#   1.4.1: If [db1] has a write-lock on t1, [db2] can still read from t1.
#   1.4.2: If [db1] has a write-lock on the db schema (sqlite_master table), 
#          [db2] cannot read from the schema.
#   1.4.3: If [db1] has a read-lock on t1, [db2] cannot write to t1.
#
do_test shared6-1.4.1 {
  execsql { PRAGMA read_uncommitted = 1 } db2
  execsql {
    BEGIN;
    INSERT INTO t1 VALUES(5, 6);
  } db1
  execsql { SELECT * FROM t1 } db2
} {1 2 5 6}
do_test shared6-1.4.2 {
  execsql { CREATE TABLE t4(a, b) } db1
  catchsql { SELECT * FROM t1 } db2
} {1 {database table is locked}}
do_test shared6-1.4.3 {
  execsql {
    COMMIT;
    BEGIN;
    SELECT * FROM t1;
  } db1
  catchsql { INSERT INTO t1 VALUES(7, 8) } db2
} {1 {database table is locked: t1}}

do_test shared6-1.X {
  db1 close
  db2 close
} {}

#-------------------------------------------------------------------------
# The following tests - shared6-2.* - test that two database connections
# that connect to the same file using different VFS implementations do
# not share a cache.
#
if {$::tcl_platform(platform) eq "unix"} {
  do_test shared6-2.1 {
    sqlite3 db1 test.db -vfs unix
    sqlite3 db2 test.db -vfs unix
    sqlite3 db3 test.db -vfs unix-none
    sqlite3 db4 test.db -vfs unix-none
  } {}

  do_test shared6-2.2 {
    execsql { BEGIN; INSERT INTO t1 VALUES(9, 10); } db1
    catchsql { SELECT * FROM t1 } db2
  } {1 {database table is locked: t1}}
  do_test shared6-2.3 {
    execsql { SELECT * FROM t1 } db3
  } {1 2 5 6}

  do_test shared6-2.3 {
    execsql { COMMIT } db1
    execsql { BEGIN; INSERT INTO t1 VALUES(11, 12); } db3
    catchsql { SELECT * FROM t1 } db4
  } {1 {database table is locked: t1}}

  do_test shared6-2.4 {
    execsql { SELECT * FROM t1 } db1
  } {1 2 5 6 9 10}

  do_test shared6-2.5 {
    execsql { COMMIT } db3
  } {}

  do_test shared6-2.X {
    db1 close
    db2 close
    db3 close
    db4 close
  } {}
}

#-------------------------------------------------------------------------
# Test that it is possible to open an exclusive transaction while 
# already holding a read-lock on the database file. And that it is
# not possible if some other connection holds such a lock.
#
do_test shared6-3.1 {
  sqlite3 db1 test.db
  sqlite3 db2 test.db
  sqlite3 db3 test.db
} {}
db1 eval {SELECT * FROM t1} {
  # Within this block [db1] is holding a read-lock on t1. Test that
  # this means t1 cannot be written by [db2].
  #
  do_test shared6-3.2 {
    catchsql { INSERT INTO t1 VALUES(1, 2) } db2
  } {1 {database table is locked: t1}}

  do_test shared6-3.3 {
    execsql { BEGIN EXCLUSIVE } db1
  } {}
  break
}
do_test shared6-3.4 {
  catchsql { SELECT * FROM t1 } db2
} {1 {database schema is locked: main}}
do_test shared6-3.5 {
  execsql COMMIT db1
} {}
db2 eval {SELECT * FROM t1} {
  do_test shared6-3.6 {
    catchsql { BEGIN EXCLUSIVE } db1
  } {1 {database table is locked}}
  break
}
do_test shared6-3.7 {
  execsql { BEGIN } db1
  execsql { BEGIN } db2
} {}
db2 eval {SELECT * FROM t1} {
  do_test shared6-3.8 {
    catchsql { INSERT INTO t1 VALUES(1, 2) } db1
  } {1 {database table is locked: t1}}
  break
}
do_test shared6-3.9 {
  execsql { BEGIN ; ROLLBACK } db3
} {}
do_test shared6-3.10 {
  catchsql { SELECT * FROM t1 } db3
} {1 {database table is locked}}
do_test shared6-3.X {
  db1 close
  db2 close
  db3 close
} {}

do_test shared6-4.1 {
  #forcedelete test.db test.db-journal
  sqlite3 db1 test.db
  sqlite3 db2 test.db

  set ::STMT [sqlite3_prepare_v2 db1 "SELECT * FROM t1" -1 DUMMY]
  execsql { CREATE TABLE t5(a, b) } db2
} {}
do_test shared6-4.2 {
  sqlite3_finalize $::STMT
} {SQLITE_OK}
do_test shared6-4.X {
  
  db1 close
  db2 close
} {}

sqlite3_enable_shared_cache $::enable_shared_cache
finish_test