A 5.5 version of the fix for Bug #54360 "Deadlock DROP/ALTER/CREATE

DATABASE with open HANDLER"

Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.

Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)

By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".

The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().

This patch also adds a simple template to help work with 
the mysys HASH data structure.

Most of the patch was written by Konstantin Osipov.

1 files changed, 237 insertions, 0 deletions

diff --git a/mysql-test/r/mdl_sync.result b/mysql-test/r/mdl_sync.result
index 67d778211dd..1b0ffc588e1 100644
--- a/mysql-test/r/mdl_sync.result
+++ b/mysql-test/r/mdl_sync.result
@@ -2527,3 +2527,240 @@ SET DEBUG_SYNC= "now SIGNAL completed";
 Field	Type	Collation	Null	Key	Default	Extra	Privileges	Comment
 a	char(255)	latin1_swedish_ci	YES		NULL		#	
 DROP TABLE t1;
+#
+# Tests for schema-scope locks
+#
+DROP DATABASE IF EXISTS db1;
+DROP DATABASE IF EXISTS db2;
+# Test 1: 
+# CREATE DATABASE blocks database DDL on the same database, but
+# not database DDL on different databases. Tests X vs X lock.
+#
+# Connection default
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+CREATE DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+CREATE DATABASE db1;
+# Connection con3
+CREATE DATABASE db2;
+ALTER DATABASE db2 DEFAULT CHARACTER SET utf8;
+DROP DATABASE db2;
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: CREATE DATABASE db1
+# Connection con2
+# Reaping: CREATE DATABASE db1
+ERROR HY000: Can't create database 'db1'; database exists
+# Test 2:
+# ALTER DATABASE blocks database DDL on the same database, but
+# not database DDL on different databases. Tests X vs X lock.
+#
+# Connection default
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+ALTER DATABASE db1 DEFAULT CHARACTER SET utf8;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+ALTER DATABASE db1 DEFAULT CHARACTER SET utf8;
+# Connection con3
+CREATE DATABASE db2;
+ALTER DATABASE db2 DEFAULT CHARACTER SET utf8;
+DROP DATABASE db2;
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: ALTER DATABASE db1 DEFAULT CHARACTER SET utf8
+# Connection con2
+# Reaping: ALTER DATABASE db1 DEFAULT CHARACTER SET utf8
+# Connection default
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+ALTER DATABASE db1 DEFAULT CHARACTER SET utf8;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+DROP DATABASE db1;
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: ALTER DATABASE db1 DEFAULT CHARACTER SET utf8
+# Connection con2
+# Reaping: DROP DATABASE db1
+CREATE DATABASE db1;
+# Test 3:
+# Two ALTER..UPGRADE of the same database are mutually exclusive, but
+# two ALTER..UPGRADE of different databases are not. Tests X vs X lock.
+#
+# Connection default
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+ALTER DATABASE `#mysql50#a-b-c` UPGRADE DATA DIRECTORY NAME;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+ALTER DATABASE `#mysql50#a-b-c` UPGRADE DATA DIRECTORY NAME;
+# Connection con3
+ALTER DATABASE `#mysql50#a-b-c-d` UPGRADE DATA DIRECTORY NAME;
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: ALTER DATABASE '#mysql50#a-b-c' UPGRADE DATA DIRECTORY NAME
+# Connection con2
+# Reaping: ALTER DATABASE '#mysql50#a-b-c' UPGRADE DATA DIRECTORY NAME
+ERROR 42000: Unknown database '#mysql50#a-b-c'
+DROP DATABASE `a-b-c`;
+DROP DATABASE `a-b-c-d`;
+# Test 4:
+# DROP DATABASE blocks database DDL on the same database, but
+# not database DDL on different databases. Tests X vs X lock.
+#
+# Connection default
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+DROP DATABASE db1;
+# Connection con3
+CREATE DATABASE db2;
+ALTER DATABASE db2 DEFAULT CHARACTER SET utf8;
+DROP DATABASE db2;
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: DROP DATABASE db1
+ERROR HY000: Can't drop database 'db1'; database doesn't exist
+# Connection default
+CREATE DATABASE db1;
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+ALTER DATABASE db1 DEFAULT CHARACTER SET utf8;
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: ALTER DATABASE db1 DEFAULT CHARACTER SET utf8
+ERROR HY000: Can't create/write to file './db1/db.opt' (Errcode: 2)
+# Test 5:
+# Locked database name prevents CREATE of tables in that database.
+# Tests X vs IX lock.
+#
+# Connection default
+CREATE DATABASE db1;
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+CREATE TABLE db1.t1 (a INT);
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: CREATE TABLE db1.t1 (a INT)
+ERROR 42000: Unknown database 'db1'
+# Test 6:
+# Locked database name prevents RENAME of tables to/from that database.
+# Tests X vs IX lock.
+#
+# Connection default
+CREATE DATABASE db1;
+CREATE TABLE db1.t1 (a INT);
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+RENAME TABLE db1.t1 TO test.t1;
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: RENAME TABLE db1.t1 TO test.t1
+ERROR HY000: Can't find file: './db1/t1.frm' (errno: 2)
+# Connection default
+CREATE DATABASE db1;
+CREATE TABLE test.t2 (a INT);
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+RENAME TABLE test.t2 TO db1.t2;
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: RENAME TABLE test.t2 TO db1.t2
+ERROR HY000: Error on rename of './test/t2.MYI' to './db1/t2.MYI' (Errcode: 2)
+DROP TABLE test.t2;
+# Test 7:
+# Locked database name prevents DROP of tables in that database.
+# Tests X vs IX lock.
+#
+# Connection default
+CREATE DATABASE db1;
+CREATE TABLE db1.t1 (a INT);
+SET DEBUG_SYNC= 'after_wait_locked_schema_name SIGNAL locked WAIT_FOR blocked';
+# Sending:
+DROP DATABASE db1;
+# Connection con2
+SET DEBUG_SYNC= 'now WAIT_FOR locked';
+# Sending:
+DROP TABLE db1.t1;
+# Connection con3
+SET DEBUG_SYNC= 'now SIGNAL blocked';
+# Connection default
+# Reaping: DROP DATABASE db1
+# Connection con2
+# Reaping: DROP TABLE db1.t1
+ERROR 42S02: Unknown table 't1'
+# Connection default
+SET DEBUG_SYNC= 'RESET';
+#
+# End of tests for schema-scope locks
+#
+#
+# Tests of granted global S lock (FLUSH TABLE WITH READ LOCK)
+#
+CREATE DATABASE db1;
+CREATE TABLE db1.t1(a INT);
+# Connection default
+FLUSH TABLE WITH READ LOCK;
+# Connection con2
+CREATE TABLE db1.t2(a INT);
+# Connection default
+UNLOCK TABLES;
+# Connection con2
+# Reaping CREATE TABLE db1.t2(a INT)
+# Connection default
+FLUSH TABLE WITH READ LOCK;
+# Connection con2
+ALTER DATABASE db1 DEFAULT CHARACTER SET utf8;
+# Connection default
+UNLOCK TABLES;
+# Connection con2
+# Reaping ALTER DATABASE db1 DEFAULT CHARACTER SET utf8
+# Connection default
+FLUSH TABLE WITH READ LOCK;
+# Connection con2
+FLUSH TABLE WITH READ LOCK;
+UNLOCK TABLES;
+# Connection default
+UNLOCK TABLES;
+DROP DATABASE db1;