MDEV-11412 Ensure that table is truly dropped when using DROP TABLE

The used code is largely based on code from Tencent

The problem is that in some rare cases there may be a conflict between .frm
files and the files in the storage engine. In this case the DROP TABLE
was not able to properly drop the table.

Some MariaDB/MySQL forks has solved this by adding a FORCE option to
DROP TABLE. After some discussion among MariaDB developers, we concluded
that users expects that DROP TABLE should always work, even if the
table would not be consistent. There should not be a need to use a
separate keyword to ensure that the table is really deleted.

The used solution is:
- If a .frm table doesn't exists, try dropping the table from all storage
  engines.
- If the .frm table exists but the table does not exist in the engine
  try dropping the table from all storage engines.
- Update storage engines using many table files (.CVS, MyISAM, Aria) to
  succeed with the drop even if some of the files are missing.
- Add HTON_AUTOMATIC_DELETE_TABLE to handlerton's where delete_table()
  is not needed and always succeed. This is used by ha_delete_table_force()
  to know which handlers to ignore when trying to drop a table without
  a .frm file.

The disadvantage of this solution is that a DROP TABLE on a non existing
table will be a bit slower as we have to ask all active storage engines
if they know anything about the table.

Other things:
- Added a new flag MY_IGNORE_ENOENT to my_delete() to not give an error
  if the file doesn't exist. This simplifies some of the code.
- Don't clear thd->error in ha_delete_table() if there was an active
  error. This is a bug fix.
- handler::delete_table() will not abort if first file doesn't exists.
  This is bug fix to handle the case when a drop table was aborted in
  the middle.
- Cleaned up mysql_rm_table_no_locks() to ensure that if_exists uses
  same code path as when it's not used.
- Use non_existing_Table_error() to detect if table didn't exists.
  Old code used different errors tests in different position.
- Table_triggers_list::drop_all_triggers() now drops trigger file if
  it can't be parsed instead of leaving it hanging around (bug fix)
- InnoDB doesn't anymore print error about .frm file out of sync with
  InnoDB directory if .frm file does not exists. This change was required
  to be able to try to drop an InnoDB file when .frm doesn't exists.
- Fixed bug in mi_delete_table() where the .MYD file would not be dropped
  if the .MYI file didn't exists.
- Fixed memory leak in Mroonga when deleting non existing table
- Fixed memory leak in Connect when deleting non existing table

Bugs fixed introduced by the original version of this commit:
MDEV-22826 Presence of Spider prevents tables from being force-deleted from
           other engines

1 files changed, 133 insertions, 0 deletions

diff --git a/mysql-test/main/drop_table_force.result b/mysql-test/main/drop_table_force.result
new file mode 100644
index 00000000000..bb4ecc060b0
--- /dev/null
+++ b/mysql-test/main/drop_table_force.result
@@ -0,0 +1,133 @@
+CALL mtr.add_suppression("Operating system error number");
+CALL mtr.add_suppression("The error means the system cannot");
+CALL mtr.add_suppression("returned OS error 71");
+#Test1: table with missing .ibd can be dropped directly
+create table t1(a int)engine=innodb;
+drop table t1;
+db.opt
+# Test droping table without frm without super privilege
+create table t1(a int) engine=innodb;
+create user test identified by '123456';
+grant all privileges on test.t1 to 'test'@'%'identified by '123456' with grant option;
+connect  con_test, localhost, test,'123456', ;
+connection con_test;
+drop table t1;
+drop table t1;
+ERROR 42S02: Unknown table 'test.t1'
+connection default;
+disconnect con_test;
+drop user test;
+db.opt
+#Test4: drop table can drop consistent table as well
+create table t1(a int) engine=innodb;
+drop table t1;
+db.opt
+#Test5: drop table with triger, and with missing frm
+create table t1(a int)engine=innodb;
+create trigger t1_trg before insert on t1 for each row begin end;
+drop table t1;
+drop table t1;
+ERROR 42S02: Unknown table 'test.t1'
+db.opt
+#Test6: table with foreign key references can not be dropped
+CREATE TABLE parent (id INT NOT NULL, PRIMARY KEY (id)) ENGINE=INNODB;
+CREATE TABLE child (id INT, parent_id INT, INDEX par_ind (parent_id), FOREIGN KEY (parent_id) REFERENCES parent(id) ON DELETE CASCADE) ENGINE=INNODB;
+drop table parent;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table child;
+drop table parent;
+db.opt
+#Test7: drop table twice
+create table t1(a int)engine=innodb;
+drop table t1;
+db.opt
+drop table if exists t1;
+Warnings:
+Note	1051	Unknown table 'test.t1'
+db.opt
+#Test8: check compatibility with if exists
+create table t1(a int)engine=innodb;
+drop table t1;
+db.opt
+drop table if exists t1;
+Warnings:
+Note	1051	Unknown table 'test.t1'
+#Test9: check compatibility with restrict/cascade
+CREATE TABLE parent (id INT NOT NULL, PRIMARY KEY (id)) ENGINE=INNODB;
+CREATE TABLE child (id INT, parent_id INT, INDEX par_ind (parent_id), FOREIGN KEY (parent_id) REFERENCES parent(id) ON DELETE CASCADE) ENGINE=INNODB;
+drop table parent;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table parent restrict;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table parent cascade;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table parent;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table parent restrict;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table parent cascade;
+ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails
+drop table child;
+drop table parent;
+#Test10: drop non-innodb engine table returns ok
+create table t1(a int) engine=myisam;
+drop table t1;
+create table t1(a int) engine=myisam;
+drop table t1;
+Warnings:
+Warning	1017	Can't find file: './test/t1.MYI' (errno: 2 "No such file or directory")
+create table t1(a int) engine=myisam;
+drop table t1;
+Warnings:
+Warning	1017	Can't find file: './test/t1.MYI' (errno: 2 "No such file or directory")
+db.opt
+create table t1(a int) engine=aria;
+db.opt
+t1.MAI
+drop table t1;
+ERROR 42S02: Unknown table 'test.t1'
+show warnings;
+Level	Code	Message
+Error	29	File './test/t1.MAD' not found (Errcode: 2 "No such file or directory")
+Error	1051	Unknown table 'test.t1'
+db.opt
+create table t2(a int) engine=aria;
+flush tables;
+db.opt
+t2.MAD
+drop table t2;
+ERROR 42S02: Unknown table 'test.t2'
+show warnings;
+Level	Code	Message
+Error	1051	Unknown table 'test.t2'
+db.opt
+create table t2(a int) engine=aria;
+flush tables;
+db.opt
+t2.frm
+drop table t2;
+Warnings:
+Warning	1017	Can't find file: './test/t2.MAI' (errno: 2 "No such file or directory")
+create table t2(a int not null) engine=CSV;
+flush tables;
+drop table t2;
+db.opt
+create table t2(a int not null) engine=CSV;
+flush tables;
+drop table t2;
+db.opt
+create table t2(a int not null) engine=archive;
+flush tables;
+select * from t2;
+a
+flush tables;
+select * from t2;
+ERROR 42S02: Table 'test.t2' doesn't exist
+db.opt
+drop table t2;
+ERROR 42S02: Unknown table 'test.t2'
+create table t2(a int not null) engine=archive;
+flush tables;
+drop table t2;
+ERROR 42S02: Unknown table 'test.t2'
+db.opt