Due to wsrep uses its own xid format for its recovery,
the xid hashing has to be refined.
When a xid object is not in the server "mysql" format,
the hash record made to contain the xid also in the full format.

In commit 1bd681c8 we introduced
a work-around for the missing MDL protection when the internal
tables of FULLTEXT INDEX are dropped during DDL operations.
That work-around suffered from a race condition. A purge thread
could have narrowly passed purge_sys.check_stop_FTS() and then
(while holding dict_sys.mutex) acquire a table reference right
after fts_lock_table() determined that no references were being
held.

fts_lock_table(): Protect the reference check with dict_sys.mutex.

Thanks to Thirunarayanan Balathandayuthapani for repeating the
failure and testing the fix.

Before any committed DDL operation returns control to the caller,
we must ensure that it will have been durably committed before the
ddl_log state may be changed, no matter if
innodb_flush_log_at_trx_commit=0 is being used.

Operations that would involve deleting files were already safe,
because the durable write of the FILE_DELETE record that would precede
the file deletion would also have made the commit durable.

Furthermore, when we clean up ADD INDEX stubs that were left behind
by a previous ha_innobase::commit_inplace_alter_table(commit=false)
when MDL could not be acquired, we will use the same interface as
for dropping indexes. This safety measure should be dead code,
because ADD FULLTEXT INDEX is not supported online, and dropping indexes
only involves file deletion for FULLTEXT INDEX.

ha_innobase::extra(HA_EXTRA_END_ALTER_COPY): Flush the redo log
because the main transaction will not have written any log and
thus will not initiate any log write either. But the DDL recovery
layer expects that the operation will have been committed.

1. work around MDEV-25912 to not apply assert
   at wsrep running time;
2. handle wsrep mode of the server recovery
3. convert hton calls to static binlog_commit ones.
4. satisfy MSAN complain on uninitialized std::pair

- Replace strncpy() with strmake() to ensure things are \0 terminated
- Initialized some variables that caused compiler warnings
- Increased buffer that caused warnings from strncpy

One warning from InnoDB, others from Connect.

Author: Anel Husakovic <anel@mariadb.org>

Other things:
- Do not use ccache when building with gcov

This is used by InnoDB to detect if CREATE...SELECT is used

Other things:
- Changed InnoDB to use thd_ddl_options()
- Removed lock checking code for create...select (Approved by Marko)

Now the output is only written every 60 second (as it used to be before my
latest change to sleep_until_file_created()).

Test times when using --valgrind are now 4 hours and server start/shutdown
time 180 seconds.
The whole test suite time is caped at 1 day instead of 7 days

Reviewer: Monty

As a part of this MDEV following changes were made:
1) Mariadb named executables used instead of mysql named executables in scripts
2) renamed mysql-test-run and mysql-stress-test to mariadb-test-run and
mariadb-stress-test and created a symlink.

dict_table_schema_check(): Simply remove the debug assertion.
We will still return a failure.

In commit 49e2c8f0 (MDEV-25743)
we made dict_sys_t::find() incompatible with the rest of the
table name hash table operations in case the table name contains
non-ASCII octets (using a compatibility mode that facilitates the
upgrade into the MySQL 5.0 filename-safe encoding) and the target
platform implements signed char.

ut_fold_string(): Remove; replace with my_crc32c(). This also makes
table name hash value calculations independent on whether char
is unsigned or signed.

The server still may abort if there is no enough free space in the
ring buffer to resubmit the IO job, but the behavior is equal to
the failure of os_aio() -> submit_io().

In commit de407e7c a debug assertion
was added that would not always hold: We could have TRX_STATE_PREPARED
here. But, in that case, the transaction should not have been chosen
as a deadlock victim.

Problem:
=======
When the semisync master is crashed and restarted as slave it could
recover transactions that former slaves may never have seen.
A known method existed to clear out all prepared transactions
with --tc-heuristic-recover=rollback does not care to adjust
binlog accordingly.

Fix:
===
The binlog-based recovery is made to concern of the slave semisync role of
post-crash restarted server.
No changes in behavior is done to the "normal" binloggging server
and the semisync master.

When the restarted server is configured with
  --rpl-semi-sync-slave-enabled=1
the refined recovery attempts to roll back prepared transactions
and truncate binlog accordingly.
In case of a partially committed (that is committed at least
in one of the engine participants) such transaction gets committed.
It's guaranteed no (partially as well) committed transactions
exist beyond the truncate position.
In case there exists a non-transactional replication event
(being in a way a committed transaction) past the
computed truncate position the recovery ends with an error.

As after master crash and failover to slave, the demoted-to-slave
ex-master must be ready to face and accept its own (generated by)
events, without generally necessary --replicate-same-server-id.
So the acceptance conditions are relaxed for the semisync slave
to accept own events without that option.
While gtid_strict_mode ON ensures no duplicate transaction can be
(re-)executed the master_use_gtid=none slave has to be
configured with --replicate-same-server-id.

*NOTE* for reviewers.

This patch does not handle the user XA which is done
in next git commit.

the test tests whether short options work on the server command line

* remove 'show variables' for variables not affected by short options
* remove options, that are not short
* remove options, that cannot be tested from SQL
  * in particular, -T12 doesn't affect the test output,
    but cases ~30sec delay on shutdown
* use -W1 as -W2 is the default, so doesn't affect the test output

to match the naming pattern of all other Protocol::store_xxx() methods

in particular, it overwrites pre-allocated buffer in val_buffer,
so following val_buffer->append()'s cause totally unnecessary
mallocs.

also avoid an oxymoron of using `MYSQL_PLUGIN_IMPORT` under
`#ifdef MYSQL_SERVER`, and empty_clex_str is so trivial that a plugin
can define it if needed.

We no longer maintain the unstable-tests collection.
In commit 3635280c we added
a smoke test collection, which independent MariaDB package maintainers
can expect to pass.

            should be updated only when adaptive hashing is turned-on

Currently, btr_cur_n_non_sea is used to track the search that missed
adaptive hash index. adaptive hash index is turned off by default
but the said variable is updated always though the value of it makes sense
only when an adaptive index is enabled. It is meant to check how many
searches didn't go through an adaptive hash index.

Given a global variable that is updated on each search path it causes
a contention with a multi-threaded workload.

Patch moves the said variables inside a loop that is now updated
only when the adaptive hash index is enabled and that in theory should
also, reduce the update frequency of the said variable as the majority of
the request should be serviced through the adaptive hash index.

Variables (btr_cur_n_non_sea and btr_cur_n_sea) are also converted to
use distributed counter to avoid contention.

User visible changes:

This also means that user will now see
Innodb_adaptive_hash_non_hash_searches (viewed as part of show status)
only if code is compiled with DWITH_INNODB_AHI=ON (default) and it will
be updated only if innodb_adaptive_hash_index=1 else it reported as 0.

lock_wait_rpl_report(): Tolerate the loss of a lock wait.
commit c68007d9 (MDEV-24738)
had introduced this rare failure.

This is a complete rewrite of DROP TABLE, also as part of other DDL,
such as ALTER TABLE, CREATE TABLE...SELECT, TRUNCATE TABLE.

The background DROP TABLE queue hack is removed.
If a transaction needs to drop and create a table by the same name
(like TRUNCATE TABLE does), it must first rename the table to an
internal #sql-ib name. No committed version of the data dictionary
will include any #sql-ib tables, because whenever a transaction
renames a table to a #sql-ib name, it will also drop that table.
Either the rename will be rolled back, or the drop will be committed.

Data files will be unlinked after the transaction has been committed
and a FILE_RENAME record has been durably written. The file will
actually be deleted when the detached file handle returned by
fil_delete_tablespace() will be closed, after the latches have been
released. It is possible that a purge of the delete of the SYS_INDEXES
record for the clustered index will execute fil_delete_tablespace()
concurrently with the DDL transaction. In that case, the thread that
arrives later will wait for the other thread to finish.

HTON_TRUNCATE_REQUIRES_EXCLUSIVE_USE: A new handler flag.
ha_innobase::truncate() now requires that all other references to
the table be released in advance. This was implemented by Monty.

ha_innobase::delete_table(): If CREATE TABLE..SELECT is detected,
we will "hijack" the current transaction, drop the table in
the current transaction and commit the current transaction.
This essentially fixes MDEV-21602. There is a FIXME comment about
making the check less failure-prone.

ha_innobase::truncate(), ha_innobase::delete_table():
Implement a fast path for temporary tables. We will no longer allow
temporary tables to use the adaptive hash index.

dict_table_t::mdl_name: The original table name for the purpose of
acquiring MDL in purge, to prevent a race condition between a
DDL transaction that is dropping a table, and purge processing
undo log records of DML that had executed before the DDL operation.
For #sql-backup- tables during ALTER TABLE...ALGORITHM=COPY, the
dict_table_t::mdl_name will differ from dict_table_t::name.

dict_table_t::parse_name(): Use mdl_name instead of name.

dict_table_rename_in_cache(): Update mdl_name.

For the internal FTS_ tables of FULLTEXT INDEX, purge would
acquire MDL on the FTS_ table name, but not on the main table,
and therefore it would be able to run concurrently with a
DDL transaction that is dropping the table. Previously, the
DROP TABLE queue hack prevented a race between purge and DDL.
For now, we introduce purge_sys.stop_FTS() to prevent purge from
opening any table, while a DDL transaction that may drop FTS_
tables is in progress. The function fts_lock_table(), which will
be invoked before the dictionary is locked, will wait for
purge to release any table handles.

trx_t::drop_table_statistics(): Drop statistics for the table.
This replaces dict_stats_drop_index(). We will drop or rename
persistent statistics atomically as part of DDL transactions.
On lock conflict for dropping statistics, we will fail instantly
with DB_LOCK_WAIT_TIMEOUT, because we will be holding the
exclusive data dictionary latch.

trx_t::commit_cleanup(): Separated from trx_t::commit_in_memory().
Relax an assertion around fts_commit() and allow DB_LOCK_WAIT_TIMEOUT
in addition to DB_DUPLICATE_KEY. The call to fts_commit() is
entirely misplaced here and may obviously break the consistency
of transactions that affect FULLTEXT INDEX. It needs to be fixed
separately.

dict_table_t::n_foreign_key_checks_running: Remove (MDEV-21175).
The counter was a work-around for missing meta-data locking (MDL)
on the SQL layer, and not really needed in MariaDB.

ER_TABLE_IN_FK_CHECK: Replaced with ER_UNUSED_28.

HA_ERR_TABLE_IN_FK_CHECK: Remove.

row_ins_check_foreign_constraints(): Do not acquire
dict_sys.latch either. The SQL-layer MDL will protect us.

This was reviewed by Thirunarayanan Balathandayuthapani
and tested by Matthias Leich.

We must invoke online_retry_drop_indexes() before
ha_innobase_inplace_ctx::trx->id is assigned.

The implementation of MDEV-24626 was not entirely correct.
We could occasionally fail to remove some *.ibd files on recovery.

deferred_spaces: Keep track of FILE_DELETE records.

deferred_spaces.add(): Do not allow duplicate file names.

recv_rename_files(): Preserve some of renamed_spaces entries for
deferred_spaces.reinit_all().

Thanks to Thirunarayanan Balathandayuthapani for noticing that
deferred_spaces.add() must filter out duplicate file names,
as well as some debugging help.