redo_rseg_mutex, noredo_rseg_mutex: Remove the PERFORMANCE_SCHEMA keys.
The rollback segment mutex will be uninstrumented.

trx_sys_t: Remove pointer indirection for rseg_array, temp_rseg.
Align each element to the cache line.

trx_sys_t::rseg_id(): Replaces trx_rseg_t::id.

trx_rseg_t::ref: Replaces needs_purge, trx_ref_count, skip_allocation
in a single std::atomic<uint32_t>.

trx_rseg_t::latch: Replaces trx_rseg_t::mutex.

trx_rseg_t::history_size: Replaces trx_sys_t::rseg_history_len

trx_sys_t::history_size_approx(): Replaces trx_sys.rseg_history_len
in those places where the exact count does not matter. We must not
acquire any trx_rseg_t::latch while holding index page latches, because
normally the trx_rseg_t::latch is acquired before any page latches.

trx_sys_t::history_exists(): Replaces trx_sys.rseg_history_len!=0
with an approximation.

We remove some unnecessary trx_rseg_t::latch acquisition around
trx_undo_set_state_at_prepare() and trx_undo_set_state_at_finish().
Those operations will only access fields that remain constant
after trx_rseg_t::init().

recv_sys_t::recover_deferred(): Set the file size to match the number
of pages. Mariabackup might copy the file while it was being extended.

dict_check_sys_tables(): Correctly advance the cursor position.
This fixes a regression that was caused by
commit 49e2c8f0 (MDEV-25743).

Cherry-picking only test case.

commit_try_rebuild(): Invoke trx_t::drop_table_statistics()
with the correct (original) name of the table.
This fixes a regression that was introduced in
commit 1bd681c8 (MDEV-25506 part 3).

If an ALTER TABLE that affected a table with FULLTEXT INDEX was
in progress while a backup was made, InnoDB would crash or hang
during the first startup after restoring the backup,
while trying to drop the #sql-alter- table for the DDL operation.

drop_garbage_tables_after_restore(): Invoke dict_sys.unlock()
before invoking the FTS functions. Also, invoke purge_sys.stop_FTS()
in debug builds to silence debug assertions. (Purge is not yet
running at this point.)

trx_undo_mem_create_at_db_start(): Relax too strict upgrade checks
that were introduced in
commit e46f76c9 (MDEV-15912).
On commit, pages will typically be set to TRX_UNDO_CACHED state.
Having the type TRX_UNDO_INSERT in such pages is common and
unproblematic; the type would be reset in trx_undo_reuse_cached().

trx_rseg_array_init(): On failure, clean up the rollback segments
that were initialized so far, to avoid an assertion failure later
during shutdown.

init_crypt_key(): On failure, set info->key_version to
ENCRYPTION_KEY_VERSION_INVALID.

log_crypt_101_read_block(): Refuse to attempt decryption if
info->key_version is ENCRYPTION_KEY_VERSION_INVALID.

This bug affected queries with views / derived_tables / CTEs whose
specifications were of the form
  (SELECT ... LIMIT <n>) ORDER BY ...
Units representing such specifications contains one SELECT_LEX structure
for (SELECT ... LIMIT <n>) and additionally SELECT_LEX structure for
fake_select_lex. This fact should have been taken into account in the
function mysql_derived_fill().

This patch has to be applied to 10.2 and 10.3 only.

This bug affected queries with views / derived_tables / CTEs whose
specifications were of the form
  (SELECT ... LIMIT <n>) ORDER BY ...
Units representing such specifications contains one SELECT_LEX structure
for (SELECT ... LIMIT <n>) and additionally SELECT_LEX structure for
fake_select_lex. This fact should have been taken into account in the
function mysql_derived_fill().

This patch has to be applied to 10.2 and 10.3 only.

trx_undo_report_row_operation(): Fix a race condition that was introduced
in commit f74023b9 (MDEV-15090).
We must not access undo_block after the page latch has been released
in mtr_t::commit(), because the block could be evicted or replaced.

fil_crypt_rotate_page(): If a page is already marked as dirty,
do not move it in buf_pool.flush_list. Actual re-encryption
will happen in buf_flush_page(), and moving the page in
buf_pool.flush_list may only postpone the operation.

In the merge commit d3e4fae7
a message about innodb_force_recovery was accidentally duplicated.

- Adding socket check for MariaDB/Mysql driver

Reviewed by: serg@mariadb.com

mytop fall-back to DBD::mysql if DBD::MariaDB is not available

Apply #1546

Let us simply refuse an upgrade from earlier versions if the
upgrade procedure was not followed. This simplifies the purge,
commit, and rollback of transactions.

Before upgrading to MariaDB 10.3 or later, a clean shutdown
of the server (with innodb_fast_shutdown=1 or 0) is necessary,
to ensure that any incomplete transactions are rolled back.
The undo log format was changed in MDEV-12288. There is only
one persistent undo log for each transaction.

Builds on travis-ci.org ceased on 2021-06-15.

see also 068246c0 and 690ae1de

see also 068246c0

see also a5f6eca5

The issue was that we sent two different signals to different threads
after each other. The DEBUG_SYNC functionality cannot handle this (as
the signal is stored in a global variable) and the first one can get
lost.

Fixed by using the same signal for both threads.

When doing CREATE TABLE ... ENGINE=MyISAM SELECT ...
the MyISAM table was not completely flushed at commit
which gave some warnings about table not closed in the
atomic test suite.

Fixed by flushing the table in select_insert::prepare_eof().

- Rename DDL_IGNORE_LOG_ENTRY_CODE to DDL_LOG_IGNORE_ENTRY_CODE
  This makes it similar to all other ddl_log_entry_code's.
- Added some new comments
- ddl_log_revert() now returns != 0 if revert didn't succeed

spider tests use

--let $var= many;sql;statements
--eval $var

and this doesn't work in ps