Fixes warning when doing:
./sql/mariadbd --socket=/tmp/xxxx/ddd

trx_purge_truncate_rseg_history(): Avoid a leak similar to the one
that was fixed in MDEV-31324, in case a supposedly cached undo log
page is not found in the rseg.undo_cached list.

The previous fix in MDEV-24629 had a version end of life date.

Thanks @pgnd on Zulip for noticing.

This commit contains a merge from 10.5-MDEV-29293-squash
into 10.6.

Although the bug MDEV-29293 was not reproducible with 10.6,
the fix contains several improvements for wsrep KILL query and
BF abort handling, and addresses the following issues:

* MDEV-30307 KILL command issued inside a transaction is
  problematic for galera replication:
  This commit will remove KILL TOI replication, so Galera side
  transaction context is not lost during KILL.
* MDEV-21075 KILL QUERY maintains nodes data consistency but
  breaks GTID sequence: This is fixed as well as KILL does not
  use TOI, and thus does not change GTID state.
* MDEV-30372 Assertion in wsrep-lib state: This was caused by
  BF abort or KILL when local transaction was in the middle
  of group commit. This commit disables THD::killed handling
  during commit, so the problem is avoided.
* MDEV-30963 Assertion failure !lock.was_chosen_as_deadlock_victim
  in trx0trx.h:1065: The assertion happened when the victim was
  BF aborted via MDL while it was committing. This commit changes
  MDL BF aborts so that transactions which are committing cannot
  be BF aborted via MDL. The RQG grammar attached in the issue
  could not reproduce the crash anymore.

Original commit message from 10.5 fix:

    MDEV-29293 MariaDB stuck on starting commit state

    The problem seems to be a deadlock between KILL command execution
    and BF abort issued by an applier, where:
    * KILL has locked victim's LOCK_thd_kill and LOCK_thd_data.
    * Applier has innodb side global lock mutex and victim trx mutex.
    * KILL is calling innobase_kill_query, and is blocked by innodb
      global lock mutex.
    * Applier is in wsrep_innobase_kill_one_trx and is blocked by
      victim's LOCK_thd_kill.

    The fix in this commit removes the TOI replication of KILL command
    and makes KILL execution less intrusive operation. Aborting the
    victim happens now by using awake_no_mutex() and ha_abort_transaction().
    If the KILL happens when the transaction is committing, the
    KILL operation is postponed to happen after the statement
    has completed in order to avoid KILL to interrupt commit
    processing.

    Notable changes in this commit:
    * wsrep client connections's error state may remain sticky after
      client connection is closed. This error message will then pop
      up for the next client session issuing first SQL statement.
      This problem raised with test galera.galera_bf_kill.
      The fix is to reset wsrep client error state, before a THD is
      reused for next connetion.
    * Release THD locks in wsrep_abort_transaction when locking
      innodb mutexes. This guarantees same locking order as with applier
      BF aborting.
    * BF abort from MDL was changed to do BF abort on server/wsrep-lib
      side first, and only then do the BF abort on InnoDB side. This
      removes the need to call back from InnoDB for BF aborts which originate
      from MDL and simplifies the locking.
    * Removed wsrep_thd_set_wsrep_aborter() from service_wsrep.h.
      The manipulation of the wsrep_aborter can be done solely on
      server side. Moreover, it is now debug only variable and
      could be excluded from optimized builds.
    * Remove LOCK_thd_kill from wsrep_thd_LOCK/UNLOCK to allow more
      fine grained locking for SR BF abort which may require locking
      of victim LOCK_thd_kill. Added explicit call for
      wsrep_thd_kill_LOCK/UNLOCK where appropriate.
    * Wsrep-lib was updated to version which allows external
      locking for BF abort calls.

    Changes to MTR tests:
    * Disable galera_bf_abort_group_commit. This test is going to
      be removed (MDEV-30855).
    * Make galera_var_retry_autocommit result more readable by echoing
      cases and expectations into result. Only one expected result for
      reap to verify that server returns expected status for query.
    * Record galera_gcache_recover_manytrx as result file was incomplete.
      Trivial change.
    * Make galera_create_table_as_select more deterministic:
      Wait until CTAS execution has reached MDL wait for multi-master
      conflict case. Expected error from multi-master conflict is
      ER_QUERY_INTERRUPTED. This is because CTAS does not yet have open
      wsrep transaction when it is waiting for MDL, query gets interrupted
      instead of BF aborted. This should be addressed in separate task.
    * A new test galera_bf_abort_registering to check that registering trx gets
      BF aborted through MDL.
    * A new test galera_kill_group_commit to verify correct behavior
      when KILL is executed while the transaction is committing.
Co-authored-by: Seppo Jaakola <seppo.jaakola@iki.fi>
Co-authored-by: Jan Lindström <jan.lindstrom@galeracluster.com>
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

The problem seems to be a deadlock between KILL command execution
and BF abort issued by an applier, where:
* KILL has locked victim's LOCK_thd_kill and LOCK_thd_data.
* Applier has innodb side global lock mutex and victim trx mutex.
* KILL is calling innobase_kill_query, and is blocked by innodb
  global lock mutex.
* Applier is in wsrep_innobase_kill_one_trx and is blocked by
  victim's LOCK_thd_kill.

The fix in this commit removes the TOI replication of KILL command
and makes KILL execution less intrusive operation. Aborting the
victim happens now by using awake_no_mutex() and ha_abort_transaction().
If the KILL happens when the transaction is committing, the
KILL operation is postponed to happen after the statement
has completed in order to avoid KILL to interrupt commit
processing.

Notable changes in this commit:
* wsrep client connections's error state may remain sticky after
  client connection is closed. This error message will then pop
  up for the next client session issuing first SQL statement.
  This problem raised with test galera.galera_bf_kill.
  The fix is to reset wsrep client error state, before a THD is
  reused for next connetion.
* Release THD locks in wsrep_abort_transaction when locking
  innodb mutexes. This guarantees same locking order as with applier
  BF aborting.
* BF abort from MDL was changed to do BF abort on server/wsrep-lib
  side first, and only then do the BF abort on InnoDB side. This
  removes the need to call back from InnoDB for BF aborts which originate
  from MDL and simplifies the locking.
* Removed wsrep_thd_set_wsrep_aborter() from service_wsrep.h.
  The manipulation of the wsrep_aborter can be done solely on
  server side. Moreover, it is now debug only variable and
  could be excluded from optimized builds.
* Remove LOCK_thd_kill from wsrep_thd_LOCK/UNLOCK to allow more
  fine grained locking for SR BF abort which may require locking
  of victim LOCK_thd_kill. Added explicit call for
  wsrep_thd_kill_LOCK/UNLOCK where appropriate.
* Wsrep-lib was updated to version which allows external
  locking for BF abort calls.

Changes to MTR tests:
* Disable galera_bf_abort_group_commit. This test is going to
  be removed (MDEV-30855).
* Record galera_gcache_recover_manytrx as result file was incomplete.
  Trivial change.
* Make galera_create_table_as_select more deterministic:
  Wait until CTAS execution has reached MDL wait for multi-master
  conflict case. Expected error from multi-master conflict is
  ER_QUERY_INTERRUPTED. This is because CTAS does not yet have open
  wsrep transaction when it is waiting for MDL, query gets interrupted
  instead of BF aborted. This should be addressed in separate task.
* A new test galera_kill_group_commit to verify correct behavior
  when KILL is executed while the transaction is committing.
Co-authored-by: Seppo Jaakola <seppo.jaakola@iki.fi>
Co-authored-by: Jan Lindström <jan.lindstrom@galeracluster.com>
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

Add .gitlab-ci.yml file to earliest supported branch to enable
automated building and testing for all MariaDB major branches.

Note to mergers:
GitLab CI is available for branches >= 10.6. This commit includes a
GitLab CI file identical to that in branches >= 10.6, except for the
MARIADB_MAJOR_VERSION variable which should reflect the branch version.
A modified CI will be included in branches 10.4 with PR !2418.
Also changed is the `allow_failure: true` for the MSAN build,
which should be merged up to later branches.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.

srv_export_innodb_status(): Update
export_vars.innodb_buffer_pool_read_requests as it was done
before commit a55b951e (MDEV-26827).
If innodb_status_variables[] pointed to a sharded variable, it would
only access the first shard.

innodb_counter_info[]: Revert a change that was accidentally made in
commit 204e7225

This is a 10.6 port of commit 2f9e2647
from MariaDB Server 10.9 that is missing some optimization due to a
more complex redo log format and recovery logic
(which was simplified in commit 685d958e).

The progress reporting of InnoDB crash recovery was rather intermittent.
Nothing was reported during the single-threaded log record parsing, which
could consume minutes when parsing a large log. During log application,
there only was progress reporting in background threads that would be
invoked on data page read completion.

The progress reporting here will be detailed like this:

InnoDB: Starting crash recovery from checkpoint LSN=628599973,5653727799
InnoDB: Read redo log up to LSN=1963895808
InnoDB: Multi-batch recovery needed at LSN 2534560930
InnoDB: Read redo log up to LSN=3312233472
InnoDB: Read redo log up to LSN=1599646720
InnoDB: Read redo log up to LSN=2160831488
InnoDB: To recover: LSN 2806789376/2806819840; 195082 pages
InnoDB: To recover: LSN 2806789376/2806819840; 63507 pages
InnoDB: Read redo log up to LSN=3195776000
InnoDB: Read redo log up to LSN=3687099392
InnoDB: Read redo log up to LSN=4165315584
InnoDB: To recover: LSN 4374395699/4374440960; 241454 pages
InnoDB: To recover: LSN 4374395699/4374440960; 123701 pages
InnoDB: Read redo log up to LSN=4508724224
InnoDB: Read redo log up to LSN=5094550528
InnoDB: To recover: 205230 pages

The previous messages "Starting a batch to recover" or
"Starting a final batch to recover" will be replaced by
"To recover: ... pages" messages.

If a batch lasts longer than 15 seconds, then there will be
progress reports every 15 seconds, showing the number of remaining pages.
For the non-final batch, the "To recover:" message includes two end LSN:
that of the batch, and of the recovered log. This is the primary measure
of progress. The batch will end once the number of pages to recover
reaches 0.

If recovery is possible in a single batch, the output will look like this,
with a shorter "To recover:" message that counts only the remaining pages:

InnoDB: Starting crash recovery from checkpoint LSN=628599973,5653727799
InnoDB: Read redo log up to LSN=1984539648
InnoDB: Read redo log up to LSN=2710875136
InnoDB: Read redo log up to LSN=3358895104
InnoDB: Read redo log up to LSN=3965299712
InnoDB: Read redo log up to LSN=4557417472
InnoDB: Read redo log up to LSN=5219527680
InnoDB: To recover: 450915 pages

We will also speed up recovery by improving the memory management and
implementing multi-threaded recovery of data pages that will not need
to be read into the buffer pool ("fake read"). Log application in the
"fake read" threads will be protected by an atomic being_recovered field
and exclusive buf_page_t::lock.

Recovery will reserve for data pages two thirds of the buffer pool,
or 256 pages, whichever is smaller. Previously, we could only use at most
one third of the buffer pool for buffered log records. This would typically
mean that with large buffer pools, recovery unnecessary consisted of
multiple batches.

If recovery runs out of memory, it will "roll back" or "rewind" the current
mini-transaction. The recv_sys.recovered_lsn and recv_sys.pages
will correspond to the "out of memory LSN", at the end of the previous
complete mini-transaction.

If recovery runs out of memory while executing the final recovery batch,
we can simply invoke recv_sys.apply(false) to make room, and resume
parsing.

If recovery runs out of memory before the final batch, we will
scan the redo log to the end and check for any missing or inconsistent
files. In this version of the patch, we will throw away any previously
buffered recv_sys.pages and rescan the log from the checkpoint onwards.

recv_sys_t::pages_it: A cached iterator to recv_sys.pages.

recv_sys_t::is_memory_exhausted(): Remove. We will have out-of-memory
handling deep inside recv_sys_t::parse().

recv_sys_t::rewind(), page_recv_t::recs_t::rewind():
Remove all log starting with a specific LSN.

IORequest::write_complete(), IORequest::read_complete():
Replaces fil_aio_callback().

read_io_callback(), write_io_callback(): Replaces io_callback().

IORequest::fake_read_complete(), fake_io_callback(), os_fake_read():
Process a "fake read" request for concurrent recovery.

recv_sys_t::apply_batch(): Choose a number of successive pages
for a recovery batch.

recv_sys_t::erase(recv_sys_t::map::iterator): Remove log records for a
page whose recovery is not in progress. Log application threads
will not invoke this; they will only set being_recovered=-1 to indicate
that the entry is no longer needed.

recv_sys_t::garbage_collect(): Remove all being_recovered=-1 entries.

recv_sys_t::wait_for_pool(): Wait for some space to become available
in the buffer pool.

mlog_init_t::mark_ibuf_exist(): Avoid calls to
recv_sys::recover_low() via ibuf_page_exists() and buf_page_get_low().
Such calls would lead to double locking of recv_sys.mutex, which
depending on implementation could cause a deadlock. We will use
lower-level calls to look up index pages.

buf_LRU_block_remove_hashed(): Disable consistency checks for freed
ROW_FORMAT=COMPRESSED pages. Their contents could be uninitialized garbage.
This fixes an occasional failure of the test
innodb.innodb_bulk_create_index_debug.

Tested by: Matthias Leich

MDEV-31256 fil_node_open_file() releases fil_system.mutex allowing other thread to open its file node

There is room between mutex_exit(&fil_system.mutex) and
mutex_enter(&fil_system.mutex) calls in fil_node_open_file(). During this
room another thread can open the node, and ut_ad(!node->is_open())
assertion in fil_node_open_file_low() can fail.

The fix is not to open node if it was already opened by another thread.

trx_purge_free_segment(), trx_purge_truncate_rseg_history():
Replace some unreachable code with debug assertions.
A buffer-fix does prevent pages from being evicted
from the buffer pool; see buf_page_t::can_relocate().

Tested by: Matthias Leich

trx_purge_truncate_history(): Only call trx_purge_truncate_rseg_history()
if the rollback segment is safe to process. This will avoid leaking undo
log pages that are not yet ready to be processed. This fixes a regression
that was introduced in
commit 0de3be8c (MDEV-30671).

trx_sys_t::any_active_transactions(): Separately count XA PREPARE
transactions.

srv_purge_should_exit(): Terminate slow shutdown if the history size
does not change and XA PREPARE transactions exist in the system.
This will avoid a hang of the test innodb.recovery_shutdown.

Tested by: Matthias Leich

The CODEOWNERS was added almost 3 years ago but never saw any adoption.
Only one person used it (me) to mark what files I maintain and for which
I wish to review commits. No other maintainers or code paths were added,
so clean it away for clarity.

Add Modern Perl headers. Perl 5.16 is still fairly
old from 2012.

Enable UTF-8, warnings and make script 'strict'

Small fixes for perlcritic reported problems and some crashes

I/O layer ":utf8" used at line 268, column 16.  Use ":encoding(UTF-8)" to get strict validation.  (Severity: 5)
"return" statement with explicit "undef" at line 806, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 6844, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7524, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7527, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7599, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7602, column 4.  See page 199 of PBP.  (Severity: 5)
Expression form of "eval" at line 7784, column 4.  See page 161 of PBP.  (Severity: 5)
Expression form of "eval" at line 7806, column 4.  See page 161 of PBP.  (Severity: 5)
Glob written as <...> at line 8016, column 25.  See page 167 of PBP.  (Severity: 5)
"return" statement followed by "sort" at line 9195, column 60.  Behavior is undefined if called in scalar context.  (Severity: 5)
Expression form of "eval" at line 9846, column 10.  See page 161 of PBP.  (Severity: 5)

buf_read_page_low(): Remove an error message and a debug assertion
that can be triggered when using innodb_page_size=4k and
innodb_file_per_table=0. In that case, buf_read_ahead_linear()
may be invoked on page 255, which is one less than the first
page of the doublewrite buffer (256).

fil_space_t::flush_freed(): Renamed from buf_flush_freed_pages();
this is a backport of aa458506 from 10.6.
Invoke log_write_up_to() on last_freed_lsn, instead of avoiding
the operation when the log has not yet been written.
A more costly alternative would be that log_checkpoint() would invoke
this function on every affected tablespace.

buf_read_ahead_linear(): Correct some calculations that were broken
in commit b1ab211d (MDEV-15053).

Thanks to Daniel Black for providing a test case and initial debugging.

Tested by: Matthias Leich

btr_cur_need_opposite_intention(): Check also page_zip_available()
so that we will escalate to exclusive index latch when a non-leaf
page may have to be split further due to ROW_FORMAT=COMPRESSED page
overflow.

Tested by: Matthias Leich

best_access_path(): Simplify the logic for computing fanout.
This fixes up commit 4329ec5d

Command lsof can fail on Debian install.
Revert logic more like old one to make sure that there is no failing
and still does don't boundce on shellcheck.

Debian install scripts if-clauses are not formatted
as they should be. This commit formats Debian
Pre and Post script if-clauses.

Commit fixes several ShellCheck found problems in Debian
Pre- and Postscripts.

Debian script mariadb-server-10.6.postrm contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...

Debian script mariadb-server-10.6.postinst contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2129 -- Consider using { cmd1; cmd2; } >>...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...
  https://www.shellcheck.net/wiki/SC1072 -- Expected test to end here (don't ...
  https://www.shellcheck.net/wiki/SC1073 -- Couldn't parse this test expressi...
  https://www.shellcheck.net/wiki/SC1009 -- The mentioned syntax error was in...

Debian script mariadb-server-10.6.preinst contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2231 -- Quote expansions in this for loop...
  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...
  https://www.shellcheck.net/wiki/SC2001 -- See if you can use ${variable//se...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...
  https://www.shellcheck.net/wiki/SC1007 -- Remove space after = if trying to...

There is several misindentation inside Debian post and pre
installation scripts. False indentation with space
as indent space should be 2 and indentation with tabs.

Derived table creation code would call Field::make_new_field() which would
memcpy the Field object from the source table, including Field::read_stats.

But the temp. table as a whole had table->stats_is_read=false. Which was
correct but not consistent with Field::read_stats and caused an assertion.

Fixed by making sure that Field::read_stats=NULL for fields in the new
temporary (i.e. work) tables.

The problem, introduced in patch for MDEV-26301:

When check_join_cache_usage() decides not to use join buffer, it must
adjust the access method accordingly. For BNL-H joins this means switching
from pseudo-"ref access"(with index=MAX_KEY) to some other access method.

Failing to do this will cause assertions down the line when code that is
not aware of BNL-H will try to initialize index use for ref access with
index=MAX_KEY.

The fix is to follow the regular code path to disable the join buffer for
the join_tab ("goto no_join_cache") instead of just returning from
check_join_cache_usage().