The old code collected a list of THD's, locked the THD's from getting
deleted by locking two mutex and then later in a separate loop
sent a kill signal to each THD.

The problem with this approach is that, as THD's can be reused,
the second time the THD is killed, the mutex can be taken in
different order, which signals failures in safe_mutex.

Fixed by sending the kill signal directly and not collect the THD's
in a list to be signaled later.  This is the same approach we are using
in kill_zombie_dump_threads().

Other things:
- Reset safe_mutex_t->locked_mutex when freed (Safety fix)

This was needed to get semisync to work on Windows.

rpl_semi_sync_slave_enabled_consistent.test and the first part of
the commit message comes from Brandon Nesterenko.

A test to show how to induce the "Read semi-sync reply magic number
error" message on a primary. In short, if semi-sync is turned on
during the hand-shake process between a primary and replica, but
later a user negates the rpl_semi_sync_slave_enabled variable while
the replica's IO thread is running; if the io thread exits, the
replica can skip a necessary call to kill_connection() in
repl_semisync_slave.slave_stop() due to its reliance on a global
variable. Then, the replica will send a COM_QUIT packet to the
primary on an active semi-sync connection, causing the magic number
error.

The test in this patch exits the IO thread by forcing an error;
though note a call to STOP SLAVE could also do this, but it ends up
needing more synchronization. That is, the STOP SLAVE command also
tries to kill the VIO of the replica, which makes a race with the IO
thread to try and send the COM_QUIT before this happens (which would
need more debug_sync to get around). See THD::awake_no_mutex for
details as to the killing of the replica’s vio.

Notes:
- The MariaDB documentation does not make it clear that when one
  enables semi-sync replication it does not matter if one enables
  it first in the master or slave. Any order works.

Changes done:
- The rpl_semi_sync_slave_enabled variable is now a default value for
  when semisync is started. The variable does not anymore affect
  semisync if it is already running. This fixes the original reported
  bug.  Internally we now use repl_semisync_slave.get_slave_enabled()
  instead of rpl_semi_sync_slave_enabled. To check if semisync is
  active on should check the @@rpl_semi_sync_slave_status variable (as
  before).
- The semisync protocol conflicts in the way that the original
  MySQL/MariaDB client-server protocol was designed (client-server
  send and reply packets are strictly ordered and includes a packet
  number to allow one to check if a packet is lost). When using
  semi-sync the master and slave can send packets at 'any time', so
  packet numbering does not work. The 'solution' has been that each
  communication starts with packet number 1, but in some cases there
  is still a chance that the packet number check can fail.  Fixed by
  adding a flag (pkt_nr_can_be_reset) in the NET struct that one can
  use to signal that packet number checking should not be done. This
  is flag is set when semi-sync is used.
- Added Master_info::semi_sync_reply_enabled to allow one to configure
  some slaves with semisync and other other slaves without semisync.
  Removed global variable semi_sync_need_reply that would not work
  with multi-master.
- Repl_semi_sync_master::report_reply_packet() can now recognize
  the COM_QUIT packet from semisync slave and not give a
  "Read semi-sync reply magic number error" error for this case.
  The slave will be removed from the Ack listener.
- On Windows, don't stop semisync Ack listener just because one
  slave connection is using socket_id > FD_SETSIZE.
- Removed busy loop in Ack_receiver::run() by using
 "Self-pipe trick" to signal new slave and stop Ack_receiver.
- Changed some Repl_semi_sync_slave functions that always returns 0
  from int to void.
- Added Repl_semi_sync_slave::slave_reconnect().
- Removed dummy_function Repl_semi_sync_slave::reset_slave().
- Removed some duplicate semisync notes from the error log.
- Add test of "if (get_slave_enabled() && semi_sync_need_reply)"
  before calling Repl_semi_sync_slave::slave_reply().
  (Speeds up the code as we can skip all initializations).
- If epl_semisync_slave.slave_reply() fails, we disable semisync
  for that connection.
- We do not call semisync.switch_off() if there are no active slaves.
  Instead we check in Repl_semi_sync_master::commit_trx() if there are
  no active threads. This simplices the code.
- Changed assert() to DBUG_ASSERT() to ensure that the DBUG log is
  flushed in case of asserts.
- Removed the internal rpl_semi_sync_slave_status as it is not needed
  anymore. The @@rpl_semi_sync_slave_status status variable is now
  mapped to rpl_semi_sync_enabled.
- Removed rpl_semi_sync_slave_enabled  as it is not needed anymore.
  Repl_semi_sync_slave::get_slave_enabled() contains the active status.
- Added checking that we do not add a slave twice with
  Ack_receiver::add_slave(). This could happen with old code.
- Removed Repl_semi_sync_master::check_and_switch() as it is not
  needed anymore.
- Ensure that when we call Ack_receiver::remove_slave() that the slave
  is removed from the listener before function returns.
- Call listener.listen_on_sockets() outside of mutex for better
  performance and less contested mutex.
- Ensure that listening is ignoring newly added slaves when checking for
  responses.
- Fixed the master ack_receiver listener is not killed if there are no
  connected slaves (and thus stop semisync handling of future
  connections). This could happen if all slaves sockets where would be
  marked as unreliable.
- Added unlink() to base_ilist_iterator and remove() to
  I_List_iterator. This enables us to remove 'dead' slaves in
  Ack_recever::run().
- kill_zombie_dump_threads() now does killing of dump threads properly.
  - It can now kill several threads (should be impossible but could
    happen if IO slaves reconnects very fast).
  - We now wait until the dump thread is done before starting the
    dump.
- Added an error if kill_zombie_dump_threads() fails.
- Set thd->variables.server_id before calling
  kill_zombie_dump_threads(). This simplies the code.
- Added a lot of comments both in code and tests.
- Removed DBUG_EVALUATE_IF "failed_slave_start" as it is not used.

Test changes:
- rpl.rpl_session_var2 added which runs rpl.rpl_session_var test with
  semisync enabled.
- Some timings changed slight with startup of slave which caused
  rpl_binlog_dump_slave_gtid_state_info.text to fail as it checked the
  error log file before the slave had started properly. Fixed by
  adding wait_for_pattern_in_file.inc that allows waiting for the
  pattern to appear in the log file.
- Tests have been updated so that we first set
  rpl_semi_sync_master_enabled on the master and then set
  rpl_semi_sync_slave_enabled on the slaves (this is according to how
  the MariaDB documentation document how to setup semi-sync).
- Error text "Master server does not have semi-sync enabled" has been
  replaced with "Master server does not support semi-sync" for the
  case when the master supports semi-sync but semi-sync is not
  enabled.

Other things:
- Some trivial cleanups in Repl_semi_sync_master::update_sync_header().
- We should in 11.3 changed the default value for
  rpl-semi-sync-master-wait-no-slave from TRUE to FALSE as the TRUE
  does not make much sense as default. The main difference with using
  FALSE is that we do not wait for semisync Ack if there are no slave
  threads.  In the case of TRUE we wait once, which did not bring any
  notable benefits except slower startup of master configured for
  using semisync.

Co-author: Brandon Nesterenko <brandon.nesterenko@mariadb.com>

This solves the problem reported in MDEV-32960 where a new
slave may not be registered in time and the master disables
semi sync because of that.

client is not using any database to execute the SQL.

Analysis:
When there is no database, the database string is NULL so (null) gets
printed.
Fix:
Print NULL instead of (null) because when there is no database SELECT
DATABASE() return NULL. SO NULL is more appropriate choice.

to SQL error plugin

New plugin variable "with_db_and_thread_info" is added which prints the
thread id and databse name to the logfile. the value is stored in variable
"with_db_and_thread_info"

log_sql_errors() is responsible for printing in the log. If detailed is
enabled, print thread id and database name both, otherwise skip it.

Notably MDEV-33290, columnstore disable stays in 10.5.

MCOL-5611 supporting with Boost-1.80, the version "next_prime"
disappears from https://github.com/boostorg/unordered/blob/boost-1.79.0/include/boost/unordered/detail/implementation.hpp
makes it the currenly highest supported versions.

Lets check this version.

While CMake-3.19+ supports version ranges in package determinations this
isn't supported for Boost in Cmake-3.28. So we check for the 1.80 and
don't compile ColumnStore.

Statements affect by this bug are all SQL statements that
1) prefixed with "EXPLAIN"
2) have a lower level join structure created for a union subquery.

A bug in select_describe() passed an incorrect "result" object to
mysql_explain_union(), resulting in unpredictable behaviour and
out of context calls.

Reviewed by: Oleksandr Byelkin, sanja@mariadb.com

An existing binlog checksum can be overridden to 0 if writing a NULL
payload when using Zlib for the computation. That is, calling into
Zlib's crc32 with empty data initializes an incremental CRC
computation to 0.

This patch changes the Log_event_writer::write_data() to exit
immediately if there is nothing to write, thereby bypassing the
checksum computation. This follows the pattern of
Log_event_writer::encrypt_and_write(), which also exits immediately
if there is no data to write.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

A mix of path separators looks odd.

  InnoDB: Loading buffer pool(s) from C:\xampp\mysql\data/ib_buffer_pool

This was changed in cf552f58

Both forward slashes and backward slashes work on Windows. We do not
use \\?\ names.

So we improve the consistent look of it so it doesn't look like a bug.

Normalize, in this case, the path separator to \ for making the filename.

Reported thanks to Github user @celestinoxp.

Closes: https://github.com/ApacheFriends/xampp-build/issues/33
Reviewed by: Marko Mäkelä and Vladislav Vaintroub

use pkg-config to find pcre2, if possible

rename PCRE_INCLUDES to use PKG_CHECK_MODULES naming, PCRE_INCLUDE_DIRS

MDEV-32968  InnoDB fails to restore tablespace first page from doublewrite buffer when page is empty

recv_dblwr_t::find_first_page(): Free the allocated memory
to read the first 3 pages from tablespace.

innodb.doublewrite: Added sleep to ensure page cleaner thread
wake up from my_cond_wait

Revert "MDEV-32899 InnoDB is holding shared dict_sys.latch while waiting for FOREIGN KEY child table lock on DDL"

This reverts commit 569da6a7,
commit 768a7361, and
commit ba6bf7ad
because of a regression that was filed as MDEV-33104.

In commit a55b951e (MDEV-26827)
an error was introduced in a rarely executed code path of the
buf_flush_page_cleaner() thread. As a result, the function
buf_flush_LRU() could be invoked while not holding buf_pool.mutex.

Reviewed by: Debarun Banerjee

buf_flush_LRU(): Display a warning if no pages could be evicted and
no writes initiated.

buf_pool_t::need_LRU_eviction(): Renamed from buf_pool_t::ran_out().
Check if the amount of free pages is smaller than innodb_lru_scan_depth
instead of checking if it is 0.

buf_flush_page_cleaner(): For the final LRU flush after a checkpoint
flush, use a "budget" of innodb_io_capacity_max, like we do in the
case when we are not in "furious" checkpoint flushing.

Co-developed by: Debarun Banerjee
Reviewed by: Debarun Banerjee
Tested by: Matthias Leich

Noted by Susmeet Khaire - thanks.

The directio(3C) function on Solaris is supported on NFS and UFS
while the majority of users should be on ZFS, which is a copy-on-write
file system that implements transparent compression and therefore
cannot support unbuffered I/O.

Let us remove the call to directio() and simply treat
innodb_flush_method=O_DIRECT in the same way as the previous
default value innodb_flush_method=fsync on Solaris. Also, let us
remove some dead code around calls to os_file_set_nocache() on
platforms where fcntl(2) is not usable with O_DIRECT.

On IBM AIX, O_DIRECT is not documented for fcntl(2), only for open(2).

The parameter innodb_undo_log_truncate=ON enables a multi-phased logic:
1. Any "producers" (new starting transactions) are prohibited
from using the rollback segments that reside in the undo tablespace.
2. Any transactions that use any of the rollback segments must be
committed or aborted.
3. The purge of committed transaction history must process all the
rollback segments.
4. The undo tablespace is truncated and rebuilt.
5. The rollback segments are re-enabled for new transactions.

There was one flaw in this logic: The first step was not being invoked
as often as it could be, and therefore innodb_undo_log_truncate=ON
would have no chance to work during a heavy write workload.

Independent of innodb_undo_log_truncate, even after
commit 86767bcc
we are missing some chances to free processed undo log pages.
If we prohibited the creation of new transactions in one busy
rollback segment at a time, we would be eventually guaranteed
to be able to free such pages.

purge_sys_t::skipped_rseg: The current candidate rollback segment
for shrinking the history independent of innodb_undo_log_truncate.

purge_sys_t::iterator::free_history_rseg(): Renamed from
trx_purge_truncate_rseg_history(). Implement the logic
around purge_sys.m_skipped_rseg.

purge_sys_t::truncate_undo_space: Renamed from truncate.

purge_sys.truncate_undo_space.last: Changed the type to integer
to get rid of some pointer dereferencing and conditional branches.

purge_sys_t::truncating_tablespace(), purge_sys_t::undo_truncate_try():
Refactored from trx_purge_truncate_history().
Set purge_sys.truncate_undo_space.current if applicable,
or return an already set purge_sys.truncate_undo_space.current.

purge_coordinator_state::do_purge(): Invoke
purge_sys_t::truncating_tablespace() as part of the normal work loop,
to implement innodb_undo_log_truncate=ON as often as possible.

trx_purge_truncate_rseg_history(): Remove a redundant parameter.

trx_undo_truncate_start(): Replace dead code with a debug assertion.

Correctness tested by: Matthias Leich
Performance tested by: Axel Schwenke
Reviewed by: Debarun Banerjee

Adding GEOMETRY type user variables.

Since 0930eb86, system table creation
needed for spider init is delayed to the signal_ddl_recovery_done
callback. Since it is part of the init, failure should result in
spider deinit.

We also remove the call to spider_init_system_tables() from
spider_db_init(), as it was removed in the commit mentioned above and
accidentally restored in a merge.

MDEV-32968  InnoDB fails to restore tablespace first page from doublewrite buffer when page is empty

- InnoDB fails to find the space id from the page0 of
the tablespace. In that case, InnoDB can use
doublewrite buffer to recover the page0 and write
into the file.

- buf_dblwr_t::init_or_load_pages(): Loads only the pages
which are valid.(page lsn >= checkpoint). To do that,
InnoDB has to open the redo log before system
tablespace, read the latest checkpoint information.

recv_dblwr_t::find_first_page():
1) Iterate the doublewrite buffer pages and find the 0th page
2) Read the tablespace flags, space id from the 0th page.
3) Read the 1st, 2nd and 3rd page from tablespace file and
compare the space id with the space id which is stored
in doublewrite buffer.
4) If it matches then we can write into the file.
5) Return space which matches the pages from the file.

SysTablespace::read_lsn_and_check_flags(): Remove the
retry logic for validating the first page. After
restoring the first page from doublewrite buffer,
assign tablespace flags by reading the first page.

recv_recovery_read_max_checkpoint(): Reads the maximum
checkpoint information from log file

recv_recovery_from_checkpoint_start(): Avoid reading
the checkpoint header information from log file

Datafile::validate_first_page(): Throw error in case
of first page validation fails.

Upstream Debian Sid which will become Debian Trixie (13)
have dropped NCurses version 5 and changed dev package name just
libncurses-dev

Add INSERT ... SELECT to the list of commands that can be traced

Approved by Sergei Petrunia (sergey@mariadb.com)

The problem is the test is skipped after sourcing include/master-slave.inc.
This leaves the slave threads running after the test is skipped, causing a
following test to fail during rpl setup.

Also rename have_normal_bzip.inc to the more appropriate _zlib.
Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

- Closes PR #2839
- Usage of `Column_definition_fix_attributes()` suggested by Alexandar
  Barkov - thanks bar, that is better than hook in server code
  (reverted 22f3ebe4)
  - This method is called after parsing the data type:
    * in `CREATE/ALTER TABLE`
    * in SP: return data type, parameter data type, variable data type
  - We want to disallow all these use cases of MYSQL_JSON.

- Reviewer: bar@mariadb.com
            cvicentiu@mariadb.org

This reverts commit 22f3ebe4.

Closes PR #2839
Reviewer: cvicentiu@mariadb.org

- We don't test `json` MySQL tables from `std_data` since the error `ER_TABLE_NEEDS_REBUILD
` is invoked. However MDEV-32235 will override this test after merge,
but leave it to show behavior and historical changes.

- Closes PR #2833
Reviewer: <cvicentiu@mariadb.org>
          <serg@mariadb.com>

All Spider tables are recorded in the system table
mysql.spider_tables. Deleting a spider table removes the corresponding
rows from the system table, among other things. This patch makes it so
that if spider could not find any record in the system table to delete
for a given table, it should correctly report that no such Spider
table exists.