When navigating through the existing links in the README, it is not
immediately obvious where to go to find instructions in building
and testing the source code. Since the README is often the first
thing people see when looking at a repository, this information
should be front and centre so that newcomers to the project can
get setup as quickly as possible.

The condition checked the value of the leftmost byte before checking if
at least one byte is still available in the buffer.
Changing the order in the condition: check for a byte availability before
checking the byte value.

increase the MASTER_CONNECT_RETRY time under valgrind,
otherwise the slave gives up retrying before the master is ready

also, cosmetic cleanup of rpl_semi_sync_master_shutdown.test

The crash at running mysqlbinlog on a SEQUENCE containing binlog file
was caused MDEV-29621 fixes that did not check which of the slave
or binlog applier executes a block introduced there.

The block is meaningful only for the parallel slave applier, so
it's safe to fix this bug with identified the actual applier and
skipping the block when it's the mysqlbinlog one.

MDEV-29149 Assertion `!is_valid_datetime() || fraction_remainder(((item->decimals) < (6) ? (item->decimals) : (6))) == 0' failed in Datetime_truncation_not_needed::Datetime_truncation_not_needed

TIME-alike string and numeric arguments to TIMEDIFF()
can get additional fractional seconds during the supported
TIME range adjustment in get_time().

For example, during TIMEDIFF('839:00:00','00:00:00') evaluation
in Item_func_timediff::get_date(), the call for args[0]->get_time()
returns MYSQL_TIME '838:59:59.999999'.

Item_func_timediff::get_date() did not handle these extra digits
and returned a MYSQL_TIME result with fractional digits outside
of Item_func_timediff::decimals. This mismatch could further be
caught by a DBUG_ASSERT() in various other pieces of the code,
leading to a crash.

Fix:

In case if get_time() returned MYSQL_TIMESTAMP_TIME,
let's truncate all extra digits using my_time_trunc(&l_time,decimals).
This guarantees that the rest of the code returns a MYSQL_TIME
with second_part not conflicting with Item_func_timediff::decimals.

Additional corrections after merge from 10.4 branch
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

When the system variables @@debug_dbug was assigned to
some expression, Sys_debug_dbug::do_check() did not properly
convert the value from the expression character set to utf8.
So the value was erroneously re-interpretted as utf8 without
conversion. In case of a tricky expression character set
(e.g. utf16le), this led to unexpected results.

Fix:

Re-using Sys_var_charptr::do_string_check() in Sys_debug_dbug::do_check().

The signal handler thread can use various different runtime
resources when processing a SIGHUP (e.g. master-info information)
due to calling into reload_acl_and_cache(). Currently, the shutdown
process waits for the termination of the signal thread after
performing cleanup. However, this could cause resources actively
used by the signal handler to be freed while reload_acl_and_cache()
is processing.

The specific resource that caused MDEV-30260 is a race condition for
the hostname_cache, such that mysqld would delete it in
clean_up()::hostname_cache_free(), before the signal handler would
use it in reload_acl_and_cache()::hostname_cache_refresh().

Another similar resource is the active_mi/master_info_index. There
was a race between its deletion by the main thread in end_slave(),
and their usage by the Signal Handler as a part of
Master_info_index::flush_all_relay_logs.read(active_mi) in
reload_acl_and_cache().

This patch fixes these race conditions by relocating where server
shutdown waits for the signal handler to die until after
server-level threads have been killed (i.e., as a last step of
close_connections()). With respect to the hostname_cache, active_mi
and master_info_cache, this ensures that they cannot be destroyed
while the signal handler is still active, and potentially using
them.

Additionally:

 1) This requires that Events memory is still in place for SIGHUP
handling's mysql_print_status(). So event deinitialization is moved
into clean_up(), but the event scheduler still needs to be stopped
in close_connections() at the same spot.

 2) The function kill_server_thread is no longer used, so it is
deleted

 3) The timeout to wait for the death of the signal thread was not
consistent with the comment. The comment mentioned up to 10 seconds,
whereas it was actually 0.01s. The code has been fixed to wait up to
10 seconds.

 4) A warning has been added if the signal handler thread fails to
exit in time.

 5) Added pthread_join() to end of wait_for_signal_thread_to_end()
if it hadn't ended in 10s with a warning. Note this also removes
the pthread_detached attribute from the signal_thread to allow
for the pthread_join().

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

What's happening:
1. Query_cache::insert() locks the QC and verifies that it's enabled
2. parallel thread tries to disable it. trylock fails (QC is locked)
   so the status becomes DISABLE_REQUEST
3. Query_cache::insert() calls Query_cache::write_result_data()
   which allocates a new block and unlocks the QC.
4. Query_cache::unlock() notices there are no more QC users and a
   pending DISABLE_REQUEST so it disables the QC and frees all the
   memory, including the new block that was just allocated
5. Query_cache::write_result_data() proceeds to write into the freed block

Fix: change m_cache_status under a mutex.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

These patches:

  # commit 74891ed2
  #
  #  MDEV-11514, MDEV-11497, MDEV-11554, MDEV-11555 - IN and CASE type aggregation problems

  # commit 53499cd1
  #
  # MDEV-31303 Key not used when IN clause has both signed and usigned values

earlier fixed MDEV-18898.

Adding only an MTR case.

	modified:   mysql-test/main/func_in.result
	modified:   mysql-test/main/func_in.test

Problem was too tight condition on ha_commit_trans to not
allow non transactional storage engines participate 2pc
in Galera case. This is required because transaction
using e.g. procedures might read mysql.proc table inside
a trasaction and these tables use at the moment Aria
storage engine that does not support 2pc.

Fixed by allowing read only transactions to storage
engines that do not support two phase commit to participate
2pc transaction. These will be committed later separately.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

The patch for MDEV-18319 BIGINT UNSIGNED Performance issue
fixed this problem in 10.5.23.

This patch adds only an MTR test to cover MDEV-18319.

Before patch, maintenance timer will tick every 0.4 seconds.
After this patch, timer will tick every 0.4 seconds when necessary(
there are delayed thread creation), switching off completely after 20
seconds of being idle.

Only locked will participate in the query in this case. Chances are
that not-locked partitions were not opened, which is the cause of the
crash in the added test case spider/bugfix.mdev_33731 without this
patch.

fixes sporadic unit.conc_ps_bugs failures

the value of 200 isn't enough for some tests anymore, this causes
some random threads to become not instrumented and any table operations
there are not reflected in the perfschema. If, say, a DROP TABLE
doesn't change perfschema state, perfschema tables might show
ghost tables that no longer exist in the server

32-bit followup for 8bb8820d

main.mdl_sync 'innodb'                   w32 [ fail ]
        Test ended at 2024-04-06 14:11:15

CURRENT_TEST: main.mdl_sync
--- main/mdl_sync.result
+++ main/mdl_sync.reject
@@ -2458,6 +2458,7 @@
 SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
 LOCK_MODE	LOCK_TYPE	TABLE_SCHEMA	TABLE_NAME
 MDL_BACKUP_FTWRL2	Backup lock
+MDL_SHARED	Table metadata lock	test	t2
 unlock tables;
 connection default;
 # Reaping UPDATE

in particular, debug_sync timeout and wait_for_pos timeout

these warnings are expected and are auto-resolved by galera

policy CMP0093 was added in cmake 3.15
let's support cmake from 2.8.12, that's what our
CMAKE_MINIMUM_REQUIRED() says

Its important to fail early and only contine with the include after
the boost version check succeeds.

Needs to succeed on ealier verisons too so can't just fail if too new.
As such, do a version check.

improve debuggability

as it was thinking it was enabled even if initialize_performance_schema
wasn't called at all

This commit fixes the following issues:
- memory leak checking enabled for mysqltest. This cover all cases except
  calls to 'die()' that only happens in case of internal failures in
  mysqltest. die() is not called anymore in the result files differs.
- One can now run mtr --embedded without failures (this crashed or hang
  before)
- cleanup_and_exit() has a new parameter that indicates that it is called
  from die(), in which case we should not do memory leak checks. We now
  always call cleanup_and_exit() instead of exit() to be able to free up
  memory and discover memory leaks.
- Lots of new assert to catch error conditions
- More DBUG statements.
- Fixed that all results are freed in mysqltest (Fixed a memory leak in
  mysqltest when using prepared statements).
- Fixed race condition in do_stmt_close() that caused embedded server
  to not free memory. (Memory leak in mysqltest with embedded server).
- Fixed two memory leaks in embedded server when using prepared statements.
  These memory leaks caused timeout hangs in mtr when server was compiled
  with safemalloc. This issue was not noticed (except as timeouts) as
  memory report checking was done but output of it was disabled.

not only under valgrind

it seems that the test can get IO thread running or not,
there's a comment about it. Thus stop_slave_io.inc is told
to ignore errors.

Make stop_slave_io.inc also disable warnings in this case,
in particular "1255 Slave already has been stopped"

failed on amd64-centos-stream8

on a busy system it might take time for buffer_page_written_index_leaf
to reach the correct value. Wait for it.

also, tag identical statements to be different in the result file.

add 10.5-specific global suppression.
the extra warning is gone in 10.6

Fix in this commit handles foreign key value appending into write set
so that db and table names are converted from the filepath format
to tablename format. This is compatible with key values appended from
elsewhere in the code base

There is a mtr test galera.galera_table_with_hyphen for regression testing

Reviewer: monty@mariadb.com

"Operator does not exists" should rather read "Operator does not exist".

Item_func_dyncol_create::print_arguments() printed only CHARSET clause
without COLLATE.

Therefore,

HEX(column_create(1,'1212' AS CHAR CHARACTER SET utf8mb3 COLLATE utf8mb3_bin))

inside a VIEW changed to just:

HEX(column_create(1,'1212' AS CHAR CHARACTER SET utf8mb3))

which changed the collation ID seen in the HEX output.

Note, the collation ID inside column_create() is not really much important.
(It's only important what the character set is).
And for COLLATE, the more important thing is what's later written
in the AS clause of COLUMN_GET:

SELECT
   COLUMN_GET(
    column_create(1,'1212' AS CHAR CHARACTER SET utf8mb3 COLLATE utf8mb3_bin)
    column_nr AS type  -- this type is more important
   );

Still, let's add the COLLATE clause into the COLUMN_CREATE() print output,
although it's not important for now for anything else than just the HEX output.
At least to make VIEW work in a more predictable way with HEX(COLUMN_CREATE()).

Also, in the future we can start using somehow the collation ID written inside
COLUMN_CREATE(), for example by making the `AS type` clause optional in
COLUMN_GET():
  COLUMN_GET(dyncol_blob, column_nr [AS type]);
instead of:
  COLUMN_GET(dyncol_blob, column_nr AS type);

SQL Server compatibility layer may need this for
the SQL_Variant data type support.