We must ensure that the NUL will not terminate the query string.

Replace the 30-second sleep in the test with proper
DEBUG_SYNC interlocking.

queues.c cleanup and refactoring.

Restore old version of _downhead() (from before cd483c55)
that works well in an average case. Use it for queue_fix().

Move existing specialized version of _downhead() to queue_replace()
where it'll be handling the case it was specifically optimized for
(moving the element to the end of the queue).
And correct it to fix the heap not only down, but also up
(this fixes BUG#30301356).

Add unit tests.

Collateral cosmetic fixes.

CONCAT_WS didn't have it

DESCRIPTION:
============
There can be issues if the packets sent by the server
are not proper. Certain checks should be performed at the
client side while unpacking fields data.

FIX:
====
Check for the appropriate fields data and error out if it
is not present.

RB: 23601

The event scheduler has a THD which is used for e.g. keeping track
of the timing of the events. Thus, each scheduling of an event will
make use of this THD, which in turn allocates memory in the THD's
mem root. However, the mem root was never cleared, and hence, the
memory occupied would monotonically increase throughout the life
time of the server.

The root cause was found by Jon Olav Hauglid, and this fix clears the
THD's mem root for each event being scheduled.

Change-Id: I462d2b9fd9658c9f33ab5080f7cd0e0ea28382df

in fact, in MariaDB it cannot, but it can show spurious slaves
in SHOW SLAVE HOSTS.

slave was registered in COM_REGISTER_SLAVE and un-registered after
COM_BINLOG_DUMP. If there was no COM_BINLOG_DUMP, it would never
unregister.

test case

Cause:
In case of version based condtional comments, if the condition evaluates
to false, it is converted to a regular comment for replication by
replacing "!"  by " ".

Nested comment in a conditional comment is replicated as is. Nested
comments are supported only in case of conditional comments and when a
the comment on slave is no more a conditional comment, the statement
execution fails on the slave.

Fix:
Convert the nested comment, start from "/*" to "(*" and comment end from
"*/" to "*)" for replication.

Change-Id: I1a8e385a267b2370529eade094f0258fa96886c0

The name was correctly encoded in UTF-8 before
commit 0ce12f70.

In case of ipv6 not enabled tests like `main.ipv6, rpl.rpl_ipv6` failed on
aarch buildbot.
Fix it by following commits 70dcb46e and 0bae1957 for
`10.2`.

The first patch for the bug was erroneous: it did not take into account
the fact that the modified function get_key_scans_params() was called in
different contexts. As a result the patch caused a regression bug MDEV-22191.
The patch for this bug introduced an extra parameter. Actually we can
do without this parameter and use the fourth parameter for the same
puropose - to differentiate between the calls of the function for range
access and for index merge access.

Also removed the call of get_key_scans_params() in the code of the function
merge_same_index_scans() as not needed.

This PR fixes wrong size argument passed in `strncmp(arg, "--parent-pid", 10)` as the `"--parent-pid"` string has length of 12.

Closes #1502

When index_merge_sort_union is turned off only ror scans were considered for range
scans, which is wrong.
To fix the problem ensure both ror scans and non ror scans are considered for range
access

It took me a long time to debug why my configs were not being loaded,
and judging from online discussions I'm not the only one. Make the
comment in the default my.cnf a bit more helpful.

The !includedir directive is implemented in mysys/my_default.c.

- f_extensions[] is a list of file extensions. It includes .ini and .cnf
  on Windows, and only .cnf on all other platforms.
- search_default_file_with_ext() contains the !includedir directive. It
  filters files in the directory to those matching f_extensions[].

This file should only be applicable on Unix-like platforms, so only
files with the .cnf extension are read.

Closes #1485

This bug could manifest itself in a very rare cases when the optimizer
chose an execution plan by which a joined table was accessed by a table
scan and the optimizer was checking whether ranges checked for each record
could improve this plan. In such cases the optimizer evaluates range
conditions over a table that depend on other tables. For such conditions
the constructed SEL_ARG trees are marked as MAYBE_KEY. If a SEL_ARG object
constructed for a sargable condition marked as RANGE_KEY had the same
first key part as a MAYBE_KEY SEL_ARG object and the key_and() function
was called for this pair of SEL_ARG objects then an invalid SEL_ARG
object could be constructed that ultimately could lead to a crash before
the execution phase.

          'index_merge_sort_union=off'

When index_merge_sort_union is set to 'off' and  index_merge_union is set
to 'on' then any evaluated index merge scan must consist only of ROR scans.
The cheapest out of such index merges must be chosen. This index merge
might not be the cheapest index merge.

Also, remove some trailing white space and add missing static
qualifier to free_annotate_event().

Emulate older API

Deleted with commit: c70a9fa1

test case only

Remove the offending test case. This sort of error is hard to test in
all possible corner cases and thus makes the test less valuable. The
overflow error will be covered by warnings generated by the compiler,
which is much more reliable in the general case.

* size represents the size of an element in the Unique class
* full_size is used when the Unique class counts the number of
duplicates stored per element. This requires additional space per Unique
element.

The string doesn't appear to be null-terminated when binlog checksums are
enabled. This causes a corrupt binlog name in the error message when a
slave is ahead of the master.

Moved to the next problematic year (2038).

Fixed the condition for waking up/creating another thread.

If there is some work to do (if the request queue is not empty),
a thread should be woken or created.

The condition was incorrect since 18c9b345

crashes on Debian 10

$glob_mysql_test_dir was the wrong directory for strace output as
it was for in-tree builds only so failed for:
* out of tree builds
* --parallel; and
* --mem

strace output wasn't saved.

strace-option never replaced existing arguments (so ammended
documentation).

strace-client didn't accept an argument as described.

Replaced specification of client with this with 'stracer' to be
consistent with --debugger option.

For consistency with debugger options, --client-strace was added to
execute the strace on the mysqltest.

Example: Running one test

$ ./mtr --strace --client-strace funcs_1.is_table_constraints
Logging: ./mtr  --strace --client-strace funcs_1.is_table_constraints
vardir: /home/anel/mariadb/5.5/mysql-test/var
Checking leftover processes...
Removing old var directory...
 - WARNING: Using the 'mysql-test/var' symlink
Creating var directory '/home/anel/mariadb/5.5/mysql-test/var'...
Checking supported features...
MariaDB Version 5.5.67-MariaDB-debug
Installing system database...
 - SSL connections supported
 - binaries are debug compiled
Collecting tests...

==============================================================================

TEST                                      RESULT   TIME (ms) or COMMENT
--------------------------------------------------------------------------

worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019
funcs_1.is_table_constraints             [ pass ]   1270
--------------------------------------------------------------------------
The servers were restarted 0 times
Spent 1.270 of 3 seconds executing testcases

Completed: All 1 tests were successful

$ find -L . -name \*strace -ls
      653     56 -rw-r--r--   1 anel     anel        57147 Nov 29 15:08 ./var/log/mysqltest.strace
      646   1768 -rw-r--r--   1 anel     anel      1809855 Nov 29 15:08 ./var/log/mysqld.1.strace

Example: Running test in parallel

$ mysql-test/mtr --strace --client-strace  --mem --parallel=3  main.select
Logging: /home/dan/software_projects/mariadb-server/mysql-test/mysql-test-run.pl  --strace --client-strace --mem --parallel=3 main.select
vardir: /home/dan/software_projects/build-mariadb-10.3/mysql-test/var
Checking leftover processes...
Removing old var directory...
Creating var directory '/home/dan/software_projects/build-mariadb-10.3/mysql-test/var'...
 - symlinking 'var' to '/dev/shm/var_auto_0v2E'
Checking supported features...
MariaDB Version 5.5.67-MariaDB
 - SSL connections supported
Collecting tests...
Installing system database...

==============================================================================

TEST                                  WORKER RESULT   TIME (ms) or COMMENT
--------------------------------------------------------------------------

worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019
worker[3]  - 'localhost:16040' was not free
worker[2] Using MTR_BUILD_THREAD 301, with reserved ports 16020..16039
worker[3] Using MTR_BUILD_THREAD 303, with reserved ports 16060..16079
main.select                              w1 [ pass ]   7310
--------------------------------------------------------------------------
The servers were restarted 0 times
Spent 7.310 of 11 seconds executing testcases

Completed: All 1 tests were successful.

$ find mysql-test/var/ -name \*strace -ls
  5213766   1212 -rw-r--r--   1  dan      dan       1237817 May 20 16:47 mysql-test/var/1/log/mysqltest.strace
  5214733  13016 -rw-r--r--   1  dan      dan      13328335 May 20 16:47 mysql-test/var/1/log/mysqld.1.strace

$ mysql-test/mtr --strace --client-strace --strace-option='-e' --strace-option='trace=openat'  --mem --parallel=3  main.select
...
$ find mysql-test/var/ -name \*strace -ls
  5220790      8 -rw-r--r--   1  dan      dan          6291 May 20 17:02 mysql-test/var/3/log/mysqltest.strace
  5224140    308 -rw-r--r--   1  dan      dan        314356 May 20 17:02 mysql-test/var/3/log/mysqld.1.strace
$ more mysql-test/var/3/mysqltest.strace
1692  openat(AT_FDCWD, "/home/dan/software_projects/mariadb-server/libmysql/.libs/tls/x86_64/x86_64/libpthread.so.0", O_RDONLY|O_CLOEXEC) =
-1 ENOENT (No such file or directory)
1692  openat(AT_FDCWD, "/home/dan/software_projects/mariadb-server/libmysql/.libs/tls/x86_64/libpthread.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOE
NT (No such file or directory)

Closes #600

Closes #1403