The function wsrep_on() was being called rather frequently
in InnoDB and XtraDB. Let us cache it in trx_t and invoke
trx_t::is_wsrep() instead.

innobase_trx_init(): Cache trx->wsrep = wsrep_on(thd).

ha_innobase::write_row(): Replace many repeated calls to current_thd,
and test the cheapest condition first.

fix embedded innodb_plugin tests

followup for 7198c6ab

Backport INSALL_SYMLINK cmake macro from 10.3.
It'll make libmysqlclient_r.* symlinks to link to the actual
shared library file, not to another symlink.

As a bonus it'll fix cmake warning about deprecated LOCATION property

This is a backport of the applicable part of
commit 93475aff and
commit 2c39f69d
from 10.4.

Before 10.4 and Galera 4, WSREP_ON is a macro that points to
a global Boolean variable, so it is not that expensive to
evaluate, but we will add an unlikely() hint around it.

WSREP_ON_NEW: Remove. This macro was introduced in
commit c863159c
when reverting WSREP_ON to its previous definition.

We replace some use of WSREP_ON with WSREP(thd), like it was done
in 93475aff. Note: the macro
WSREP() in 10.1 is equivalent to WSREP_NNULL() in 10.4.

Item_func_rand::seed_random(): Avoid invoking current_thd
when WSREP is not enabled.

_ma_fetch_keypage(): Correct an assertion that used to always hold.
Thanks to clang -Wint-in-bool-context for flagging this.

double_to_datetime_with_warn(): Suppress -Wimplicit-int-float-conversion
by adding a cast. LONGLONG_MAX converted to double will actually be
LONGLONG_MAX+1.

Since commit 7198c6ab
the ./mtr --embedded tests would fail to start innodb_plugin
because of an undefined reference to the symbol wsrep_log().

Let us define a stub for that function. The embedded server
is never built WITH_WSREP, but there are no separate storage
engine builds for the embedded server. Hence, by default,
the dynamic InnoDB storage engine plugin would be built WITH_WSREP
and it would fail to load into the embedded server library due to
a reference to the undefined symbol.

read TLS with my_thread_var
write TLS with set_mysys_var()

my_thread_var is no longer __attribute__ ((const)): this attribute
is simply incorrect here. Read gcc manual for more information.
sql/threadpool_generic.cc fails with that attribute.

row_vers_vc_matches_cluster(): Remove the parameter in_purge,
which was always passed as in_purge=true.

This parameter became constant in
mysql/mysql-server@1dec14d346ac55fe72989dccb071f84b3b0d3bd6
and it always was constant in MariaDB starting from the
introduction of the function in
commit 2e814d47 (MariaDB 10.2.2).

row_prebuilt_free(): Do not attempt to drop orphan indexes
that might have been left behind by a failed ADD UNIQUE INDEX.
This avoids the execution of unwanted transactions during shutdown.

mysqld_exit(): Change the assertion failure on
global_status_var.global_memory_used == 0
to fprintf, like in 0bcb65d3

It appears that in some cases, that variable may be nonzero
even when LeakSanitizer (WITH_ASAN) would not report errors.
This was observed in 10.4 88cf6f1c
with the MDEV-22348 test case (Aria startup failure when running
main.default_storage_engine).

Test do we have galera debug library with debug_sync functionality
needs to be earlier.

Also add a check for tmp file being empty and bail out with a clear
error message in such a case, as mysqld_safe prevents normal stderr
from being displayed anywhere and would fail silently on this.

MDEV-22181 : galera.galera_sst_mysqldump_with_key MTR failed: INSERT failed: 1146: Table 'test.t1' doesn't exist

Add wait condition to make sure table test.t1 is replicated
to node_2 before we insert to it.

config.

The solution is to read the system variable value on startup and to fill
databases_exclude_hash.

xb_load_list_string() became non-static and was reformatted. The system
variable value is read and processed in get_mysql_vars(), which was also
reformatted.

Patches of interest:374dae3e, 374dae3e

Backported fix from 10.5

Part of:
MDEV-21056 Assertion `global_status_var.global_memory_used == 0'
failed upon shutdown after query with DEFAULT on a geometry
field

Fixed by changing the ASSERT for memory leaks to a printf() on
stderr. This has needed as all mutex in mysys has been deleted and we
can't call functions like my_open() anymore.

Also added printing of leaks if safemalloc is used (like we do in 10.5)

- Remove memory leaks reported by safemalloc
- Changed that all 0x strings are converted. This is needed
  to easily be able to resolve safemalloc backtraces

MDEV-21056  Assertion `global_status_var.global_memory_used == 0'
failed upon shutdown after query with DEFAULT on a geometry
field

MDEV-22275 Assertion `global_status_var.global_memory_used == 0'
failed, bytes lost, or LeakSanitizer: detected memory leaks
after using temporary table with fulltext key

This affected MyISAM and Aria temporary tables

maria_page_crc_check_index(): Do not attempt to convert
HA_ERR_WRONG_CRC (176) to my_bool (char).
On platforms where char is signed, the 176 will be converted to -80.

It turns out that the callers only care whether the result is zero.
Let us return 1 in this case, like we do in all other error cases.

Several tests that involve stored procedures fail on 10.4 kvm-asan
(clang 10) due to stack overrun. The main contributor to this stack
overrun is mysql_execute_command(), which is invoked recursively
during stored procedure execution.

Rebuilding with cmake -DWITH_WSREP=OFF shrunk the stack frame size
of mysql_execute_command() by more than 10 kilobytes in a
WITH_ASAN=ON, CMAKE_BUILD_TYPE=Debug build. The culprit
turned out to be the macro WSREP_LOG, which is allocating a
separate 1KiB buffer for every occurrence.

We replace the macro with a function, so that the stack will be
allocated only when the function is actually invoked. In this way,
no stack space will be wasted by default (when WSREP and Galera
are disabled).

This backports commit b6c5657e
from MariaDB 10.3.1.

Without ASAN, compilers can be smarter and optimize the stack usage.
The original commit message mentions that 1KiB was saved on GCC 5.4,
and 4KiB on Mac OS X Lion, which presumably uses a clang-based compiler.

tests are:
engines/funcs.jp_comment_column
engines/funcs.jp_comment_index
engines/funcs.jp_comment_table

After MDEV-12353, the consistency check that I originally added for
commit 1b9fe0bb
(InnoDB Plugin for MySQL 5.1) started randomly failing.

It turns out that the IMPORT TABLESPACE code was always incorrect:
it did not update the (redundantly stored) tablespace ID
in index tree root pages. It only does that for page headers
and BLOB pointers.

PageConverter::update_index_page(): Update the tablespace ID
in the BTR_SEG_TOP and BTR_SEG_LEAF of index root pages.

This is a backport of commit b8b3edff.

For some reason, when mbstream is compiled with GCC 10,
ld will fail to link it due to a multiple definition of
datasink_buffer. The code appears to have been like that
since the very beginning.

Let us remove the duplicate dummy definition.