buf_page_get_low(): Assert that the block not be read-fixed.
It may be write-fixed while we only hold a shared latch on the page.
Page writes are protected by U latches, which are compatible with S.
In all other places where we assert that the block not be IO-fixed,
we are holding U or X latch, which does prevent concurrent file I/O.

Cannot have a function trx_has_lock_x hot and cold.

There is only a very small range of gcc compiler versions
that allow the built_{htm} functions to be defined without -mhtm
being specified as a global C{,XX}FLAGS.

Because the design is centered around enable HTM only in the
functional blocks that use it, this breaks on the inclusion
of the htmxlintrin.h header that includes this.

As a partial mitigation, extented to GNU/clang compilers,
transaction functions gain the attribute "hot".

In general the use of htm is around the optimistic
transaction ability of the function. The key part of using the
hot attribute is to place these functions together so that
a maximization of icache, tlb and OS paging can ensure that
these can be ready to execute by any thread/cpu with the
minimum amount of overhead.

POWER is particularly affected here because the xbegin/xend
functions are not inline.

srw_lock.cc requires the -mhtm cflag, both in the storage
engine and the unit tests.

The commits a73acf6c and
4d74bac8 updated the PCRE library to a new
version, which in turn requires CMake 3.0. That does not exist in CentOS 7
nor 8, so builds started failing.

Actually the build should not be downloading anything at all. The root
cause was that pcre2-devel was missing from the dependencies. This was
originally not detected, as the download fallback had masked the issue.

MDEV-27025 allows to insert records before the record on which DELETE is
locked, as a result the DELETE misses those records, what causes serious ACID
violation.

Revert MDEV-27025, MDEV-27550. The test which shows the scenario of ACID
violation is added.

During an increase in resize, the new curr_size got a value
less than old_size.

As n_chunks_new and n_chunks have a strong correlation to the
resizing operation in progress, we can use them and remove the
need for old_size.

For convienece the n_chunks_new < n_chunks is now the is_shrinking
function.

The volatile compiler optimization on n_chunks{,_new} is removed
as real mutex uses are needed.

Other n_chunks_new/n_chunks methods:

n_chunks_new and n_chunks almost always read and altered under
the pool mutex.

Exceptions are:
* i_s_innodb_buffer_page_fill,
* buf_pool_t::is_uncompressed (via is_blocked_field)
These need reexamining for the need of a mutex, however comments
indicates this already.

get_n_pages has uses in buffer pool load, recover log memory
exhaustion estimates and innodb status so take the minimum number
of chunks for safety.

The buf_pool_t::running_out function also uses curr_size/old_size.
We replace this hot function calculation with just n_chunks_new.
This is the new size of the chunks before the resizing occurs.

If we are resizing down, we've already got the case we had previously
(as the minimum). If we are resizing upwards, we are taking an
optimistic view that there will be buffer chunks available for locks.
As this memory allocation is occurring immediately next the resizing
function it seems likely.

Compiler hint UNIV_UNLIKELY removed to leave it to the branch
predictor to make an informed decision.

Added test case of a smaller size than the Marko/Roel original
in JIRA reducing the size to 256M. SEGV hits roughly 1/10 times
but its better than a 21G memory size.

Reviewer: Marko

The virtual member function handler::reset_auto_increment(ulonglong)
is only ever invoked by the default implementation of the virtual
member function handler::truncate().

Because ha_innobase::truncate() overrides handler::truncate() without
ever invoking handler::truncate(), some InnoDB member functions are
never called.

ha_innobase::innobase_reset_autoinc(), ha_innobase::reset_auto_increment():
Removed (unreachable code).

ha_innobase::delete_all_rows(): Removed. The default implementation
handler::delete_all_rows() works just as fine.

- InnoDB FTS DDL decrements the FTS_DOC_ID when there is a
deleted marked record involved. FTS_DOC_ID must never be
reused. The purpose of FTS_DOC_ID is to be a unique row
identifier that will be changed whenever a fulltext indexed
column is updated.

btr_cur_optimistic_insert(): Disregard DEBUG_DBUG injection to
invoke btr_page_reorganize() if the page (and the table) is empty.
Otherwise, an assertion would fail in btr_page_reorganize_low()
because PAGE_MAX_TRX_ID is 0 in an empty secondary index leaf page.

maturity level

Fix: Bumped maturity of the mysql_json plugin to gamma.

Among others:
existance -> existence
reinitialze -> reinitialize
successfuly -> successfully

create_table_info_t::innobase_table_flags(): Ignore page_compressed
and page_compression_level on TEMPORARY tables.

ha_innobase::truncate(): Add a debug assertion that create() must succeed
on temporary tables.

Fixed by not sending --group option to the server (for now)

Reviwer: Sergei Golubchik

udf_handler::fix_fields(): Execute an assignment outside "if"
so that GCC 12 will not issue a bogus-looking warning.
Also, deduplicate some error handling code.

 - Server incorrectly downgrading the MDL after prepare phase when
table is empty. mdl_exclusive_after_prepare is being set in
prepare phase only. But mdl_exclusive_after_prepare condition was
misplaced and checked before prepare phase by
commit d270525d and it is now
changed to check after prepare phase.

 - main.innodb_mysql_sync test case was changed to avoid locking
optimization when table is empty.

The test innodb.log_file_size would occasionally crash in
a debug assertion failure in srv_prepare_to_delete_redo_log_file().
In the core dump, the assertion would hold.

buf_pool_t::any_io_pending(): Avoid dirty reads by acquiring
buf_pool.mutex. This function is only being invoked in debug builds,
so we do not care about any performance impact.

Already the detection part of have_crypt.inc must be skipped
in WITH_MSAN builds until the SIGSEGV in the crypt() interceptor
has been fixed.

The follwoing could happen if InnoDB did some background work while
test was running:

@@ -5,6 +5,8 @@
 SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
 LOCK_MODE      LOCK_TYPE       TABLE_SCHEMA    TABLE_NAME
 MDL_SHARED_HIGH_PRIO   Table metadata lock     test    t1
+MDL_SHARED     Table metadata lock     mysql   innodb_table_stats
+MDL_SHARED     Table metadata lock     mysql   innodb_index_stat

We will move all tests of the ENCRYPT() function to the test
main.func_crypt, which will be disabled in MSAN builds for now.

In merge cc1d9062 the 32-bit builds
were broken.