In case of a non-recovery XA rollback/commit in the same connection,
thon->rollback is called instead of rollback_by_xid, Though previously,
thd_ha_data was moved to thd->transaction->xid_state.xid in hton->prepare.

Like it wasn't enough, XA PREPARE can be skipped upon user and thus we
can end up in hton->commit/rollback with and unprepared XA, so checking
xid_state.is_explicit_XA is not enough -- we should check
xid_state.get_state_code() == XA_PREPARED, which will also guarantee
is_explicit_XA() == true.

XA support for online alter was totally missing.

Tying on binlog_hton made this hardly visible: simply having binlog_commit
called from xa_commit made an impression that it will automagically work
for online alter, which turns out wrong: all binlog does is writes
"XA END" into trx cache and flushes it to a real binlog.

In comparison, online alter can't do the same, since online replication
happens in a single transaction.

Solution: make a dedicated XA support.
* Extend struct xid_t with a pointer to Online_alter_cache_list
* On prepare: move online alter cache from THD::ha_data to XID passed
* On XA commit/rollback: use the online alter cache stored in this XID.
  This makes us pass xid_cache_element->xid to xa_commit/xa_rollback
  instead of lex->xid
* Use manual memory management for online alter cache list, instead of
  mem_root allocation, since we don't have mem_root connected to the XA
  transaction.

Use standard handlerton functions for savepoint add/rollback.

To identify the savepoint, the pointer passed is used.

Every table that has online alter in progress maintains a list of
savepoints independently.

Also this removes setting a value to a global variable savepoint_alloc_size
without any protection, which was a race condition bug.

Move all the functions dedicated to online alter to a newly created
online_alter.cc.

With that, make many functions static and simplify the static functions
naming.

Also, rename binlog_log_row_online_alter -> online_alter_log_row.

Assertion `!writer.checksum_len || writer.remains == 0' fails upon
concurrent online ALTER and transactions with failing statements and binary
log enabled.
Also another assertion, `pos != (~(my_off_t) 0)', fails in my_seek, upon
reinit_io_cache, on a simplified test. This means that IO_CACHE wasn't
properly initialized, or had an error before.

The overall problem is a deep interference with the effect of an installed
binlog_hton: the assumption about that thd->binlog_get_cache_mngr() is,
sufficiently, NULL, when we shouldn't run the binlog part of
binlog_commit/binlog_rollback, is wrong: as turns out, sometimes the binlog
handlerton can be not installed in current thd, but binlog_commit can be
called on behalf of binlog, as in the bug reported.

One separate condition found is XA recovery of the orphaned transaction,
when binlog_commit is also called, but it has nothing to do with
online alter.

Solution:
Extract online alter operations into a separate handlerton.

1032 (Can't find record) could be emitted when ALTER TABLE is execued vs
concurrent DELETE/UPDATE/other DML that would require search on the online
ALTER's side.

Innodb's INPLACE, in comparison, creates a new trx_t and uses it in scope
of the alter table context.

ALTER TABLE class of statements (i.g. CREATE INDEX, OPTIMIZE, etc.) is
expected to be unaffected by the value of current session's transaction
isolation.

This patch save-and-restores thd->tx_isolation and sets in to
ISO_REPEATABLE_READ for almost a whole mysql_alter_table duration, to avoid
any possible side-effect of it. This should be primarily done before the
lock_tables call, to initialize the storage engine's local value correctly
during the store_lock() call.

sql_table.cc: set thd->tx_isolation to ISO_REPEATABLE_READ in
mysql_alter_table and then restore it to the original value in the end of
the call.

data from a table similar to other JSON functions

Analysis:
Since we are fetching values for every row ( because we are running SELECT
for all rows of a table ), correct value can be only obtained at the time of
calling val_int() because it is called to get value for each row.
Fix:
Set up hash for each row instead of doing it during fixing fields.

In MemorySanitizer builds of 10.10 and 10.11, we would rather often
have the assertion fail in innodb_init() during mariadb-backup --prepare.
The assertion could also fail during InnoDB startup, but less often.

Before commit 685d958e in 10.8 the
log file cleanup after a successfully applied backup is different,
and the os_aio_pending_writes() assertion is in srv0start.cc.

IORequest::write_complete(): Invoke node->complete_write() before
releasing the page latch, so that a log checkpoint that is about to
execute concurrently will not miss a fdatasync() or fsync() on the
file, in case this was the first write since the last such call.

create_log_file(), srv_start(): Replace the debug assertion with
a debug check. For all intents and purposes, all writes could have
been completed but some write_io_callback() may not have invoked
io_slots::release() yet.

This was introduced in last merge with 10.6
The reason is that 10.6 does not need anything special to free histograms
as everything is allocated on a memroot.
In 10.10 histograms is using the vector class, which has some problems:
- No automatic free
- No memory usage accounting
(we should at some point remove vector usage because of the above problem)

Fixed by expliciting freeing histograms when freeing TABLE_STATISTICS
objects.

- Remove some references to dead macros

It was disabled in the recent 10.6->10.10 merge.

- InnoDB fails to check the overflow buffer while applying
the operation to the table that was rebuilt. This is caused
by commit 3cef4f8f (MDEV-515).

Fixed missing initialization of Alter_info()

This could cause crashes in some create table like scenarios
where some generated indexes where automatically dropped.

I also added a test that we do not try to drop from index_stats for
temporary tables.

The intentention was always to not create histograms for single value
unique keys (as histograms is not useful in this case), but because of
a bug in the code this was still done.

The changes in the test cases was mainly because hist_size is now NULL
for these kind of columns.

The MDEV-29693 conflict resolution is from Monty, as well as is
a bug fix where ANALYZE TABLE wrongly built histograms for
single-column PRIMARY KEY.
Also includes a fix for safe_malloc error reporting.

Other things:
- Copied main.log_slow from 10.4 to avoid mtr issue

Disabled test:
- spider/bugfix.mdev_27239 because we started to get
  +Error	1429 Unable to connect to foreign data source: localhost
  -Error	1158 Got an error reading communication packets
- main.delayed
  - Bug#54332 Deadlock with two connections doing LOCK TABLE+INSERT DELAYED
    This part is disabled for now as it fails randomly with different
    warnings/errors (no corruption).

MDEV-32272 lock_release_on_prepare_try() does not release lock if supremum bit is set along with other bits set in lock's bitmap

The error is caused by MDEV-30165 fix with the following commit:
d13a57ae

There is logical error in lock_release_on_prepare_try():

        if (supremum_bit)
          lock_rec_unlock_supremum(*cell, lock);
        else
          lock_rec_dequeue_from_page(lock, false);

Because there can be other bits set in the lock's bitmap, and the lock
type can be suitable for releasing criteria, but the above logic
releases only supremum bit of the lock.

The fix is to release lock if it suits for releasing criteria and unlock
supremum if supremum is locked otherwise.

Tere is also the test for the case, which was reported by QA team. I
placed it in a separate files, because it requires debug build.

Reviewed by: Marko Mäkelä

MDEV-31098  InnoDB Recovery doesn't display encryption message when no encryption configuration passed

- InnoDB fails to report the error when encryption configuration
wasn't passed. This patch addresses the issue by adding
the error while loading the tablespace and deferring the
tablespace creation.

There are many filesystem related errors that can occur with
MariaBackup. These already outputed to stderr with a good description of
the error. Many of these are permission or resource (file descriptor)
limits where the assertion and resulting core crash doesn't offer
developers anything more than the log message. To the user, assertions
and core crashes come across as poor error handling.

As such we return an error and handle this all the way up the stack.

log_t::create(), log_t::attach(): Return whether the initialisation
succeeded. It may fail if too large an innodb_log_buffer_size is specified.

recv_sys_t::close_files(): Actually close the data files so that the
test mariabackup.huge_lsn,strict_crc32 will not fail on Microsoft Windows
when renaming ib_logfile101 due to a leaked file handle of ib_logfile0.

recv_sys_t::find_checkpoint(): Register recv_sys.files[0] as OS_FILE_CLOSED
because the file handle has already been attached to log_sys.log and
we do not want to close the file twice.

recv_sys_t::read(): Access the first log file via log_sys.log.

This is a port of commit 6e9b421f
adapted to commit 685d958e (MDEV-14425).

The test case is omitted, because it would fail to fail when the log
is stored in persistent memory (or "fake PMEM" on Linux /dev/shm).

In case the option require_secure_transport is on the user can't
establish a secure ssl connection over TCP protocol. Inability to set up
a ssl session over TCP was caused by the fact that a type of client's
connection was checked before ssl handshake performed (ssl handshake
happens at the function acl_authenticate()). At that moment vio type has
the value VIO_TYPE_TCPIP for client connection that uses TCP transport.
In result, checking for allowable vio type for fails despite the fact
that SSL session being established. To fix the issue move checking of
vio type for allowable values inside the function
  parse_client_handshake_packet()
right after client's capabilities discovered that SSL is not requested
by the client.

The system variable spider_disable_group_by_handler, if on, will
disable the spider group by handler (gbh), and such disablement serves
as workaround to bugs caused by gbh, labelled with spider-gbh on jira,
including MDEV-26247, MDEV-28998, MDEV-29163, MDEV-30392, MDEV-31645.
Tests for these tickets are added accordingly with the workaround in
place.

The problem was that RANGE_OPT_PARAM was not completely initialized in
some cases.
Added bzero() to ensure that all elements are always initialized.

Fixed hang when renaming index to original name

Use Dummy_error_handler in open_stat_tables() to ignore all errors
when opening statistics tables.

In commit 5ea5291d @sanja-byelkin for unknown reason switched the file mode
for 3 Galera tzinfo related test files from 644 -> 755. This exists only
from branch 10.6 onward:

    $ git checkout 10.5
    $ find mysql-test -executable -name *.test -or -executable -name *.result
    (no results)
    $ git checkout 10.6
    $ find mysql-test -executable -name *.test -or -executable -name *.result
    mysql-test/suite/galera/t/mysql_tzmysql-test/suite/galera/t/mysql_tzinfo_to_sql.test
    mysql-test/suite/galera/t/mariadb_tzinfo_to_sql.test
    mysql-test/suite/galera/r/mariadb_tzinfo_to_sql.resultinfo_to_sql.test

mysql-test/suite/galera/t/mariadb_tzinfo_to_sql.test
mysql-test/suite/galera/r/mariadb_tzinfo_to_sql.result

No test file nor test result file should be executable, so run chmod -x
on them.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.

log_t::create(): Return whether the initialisation succeeded.
It may fail if too large an innodb_log_buffer_size is specified.