prepare_inplace_alter_table_dict(): In the error handling, relax
a debug assertion for the case that we did not execute
dict_stats_wait_bg_to_stop_using_table() yet.

For no good reason, innodb_encryption_threads was limited to
4,294,967,295. Expectedly, the server would crash if such an
insane value was specified. Let us limit the maximum to 255.

The encryption threads are not doing much useful work.
They are basically only dirtying pages by performing
dummy writes via the redo log. The encryption key rotation
or the in-place addition or removal of encryption
will take place in the page cleaner.

In a quick test on a 20-core CPU (40 threads in total),
the sweet spot on an otherwise idle server seemed to be
innodb_encryption_threads=16 for the test
encryption.encrypt_and_grep. The new limit 255 should be
more than enough for even bigger servers.

fts_indexes field in fts_update_t never used. So replace fts_update_t
with doc_id_t in the code

MDEV-18838 : galera.galera_toi_truncate: Test failure: mysqltest: query 'reap' succeeded - should have failed with errno 1213

Test cleanup.

This is a new test from upstream that did not expect the correct value
of the command slot of the Dump thread when the latter gets killed.

The test is made to expect "Killed" string as the command
in show-processlist as it is supposed to when a thread gets killed.

dict_index_remove_from_cache_low(): Add a missing #ifdef around
dict_index_t::freed().

This is a regression due to MDEV-16376
commit 8dc70c86.
To make dict_index_t::detach_columns() idempotent,
we cleared dict_index_t::n_fields. But, this could
cause trouble with purge after a secondary index
creation failed (not even involving virtual columns).

A better way is to clear the dict_field_t::col pointers
that point to virtual columns that are being freed
due to aborting index creation on an index that depends
on a virtual column.

Note: the v_cols[] of an existing dict_table_t object will
never be modified. If any virtual columns are added or removed,
ha_innobase::commit_inplace_alter_table() would invoke
dict_table_remove_from_cache() and reload the table to dict_sys.
Index creation is a special case where the dict_index_t points
to virtual columns that do not yet exist in dict_table_t.

Removing a wrong DBUG_ASSERT:
When Item_param gets "unfixed" in cleanup(), its "fixed" gets assigned
to false, while item_item keeps the value. So the assert was wrong.

Perhaps, instead of removing the assert, it was possible to reset
item_type to NO_VALUE in cleanup. But this is not very important:
it's implemented in 10.4 in a better way:
Item_param::is_fixed() always returns true and it does not need to be "unfixed".

error is logged

The fix is to set flag in ib::error::~error() and check it in
mariabackup.

ib::error::error() is replaced with ib::warn::warn() in
AIO::linux_create_io_ctx() because of two reasons:

1) if we leave it as is, then mariabackup MTR tests will fail with --mem
option, because Linux AIO can not be used on tmpfs,

2) when Linux AIO can not be initialized, InnoDB falls back to simulated
AIO, so such sutiation is not fatal error, it should be treated as warning.

lock_table_locks_lookup(): Relax the assertion.
Locks must not exist while online secondary index creation is
in progress. However, if CREATE UNIQUE INDEX has not been committed
yet, but the index creation has been completed, concurrent DML
transactions may acquire record locks on the index. Furthermore,
such concurrent DML may cause duplicate key violation, causing
the DDL operation to be rolled back. After that, the online_status
may be ONLINE_INDEX_ABORTED or ONLINE_INDEX_ABORTED_DROPPED.

So, the debug assertion may only forbid the state ONLINE_INDEX_CREATION.

MDEV-18457 Assertion `(bitmap->map +
           (bitmap->full_head_size/6*6)) <= full_head_end failed

The problem was that full_head_size was not calculated correctly
in the case when insert_order was inforced, which is the case
for SHOW commands.

The assert was caused by early cleanup of a user variable participant
in BINLOG @var,@var where it plays twice. That was unexpected by the base
code to clear its value prematurely.

Fixed with relocating the user var destruction after operations with
its value is over.

In commit ad6171b9 (MDEV-22456)
we removed the acquisition of the adaptive hash index latch
from the caller of btr_search_update_hash_ref().
The tests innodb.innodb_buffer_pool_resize_with_chunks
and innodb.innodb_buffer_pool_resize
would occasionally fail starting with 10.3,
due to MDEV-12288 causing more purge activity during the test.

btr_search_update_hash_ref(): After acquiring the adaptive hash index
latch, check that the adaptive hash index is still enabled on the page.

The problem is caused by the operation of netcat streamer and does
not appear on systems where socat is installed. We need to add the
"-N" option for netcat to call shutdown() on the socket when receiving
EOF from STDIN.

Localhost, depending on the platform can return any
127.0.0.1/8 address.

Also clean away dead code that is not used and will never have any use
on the 10.2 branch.

There is a 4 MB hard limit on Travis-CI and build output needs to be less
than that. Silencing the 'make install' step gets rid of a lot of
"Installing.." and "Missing.." and removing all mysql-test files will
make the dh_missing warnings much shorter.

Cherry-picked from 41952c85.

Backported from 30b44aae.

Also, adding 10.2 related changes for MDEV-22579

In commit b1742a5c we forgot
FLUSH TABLES, potentially causing errors for MyISAM system tables.

The rw_lock_stats were incorrectly updated.
While global statistics have limited usefulness, we cannot
remove them from a GA version. This contribution is slightly
improving performance in write workloads.

The code erroneously allowed both:
INSERT INTO t1 (vcol) VALUES (DEFAULT);
INSERT INTO t1 (vcol) VALUES (DEFAULT(non_virtual_column));

The former is OK, but the latter is not.
Adding a new virtual method in Item:

virtual bool vcol_assignment_allowed_value() const { return false; }

Item_null, Item_param and Item_default_value override it.

Item_default_value overrides it in the way to:
- allow DEFAULT
- disallow DEFAULT(col)

If the InnoDB buffer pool contains many pages for a table or index
that is being dropped or rebuilt, and if many of such pages are
pointed to by the adaptive hash index, dropping the adaptive hash index
may consume a lot of time.

The time-consuming operation of dropping the adaptive hash index entries
is being executed while the InnoDB data dictionary cache dict_sys is
exclusively locked.

It is not actually necessary to drop all adaptive hash index entries
at the time a table or index is being dropped or rebuilt. We can let
the LRU replacement policy of the buffer pool take care of this gradually.
For this to work, we must detach the dict_table_t and dict_index_t
objects from the main dict_sys cache, and once the last
adaptive hash index entry for the detached table is removed
(when the garbage page is evicted from the buffer pool) we can free
the dict_table_t and dict_index_t object.

Related to this, in MDEV-16283, we made ALTER TABLE...DISCARD TABLESPACE
skip both the buffer pool eviction and the drop of the adaptive hash index.
We shifted the burden to ALTER TABLE...IMPORT TABLESPACE or DROP TABLE.
We can remove the eviction from DROP TABLE. We must retain the eviction
in the ALTER TABLE...IMPORT TABLESPACE code path, so that in case the
discarded table is being re-imported with the same tablespace identifier,
the fresh data from the imported tablespace will replace any stale pages
in the buffer pool.

rpl.rpl_failed_drop_tbl_binlog: Remove the test. DROP TABLE can
no longer be interrupted inside InnoDB.

fseg_free_page(), fseg_free_step(), fseg_free_step_not_header(),
fseg_free_page_low(), fseg_free_extent(): Remove the parameter
that specifies whether the adaptive hash index should be dropped.

btr_search_lazy_free(): Lazily free an index when the last
reference to it is dropped from the adaptive hash index.

buf_pool_clear_hash_index(): Declare static, and move to the
same compilation unit with the bulk of the adaptive hash index
code.

dict_index_t::clone(), dict_index_t::clone_if_needed():
Clone an index that is being rebuilt while adaptive hash index
entries exist. The original index will be inserted into
dict_table_t::freed_indexes and dict_index_t::set_freed()
will be called.

dict_index_t::set_freed(), dict_index_t::freed(): Note that
or check whether the index has been freed. We will use the
impossible page number 1 to denote this condition.

dict_index_t::n_ahi_pages(): Replaces btr_search_info_get_ref_count().

dict_index_t::detach_columns(): Move the assignment n_fields=0
to ha_innobase_inplace_ctx::clear_added_indexes().
We must have access to the columns when freeing the
adaptive hash index. Note: dict_table_t::v_cols[] will remain
valid. If virtual columns are dropped or added, the table
definition will be reloaded in ha_innobase::commit_inplace_alter_table().

buf_page_mtr_lock(): Drop a stale adaptive hash index if needed.

We will also reduce the number of btr_get_search_latch() calls
and enclose some more code inside #ifdef BTR_CUR_HASH_ADAPT
in order to benefit cmake -DWITH_INNODB_AHI=OFF.

When neither MSAN nor Valgrind are enabled, declare
Field::mark_unused_memory_as_defined() as an empty inline function,
instead of declaring it as a virtual function.

MDEV-22073 MSAN use-of-uninitialized-value in
collect_statistics_for_table()

Other things:
innodb.analyze_table was changed to mainly test statistic
collection. Was discussed with Marko.

Other things:
- Removed innodb_encryption_tables.test from valgrind as it
  takes a REALLY long time

For the case when the optimizer does the IN-EXISTS transformation,
the equality condition is injected in the WHERE OR HAVING clause of
the subquery. If the select list of the subquery has a reference to
the parent select make sure to use the reference and not the original
item.

On a checksum failure of a ROW_FORMAT=COMPRESSED page,
buf_LRU_free_one_page() would invoke buf_LRU_block_remove_hashed()
which will read the uncompressed page frame, although it would not
be initialized. With bad enough luck, fil_page_get_type(page)
could return an unrecognized value and cause the server to abort.

buf_page_io_complete(): On the corruption of a ROW_FORMAT=COMPRESSED
page, zerofill the uncompressed page frame.