Step#5: changing the function remove_eq_conds() into a virtual method in Item.
It removes 6 virtual calls for Item_func::type(), and adds only 2
virtual calls for Item***::remove_eq_conds().

This is an addition to original patch. Embedded server does extra calls of
PROFILING::start_new_query() and PROFILING::finish_current_query(), which
cause DBUG_ASSERT(!current) failure.

Removed these extra calls: dispatch_command() does all needed job.

Avoid calling current_thd from thd_kill_level(). This reduces number of
pthread_getspecific() calls from 776 to 354.

Also thd_kill_level(NULL) is not permitted anymore: this saves one condition.

Analysis: Problem was that we did create crypt data for encrypted table but
this new crypt data was not written to page 0. Instead a default crypt data
was written to page 0 at table creation.

Fixed by explicitly writing new crypt data to page 0 after successfull
table creation.

Step 4 (there will be more)

when checking for a flag, use & not ==

* check key version per key id (that is, per tablespace).
* wake encryption thread when a tablespace needs re-encryption

show that two keys can be different if they have different ids
or different versions.

fix encryption of the last partial block

* now really encrypt it, using key and iv
* support the case of very short plaintext (less than one block)
* recommend aes_ctr over aes_cbc, because the former
  doesn't have problems with partial blocks

* don't use do_crypt() for stream cipher AES_CTR
* rename do_crypt to block_crypt to emphasize its specialization

InnoDB: refuse to start if encryption is requested but no
encryption plugin is available

chomp the secret, as read from the file. remove trailing
CR and LF bytes.

applied upstream patch

remove few tests for variables that never existed (merge error)

Added THD argument to select_result and all derivative classes.
This reduces number of pthread_getspecific calls from 796 to 776 per OLTP RO
transaction.

Recording --ps and --embedded tests (a postfix for MDEV-7807)

Removed yet more mysql_reset_thd_for_next_command(). Call
THD::reset_for_next_command() directly instead.

sql_alloc() has additional costs compared to direct mem_root allocation:
- function call: it is defined in a separate translation unit and can't be
  inlined
- it needs to call pthread_getspecific() to get THD::mem_root

It is called dozens of times implicitely at least by:
- List<>::push_back()
- List<>::push_front()
- new (for Sql_alloc derived classes)
- sql_memdup()

Replaced lots of implicit sql_alloc() calls with direct mem_root allocation,
passing through THD pointer whenever it is needed.

Number of sql_alloc() calls reduced 345 -> 41 per OLTP RO transaction.
pthread_getspecific() overhead dropped 0.76 -> 0.59
sql_alloc() overhed dropped 0.25 -> 0.06

delete_dynamic() was called 9-11x per OLTP RO query + 3x per BEGIN/COMMIT.

3 calls were performed by LEX_MASTER_INFO. Added condition to call those only
for CHANGE MASTER.

1 call was performed by lock_table_names()/Hash_set/my_hash_free(). Hash_set was
supposed to be used for DDL and LOCK TABLES to gather database names, while it
was initialized/freed for DML too. In fact Hash_set didn't do any useful job
here. Hash_set was removed and MDL requests are now added directly to the list.

The rest 5-7 calls are done by optimizer, mostly by Explain_query and friends.
Since dynamic arrays are used in most cases, they can hardly be optimized.

my_hash_free() overhead dropped 0.02 -> out of radar.
delete_dynamic() overhead dropped 0.12 -> 0.04.

Removed mysql_reset_thd_for_next_command(). Call THD::reset_for_next_command()
directly instead.

mysql_reset_thd_for_next_command() overhead dropped 0.04% -> out of radar.
THD::reset_for_next_command() overhead didn't increase.

PROFILING::start_new_query() optimizations:
- no need to check "current": added assertion instead
- "enabled" now means "is enabled currently" instead of "was enabled at query
  start". Old meaning was useless, new meaning echoes OPTION_PROFILING so
  that start_new_query() can be defined in sql_profile.h.
- remnants of start_new_query() moved to sql_profile.h so it can be inlined

PROFILING::start_new_query() overhead dropped 0.08% -> out of radar.

PROFILING::set_query_source() optimizations:
- no need to check "enabled": !enabled && current is impossible
- remnants of set_query_source() moved to sql_profile.h so it can be inlined

PROFILING::set_query_source() overhead dropped 0.02% -> out of radar.

PROFILING::finish_current_query() optimizations:
- moved "current" check out to sql_profile.h so it can be inlined

PROFILING::finish_current_query() overhead dropped 0.10% -> out of radar.

THD::enter_stage() optimizations:
- stage backup code moved to THD::backup_stage(), saves one condition
- moved check for "new_stage" out to callers that actually need it
- remnants of enter_stage() moved to sql_class.h so it can be inlined

THD::enter_stage() overhead dropped 0.48% -> 0.07%.

PROFILING::status_change() optimizations:
- "status_arg" is now checked by QUERY_PROFILE::new_status()
- no need to check "enabled": !enabled && current is impossible
- remnants of status_change() moved to sql_profile.h so it can be inlined

PROFILING::status_change() overhead dropped 0.1% -> out of radar.

.. wsrep.binlog_format, wsrep.mdev_6832 fail in buildbot

Galera-3.9 logs an additional warning in the error log if
it fails to find gvwstate.dat file. Update wsrep/suite.pm.

MDEV-7926 Server crashes in get_geometry_column_record on concurrent SELECT FROM I_S.GEOMETRY_COLUMNS with join and DDL.
         The bug was that open_tables() returned error in case of
        thd->killed() without properly calling thd->send_kill_message()
        to set the correct error. This was fixed already in get_schema_column_record,
        so the code was just copied to get_geometry_column_record.

UNIV_LIKELY()/UNIV_UNLIKELY() hints are supposed to improve branch prediction.
Currently, they're expected to work only if cond evaluates to TRUE or FALSE.

However there're a few conditions that may evaluate to different values, e.g.:

page/page0zip.cc:		if (UNIV_LIKELY(c_stream->avail_in)) {
page/page0zip.cc:			if (UNIV_LIKELY(c_stream->avail_in)) {
dict/dict0mem.cc:		if (UNIV_LIKELY(i) && UNIV_UNLIKELY(!table->col_names)) {

Fixed these conditions so that they evaluate TRUE/FALSE.

MDEV-8113: Parallel slave: slave hangs on ALTER TABLE (or other DDL) as the first event after slave start

In optimistic parallel replication, it is not safe to try to run a following
transaction in parallel with a DDL statement, and there is code to prevent
this.

However, the code was missing the case where the DDL is the very first event
after slave start. In this case, following transactions could run in
parallel with the DDL, which can cause the slave to hang or even corrupt
slave in unlucky cases.

Fix incorrect types and compiler warnings.

MDEV-8021 "InnoDB: Tablespace id 4 encrypted but encryption service not available. Can't continue opening tablespace" on server restart when there are encrypted tables

key id was written in the wrong place on the tablespace first page
(thus its value could not be read back later)

Merged new version of InnoDB/XtraDB redo log encryption from Google
provided by Jonas Oreland.

On Windows, the files get checked out with CRLF thanks
to .gitattributes.

Adding a new column INFORMATION_SCHEMA.PROCESSLIST.INFO_BINARY.

            table

Performance schema discovery fails if connection has no active database set.

This happened due to restriction in SQL parser: table name with no database name
is ambiguous in such case.

Fixed by temporary substitution of default database with being discovered table
database.

initializers.

XA COMMIT/ROLLBACK of XA transaction owned by different thread may access
freed memory if that thread disconnects at the same time.

Also concurrent XA COMMIT/ROLLBACK of recovered XA transaction were not
serialized properly.

c99 style for assigning structure members

MDEV-8046: Server crashes in pfs_mutex_enter_func on select from I_S.INNODB_TABLESPACES_ENCRYPTION if InnoDB is disabled

Problem was that information schema tables innodb_tablespaces_encryption and
innodb_tablespaces_scrubbing where missing required check is InnoDB enabled
or not.

Problem was that e.g. on crash recovery fil_space_crypt_close_tablespace
and fil_space_crypt_mark_space_closing access mutex that is not yet
initialized. Mutex is naturally initialized only if encryption is
configured.