In CREATE SEQUENCE or CREATE TEMPORARY SEQUENCE, we should not start
an InnoDB transaction for inserting the sequence status record into
the underlying no-rollback table. Because we did this, a debug assertion
failure would fail in START TRANSACTION WITH CONSISTENT SNAPSHOT after
CREATE TEMPORARY SEQUENCE was executed.

row_ins_step(): Do not start the transaction. Let the caller do that.

que_thr_step(): Start the transaction before calling row_ins_step().

row_ins_clust_index_entry(): Skip locking and undo logging for no-rollback
tables, even for temporary no-rollback tables.

row_ins_index_entry(): Allow trx->id==0 for no-rollback tables.

row_insert_for_mysql(): Do not start a transaction for no-rollback tables.

trx reference counter was updated under mutex and read without any
protection. This is both slow and unsafe. Use atomic operations for
reference counter accesses.

trx_sys_t::rw_trx_set is implemented as std::set, which does a few quite
expensive operations under trx_sys_t::mutex protection: e.g. malloc/free
when adding/removing elements. Traversing b-tree is not that cheap either.

This has negative scalability impact, which is especially visible when running
oltp_update_index.lua benchmark on a ramdisk.

To reduce trx_sys_t::mutex contention std::set is replaced with LF_HASH. None
of LF_HASH operations require trx_sys_t::mutex (nor any other global mutex)
protection.

Another interesting issue observed with std::set is reproducible ~2% performance
decline after benchmark is ran for ~60 seconds. With LF_HASH results are stable.

All in all this patch optimises away one of three trx_sys->mutex locks per
oltp_update_index.lua query. The other two critical sections became smaller.

Relevant clean-ups:

Replaced rw_trx_set iteration at startup with local set. The latter is needed
because values inserted to rw_trx_list must be ordered by trx->id.

Removed redundant conditions from trx_reference(): it is (and even was) never
called with transactions that have trx->state == TRX_STATE_COMMITTED_IN_MEMORY.
do_ref_count doesn't (and probably even didn't) make any sense: now it is called
only when reference counter increment is actually requested.

Moved condition out of mutex in trx_erase_lists().

trx_rw_is_active(), trx_rw_is_active_low() and trx_get_rw_trx_by_id() were
greatly simplified and replaced by appropriate trx_rw_hash_t methods.

Compared to rw_trx_set, rw_trx_hash holds transactions only in PREPARED or
ACTIVE states. Transactions in COMMITTED state were required to be found
at InnoDB startup only. They are now looked up in the local set.

Removed unused trx_assert_recovered().

Removed unused innobase_get_trx() declaration.

Removed rather semantically incorrect trx_sys_rw_trx_add().

Moved information printout from trx_sys_init_at_db_start() to
trx_lists_init_at_db_start().

The warning was originally added in
commit c6766305
(MySQL 4.1.12, 5.0.3) to trace claimed undo log corruption that
was analyzed in https://lists.mysql.com/mysql/176250
on November 9, 2004.

Originally, the limit was 20,000 undo log headers or transactions,
but in commit 9d6d1902
in MySQL 5.5.11 it was increased to 2,000,000.

The message can be triggered when the progress of purge is prevented
by a long-running transaction (or just an idle transaction whose
read view was started a long time ago), by running many transactions
that UPDATE or DELETE some records, then starting another transaction
with a read view, and finally by executing more than 2,000,000
transactions that UPDATE or DELETE records in InnoDB tables. Finally,
when the oldest long-running transaction is completed, purge would
run up to the next-oldest transaction, and there would still be more
than 2,000,000 transactions to purge.

Because the message can be triggered when the database is obviously
not corrupted, it should be removed. Heavy users of InnoDB should be
monitoring the "History list length" in SHOW ENGINE INNODB STATUS;
there is no need to spam the error log.

- Skip 'clean' if not a git repository
  (Good for tar files)
- Add configuration for ASAN builds

Roll back to most general duplicate removing strategi in case of different stratagies for one position.

Problem was timing between the thread that was killed and reading the
binary log.

Updated the test to wait until the killed thread was properly terminated
before checking what's in the binary log.

To make check safe, I changed "threads_connected" to be updated after
thd::cleanup() is done, to ensure that all binary logs updates are done
before the variable is changed.  This was mainly done to get the
test deterministic and have now other real influence in how the server
works.

Replace most occurrences of the REFMAN macro. For some pages there
is no replacement yet.

recv_log_recover_10_3(): Determine if a log from MariaDB 10.3 is clean.

recv_find_max_checkpoint(): Allow startup with a clean 10.3 redo log.

srv_prepare_to_delete_redo_log_files(): When starting up with a 10.3 log,
display a "Downgrading redo log" message instead of "Upgrading".

Backport the fix from 10.0.33 to 5.5, in case someone compiles XtraDB
with -DUNIV_LOG_ARCHIVE

The XtraDB option innodb_track_changed_pages causes
the function log_group_read_log_seg() to be invoked
even when recv_sys==NULL, leading to the SIGSEGV.

This regression was caused by
MDEV-11027 InnoDB log recovery is too noisy

is set to ERR

This matches gcc/clang handling.

with recursive reference in subquery

If a recursive CTE uses a subquery with recursive reference then
the virtual function reset() must be called after each iteration
performed at the execution of the CTE.

This bug affected tables where the PRIMARY KEY contains variable-length
columns, and ROW_FORMAT is COMPACT or DYNAMIC.

rec_init_offsets_comp_ordinary(): Do not short-cut the parsing
of the record header for records that contain explicit values
for instantly added columns.

rec_copy_prefix_to_buf(): Copy more header for records that
contain explicit values for instantly added columns.

row_purge_reset_trx_id(): Display a DBUG message about resetting the
DB_TRX_ID.

innodb/buf_LRU_get_free_block
	Add debug instrumentation to produce error message about
	no free pages. Print error message only once and do not
	enable innodb monitor.

xtradb/buf_LRU_get_free_block
	Add debug instrumentation to produce error message about
	no free pages. Print error message only once and do not
	enable innodb monitor. Remove code that does not seem to
	be used.

innodb-lru-force-no-free-page.test
	New test case to force produce desired error message.

row_insert_for_mysql(): Remove some duplicated code

in JOIN::inject_best_splitting_cond

The value of SplM_opt_info::last_plan should be set to NULL
before any search for a splitting plan for a splittable
materialized table.

dict_foreign_find_index(): Ignore incompletely created indexes.
After a failed ADD UNIQUE INDEX, an incompletely created index
could be left behind until the next ALTER TABLE statement.

recv_parse_or_apply_log_rec_body(): Tolerate MLOG_4BYTES for
dummy-writing the FIL_PAGE_SPACE_ID, written by fil_crypt_rotate_page().

rec_get_trx_id(): Because rec is not necessarily residing in
a buffer pool page (it could be an old version of a clustered index
record, allocated from heap), remove the debug assertions that
depend on page_align(rec).

There is a race condition on a test. con1 is the older transaction
as it query started wait first. Test continues so that con1 gets
lock wait timeout first. There is possibility that default connection
gets lock timeout also or as con1 is rolled back it gets the locks
it waited and does the update. Fixed by removing query outputs as
they could vary and accepting success from default connection
query.