the top level

Added new enum variable `wsrep_mode` which can be used to turn on WSREP
features which are not part of default behaviour.
Added enum `BINLOG_ROW_FORMAT_ONLY`, `REQUIRED_PRIMARY_KEY` and
`STRICT_REPLICATION`. `wsrep-mode=STRICT_REPLICATION` behaves
like variable `wsrep_strict_ddl`.

Variable wsrep_strict_ddl is deprecated and if set we use
new wsrep_mode setting instead.

Reviewed and improved by: Jan Lindström <jan.lindstrom@mariadb.com>

We implement an idea that was suggested by Michael 'Monty' Widenius
in October 2017: When InnoDB is inserting into an empty table or partition,
we can write a single undo log record TRX_UNDO_EMPTY, which will cause
ROLLBACK to clear the table.

For this to work, the insert into an empty table or partition must be
covered by an exclusive table lock that will be held until the transaction
has been committed or rolled back, or the INSERT operation has been
rolled back (and the table is empty again), in lock_table_x_unlock().

Clustered index records that are covered by the TRX_UNDO_EMPTY record
will carry DB_TRX_ID=0 and DB_ROLL_PTR=1<<55, and thus they cannot
be distinguished from what MDEV-12288 leaves behind after purging the
history of row-logged operations.

Concurrent non-locking reads must be adjusted: If the read view was
created before the INSERT into an empty table, then we must continue
to imagine that the table is empty, and not try to read any records.
If the read view was created after the INSERT was committed, then
all records must be visible normally. To implement this, we introduce
the field dict_table_t::bulk_trx_id.

This special handling only applies to the very first INSERT statement
of a transaction for the empty table or partition. If a subsequent
statement in the transaction is modifying the initially empty table again,
we must enable row-level undo logging, so that we will be able to
roll back to the start of the statement in case of an error (such as
duplicate key).

INSERT IGNORE will continue to use row-level logging and locking, because
implementing it would require the ability to roll back the latest row.
Since the undo log that we write only allows us to roll back the entire
statement, we cannot support INSERT IGNORE. We will introduce a
handler::extra() parameter HA_EXTRA_IGNORE_INSERT to indicate to storage
engines that INSERT IGNORE is being executed.

In many test cases, we add an extra record to the table, so that during
the 'interesting' part of the test, row-level locking and logging will
be used.

Replicas will continue to use row-level logging and locking until
MDEV-24622 has been addressed. Likewise, this optimization will be
disabled in Galera cluster until MDEV-24623 enables it.

dict_table_t::bulk_trx_id: The latest active or committed transaction
that initiated an insert into an empty table or partition.
Protected by exclusive table lock and a clustered index leaf page latch.

ins_node_t::bulk_insert: Whether bulk insert was initiated.

trx_t::mod_tables: Use C++11 style accessors (emplace instead of insert).
Unlike earlier, this collection will cover also temporary tables.

trx_mod_table_time_t: Add start_bulk_insert(), end_bulk_insert(),
is_bulk_insert(), was_bulk_insert().

trx_undo_report_row_operation(): Before accessing any undo log pages,
invoke trx->mod_tables.emplace() in order to determine whether undo
logging was disabled, or whether this is the first INSERT and we are
supposed to write a TRX_UNDO_EMPTY record.

row_ins_clust_index_entry_low(): If we are inserting into an empty
clustered index leaf page, set the ins_node_t::bulk_insert flag for
the subsequent trx_undo_report_row_operation() call.

lock_rec_insert_check_and_lock(), lock_prdt_insert_check_and_lock():
Remove the redundant parameter 'flags' that can be checked in the caller.

btr_cur_ins_lock_and_undo(): Simplify the logic. Correctly write
DB_TRX_ID,DB_ROLL_PTR after invoking trx_undo_report_row_operation().

trx_mark_sql_stat_end(), ha_innobase::extra(HA_EXTRA_IGNORE_INSERT),
ha_innobase::external_lock(): Invoke trx_t::end_bulk_insert() so that
the next statement will not be covered by table-level undo logging.

ReadView::changes_visible(trx_id_t) const: New accessor for the case
where the trx_id_t is not read from a potentially corrupted index page
but directly from the memory. In this case, we can skip a sanity check.

row_sel(), row_sel_try_search_shortcut(), row_search_mvcc():
row_sel_try_search_shortcut_for_mysql(),
row_merge_read_clustered_index(): Check dict_table_t::bulk_trx_id.

row_sel_clust_sees(): Replaces lock_clust_rec_cons_read_sees().

lock_sec_rec_cons_read_sees(): Replaced with lower-level code.

btr_root_page_init(): Refactored from btr_create().

dict_index_t::clear(), dict_table_t::clear(): Empty an index or table,
for the ROLLBACK of an INSERT operation.

ROW_T_EMPTY, ROW_OP_EMPTY: Note a concurrent ROLLBACK of an INSERT
into an empty table.

This is joint work with Thirunarayanan Balathandayuthapani,
who created a working prototype.
Thanks to Matthias Leich for extensive testing.

In commit 03ca6495 (MDEV-24142)
we replaced a debug data structure that holds information about
S-latch holders with a std::set, which does not allow duplicates.

The assertion failed in btr_search_guess_on_hash() in an
s_lock_try() operation.

The reason why recursive S-latch requests are not normally allowed
is that if some other thread has enqueued a waiting X-lock, then
further S-latch requests will block until the exclusive lock has been
granted and released. If a thread were already holding one S-latch
while waiting for the X-latch to be granted and released by another
thread, the two threads would deadlock.

However, the nonblocking s_lock_try() is perfectly fine;
it will immediately return failure in case of conflict.

sux_lock::readers: Use std::unordered_multiset instead of std::set.

sux_lock::s_lock_register(): Allow 'duplicate' requests. Blocking-mode
latch acquisitions are already covered by !have_s() assertions.

sux_lock::s_unlock(): Erase only one element from readers.

buf_page_try_get(): Revert to s_lock_try(). It had been previously
changed to the more intrusive u_lock_try() in response to the
debug check failing.

We may end up with an empty leaf page (containing only an ADD COLUMN
metadata record) that is not the root page.

innobase_add_instant_try(): Disable an optimization for a non-canonical
empty table that contains a metadata record somewhere else than in
the root page.

btr_pcur_store_position(): Tolerate a non-canonical empty table.

MDEV-24659 Assertion !fsp_is_system_temporary(bpage->id().space()) failed in buf_flush_relocate_on_flush_list()

When commit 5eb53955 (MDEV-12227)
removed the pages of temporary tables from the buf_pool.flush_list,
an adjustment to the buffer pool resizing was forgotten.

buf_pool_t::realloc(): Do not invoke buf_flush_relocate_on_flush_list()
for pages that belong to the temporary tablespace. Also, deduplicate
some code at the end.

buf_page_t::set_corrupt_id(): Tolerate oldest_modification()==1
(the dummy value) for temporary tablespace pages. The revised
buf_pool_t::realloc() may invoke this on dirty temporary tablespace pages.

Ever since commit 947efe17
InnoDB no longer writes binlog position in one place.
It will not at all be written to the TRX_SYS page, and
instead it will be written to the undo log header page that
changes the transaction state.

trx_rseg_mem_restore(): Recover the information from the latest
written page.

fts_optimize_request_sync_table() can avoid the repetitive
FTS SYNC request of the table if the table already has FTS_SYNC
message in fts_optimize_wq queue.

Reviewed-by: Marko Mäkelä

MDEV-24463 : galera.galera_sst_mysqldump_with_key MTR failed: 'INSERT failed: 1213: Deadlock found when trying to get lock

We need to complete SST if both new and old start positions are
not same as initial positions. If they are initial positions
just set local uuid and seqno.

While reusing the cached undo log block, mtr expects the page
write to change while writing the trx id. cached undo log block
could contain bytes which were originally written for some other
transaction. So InnoDB should make mtr to do MAYBE_NOP while reusing
cached undo log block.

Reviewed-by: Marko Mäkelä

fts_optimize_callback() could be called after processing
FTS_MSG_STOP due to timer initiated callback. This issue
is caused by commit 38fd7b7d
(MDEV-21452). In that case, fts_optimize_callback() should
check whether it processed FTS_MSG_STOP already.

Reviewed-by: Marko Mäkelä

I_S tables were materialized too late, an attempt to use table
statistics before the table was created caused a crash.

Let's move table creation up. it only needs read_set to
be calculated properly, this happens in JOIN::optimize_inner(),
after semijoin transformation.

Note that tables are not populated at that point, so most of the
statistics would make no sense anyway. But at least field sizes
will be correct. And it won't crash.

The problem was that update_timing_fields_for_event() didn't release all
MDL locks it took.

MDEV-24596 : Assertion `state_ == s_exec || state_ == s_quitting' failed in wsrep::client_state::disable_streaming

There were multiple problems here
* wsrep_trx_fragment_size should not be set when wsrep is disabled or provider is not loaded
* wsrep_trx_fragment_unit should not be set when wsrep is disabled or provider is not loaded
* wsrep_debug has no effect if wsrep is disabled or provider is not loaded
* wsrep_start_position should not be set when wsrep is disabled or provider is not loaded any other value than default
* wsrep_start_position should be changed only when we are joiner or initialized
* wsrep_start_position should be allowed to set only a value that exits, thus
we need to add error handling to wsrep_sst_complete

Sample log error message generated:

mysql-test/var/log/mysqld.2.err:2021-01-21 13:02:30 8 [Note] Slave SQL thread exiting, replication stopped in log 'master-bin.000001' at position 329, master: 127.0.0.1:16000
mysql-test/var/log/mysqld.2.err:2021-01-21 13:02:30 7 [Note] Slave I/O thread exiting, read up to log 'master-bin.000001', position 329, master 127.0.0.1:16000
mysql-test/var/log/mysqld.2.err:2021-01-21 13:02:30 12 [Note] Slave SQL thread exiting, replication stopped in log 'master-bin.000001' at position 329; GTID position '', master: 127.0.0.1:16000

Reviewer: knielsen@knielsen-hq.org, Andrei and Sachin

Fix for MDEV-23033 fixes a problem in replication applying of transactions, which contain cascading foreign key delete for a table, which has indexed virtual column.
This fix adds slave_fk_event_map flag for table, to mark when the prelocking is needed for applying of a transaction.
See commit 608b0ee5 for more details.
However, this fix is targeted for async replication only, Rows_log_event::do_apply_event() has condition to rule out galera replication from the fix domain, and use cases suffering from MDEV-23033 and related MDEV-21153 will fail in galera cluster.

The fix in this commit removes the condition to rule out the setting of slave_fk_event_map flag from galera replication, and makes the fix in MDEV-23033 effective for galera replication as well.

However, the above fix has caused regressions for some galera_sr suite tests, which run tests for streaming replication.
This regression can be observed e.g. by: /mtr galera_sr.galera_sr_multirow_rollback  --mysqld=--slave_run_triggers_for_rbr=yes
These galera_sr suite tests were failing in last phase of replication applying, where actual transaction is already applied, and streaming replication related meta data needs to be updated in wsrep system tables.
Opening the wsrep system tables failed for corrupt data in THD::lex:query_tables_list. The fix in this commit uses back query table list for the duration of fragment update operation.

Finally, a mtr test for virtual column support has been added. galera.galera_virtual_column.test has as first test a scenario from MDEV-21153

new fix
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

Fix for MDEV-23033 fixes a problem in replication applying of transactions, which contain cascading foreign key delete for a table, which has indexed virtual column.
This fix adds slave_fk_event_map flag for table, to mark when the prelocking is needed for applying of a transaction.
See commit 608b0ee5 for more details.
However, this fix is targeted for async replication only, Rows_log_event::do_apply_event() has condition to rule out galera replication from the fix domain, and use cases suffering from MDEV-23033 and related MDEV-21153 will fail in galera cluster.

The fix in this commit removes the condition to rule out the setting of slave_fk_event_map flag from galera replication, and makes the fix in MDEV-23033 effective for galera replication as well.

Finally, a mtr test for virtual column support has been added. galera.galera_virtual_column.test has as first test a scenario from MDEV-21153
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

MDEV-24577: Fix warnings generated during compilation of plugin/auth_pam/testing/pam_mariadb_mtr.c on FreeBSD

Compiler warnings generated on building MariaDB server for BSD has the same
reason as in case building is performed on MacOS. Both platforms do use
clang as a C/C++ compiler. So, fix the compiler warnings in case the compiler
is clang doesn't matter what kind of building platform do we use for building.

This is a follow-up patch for the following bug reports:
  MDEV-23564: CMAKE failing due to deprecated Apple GSS method
  MDEV-23935: Fix warnings generated during compilation of
              plugin/auth_pam/testing/pam_mariadb_mtr.c on MacOS

Do not init encryption threads if shutdown is in progress.

- Fix long lines to be <= 80 character
- Trivial changes (no logic changes)

- Create_tmp_table::finalize didn't clear file after delete which
  could cause a double free. This is however not a likely problem as
  this code path is very unlikely to happen
- free_tmp_table() could do handler calls even if the table was never
  opened. Fixed by adding a test if the table is opened.

The table performance_schema.events_transactions_history_long that
was imported from MySQL 5.7.28 in
commit 0ea717f5
may report bogus trx_id values for InnoDB transactions.

innobase_register_trx(): Pass trx->id to trans_register_ha(),
even if it is 0. It is more appropriate to report NULL than some
arbitrary value that has been constructed from the address of a
transaction identifier.

closes #1737

Reviewers: Marko Mäkelä, Krunal Bauskar

Attempting to sign up to https://bestpractices.coreinfrastructure.org/en/projects
complains with "Implementation languages is too long (maximum is 254 characters)"

Looking at:

 curl -H "Accept: application/vnd.github.v3+json"   https://api.github.com/repos/MariaDB/server/languages

It does appear that we're (just) over the limit.

As github is based on https://github.com/github/linguist, let's just
play nice and make our languages look realistic.