Since commit 5e62b6a5 (MDEV-16264),
purge_sys_t::stop() no longer waited for all purge activity to stop.

This caused problems on FLUSH TABLES...FOR EXPORT because of
purge running concurrently with the buffer pool flush.
The assertion at the end of buf_flush_dirty_pages() could fail.

The, implemented by Vladislav Vaintroub, aims to eliminate race
conditions when stopping or resuming purge:

waitable_task::disable(): Wait for the task to complete, then replace
the task callback function with noop.

waitable_task::enable(): Restore the original task callback function
after disable().

purge_sys_t::stop(): Invoke purge_coordinator_task.disable().

purge_sys_t::resume(): Invoke purge_coordinator_task.enable().

purge_sys_t::running(): Add const qualifier, and clarify the comment.
The purge coordinator task will remain active as long as any purge
worker task is active.

purge_worker_callback(): Assert purge_sys.running().

srv_purge_wakeup(): Merge with the only caller purge_sys_t::resume().

purge_coordinator_task: Use static linkage.

srv_export_innodb_status(): While gathering
innodb_mem_adaptive_hash, acquire btr_search_latches[i]
in order to prevent a race condition with buffer pool resizing.

Release memory as soon as redo log records are processed.

Because the memory allocation and deallocation of parsed redo log
records must be protected by recv_sys.mutex, it is better to avoid
using a std::atomic field for bookkeeping.

buf_page_t::access_time: Keep track of the recv_sys.pages record
allocations. The most significant 16 bits will count allocated
blocks (which were previously counted by buf_page_t::buf_fix_count
in the debug version), and the least significant 16 bits indicate
the number of allocated bytes in the block (which was previously
managed in buf_block_t::modify_clock), which must be a positive
number, up to innodb_page_size. The byte offset 65536 is represented
as the value 0.

recv_recover_page(): Let the caller erase the log.

recv_validate_tablespace(): Acquire recv_sys_t::mutex.

Function `signal_waiters` assigned `m_committed_seqno` variable outside of
mutex lock which caused incorrect behavior of WSREP_SYNC_WAIT_UPTO_GTID.
Fixed by moving assignment inside lock. Added handling of OOM and now
error is reported.
Remove hard-coded seqno value and read seqno directly from current node state.

Also added support for MAP_SYNC. It allows to achieve decent performance
with DAX devices even when libpmem is unavailable.

Fixed Windows version of my_msync(): according to manual FlushViewOfFile()
may return before flush is actually completed. It is advised to issue
FlushFileBuffers() after FlushViewOfFile().

Fix:
===
Add "REPLICA" as an alias for "SLAVE". All commands which use "SLAVE" keyword
can be used with new alias "REPLICA".

List of commands:

On Master:
=========
SHOW REPLICA HOSTS <--> SHOW SLAVE HOSTS
Privilege "SLAVE"  <--> "REPLICA"

On Slave:
=========
START SLAVE       <--> START REPLICA
START ALL SLAVES  <--> START ALL REPLICAS
START SLAVE UNTIL <--> START REPLICA UNTIL
STOP SLAVE        <--> STOP REPLICA
STOP ALL SLAVES   <--> STOP ALL REPLICAS
RESET SLAVE       <--> RESET REPLICA
RESET SLAVE ALL   <--> RESET REPLICA ALL
SLAVE_POS         <--> REPLICA_POS

main change: rename first redo log without file close

second change: use os_offset_t to represent offset in a file

third change: fix log texts

Variable `wsrep_new_cluster` should be set to false after `wsrep_init_startup`.
Problem was that this was done before when mysqldump is used as SST method so option
wsrep-new-cluster didn't have any effect.

Support for galera GTID consistency thru cluster. All nodes in cluster
should have same GTID for replicated events which are originating from cluster.
Cluster originating commands need to contain sequential WSREP GTID seqno
Ignore manual setting of gtid_seq_no=X.

In master-slave scenario where master is non galera node replicated GTID is
replicated and is preserved in all nodes.

To have this - domain_id, server_id and seqnos should be same on all nodes.
Node which bootstraps the cluster, to achieve this, sends domain_id and
server_id to other nodes and this combination is used to write GTID for events
that are replicated inside cluster.

Cluster nodes that are executing non replicated events are going to have different
GTID than replicated ones, difference will be visible in domain part of gtid.

With wsrep_gtid_domain_id you can set domain_id for WSREP cluster.

Functions WSREP_LAST_WRITTEN_GTID, WSREP_LAST_SEEN_GTID and
WSREP_SYNC_WAIT_UPTO_GTID now works with "native" GTID format.

Fixed galera tests to reflect this chances.

Add variable to manually update WSREP GTID seqno in cluster

Add variable to manipulate and change WSREP GTID seqno. Next command
originating from cluster and on same thread will have set seqno and
cluster should change their internal counter to it's value.
Behavior is same as using @@gtid_seq_no for non WSREP transaction.

mtr_t::is_active(), mtr_t::is_committed(): Make debug-only.

Starting with commit 37344390
we would invoke memcmp() unconditionally, even if the length is zero.
But, a call to memcmp() is undefined if any parameter is a null pointer,
even if the length is zero.

In the following tests, a null pointer is being passed to the comparison:
vcol.vcol_keys_innodb gcol.gcol_keys_innodb main.func_group_innodb
innodb.innodb_bug53592

cmp_data(): Keep WITH_UBSAN happy and avoid potential future bugs
in optimized builds, like the one addressed by
commit fc168c3a (MDEV-15587).

InnoDB crash recovery used a special type of mem_heap_t that
allocates backing store from the buffer pool. That incurred
a significant overhead, leading to underutilization of memory,
and limiting the maximum contiguous allocated size of a log record.

recv_sys_t::blocks: A linked list of buf_block_t that are allocated
by buf_block_alloc() for redo log records. Replaces recv_sys_t::heap.
We repurpose buf_block_t::unzip_LRU for linking the elements.

recv_sys_t::max_log_blocks: Renamed from recv_n_pool_free_frames.

recv_sys_t::max_blocks(): Accessor for max_log_blocks.

recv_sys_t::alloc(): Allocate memory from the current recv_sys_t::blocks
element, or allocate another block.  In debug builds, various free()
member functions must be invoked, because we repurpose
buf_page_t::buf_fix_count for tracking allocations.

recv_sys_t::free_corrupted_page(): Renamed from recv_recover_corrupt_page()

recv_sys_t::is_memory_exhausted(): Renamed from recv_sys_heap_check()

recv_sys_t::pages and its elements are allocated directly by the
system memory allocator.

recv_parse_log_recs(): Remove the parameter available_memory.

We rename some variables 'store_to_hash' to 'store', because
recv_sys.pages is not actually a hash table.

This is joint work with Thirunarayanan Balathandayuthapani.

Changed Travis status to show status of branch 10.5 (it was still pointing to 10.4)

[Variant 2 of the fix: collect the attached conditions]

Problem:
make_join_select() has a section of code which starts with
 "We plan to scan all rows. Check again if we should use an index."

the code in that section will [unnecessarily] re-run the range
optimizer using this condition:

  condition_attached_to_current_table AND current_table's_ON_expr

Note that the original invocation of range optimizer in
make_join_statistics was done using the whole select's WHERE condition.
Taking the whole select's WHERE condition and using multiple-equalities
allowed the range optimizer to infer more range restrictions.

The fix:
- Do range optimization using a condition that is an AND of this table's
condition and all of the previous tables' conditions.
- Also, fix the range optimizer to prefer SEL_ARGs with type=KEY_RANGE
over SEL_ARGS with type=MAYBE_KEY, regardless of the key part.
Computing
key_and(
  SEL_ARG(type=MAYBE_KEY key_part=1),
  SEL_ARG(type=KEY_RANGE, key_part=2)
)
will now produce the SEL_ARG with type=KEY_RANGE.

class log_file_t: more or less sane RAII wrapper around redo log file
descriptor and its path.

This change is motivated by the need of using that log_file_t somewhere else.

We missed these in commit 89633995
and commit ccd87d34.

MDEV-21490: binlog tests fail with valgrind: Conditional jump or move depends on uninitialised value in sql_ex_info::init

Problem:
=======
P1) Conditional jump or move depends on uninitialised value(s)
    sql_ex_info::init(char const*, char const*, bool) (log_event.cc:3083)

code: All the following variables are not initialized.
----
  return ((cached_new_format != -1) ? cached_new_format :
    (cached_new_format=(field_term_len > 1 || enclosed_len > 1 ||
    line_term_len > 1 || line_start_len > 1 || escaped_len > 1)));

P2) Conditional jump or move depends on uninitialised value(s)
    Rows_log_event::Rows_log_event(char const*, unsigned
      int, Format_description_log_event const*) (log_event.cc:9571)

Code: Uninitialized values is reported for 'var_header_len' variable.
----
  if (var_header_len < 2 || event_len < static_cast<unsigned
      int>(var_header_len + (post_start - buf)))

P3) Conditional jump or move depends on uninitialised value(s)
    Table_map_log_event::pack_info(Protocol*) (log_event.cc:11553)

code:'m_table_id' is uninitialized.
----
  void Table_map_log_event::pack_info(Protocol *protocol)
  ...
  size_t bytes= my_snprintf(buf, sizeof(buf), "table_id: %lu (%s.%s)",
                              m_table_id, m_dbnam, m_tblnam);

Fix:
===
P1 - Fix)
Initialize cached_new_format,field_term_len, enclosed_len, line_term_len,
line_start_len, escaped_len members in default constructor.

P2 - Fix)
"var_header_len" is initialized by reading the event buffer. In case of an
invalid event the buffer will contain invalid data. Hence added a check to
validate the event data. If event_len is smaller than valid header length
return immediately.

P3 - Fix)
'm_table_id' within Table_map_log_event is initialized by reading data from
the event buffer. Use 'VALIDATE_BYTES_READ' macro to validate the current
state of the buffer. If it is invalid return immediately.

this test needs a *server* and tries to connect with $MYSQL to it

PCRE reports small frame size working with ASAN, so the test has to be ready
for the minimlas possible size.

os_file_flush_data_func(): fix builds on POSIX OSs where fdatasync()
is not avaiable

log_t::files::flush_data_only(): rename from fdatasync()

log_t::files::fsync(): removed and replaced with flush_data_only().
It will flush everything we need for using redo log files.

This is the only symlink in the repository. Symlinks can cause
trouble when using file systems or operating systems that do not
support them.

Also remove the unused file DartConfig.cmake that refers to the script.

cmake -DWITH_INNODB_EXTRA_DEBUG:BOOL=ON
was broken ever since commit 8777458a
(MDEV-6076 Persistent AUTO_INCREMENT for InnoDB).

There is a race condition between page reads that call
page_zip_validate() (while holding clustered index root page S-latch)
and writes that update PAGE_ROOT_AUTO_INC
(with buf_block_t::lock SX-latch, compatible with S-latch).

page_zip_validate_low(): Skip the PAGE_ROOT_AUTO_INC field on
clustered index root pages in order to avoid false positives.

MDEV-21551 :  Assertion `m_active_threads.size() >= m_long_tasks_count + m_waiting_task_count' failed"

Happened when running innodb_fts.sync_ddl

m_long_task_count could be wrongly reset to 0, if m_task_queue is
empty.

dict_table_t::parse_name(): Properly calculate the *tbl_name_len.

A failure was easily repeatable during the test
innodb.innodb-alter-debug for the table name test.① ("test/@2460").
The UTF-8 representation of the U+2460 is only 3 bytes "\xe2\x91\xa0"
while the filename-safe encoded counterpart of it in dict_table_t::name
is 5 bytes "@2460".

This bug, introduced by commit ea37b144
(MDEV-16678), could cause a purge task to hang.

Post-push fix. aria_pack_mdev14183 test is unstable.

The fix is the following:
1. Disable the test for embedded server.
2. Create non-"transactional" Aria table in the test, as aria_pack does not
support "transactional" Aria tables.