Problem:- In the case of multisource replication/named slave
when we run "FLUSH LOGS" , it does not flush logs.

Solution:- A new function Master_info_index->flush_all_relay_logs()
is created which will rotate relay logs for all named slave.
This will be called in reload_acl_and_cache function when
connection_name.length == 0

Problem was that all doublewrite buffer pages must fit to first
system datafile.

Ported commit 27a34df7882b1f8ed283f22bf83e8bfc523cbfde
Author: Shaohua Wang <shaohua.wang@oracle.com>
Date:   Wed Aug 12 15:55:19 2015 +0800

    BUG#21551464 - SEGFAULT WHILE INITIALIZING DATABASE WHEN
    INNODB_DATA_FILE SIZE IS SMALL

To 10.1 (with extended error printout).

btr_create(): If ibuf header page allocation fails report error and
return FIL_NULL. Similarly if root page allocation fails return a error.

dict_build_table_def_step: If fsp_header_init fails return
error code.

fsp_header_init: returns true if header initialization succeeds
and false if not.

fseg_create_general: report error if segment or page allocation fails.

innobase_init: If first datafile is smaller than 3M and could not
contain all doublewrite buffer pages report error and fail to
initialize InnoDB plugin.

row_truncate_table_for_mysql: report error if fsp header init
fails.

srv_init_abort: New function to report database initialization errors.

srv_undo_tablespaces_init, innobase_start_or_create_for_mysql: If
database initialization fails report error and abort.

trx_rseg_create: If segment header creation fails return.

MDEV-12114: install_db shows corruption for rest encryption and innodb_checksum_algorithm=strict_none

Problem was that checksum check resulted false positives that page is
both not encrypted and encryted when checksum_algorithm was
strict_none.

Encrypton checksum will use only crc32 regardless of setting.

buf_zip_decompress: If compression fails report a error message
containing the space name if available (not available during import).
And note if space could be encrypted.

buf_page_get_gen: Do not assert if decompression fails,
instead unfix the page and return NULL to upper layer.

fil_crypt_calculate_checksum: Use only crc32 method.

fil_space_verify_crypt_checksum: Here we need to check
crc32, innodb and none method for old datafiles.

fil_space_release_for_io: Allow null space.

encryption.innodb-compressed-blob is now run with crc32 and none
combinations.

Note that with none and strict_none method there is not really
a way to detect page corruptions and page corruptions after
decrypting the page with incorrect key.

New test innodb-checksum-algorithm to test different checksum
algorithms with encrypted, row compressed and page compressed
tables.

Problem was that FIL_PAGE_FLUSH_LSN_OR_KEY_VERSION field that for
encrypted pages even in system datafiles should contain key_version
except very first page (0:0) is after encryption overwritten with
flush lsn.

Ported WL#7990 Repurpose FIL_PAGE_FLUSH_LSN to 10.1
The field FIL_PAGE_FLUSH_LSN_OR_KEY_VERSION is consulted during
InnoDB startup.

At startup, InnoDB reads the FIL_PAGE_FLUSH_LSN_OR_KEY_VERSION
from the first page of each file in the InnoDB system tablespace.
If there are multiple files, the minimum and maximum LSN can differ.
These numbers are passed to InnoDB startup.

Having the number in other files than the first file of the InnoDB
system tablespace is not providing much additional value. It is
conflicting with other use of the field, such as on InnoDB R-tree
index pages and encryption key_version.

This worklog will stop writing FIL_PAGE_FLUSH_LSN_OR_KEY_VERSION to
other files than the first file of the InnoDB system tablespace
(page number 0:0) when system tablespace is encrypted. If tablespace
is not encrypted we continue writing FIL_PAGE_FLUSH_LSN_OR_KEY_VERSION
to all first pages of system tablespace to avoid unnecessary
warnings on downgrade.

open_or_create_data_files(): pass only one flushed_lsn parameter

xb_load_tablespaces(): pass only one flushed_lsn parameter.

buf_page_create(): Improve comment about where
FIL_PAGE_FIL_FLUSH_LSN_OR_KEY_VERSION is set.

fil_write_flushed_lsn(): A new function, merged from
fil_write_lsn_and_arch_no_to_file() and
fil_write_flushed_lsn_to_data_files().
Only write to the first page of the system tablespace (page 0:0)
if tablespace is encrypted, or write all first pages of system
tablespace and invoke fil_flush_file_spaces(FIL_TYPE_TABLESPACE)
afterwards.

fil_read_first_page(): read flush_lsn and crypt_data only from
first datafile.

fil_open_single_table_tablespace(): Remove output of LSN, because it
was only valid for the system tablespace and the undo tablespaces, not
user tablespaces.

fil_validate_single_table_tablespace(): Remove output of LSN.

checkpoint_now_set(): Use fil_write_flushed_lsn and output
a error if operation fails.

Remove lsn variable from fsp_open_info.

recv_recovery_from_checkpoint_start(): Remove unnecessary second
flush_lsn parameter.

log_empty_and_mark_files_at_shutdown(): Use fil_writte_flushed_lsn
and output error if it fails.

open_or_create_data_files(): Pass only one flushed_lsn variable.

it's unused now.

always use full m_SubStrVec length in pcre_exec, we don't know
how many subexpressions user's regexp will have

This corrects the patch for mdev-10006.
The current code supports only those semi-join nests that are placed at
the join top level. So such nests cannot depend on other tables or nests.

was corrupted, server crashes in opt_sum_query

Extended keys feature disabled if the length of extended key is longer than MAX_KEY_LEN

performance-schema options in option files should be loose. The tests
will be skipped after have_perfschema.inc check, but if options aren't
loose, the failure happens on server startup, before the check

MDEV-12926 encryption.innodb_onlinealter_encryption, encryption.innodb-bad-key-change failed in buildbot with valgrind

row_merge_write(): Pass the correct (possibly encrypted) buffer
to os_file_write_int_fd().

This bug was introduced in commit 65e1399e
which included a commit to merge changes from MySQL 5.6.36 to
MariaDB Server 10.0.

btr_defragment_thread(): Create the thread in the same place as other
threads. Do not invoke btr_defragment_shutdown(), because
row_drop_tables_for_mysql_in_background() in the master thread can still
keep invoking btr_defragment_remove_table().

logs_empty_and_mark_files_at_shutdown(): Wait for btr_defragment_thread()
to exit.

innobase_start_or_create_for_mysql(), innobase_shutdown_for_mysql():
Skip encryption and scrubbing in innodb_read_only_mode.

srv_export_innodb_status(): Do not export encryption or scrubbing
statistics in innodb_read_only mode, because the threads will not
be running.

InnoDB shutdown assumes that once the server has entered
SRV_SHUTDOWN_FLUSH_PHASE, no change to persistent data is allowed.
It was possible for the master thread to wake up while shutdown
is executing in SRV_SHUTDOWN_FLUSH_PHASE or
even in SRV_SHUTDOWN_LAST_PHASE.

We do not yet know if further crashes at shutdown are possible.
Also, we do not know if all the observed crashes could be explained
by the race conditions that we are now fixing.

srv_shutdown_print_master_pending(): Remove a redundant ut_time() call.

srv_shutdown(): Renamed from srv_master_do_shutdown_tasks().

srv_master_thread(): Do not resume after shutdown has been initiated.

Don't rebuild the table for ALTER TABLE delay_key_write changes.

After that, delay_key_write value in .frm may differ from the
value in .MYI. We'll do what .frm says.

Test fails, because of a bug: global delay_key_write is
cached in the THD and the cached value becomes out-of-date
when the global value changes.

This is fixed in MDEV-11335

cast pointer(64)->long(32)

Make `mysqladmin --local` use `FLUSH LOCAL` for all flush-* commands,
and only do `SET SQL_LOG_BIN=OFF` for create/drop/old_password/password.

Additionally, --local is ignored for all commands that never write
to binlog, so e.g. `mysqladmin --local version` no longer needs SUPER

MDEV-11650 plugins.cracklib_password_check, plugins.two_password_validations fail in buildbot with valgrind (Conditional jump or move depends on uninitialised value)

FederatedX wasn't discovering prefix keys correctly.
Of course, as it had the HA_NO_PREFIX_CHAR_KEYS table_flag set...

fixed valgrind warning in a debug output

Before MDEV-6812, it did not matter that merge_files[].offset was
uninitialized when no files were created.

This problem was introduced in MDEV-6812. There could be a user-visible
impact that the progress reports spit into the error log are bogus.

row_merge_build_indexes(): Initialize merge_files[i].offset.

As documented in MSDN, DeviceIoControl() needs valid (not NULL) OVERLAPPED
parameter, for files  opened with for OVERLAPPED access.

Additional tests have been done and conclusion was to update maturity to stable

due to different packaging issues.

Also, Percona thinks that tar support has  many limitations
and should be removed as well( see discussion  in
https://bugs.launchpad.net/percona-xtrabackup/+bug/1681721)

there is an alternative streaming format xbstream that is supported and
does not have these limitations.

Snappy compression method require that output buffer
used for compression is bigger than input buffer.
Similarly lzo require additional work memory buffer.
Increase the allocated buffer accordingly.

buf_tmp_buffer_t: removed unnecessary lzo_mem, crypt_buf_free and
comp_buf_free.

buf_pool_reserve_tmp_slot: use alligned_alloc and if snappy
available allocate size based on snappy_max_compressed_length and
if lzo is available increase buffer by LZO1X_1_15_MEM_COMPRESS.

fil_compress_page: Remove unneeded lzo mem (we use same buffer)
and if output buffer is not yet allocated allocate based similarly
as above.

Decompression does not require additional work area.

    Modify test to use same test as other compression method tests.

Changed global parameters will be reset by server restart.
There is no need to save and restore the original values.

In commit 360a4a03
some debug assertions were introduced to the page flushing code
in XtraDB. Add these assertions to InnoDB as well, and adjust
the InnoDB shutdown so that these assertions will not fail.

logs_empty_and_mark_files_at_shutdown(): Advance
srv_shutdown_state from the first phase SRV_SHUTDOWN_CLEANUP
only after no page-dirtying activity is possible
(well, except by srv_master_do_shutdown_tasks(), which will be
fixed separately in MDEV-12052).

rotate_thread_t::should_shutdown(): Already exit the key rotation
threads at the first phase of shutdown (SRV_SHUTDOWN_CLEANUP).

page_cleaner_sleep_if_needed(): Do not sleep during shutdown.
This change is originally from XtraDB.

Significantly reduce the amount of InnoDB, XtraDB and Mariabackup
code changes by defining pfs_os_file_t as something that is
transparently compatible with os_file_t.