fixed C++ comment in C code

Starting with MySQL 5.7, temporary tables in InnoDB are handled
differently from persistent tables. Because temporary tables are
private to a connection, concurrency control and multi-versioning
(MVCC) are not applicable. For performance reasons, purge is
disabled as well. Rollback is supported for temporary tables;
that is why we have the temporary undo logs in the first place.

Because MVCC and purge are disabled for temporary tables, we should
discard all temporary undo logs already at transaction commit,
just like we discard the persistent insert_undo logs. Before this
change, update_undo logs were being preserved.

trx_temp_undo_t: A wrapper for temporary undo logs, comprising
a rollback segment and a single temporary undo log.

trx_rsegs_t::m_noredo: Use trx_temp_undo_t.
(Instead of insert_undo, update_undo, there will be a single undo.)

trx_is_noredo_rseg_updated(), trx_is_rseg_assigned(): Remove.

trx_undo_add_page(): Remove the parameter undo_ptr.
Acquire and release the rollback segment mutex inside the function.

trx_undo_free_last_page(): Remove the parameter trx.

trx_undo_truncate_end(): Remove the parameter trx, and add the
parameter is_temp. Clean up the code a bit.

trx_undo_assign_undo(): Split the parameter undo_ptr into rseg, undo.

trx_undo_commit_cleanup(): Renamed from trx_undo_insert_cleanup().
Replace the parameter undo_ptr with undo.
This will discard the temporary undo or insert_undo log at
commit/rollback.

trx_purge_add_update_undo_to_history(), trx_undo_update_cleanup():
Remove 3 parameters. Always operate on the persistent update_undo.

trx_serialise(): Renamed from trx_serialisation_number_get().

trx_write_serialisation_history(): Simplify the code flow.
If there are no persistent changes, do not update MONITOR_TRX_COMMIT_UNDO.

trx_commit_in_memory(): Simplify the logic, and add assertions.

trx_undo_page_report_modify(): Keep a direct reference to the
persistent update_undo log.

trx_undo_report_row_operation(): Simplify some code.
Always assign TRX_UNDO_INSERT for temporary undo logs.

trx_prepare_low(): Keep only one parameter. Prepare all 3 undo logs.

trx_roll_try_truncate(): Remove the parameter undo_ptr.
Try to truncate all 3 undo logs of the transaction.

trx_roll_pop_top_rec_of_trx_low(): Remove.

trx_roll_pop_top_rec_of_trx(): Remove the redundant parameter
trx->roll_limit. Clear roll_limit when exhausting the undo logs.
Consider all 3 undo logs at once, prioritizing the persistent
undo logs.

row_undo(): Minor cleanup. Let trx_roll_pop_top_rec_of_trx()
reset the trx->roll_limit.

In the 10.1 InnoDB Plugin, a call os_event_free(buf_flush_event) was
misplaced. The event could be triggered by rollback of resurrected
transactions while shutdown was in progress. This bug was caught
by cmake -DWITH_ASAN testing. This call was only present in the
10.1 InnoDB Plugin, not in other versions, or in XtraDB.

That said, the bug affects all InnoDB versions. Shutdown assumes the
cessation of any page-dirtying activity, including the activity of
the background rollback thread. InnoDB only waited for the background
rollback to finish as part of a slow shutdown (innodb_fast_shutdown=0).
The default is a clean shutdown (innodb_fast_shutdown=1). In a scenario
where InnoDB is killed, restarted, and shut down soon enough, the data
files could become corrupted.

logs_empty_and_mark_files_at_shutdown(): Wait for the
rollback to finish, except if innodb_fast_shutdown=2
(crash-like shutdown) was requested.

trx_rollback_or_clean_recovered(): Before choosing the next
recovered transaction to roll back, terminate early if non-slow
shutdown was initiated. Roll back everything on slow shutdown
(innodb_fast_shutdown=0).

srv_innodb_monitor_mutex: Declare as static, because the mutex
is only used within one module.

In 10.2, os_event_destroy() sets the event to a NULL pointer,
while os_event_free() in earlier versions did not do that.

os_sync_free(), which hid resource leaks, was removed in MySQL 5.7.

Take into acount result of open table operation in mysql_admin_table.

Compatibility links ended up looking like this:
libmysqlclient.so.18 -> /tmp/buildd/mariadb-10.2-10.2.0/debian/tmp/usr/lib/i386-linux-gnu/libmariadb.so.3

This change fixes ln syntax to create links with correct target paths.

Reason : after running sysbench tests (rw,update_no_index), in all cases
the throughout was considerably (approx 15%) better with the patch removed.

Reverted commit info
commit 8dc03bee3ade2edcc53a3a257346f4a0a9f0b44c
Author: Yasufumi Kinoshita <yasufumi.kinoshita@oracle.com>
Date:   Wed Nov 20 17:02:24 2013 +0900

Bug #17824101 : WL#7050 CAUSES RW PERFORMANCE REGRESSION AT SOME WINDOWS ENVIRONMENT

InnoDB undo logs currently always use the innodb_page_size,
whether they are stored in the system tablespace, in a
dedicated undo tablespace, or in the temporary tablespace.
Remove redundant page_size parameters.

TrxUndoRsegsIterator::set_next(): return bool instead of page_size.

trx_rseg_mem_create(): Remove the parameter rseg_array.
Update trx_sys->rseg_array directly.

TrxUndoRsegsIterator::m_purge_sys: Remove. There is only one purge_sys.

purge_sys_t: Renamed from trx_purge_t. Define a constructor and
destructor. Allocate rseg_iter, purge_queue inline.

purge_sys->trx: Remove. Use purge_sys->sess->trx instead.

purge_sys->view_active: Remove. Access to purge_sys->view is always
protected by purge_sys->latch.

trx_purge_sys_create(): Replaced by purge_sys_t::purge_sys_t().

trx_purge_sys_close(): Replaced by purge_sys_t::~purge_sys_t().

Also in log_checkpoint(), where fil_flush_file_spaces() was
not done on Windows, it is not done.

 Remove srv_win_file_flush_method

- Rename srv_unix_file_flush_method to srv_file_flush_method, and
  rename constants to remove UNIX from them, i.e SRV_UNIX_FSYNC=>SRV_FSYNC

- Add SRV_ALL_O_DIRECT_FSYNC corresponding to current Windows default
(no buffering for either log or data, flush on both log and data)

- change os_file_open on Windows to behave identically to Unix wrt
O_DIRECT and O_DSYNC settings. map O_DIRECT to FILE_FLAG_NO_BUFFERING and
O_DSYNC to FILE_FLAG_WRITE_THROUGH

- remove various #ifdef _WIN32

MDEV-11363: Assertion `!derived->first_sel ect()->first_inner_unit() || derived->first_select()->first_inner_unit()->first_select()-> exclude_from_table_unique_test' failed in TABLE_LIST::set_check_materialized()

Do not try to materialize derived table which already merged (irreversebly).

InnoDB needs to collect transactions from the persistent data files
in trx_rseg_array_init() before trx_lists_init_at_db_start() is
executed. But there is no need to create purge_sys->purge_queue
separately from purge_sys.

trx_sys_init_at_db_start(): Change the return type to void.
Remove the direct call to trx_rseg_array_init(). It will be called
by trx_lists_init_at_db_start(), which we are calling.
Initialize the purge system read view.

trx_lists_init_at_db_start(): Call trx_purge_sys_create(), which will
invoke trx_rseg_array_init() to read the undo log segments.

trx_purge_sys_create(): Remove the parameters. Do not initialize
the purge system read view, because trx_sys->rw_trx_list has not
been recovered yet. The purge_sys->view will be initialized at
the end of trx_sys_init_at_db_start().

trx_rseg_array_init(): Remove the parameter. Use purge_sys->purge_queue
directly.

innobase_start_or_create_for_mysql(): Remove the local variable
purge_queue. Do not call trx_purge_sys_create(), because it will be
called by trx_sys_init_at_db_start().

In MySQL 5.7, there is some redundant code for supposedly handling
an upgrade from an earlier version of InnoDB.

An upgrade of InnoDB between major versions should include a
slow shutdown (innodb_fast_shutdown=0) of the previous version.

A comment in trx_lists_init_at_db_start() confused clean shutdown
and slow shutdown. A clean shutdown does not necessarily guarantee
that there are no active transactions. A slow shutdown guarantees
that.

Because there was no code to handle rollback of recovered transactions
that happened to use the rollback segment slots that MySQL 5.7.2
repurposed for temporary undo logs, the upgrade is not working in all
cases, and we may as well remove the code to handle purging.

trx_sys_t::pending_purge_rseg_array: Remove.

trx_undo_get_undo_rec_low(): Define as static. Remove the parameter
is_redo_rseg.

trx_undo_get_undo_rec(), trx_rseg_get_on_id(): Remove the parameter
is_redo_rseg.

trx_rseg_mem_free(): Remove the second parameter.

trx_sys_get_nth_rseg(): Replace with trx_rseg_get_on_id().

trx_rseg_schedule_pending_purge(): Remove.

Prepare os ANALYZE now respond as EXPLAIN.

This fixes some GCC 6.3.0 warnings and makes the code a little
more debugging-friendly.

After starting MariaDB 10.2 with an invalid value of
--innodb-flush-method= (the empty string), shutdown would
attempt to dereference some NULL pointers. This was probably broken
in commit 81b7fe9d which implemented
shutdown after aborted startup.

logs_empty_and_mark_files_at_shutdown(): Allow shutdown even if
lock_sys, log_sys, or fil_system is NULL.

os_aio_free(): Tolerate os_aio_segment_wait_events==NULL.

innobase_start_or_create_for_mysql(): Do not invoke
srv_init_abort() before initializing all mutexes for the temporary files.

innodb_shutdown(): Tolerate buf_pool_ptr==NULL.

Provide more useful progress reporting of crash recovery.

recv_sys_t::progress_time: The time of the last report.

recv_sys_t::report(ib_time_t): Determine whether progress should
be reported.

recv_scan_print_counter: Remove.

log_group_read_log_seg(): After after each I/O request, invoke
recv_sys_t::report() and report progress if needed.

recv_apply_hashed_log_recs(): Change the return type back to void
(DB_SUCCESS was always returned), and rename the parameter to last_batch.
At the start of each batch, if there are pages to be recovered,
issue a message.

MDEV-10704: Assertion `field->field->table == table_arg' failed in fill_record(THD*, TABLE*, List<Item>&, List<Item>&, bool, bool)

the bug test suite

Introduced 2f63e2e2

Compiler error was:

sql/log_event.cc: In function ‘size_t log_event_print_value(IO_CACHE*, const uchar*, uint, uint, char*, size_t)’:
sql/log_event.cc:2897:7: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
       if (!ptr)
       ^~
sql/log_event.cc:2900:9: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’
         int32 i32= uint2korr(ptr);
         ^~~~~

Added in 950abd52

Error was:

sql/item_sum.cc:3478:5: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
     if ((!args[i]->fixed &&
     ^~
/sql/item_sum.cc:3482:7: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘if’
       with_subselect|= args[i]->with_subselect;
       ^~~~~~~~~~~~~~
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

The bug was caused by a wrong order of statements in With_clause::print().
As a result any view definition containing WITH clause with several
CTE specifications was put the frm file in a syntactically incorrect
form.

Also get rid of example ini files, they do not provide any value,
just confusion

The InnoDB redo log record type MLOG_COMP_REC_SEC_DELETE_MARK has
been unused for a long time, and it has never been written after
WL#8845 introduced the redo log format identifier in MySQL 5.7.9
or MariaDB Server 10.2.2. Thus, removing the record type does not
constitute any functional change.

Define my_thread_id as an unsigned type, to avoid mismatch with
ulonglong.  Change some parameters to this type.

Use size_t in a few more places.

Declare many flag constants as unsigned to avoid sign mismatch
when shifting bits or applying the unary ~ operator.

When applying the unary ~ operator to enum constants, explictly
cast the result to an unsigned type, because enum constants can
be treated as signed.

In InnoDB, change the source code line number parameters from
ulint to unsigned type. Also, make some InnoDB functions return
a narrower type (unsigned or uint32_t instead of ulint;
bool instead of ibool).

To facilitate multiple build types in Travis, the environment variable
MYSQL_{BUILD_CC,BUILD_CXX} will be passed to cmake if used. This will
fallback to $CC/$CXX otherwise.

Added MYSQL_COMPILER_LAUNCHER (usually ccache) which isn't supported
until cmake-3.4, which isn't in travis (trusty), but hopefully a later
version can use it or in CI systems other than travis.
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

Merge branch '10.2-MDEV-120555-test_binlog_stm_ctype_ucs' of https://github.com/grooverdan/mariadb-server into grooverdan-10.2-MDEV-120555-test_binlog_stm_ctype_ucs

The function thd_supports_xa() was removed in MySQL 5.7 in WL#8843.

Remove the unused variable innodb_calling_exit which was added
in MySQL 5.7 in an attempt to avoid failures in other threads when
an I/O thread calls exit().

Since MDEV-9282, InnoDB or XtraDB MariaDB Server is not calling
exit() at all, and the variable innodb_calling_exit was never set.

Because the default build configuration of the server will remain
at -DWITH_INNODB_AHI=ON, we want to test the instrumentation.

We make and revert the test adjustments in separate commits on purpose,
so that this commit can be easily reverted later if the default
build configuration is changed to -DWITH_INNODB_AHI=OFF.

The InnoDB adaptive hash index is sometimes degrading the performance of
InnoDB, and it is sometimes disabled to get more consistent performance.
We should have a compile-time option to disable the adaptive hash index.

Let us introduce two options:

OPTION(WITH_INNODB_AHI "Include innodb_adaptive_hash_index" ON)
OPTION(WITH_INNODB_ROOT_GUESS "Cache index root block descriptors" ON)

where WITH_INNODB_AHI always implies WITH_INNODB_ROOT_GUESS.

As part of this change, the misleadingly named function
trx_search_latch_release_if_reserved(trx) will be replaced with the macro
trx_assert_no_search_latch(trx) that will be empty unless
BTR_CUR_HASH_ADAPT is defined (cmake -DWITH_INNODB_AHI=ON).

We will also remove the unused column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_TIMEOUT.
In MariaDB Server 10.1, it used to reflect the value of
trx_t::search_latch_timeout which could be adjusted during
row_search_for_mysql(). In 10.2, there is no such field.

Other than the removal of the unused column TRX_ADAPTIVE_HASH_TIMEOUT,
this is an almost non-functional change to the server when using the
default build options.

Some tests are adjusted so that they will work with both
-DWITH_INNODB_AHI=ON and -DWITH_INNODB_AHI=OFF. The test
innodb.innodb_monitor has been renamed to innodb.monitor
in order to track MySQL 5.7, and the duplicate tests
sys_vars.innodb_monitor_* are removed.