Problem:
========
When using mariadb-binlog with --raw and --stop-never, events from
the master's currently active log file should be written to their
respective log file specified by --result-file, and shown on-disk.
There is a bug where mariadb-binlog does not flush the result file
to disk when new events are received
Solution:
========
Add a function call to flush mariadb-binlog’s result file after
receiving an event in --raw mode.
Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>
(This commit is exclusively for 10.2 branch. Do not merge it to 10.3)
In case of a pattern of non-STMT_END-marked Rows-log-event (A) followed by
a STMT_END marked one (B) mysqlbinlog mixes up the base64 encoded rows events
with their pseudo sql representation produced by the verbose option:
BINLOG '
base64 encoded data for A
### verbose section for A
base64 encoded data for B
### verbose section for B
'/*!*/;
In effect the produced BINLOG '...' query is not valid and is rejected with the error.
Examples of this way malformed BINLOG could have been found in binlog_row_annotate.result
that gets corrected with the patch.
The issue is fixed with introduction an auxiliary IO_CACHE to hold on the verbose
comments until the terminal STMT_END event is found. The new cache is emptied
out after two pre-existing ones are done at that time.
The correctly produced output now for the above case is as the following:
BINLOG '
base64 encoded data for A
base64 encoded data for B
'/*!*/;
### verbose section for A
### verbose section for B
Thanks to Alexey Midenkov for the problem recognition and attempt to tackle,
and to Venkatesh Duggirala who produced a patch for the upstream whose
idea is exploited here, as well as to MDEV-23077 reporter LukeXwang who
also contributed a piece of a patch aiming at this issue.
Problem:
========
The mysqlbinlog tool is leaking memory, causing failures in various tests when
compiling and testing with AddressSanitizer or LeakSanitizer like this:
cmake -DCMAKE_BUILD_TYPE=Debug -DWITH_ASAN:BOOL=ON /path/to/source
make -j$(nproc)
cd mysql-test
ASAN_OPTIONS=abort_on_error=1 ./mtr --parallel=auto
Analysis:
=========
Two types of leaks were observed during above execution.
1) Leak in Log_event::read_log_event(char const*, unsigned int, char const**,
Format_description_log_event const*, char)
File: sql/log_event.cc:2150
For all row based replication events the memory which is allocated during
read_log_event is not freed after the event is processed. The event specific
memory has to be retained only when flashback option is enabled with
mysqlbinlog tool. In this case all the events are retained till the end
statement is received and they are processed in reverse order and they are
destroyed. But in the existing code all events are retained irrespective of
flashback mode. Hence the memory leaks are observed.
2) read_remote_annotate_event(unsigned char*, unsigned long, char const**)
File: client/mysqlbinlog.cc:194
In general the Annotate event is not printed immediately because all
subsequent rbr-events can be filtered away. Instead it will be printed
together with the first not filtered away Table map or the last rbr will be
processed. While reading remote annotate events memory is allocated for event
buffer and event's temp_buf is made to point to the allocated buffer as shown
below. The TRUE flag is used for doing proper cleanup using free_temp_buf().
i.e at the time of deletion of annotate event its destructor takes care of
clearing the temp_buf.
/*
Ensure the event->temp_buf is pointing to the allocated buffer.
(TRUE = free temp_buf on the event deletion)
*/
event->register_temp_buf((char*)event_buf, TRUE);
But existing code does the following when it receives a remote annotate_event.
if (remote_opt)
ev->temp_buf= 0;
That is code immediately sets temp_buf=0, because of which free_temp_buf()
call will return empty handed as it has lost the reference to the allocated
temporary buffer. This results in memory leak
Fix:
====
1) If not in flashback mode, destroy the memory for events once they are
processed.
2) Remove the ev->temp_buf=0 code for remote option. Let the proper cleanup to
be done as part of free_temp_buf().
Problem:
========
The mysqlbinlog tool is leaking memory, causing failures in various tests when
compiling and testing with AddressSanitizer or LeakSanitizer like this:
cmake -DCMAKE_BUILD_TYPE=Debug -DWITH_ASAN:BOOL=ON /path/to/source
make -j$(nproc)
cd mysql-test
ASAN_OPTIONS=abort_on_error=1 ./mtr --parallel=auto rpl.rpl_row_mysqlbinlog
CURRENT_TEST: rpl.rpl_row_mysqlbinlog
Direct leak of 112 byte(s) in 1 object(s) allocated from:
#0 0x4eff87 in __interceptor_malloc (/dev/shm/5.5/client/mysqlbinlog+0x4eff87)
#1 0x60eaab in my_malloc /mariadb/5.5/mysys/my_malloc.c:41:10
#2 0x5300dd in Log_event::read_log_event(char const*, unsigned int, char const**,
Format_description_log_event const*, char) /mariadb/5.5/sql/log_event.cc:1568:
#3 0x564a9c in dump_remote_log_entries(st_print_event_info*, char const*)
/mariadb/5.5/client/mysqlbinlog.cc:1978:17
Analysis:
========
'mysqlbinlog' tool is being used to read binary log events from a remote server.
While reading binary log, if a fake rotate event is found following actions are
taken.
If 'to-last-log' option is specified, then fake rotate event is processed.
In the absence of 'to-last-log' skip the fake rotate event.
In this skipped case the fake rotate event object is not getting cleaned up
resulting in memory leak.
Fix:
===
Cleanup the fake rotate event.
This issues is already fixed in MariaDB 10.0.23 and higher versions as part of
commit c3018b0ff4
There were two newly enabled warnings:
1. cast for a function pointers. Affected sql_analyse.h, mi_write.c
and ma_write.cc, mf_iocache-t.cc, mysqlbinlog.cc, encryption.cc, etc
2. memcpy/memset of nontrivial structures. Fixed as:
* the warning disabled for InnoDB
* TABLE, TABLE_SHARE, and TABLE_LIST got a new method reset() which
does the bzero(), which is safe for these classes, but any other
bzero() will still cause a warning
* Table_scope_and_contents_source_st uses `TABLE_LIST *` (trivial)
instead of `SQL_I_List<TABLE_LIST>` (not trivial) so it's safe to
bzero now.
* added casts in debug_sync.cc and sql_select.cc (for JOIN)
* move assignment method for MDL_request instead of memcpy()
* PARTIAL_INDEX_INTERSECT_INFO::init() instead of bzero()
* remove constructor from READ_RECORD() to make it trivial
* replace some memcpy() with c++ copy assignments
The problem was originally stated in
http://bugs.mysql.com/bug.php?id=82212
The size of an base64-encoded Rows_log_event exceeds its
vanilla byte representation in 4/3 times.
When a binlogged event size is about 1GB mysqlbinlog generates
a BINLOG query that can't be send out due to its size.
It is fixed with fragmenting the BINLOG argument C-string into
(approximate) halves when the base64 encoded event is over 1GB size.
The mysqlbinlog in such case puts out
SET @binlog_fragment_0='base64-encoded-fragment_0';
SET @binlog_fragment_1='base64-encoded-fragment_1';
BINLOG @binlog_fragment_0, @binlog_fragment_1;
to represent a big BINLOG.
For prompt memory release BINLOG handler is made to reset the BINLOG argument
user variables in the middle of processing, as if @binlog_fragment_{0,1} = NULL
is assigned.
Notice the 2 fragments are enough, though the client and server still may
need to tweak their @@max_allowed_packet to satisfy to the fragment
size (which they would have to do anyway with greater number of
fragments, should that be desired).
On the lower level the following changes are made:
Log_event::print_base64()
remains to call encoder and store the encoded data into a cache but
now *without* doing any formatting. The latter is left for time
when the cache is copied to an output file (e.g mysqlbinlog output).
No formatting behavior is also reflected by the change in the meaning
of the last argument which specifies whether to cache the encoded data.
Rows_log_event::print_helper()
is made to invoke a specialized fragmented cache-to-file copying function
which is
copy_cache_to_file_wrapped()
that takes care of fragmenting also optionally wraps encoded
strings (fragments) into SQL stanzas.
my_b_copy_to_file()
is refactored to into my_b_copy_all_to_file(). The former function
is generalized
to accepts more a limit argument to constraint the copying and does
not reinitialize anymore the cache into reading mode.
The limit does not do any effect on the fully read cache.
The merge only covered 10.1 up to
commit 4d248974e0.
Actually merge the changes up to
commit 0a534348c7.
Also, remove the unused InnoDB field trx_t::abort_type.
find_type_or_exit() client helper did exit(1) on error, exit(1) moved to
clients.
mysql_read_default_options() did exit(1) on error, error is passed through and
handled now.
my_str_malloc_default() did exit(1) on error, replaced my_str_ allocator
functions with normal my_malloc()/my_realloc()/my_free().
sql_connect.cc did many exit(1) on hash initialisation failure. Removed error
check since my_hash_init() never fails.
my_malloc() did exit(1) on error. Replaced with abort().
my_load_defaults() did exit(1) on error, replaced with return 2.
my_load_defaults() still does exit(0) when invoked with --print-defaults.
Problem
-------
For one-statement contains multiple row events, Flashback didn't reverse the
sequence of row events inside one-statement.
Solution
--------
Using a new array 'events_in_stmt' to store the row events of one-statement,
when parsed the last one event, then print from the last one to the first one.
In the same time, fixed another bug, without -vv will not insert the table_map
into print_event_info->m_table_map, then change_to_flashback_event() will not
execute because of Table_map_log_event is empty.
==== Description ====
Flashback can rollback the instances/databases/tables to an old snapshot.
It's implement on Server-Level by full image format binary logs (--binlog-row-image=FULL), so it supports all engines.
Currently, it’s a feature inside mysqlbinlog tool (with --flashback arguments).
Because the flashback binlog events will store in the memory, you should check if there is enough memory in your machine.
==== New Arguments to mysqlbinlog ====
--flashback (-B)
It will let mysqlbinlog to work on FLASHBACK mode.
==== New Arguments to mysqld ====
--flashback
Setup the server to use flashback. This enables binary log in row mode
and will enable extra logging for DDL's needed by flashback feature
==== Example ====
I have a table "t" in database "test", we can compare the output with "--flashback" and without.
#client/mysqlbinlog /data/mysqldata_10.0/binlog/mysql-bin.000001 -vv -d test -T t --start-datetime="2013-03-27 14:54:00" > /tmp/1.sql
#client/mysqlbinlog /data/mysqldata_10.0/binlog/mysql-bin.000001 -vv -d test -T t --start-datetime="2013-03-27 14:54:00" -B > /tmp/2.sql
Then, importing the output flashback file (/tmp/2.log), it can flashback your database/table to the special time (--start-datetime).
And if you know the exact postion, "--start-postion" is also works, mysqlbinlog will output the flashback logs that can flashback to "--start-postion" position.
==== Implement ====
1. As we know, if binlog_format is ROW (binlog-row-image=FULL in 10.1 and later), all columns value are store in the row event, so we can get the data before mis-operation.
2. Just do following things:
2.1 Change Event Type, INSERT->DELETE, DELETE->INSERT.
For example:
INSERT INTO t VALUES (...) ---> DELETE FROM t WHERE ...
DELETE FROM t ... ---> INSERT INTO t VALUES (...)
2.2 For Update_Event, swapping the SET part and WHERE part.
For example:
UPDATE t SET cols1 = vals1 WHERE cols2 = vals2
--->
UPDATE t SET cols2 = vals2 WHERE cols1 = vals1
2.3 For Multi-Rows Event, reverse the rows sequence, from the last row to the first row.
For example:
DELETE FROM t WHERE id=1; DELETE FROM t WHERE id=2; ...; DELETE FROM t WHERE id=n;
--->
DELETE FROM t WHERE id=n; ...; DELETE FROM t WHERE id=2; DELETE FROM t WHERE id=1;
2.4 Output those events from the last one to the first one which mis-operation happened.
For example:
Add some event types for the compressed event, there are:
QUERY_COMPRESSED_EVENT,
WRITE_ROWS_COMPRESSED_EVENT_V1,
UPDATE_ROWS_COMPRESSED_EVENT_V1,
DELETE_POWS_COMPRESSED_EVENT_V1,
WRITE_ROWS_COMPRESSED_EVENT,
UPDATE_ROWS_COMPRESSED_EVENT,
DELETE_POWS_COMPRESSED_EVENT.
These events inheritance the uncompressed editor events. One of their constructor functions and write
function have been overridden for uncompressing and compressing. Anything but this is totally the same.
On slave, The IO thread will uncompress and convert them When it receiving the events from the master.
So the SQL and worker threads can be stay unchanged.
Now we use zlib as compress algorithm. It maybe support other algorithm in the future.
