[MDEV-10570] Merge Existing Community Patch “Flashback”MDEV-10570-plinux

==== 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 ====

--flashback (-B)
It will let mysqlbinlog to work on FLASHBACK mode.

==== 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:

1 files changed, 17 insertions, 1 deletions

diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 4b79ea43c7c..fb85154343b 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -393,7 +393,7 @@ bool opt_bin_log_compress;
 uint opt_bin_log_compress_min_len;
 my_bool opt_log, debug_assert_if_crashed_table= 0, opt_help= 0;
 my_bool debug_assert_on_not_freed_memory= 0;
-my_bool disable_log_notes;
+my_bool disable_log_notes, opt_support_flashback= 0;
 static my_bool opt_abort;
 ulonglong log_output_options;
 my_bool opt_userstat_running;
@@ -7405,6 +7405,10 @@ struct my_option my_long_options[]=
    0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   /* We must always support the next option to make scripts like mysqltest
      easier to do */
+  {"support_flashback", 0,
+   "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",
+   &opt_support_flashback, &opt_support_flashback,
+   0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"gdb", 0,
    "Set up signals usable for debugging. Deprecated, use --debug-gdb instead.",
    &opt_debugging, &opt_debugging,
@@ -9579,6 +9583,18 @@ static int get_options(int *argc_ptr, char ***argv_ptr)
   else
     global_system_variables.option_bits&= ~OPTION_BIG_SELECTS;
 
+  if (opt_support_flashback)
+  {
+    /* Force binary logging */
+    if (!opt_bin_logname)
+      opt_bin_logname= (char*) "";                  // Use default name
+    opt_bin_log= opt_bin_log_used= 1;
+
+    /* Force format to row */
+    binlog_format_used= 1;
+    global_system_variables.binlog_format= BINLOG_FORMAT_ROW;
+  }
+
   if (!opt_bootstrap && WSREP_PROVIDER_EXISTS &&
       global_system_variables.binlog_format != BINLOG_FORMAT_ROW)
   {