online alter: extract the source to a separate file

Move all the functions dedicated to online alter to a newly created
online_alter.cc.

With that, make many functions static and simplify the static functions
naming.

Also, rename binlog_log_row_online_alter -> online_alter_log_row.

Author: FooBarrior

sql/CMakeLists.txt

@@ -218,15 +218,17 @@ MYSQL_ADD_PLUGIN(partition ha_partition.cc STORAGE_ENGINE DEFAULT STATIC_ONLY
 RECOMPILE_FOR_EMBEDDED)
 MYSQL_ADD_PLUGIN(sql_sequence ha_sequence.cc STORAGE_ENGINE MANDATORY STATIC_ONLY
 RECOMPILE_FOR_EMBEDDED)
-MYSQL_ADD_PLUGIN(online_alter_log log.cc STORAGE_ENGINE MANDATORY STATIC_ONLY
-NOT_EMBEDDED)
+MYSQL_ADD_PLUGIN(online_alter_log online_alter.cc STORAGE_ENGINE MANDATORY
+STATIC_ONLY NOT_EMBEDDED)
+
 
 ADD_LIBRARY(sql STATIC ${SQL_SOURCE})
 MAYBE_DISABLE_IPO(sql)
 DTRACE_INSTRUMENT(sql)
 TARGET_LINK_LIBRARIES(sql
   mysys mysys_ssl dbug strings vio pcre2-8
   tpool
+  online_alter_log
   ${LIBWRAP} ${LIBCRYPT} ${CMAKE_DL_LIBS} ${CMAKE_THREAD_LIBS_INIT}
   ${SSL_LIBRARIES}
   ${LIBSYSTEMD})

sql/handler.cc

@@ -7304,8 +7304,8 @@ int handler::binlog_log_row(const uchar *before_record,
 
 #ifdef HAVE_REPLICATION
   if (unlikely(!error && table->s->online_alter_binlog && is_root_handler()))
-    error= binlog_log_row_online_alter(table, before_record, after_record,
-                                       log_func);
+    error= online_alter_log_row(table, before_record, after_record,
+                                log_func);
 #endif // HAVE_REPLICATION
 
   DBUG_RETURN(error);

sql/handler.h

@@ -1098,8 +1098,6 @@ extern MYSQL_PLUGIN_IMPORT st_plugin_int *hton2plugin[MAX_HA];
 
 struct handlerton;
 
-extern handlerton *online_alter_hton;
-
 #define view_pseudo_hton ((handlerton *)1)
 
 /*
@@ -1972,9 +1970,7 @@ class Ha_trx_info
   bool is_trx_read_write() const
   {
     DBUG_ASSERT(is_started());
-    bool result= m_flags & (int) TRX_READ_WRITE;
-    DBUG_ASSERT(!result || m_ht != online_alter_hton);
-    return result;
+    return m_flags & (int) TRX_READ_WRITE;
   }
   bool is_started() const { return m_ht != NULL; }
   /** Mark this transaction read-write if the argument is read-write. */