fix(tianmu): add file extension of tianmu into hton to fix drop datab…

…ase error stoneatom#662

[summary]
When drop database, mysqld cannot find tianmu file extension and drop failed.
1. change all `rcbase_hton` to `tianmu_hton`, just like innodb, myisam,
csv ... does.
2. rm function bas_ext(), it used in 5.7, but removed in 8.0 and changed
to a variable instead.
3. Add tianmu file extension to tianmu_hton->file_extensions.

sql/handler.cc

@@ -854,8 +854,8 @@ int ha_initialize_handlerton(st_plugin_int *plugin) {
     case DB_TYPE_INNODB:
       innodb_hton = hton;
       break;
-    case DB_TYPE_TIANMU:   // stonedb8
-      tianmu_hton = hton;  // stonedb8
+    case DB_TYPE_TIANMU:
+      tianmu_hton = hton;
       break;
     default:
       break;

sql/mysqld.cc

@@ -1231,7 +1231,7 @@ handlerton *heap_hton;
 handlerton *temptable_hton;
 handlerton *myisam_hton;
 handlerton *innodb_hton;
-handlerton *tianmu_hton;  // stonedb8
+handlerton *tianmu_hton;
 
 char *opt_disabled_storage_engines;
 uint opt_server_id_bits = 0;

sql/mysqld.h

@@ -379,7 +379,7 @@ extern handlerton *myisam_hton;
 extern handlerton *heap_hton;
 extern handlerton *temptable_hton;
 extern handlerton *innodb_hton;
-extern handlerton *tianmu_hton; // stonedb8
+extern handlerton *tianmu_hton;
 
 extern uint opt_server_id_bits;
 extern ulong opt_server_id_mask;

storage/tianmu/core/engine.cpp

@@ -822,7 +822,7 @@ void Engine::UpdateAndStoreColumnComment(TABLE *table, int field_id, Field *sour
                                          CHARSET_INFO *cs) {
   // stonedb8 start convert orig_table to table, MySQL 8.0 don't have orig_table, idea from
   // ha_innodb.cc:create_table_def
-  if (source_field->table->s->db_type() == rcbase_hton) {  // do not use table (cont. default values)
+  if (source_field->table->s->db_type() == tianmu_hton) {  // do not use table (cont. default values)
     char buf_size[256] = {0};
     char buf_ratio[256] = {0};
     uint buf_size_count = 0;
@@ -1609,7 +1609,7 @@ Query_Route_To Engine::RouteTo(THD *thd, TABLE_LIST *table_list, Query_block *se
 }
 
 bool Engine::IsTianmuTable(TABLE *table) {
-  return table && table->s->db_type() == rcbase_hton;  // table->db_type is always NULL
+  return table && table->s->db_type() == tianmu_hton;  // table->db_type is always NULL
 }
 
 const char *Engine::GetFilename(Query_block *selects_list, int &is_dumpfile) {  // stonedb8

storage/tianmu/core/engine.h

@@ -43,7 +43,6 @@
 #include "util/mapped_circular_buffer.h"
 #include "util/thread_pool.h"
 
-extern handlerton *rcbase_hton;
 class Field;
 
 namespace Tianmu {

storage/tianmu/handler/ha_rcengine.cpp

@@ -26,7 +26,6 @@
 #include "mm/initializer.h"
 #include "system/file_out.h"
 
-handlerton *rcbase_hton;
 
 struct SYS_VAR {
   MYSQL_PLUGIN_VAR_HEADER;
@@ -184,23 +183,32 @@ static int init_variables() {
   return 0;
 }
 
+// Gives the file extension of an Tianmu single-table tablespace.
+static const char *ha_tianmu_exts[] = {common::TIANMU_EXT, NullS};
+
 int rcbase_init_func(void *p) {
   DBUG_ENTER(__PRETTY_FUNCTION__);
-  rcbase_hton = (handlerton *)p;
+
+  // move hton here, just like other storate like innodb, myisam, csv... does.
+  // handlerton is a singleton structure - one instance per storage engine.
+  // defined in sql/handler.h
+  handlerton *tianmu_hton;
+  tianmu_hton = (handlerton *)p;
 
   if (init_variables()) {
     DBUG_RETURN(1);
   }
 
-  rcbase_hton->state = SHOW_OPTION_YES;
-  rcbase_hton->db_type = DB_TYPE_TIANMU;
-  rcbase_hton->create = rcbase_create_handler;
-  rcbase_hton->flags = HTON_NO_FLAGS;
-  rcbase_hton->panic = rcbase_panic_func;
-  rcbase_hton->close_connection = rcbase_close_connection;
-  rcbase_hton->commit = rcbase_commit;
-  rcbase_hton->rollback = rcbase_rollback;
-  rcbase_hton->show_status = rcbase_show_status;
+  tianmu_hton->state = SHOW_OPTION_YES;
+  tianmu_hton->db_type = DB_TYPE_TIANMU;
+  tianmu_hton->create = rcbase_create_handler;
+  tianmu_hton->flags = HTON_NO_FLAGS;
+  tianmu_hton->panic = rcbase_panic_func;
+  tianmu_hton->close_connection = rcbase_close_connection;
+  tianmu_hton->commit = rcbase_commit;
+  tianmu_hton->rollback = rcbase_rollback;
+  tianmu_hton->show_status = rcbase_show_status;
+  tianmu_hton->file_extensions = ha_tianmu_exts;
 
   // When mysqld runs as bootstrap mode, we do not need to initialize
   // memmanager.
@@ -222,7 +230,7 @@ int rcbase_init_func(void *p) {
     ha_kvstore_ = new index::KVStore();
     ha_kvstore_->Init();
     ha_rcengine_ = new core::Engine();
-    ret = ha_rcengine_->Init(rcbase_hton->slot);  // stonedb8
+    ret = ha_rcengine_->Init(tianmu_hton->slot);
     {
       TIANMU_LOG(LogCtl_Level::INFO,
                  "\n"

storage/tianmu/handler/ha_tianmu.cpp

@@ -159,14 +159,6 @@ TianmuHandler::TianmuHandler(handlerton *hton, TABLE_SHARE *table_arg, bool part
   ref_length = sizeof(uint64_t);
 }
 
-// stonedb8
-/*
-const char **TianmuHandler::bas_ext() const {
-  static const char *ha_rcbase_exts[] = {common::TIANMU_EXT, 0};
-  return ha_rcbase_exts;
-}
-*/
-
 namespace {
 std::vector<bool> GetAttrsUseIndicator(TABLE *table) {
   int col_id = 0;
@@ -272,9 +264,9 @@ int TianmuHandler::external_lock(THD *thd, int lock_type) {
         tx->AddTableRD(share);
       } else {
         tx->AddTableWR(share);
-        trans_register_ha(thd, false, rcbase_hton, NULL);
+        trans_register_ha(thd, false, tianmu_hton, NULL);
         if (thd_test_options(thd, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN))
-          trans_register_ha(thd, true, rcbase_hton, NULL);
+          trans_register_ha(thd, true, tianmu_hton, NULL);
       }
     }
     ret = 0;
@@ -1106,9 +1098,9 @@ int TianmuHandler::extra([[maybe_unused]] enum ha_extra_function operation) {
 int TianmuHandler::start_stmt(THD *thd, thr_lock_type lock_type) {
   try {
     if (lock_type == TL_WRITE_CONCURRENT_INSERT || lock_type == TL_WRITE_DEFAULT || lock_type == TL_WRITE) {
-      trans_register_ha(thd, false, rcbase_hton, NULL);
+      trans_register_ha(thd, false, tianmu_hton, NULL);
       if (thd_test_options(thd, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)) {
-        trans_register_ha(thd, true, rcbase_hton, NULL);
+        trans_register_ha(thd, true, tianmu_hton, NULL);
       }
       current_txn_ = ha_rcengine_->GetTx(thd);
       current_txn_->AddTableWRIfNeeded(share);
@@ -1146,7 +1138,7 @@ bool TianmuHandler::register_query_cache_table(THD *thd, char *table_key, size_t
 
  If you do not implement this, the default delete_table() is called from
  handler.cc and it will delete all files with the file extentions returned
- by bas_ext().
+ by bas_ext(). // stonedb8 TODO bas_ext() has been deleted in mysql8.0
 
  Called from handler.cc by delete_table and  ha_create_table(). Only used
  during create if the table_flag HA_DROP_BEFORE_CREATE was specified for
@@ -1687,4 +1679,4 @@ void TianmuHandler::key_convert(const uchar *key, uint key_len, std::vector<uint
 }
 
 }  // namespace DBHandler
-}  // namespace Tianmu
+}  // namespace Tianmu

storage/tianmu/handler/ha_tianmu.h

@@ -32,7 +32,7 @@ class TianmuHandler final : public handler {
   /* The name that will be used for display purposes */
   const char *table_type() const override { return "TIANMU"; }
   /*
-   Get the row type from the storage engine.  If this method returns
+   Get the row type from the storage engine. If this method returns
    ROW_TYPE_NOT_USED, the information in HA_CREATE_INFO should be used.
    */
   // enum row_type get_row_type() const override { return ROW_TYPE_COMPRESSED; }   // stonedb8  get_row_type() is