Refactor DatabaseMetaDataPersistFacade (#35011)

Author: terrymanu

mode/core/src/main/java/org/apache/shardingsphere/mode/metadata/persist/metadata/DatabaseMetaDataPersistFacade.java

@@ -38,6 +38,7 @@
 
 import java.sql.SQLException;
 import java.util.Collection;
+import java.util.Map;
 import java.util.Map.Entry;
 
 /**
@@ -139,7 +140,8 @@ public void unregisterStorageUnits(final String databaseName, final MetaDataCont
         GenericSchemaBuilderMaterial material = new GenericSchemaBuilderMaterial(database.getResourceMetaData().getStorageUnits(),
                 database.getRuleMetaData().getRules(), reloadMetaDataContexts.getMetaData().getProps(), new DatabaseTypeRegistry(database.getProtocolType()).getDefaultSchemaName(databaseName));
         try {
-            for (Entry<String, ShardingSphereSchema> entry : GenericSchemaBuilder.build(database.getProtocolType(), material).entrySet()) {
+            Map<String, ShardingSphereSchema> schemas = GenericSchemaBuilder.build(database.getProtocolType(), material);
+            for (Entry<String, ShardingSphereSchema> entry : schemas.entrySet()) {
                 GenericSchemaManager.getToBeDroppedTables(entry.getValue(), database.getSchema(entry.getKey())).forEach(each -> table.drop(databaseName, entry.getKey(), each.getName()));
             }
         } catch (final SQLException ex) {

mode/type/standalone/core/src/main/java/org/apache/shardingsphere/mode/manager/standalone/persist/service/StandaloneMetaDataManagerPersistService.java

@@ -189,7 +189,8 @@ public void unregisterStorageUnits(final ShardingSphereDatabase database, final
         for (String each : getToBeDroppedResourceNames(database.getName(), toBeDroppedStorageUnitNames)) {
             metaDataPersistFacade.getDataSourceUnitService().delete(database.getName(), each);
             metaDataContextManager.getStorageUnitManager().unregister(database.getName(), each);
-            metaDataPersistFacade.getDatabaseMetaDataFacade().unregisterStorageUnits(database.getName(), metaDataContextManager.getMetaDataContexts());
+            MetaDataContexts reloadMetaDataContexts = metaDataContextManager.getMetaDataContexts();
+            metaDataPersistFacade.getDatabaseMetaDataFacade().unregisterStorageUnits(database.getName(), reloadMetaDataContexts);
         }
         OrderedServicesCache.clearCache();
     }