Merge pull request #586 from yhmo/0.6.0

#561 Milvus server should report exception/error message or terminate

CHANGELOG.md

@@ -33,6 +33,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - \#533 - NSG build failed with MetricType Inner Product
 - \#543 - client raise exception in shards when search results is empty
 - \#545 - Avoid dead circle of build index thread when error occurs
+- \#561 - Milvus server should report exception/error message or terminate on mysql metadata backend error
 
 ## Feature
 - \#12 - Pure CPU version for Milvus

core/src/db/meta/MySQLMetaImpl.cpp

@@ -290,45 +290,50 @@ MySQLMetaImpl::Initialize() {
     // step 4: validate to avoid open old version schema
     ValidateMetaSchema();
 
-    // step 5: create meta tables
-    try {
+    // step 5: clean shadow files
     if (mode_ != DBOptions::MODE::CLUSTER_READONLY) {
         CleanUpShadowFiles();
     }
 
-        {
+    // step 6: try connect mysql server
     mysqlpp::ScopedConnection connectionPtr(*mysql_connection_pool_, safe_grab_);
 
     if (connectionPtr == nullptr) {
-                return Status(DB_ERROR, "Failed to connect to meta server(mysql)");
+        std::string msg = "Failed to connect MySQL meta server: " + uri;
+        ENGINE_LOG_ERROR << msg;
+        throw Exception(DB_INVALID_META_URI, msg);
     }
 
     if (!connectionPtr->thread_aware()) {
-                ENGINE_LOG_ERROR << "MySQL++ wasn't built with thread awareness! Can't run without it.";
-                return Status(DB_ERROR, "MySQL++ wasn't built with thread awareness! Can't run without it.");
+        std::string msg =
+            "Failed to initialize MySQL meta backend: MySQL client component wasn't built with thread awareness";
+        ENGINE_LOG_ERROR << msg;
+        throw Exception(DB_INVALID_META_URI, msg);
     }
+
+    // step 7: create meta table Tables
     mysqlpp::Query InitializeQuery = connectionPtr->query();
 
-            InitializeQuery << "CREATE TABLE IF NOT EXISTS " << TABLES_SCHEMA.name() << " ("
-                            << TABLES_SCHEMA.ToString() + ");";
+    InitializeQuery << "CREATE TABLE IF NOT EXISTS " << TABLES_SCHEMA.name() << " (" << TABLES_SCHEMA.ToString() + ");";
 
     ENGINE_LOG_DEBUG << "MySQLMetaImpl::Initialize: " << InitializeQuery.str();
 
     if (!InitializeQuery.exec()) {
-                return HandleException("Initialization Error", InitializeQuery.error());
+        std::string msg = "Failed to create meta table 'Tables' in MySQL";
+        ENGINE_LOG_ERROR << msg;
+        throw Exception(DB_META_TRANSACTION_FAILED, msg);
     }
 
+    // step 8: create meta table TableFiles
     InitializeQuery << "CREATE TABLE IF NOT EXISTS " << TABLEFILES_SCHEMA.name() << " ("
                     << TABLEFILES_SCHEMA.ToString() + ");";
 
     ENGINE_LOG_DEBUG << "MySQLMetaImpl::Initialize: " << InitializeQuery.str();
 
     if (!InitializeQuery.exec()) {
-                return HandleException("Initialization Error", InitializeQuery.error());
-            }
-        }  // Scoped Connection
-    } catch (std::exception& e) {
-        return HandleException("GENERAL ERROR DURING INITIALIZATION", e.what());
+        std::string msg = "Failed to create meta table 'TableFiles' in MySQL";
+        ENGINE_LOG_ERROR << msg;
+        throw Exception(DB_META_TRANSACTION_FAILED, msg);
     }
 
     return Status::OK();