Add exception throw on mysql meta error (#2490)

* Add exception throw on mysql meta error
Signed-off-by: NJinHai-CN <hai.jin@zilliz.com>

* Fix lint
Signed-off-by: NJinHai-CN <hai.jin@zilliz.com>

* [skip ci] update changelog
Signed-off-by: NJinHai-CN <hai.jin@zilliz.com>

* Update
Signed-off-by: NJinHai-CN <hai.jin@zilliz.com>

* Update
Signed-off-by: Njinhai <hai.jin@zilliz.com>

* Fix Unit test
Signed-off-by: NJinHai-CN <hai.jin@zilliz.com>

CHANGELOG.md

@@ -17,6 +17,7 @@ Please mark all change in change log and use the issue from GitHub
 -   \#2429 Fix Milvus 0.9.1 performance degrade issue
 -   \#2441 Improve Knowhere code coverage
 -   \#2466 optimize k-selection implemention of faiss gpu version
+-   \#2489 Add exception throw on mysql meta error
 -   \#2495 Add creating lock file failure reason.
 
 ## Task

core/src/db/meta/MySQLConnectionPool.cpp

@@ -13,9 +13,7 @@
 #include <fiu-local.h>
 #include <thread>
 
-namespace milvus {
-namespace engine {
-namespace meta {
+namespace milvus::engine::meta {
 
 // Do a simple form of in-use connection limiting: wait to return
 // a connection until there are a reasonably low number in use
@@ -84,6 +82,4 @@ MySQLConnectionPool::max_idle_time() {
     return max_idle_time_;
 }
 
-}  // namespace meta
-}  // namespace engine
-}  // namespace milvus
+}  // namespace milvus::engine::meta

core/src/db/meta/MySQLMetaImpl.cpp

@@ -52,7 +52,7 @@ template <typename T>
 void
 DistributeBatch(const T& id_array, std::vector<std::vector<std::string>>& id_groups) {
     std::vector<std::string> temp_group;
-    constexpr uint64_t SQL_BATCH_SIZE = 50;
+    //    constexpr uint64_t SQL_BATCH_SIZE = 50; // duplicate variable
     for (auto& id : id_array) {
         temp_group.push_back(id);
         if (temp_group.size() >= SQL_BATCH_SIZE) {
@@ -246,12 +246,14 @@ MySQLMetaImpl::NextFileId(std::string& file_id) {
 
 void
 MySQLMetaImpl::ValidateMetaSchema() {
-    if (nullptr == mysql_connection_pool_) {
+    if (mysql_connection_pool_ == nullptr) {
+        throw Exception(DB_ERROR, "MySQL connection pool is invalid");
         return;
     }
 
     mysqlpp::ScopedConnection connectionPtr(*mysql_connection_pool_, safe_grab_);
     if (connectionPtr == nullptr) {
+        throw Exception(DB_ERROR, "Can't construct MySQL connection");
         return;
     }
 
@@ -336,7 +338,7 @@ MySQLMetaImpl::Initialize() {
 
     // step 3: connect mysql
     unsigned int thread_hint = std::thread::hardware_concurrency();
-    int max_pool_size = (thread_hint > 8) ? thread_hint : 8;
+    int max_pool_size = (thread_hint > 8) ? static_cast<int>(thread_hint) : 8;
     int port = 0;
     if (!uri_info.port_.empty()) {
         port = std::stoi(uri_info.port_);

core/src/db/meta/MySQLMetaImpl.h

@@ -182,7 +182,7 @@ class MySQLMetaImpl : public Meta {
     const int mode_;
 
     std::shared_ptr<MySQLConnectionPool> mysql_connection_pool_;
-    bool safe_grab_ = false;
+    bool safe_grab_ = false;  // Safely graps a connection from mysql pool
 
     std::mutex meta_mutex_;
     std::mutex genid_mutex_;

core/src/db/meta/SqliteMetaImpl.cpp

@@ -153,7 +153,7 @@ SqliteMetaImpl::ValidateMetaSchema() {
     bool is_null_connector{ConnectorPtr == nullptr};
     fiu_do_on("SqliteMetaImpl.ValidateMetaSchema.NullConnection", is_null_connector = true);
     if (is_null_connector) {
-        return;
+        throw Exception(DB_ERROR, "Connector is null pointer");
     }
 
     // old meta could be recreated since schema changed, throw exception if meta schema is not compatible

core/unittest/db/test_meta.cpp

@@ -56,7 +56,7 @@ TEST_F(MetaTest, COLLECTION_TEST) {
     ASSERT_TRUE(status.ok());
 }
 
-TEST_F(MetaTest, FALID_TEST) {
+TEST_F(MetaTest, FAILED_TEST) {
     fiu_init(0);
     auto options = GetOptions();
     auto collection_id = "meta_test_table";
@@ -66,7 +66,7 @@ TEST_F(MetaTest, FALID_TEST) {
 
     {
         FIU_ENABLE_FIU("SqliteMetaImpl.ValidateMetaSchema.NullConnection");
-        milvus::engine::meta::SqliteMetaImpl impl(options.meta_);
+        ASSERT_ANY_THROW(milvus::engine::meta::SqliteMetaImpl impl(options.meta_));
         fiu_disable("SqliteMetaImpl.ValidateMetaSchema.NullConnection");
     }
     {