fix cpp session mem leak (apache#16443)

Author: hongzhi-gao

example/client-cpp-example/src/TableModelSessionExample.cpp

@@ -22,7 +22,7 @@
 
 using namespace std;
 
-TableSession *session;
+shared_ptr<TableSession> session;
 
 void insertRelationalTablet() {
 
@@ -203,8 +203,6 @@ int main() {
         cout << "session close\n" << endl;
         session->close();
 
-        delete session;
-
         cout << "finished!\n" << endl;
     } catch (IoTDBConnectionException &e) {
         cout << e.what() << endl;

iotdb-client/client-cpp/src/main/SessionBuilder.h

@@ -79,12 +79,12 @@ class SessionBuilder : public AbstractSessionBuilder {
         return this;
     }
 
-    Session* build() {
+   std::shared_ptr<Session> build() {
         sqlDialect = "tree";
-        Session* newSession = new Session(this);
+        auto newSession = std::make_shared<Session>(this);
         newSession->open(false);
         return newSession;
-    }
+   }
 };
 
 #endif // IOTDB_SESSION_BUILDER_H

iotdb-client/client-cpp/src/main/TableSession.h

@@ -26,18 +26,14 @@
 
 class TableSession {
 private:
-    Session* session_;
+    std::shared_ptr<Session> session_;
     string getDatabase();
 public:
-    TableSession(Session* session) {
+    TableSession(std::shared_ptr<Session> session) {
         this->session_ = session;
     }
-    ~TableSession() {
-        if (session_) {
-            delete session_;
-            session_ = nullptr;
-        }
-    }
+    ~TableSession() {}
+
     void insert(Tablet& tablet, bool sorted = false);
     void executeNonQueryStatement(const std::string& sql);
     unique_ptr<SessionDataSet> executeQueryStatement(const std::string& sql);

iotdb-client/client-cpp/src/main/TableSessionBuilder.h

@@ -69,11 +69,11 @@ class TableSessionBuilder : public AbstractSessionBuilder {
         AbstractSessionBuilder::nodeUrls = nodeUrls;
         return this;
     }
-    TableSession* build() {
+    std::shared_ptr<TableSession> build() {
         sqlDialect = "table";
-        Session* newSession = new Session(this);
+        auto newSession = std::make_shared<Session>(this);
         newSession->open(false);
-        return new TableSession(newSession);
+        return std::make_shared<TableSession>(newSession);
     }
 };