Update agent as singleton

micro_ros_agent/include/agent/Agent.hpp

@@ -26,11 +26,21 @@ namespace agent {
 
 class Agent
 {
-public:
-
+private:
     Agent();
 
-    ~Agent() = default;
+    Agent(const Agent &) = delete;
+
+    Agent(Agent &&) = delete;
+
+    Agent& operator =(
+            const Agent &) = delete;
+
+    Agent& operator =(
+            Agent &&) = delete;
+
+public:
+    static Agent& getInstance();
 
     bool create(
             int argc,

micro_ros_agent/src/agent/Agent.cpp

@@ -23,15 +23,6 @@ namespace agent {
 Agent::Agent()
     : xrce_dds_agent_instance_(xrce_dds_agent_instance_.getInstance())
 {
-}
-
-bool Agent::create(
-        int argc,
-        char** argv)
-{
-    bool result = xrce_dds_agent_instance_.create(argc, argv);
-    if (result)
-    {
     /**
      * Add CREATE_PARTICIPANT callback.
      */
@@ -166,9 +157,20 @@ bool Agent::create(
         eprosima::uxr::Middleware::Kind::FASTDDS,
         eprosima::uxr::middleware::CallbackKind::DELETE_DATAREADER,
         std::move(on_delete_datareader));
-    }
+}
 
-    return result;
+Agent& Agent::getInstance()
+{
+    static Agent instance;
+    return instance;
+}
+
+bool Agent::create(
+        int argc,
+        char** argv)
+{
+    stop();
+    return xrce_dds_agent_instance_.create(argc, argv);
 }
 
 void Agent::run()
@@ -179,12 +181,12 @@ void Agent::run()
 void Agent::stop()
 {
     xrce_dds_agent_instance_.stop();
+    graph_manager_map_.clear();
 }
 
 std::shared_ptr<graph_manager::GraphManager> Agent::find_or_create_graph_manager(eprosima::fastdds::dds::DomainId_t domain_id)
 {
-
-auto it = graph_manager_map_.find(domain_id);
+    auto it = graph_manager_map_.find(domain_id);
 
     if (it != graph_manager_map_.end()) {
         return it->second;

micro_ros_agent/src/main.cpp

@@ -16,7 +16,7 @@
 
 int main(int argc, char** argv)
 {
-    uros::agent::Agent micro_ros_agent;
+    uros::agent::Agent& micro_ros_agent = micro_ros_agent.getInstance();
 
     /** Bypass '--ros-args' flag, as we use our own CLI parser.
       * As a workaround for launch files, arguments will be passed from