Support for application lifecycle message

Change-Id: I16db05bccb9ac9a2d18b949952e5ad6812b729cc

MetricUpdater.cpp

@@ -147,6 +147,42 @@ void MetricUpdater::UpdateMetricValue(
   }
 }
 
+// --------------------------------------------------------------------------
+// Application lifcycle
+// --------------------------------------------------------------------------
+//
+// When the lifecycle message is received, the state is just recorded in the
+// state variable.
+
+void MetricUpdater::LifecycleHandler( 
+     const ApplicationLifecycle & TheState, 
+     const Address TheLifecycleTopic )
+{
+  Theron::ConsoleOutput Output;
+
+  ApplicationState = TheState;
+
+  Output << "Application state updated: " << std::endl
+         << TheState.dump(2) << std::endl;
+}
+
+// The message handler used the conversion operator to read out the state 
+// carried in the message. It is based on having a static map from the textual
+// representation of the state to the enumeration.
+
+MetricUpdater::ApplicationLifecycle::operator State() const
+{
+  static std::map< std::string_view, State > LifecycleStates{
+    {"NEW", State::New},
+    {"READY", State::Ready},
+    {"DEPLOYING", State::Deploying},
+    {"RUNNING", State::Running},
+    {"FAILED", State::Failed}
+  };
+
+  return LifecycleStates.at( this->at("state").get< std::string >() );
+}
+
 // --------------------------------------------------------------------------
 // SLO Violation Events
 // --------------------------------------------------------------------------
@@ -174,7 +210,7 @@ void MetricUpdater::SLOViolationHandler(
   Output << "Metric Updater: SLO violation received " << std::endl
          << SeverityMessage.dump(2) << std::endl;
 
-  if( !ReconfigurationInProgress && 
+  if(( ApplicationState == ApplicationLifecycle::State::Running ) && 
      ( AllMetricValuesSet || 
       (!MetricValues.empty() &&
         std::ranges::none_of( std::views::values( MetricValues ), 
@@ -187,37 +223,13 @@ void MetricUpdater::SLOViolationHandler(
     ), TheSolverManager );
 
     AllMetricValuesSet  = true;
-    ReconfigurationInProgress = true;
+    ApplicationState    = ApplicationLifecycle::State::Deploying;
   }
   else
     Output << "... failed to forward the application execution context (size: " 
            << MetricValues.size() << ")" << std::endl;
 }
 
-// --------------------------------------------------------------------------
-// Reconfigured application
-// --------------------------------------------------------------------------
-//
-// When the reconfiguration message is received it is an indication tha the 
-// Optimiser Controller has reconfigured the application and that the 
-// application is running in the new configuration found by the solver. 
-// It is the event that is important m not the content of the message, and 
-// it is therefore only used to reset the ongoing reconfiguration flag.
-
-void MetricUpdater::ReconfigurationDone( 
-     const ReconfigurationMessage & TheReconfiguraton, 
-     const Address TheReconfigurationTopic )
-{
-  Theron::ConsoleOutput Output;
-
-  ReconfigurationInProgress = false;
-
-  Output << "Reconfiguration ongoing flag reset after receiving the following "
-         << "message indicating that the previous reconfiguration was"
-         << "completed: " << std::endl
-         << TheReconfiguraton.dump(2) << std::endl;
-}
-
 // --------------------------------------------------------------------------
 // Constructor and destructor
 // --------------------------------------------------------------------------
@@ -239,13 +251,13 @@ MetricUpdater::MetricUpdater( const std::string UpdaterName,
   StandardFallbackHandler( Actor::GetAddress().AsString() ),
   NetworkingActor( Actor::GetAddress().AsString() ),
   MetricValues(), ValidityTime(0), AllMetricValuesSet(false),
-  TheSolverManager( ManagerOfSolvers ),
+  ApplicationState( ApplicationLifecycle::State::New ),
-  ReconfigurationInProgress( false )
+  TheSolverManager( ManagerOfSolvers )
 {
   RegisterHandler( this, &MetricUpdater::AddMetricSubscription );
   RegisterHandler( this, &MetricUpdater::UpdateMetricValue     );
   RegisterHandler( this, &MetricUpdater::SLOViolationHandler   );
-  RegisterHandler( this, &MetricUpdater::ReconfigurationDone   );
+  RegisterHandler( this, &MetricUpdater::LifecycleHandler      );
 
   Send( Theron::AMQ::NetworkLayer::TopicSubscription(
     Theron::AMQ::NetworkLayer::TopicSubscription::Action::Subscription,
@@ -254,7 +266,7 @@ MetricUpdater::MetricUpdater( const std::string UpdaterName,
 
   Send( Theron::AMQ::NetworkLayer::TopicSubscription(
     Theron::AMQ::NetworkLayer::TopicSubscription::Action::Subscription,
-    ReconfigurationMessage::AMQTopic ), 
+    ApplicationLifecycle::AMQTopic ), 
     GetSessionLayerAddress() );
 
   Send( Theron::AMQ::NetworkLayer::TopicSubscription(
@@ -279,7 +291,7 @@ MetricUpdater::~MetricUpdater()
 
     Send( Theron::AMQ::NetworkLayer::TopicSubscription(
       Theron::AMQ::NetworkLayer::TopicSubscription::Action::CloseSubscription,
-      ReconfigurationMessage::AMQTopic ), 
+      ApplicationLifecycle::AMQTopic ), 
       GetSessionLayerAddress() );
 
     Send( Theron::AMQ::NetworkLayer::TopicSubscription(

MetricUpdater.hpp

@@ -225,6 +225,74 @@ private:
   void UpdateMetricValue( const MetricValueUpdate & TheMetricValue, 
                           const Address TheMetricTopic );
 
+  // --------------------------------------------------------------------------
+  // Application lifecycle
+  // --------------------------------------------------------------------------
+  //
+  // There is a message from the Optimiser Controller when the status of the 
+  // application changes. The state communicated in this message shows the 
+  // current state of the application and decides how the Solver will act to
+  // SLO Violations detected.
+
+  class ApplicationLifecycle
+  : public Theron::AMQ::JSONTopicMessage
+  { 
+  public:
+
+    // The topic for the reconfiguration finished messages is defined by the 
+    // optimiser as the sender.
+
+    static constexpr std::string_view AMQTopic
+                     = "eu.nebulouscloud.optimiser.controller.app_state";
+
+    // The state of the application goes from the the initial creation of 
+    // the cluster to deployments covering reconfigurations. Note that there is
+    // no state indicating that the application has terminated.
+
+    enum class State
+    {
+      New,        // Waiting for the utility evaluator
+      Ready,      // The application is ready for deployment
+      Deploying,  // The application is being deployed or redeployed
+      Running,    // The application is running
+      Failed     // The application is in an invalid state
+    };
+
+    // An arriving lifecycle message indicates a change in state and it is 
+    // therefore a way to set a state variable directly from the message by
+    // a cast operator
+
+    operator State() const;
+
+    // Constructors and destructor
+
+    ApplicationLifecycle( void )
+    : JSONTopicMessage( AMQTopic )
+    {}
+
+    ApplicationLifecycle( const ApplicationLifecycle & Other )
+    : JSONTopicMessage( Other )
+    {}
+
+    virtual ~ApplicationLifecycle() = default;
+  };
+
+  // After starting a reconfiguration with an SLO Violation, one should not 
+  // initiate another reconfiguration because the state may the possibly be 
+  // inconsistent with the SLO Violation Detector belieivng that the old 
+  // configuration is still in effect while the new configuration is being 
+  // enacted. The application lifecycle state must therefore be marked as 
+  // running before the another SLO Violation will trigger the next 
+  // reconfiguration
+
+  ApplicationLifecycle::State ApplicationState;
+
+  // The handler for the lifecycle message simply updates this variable by 
+  // setting it to the state received in the lifecycle message.
+
+  void LifecycleHandler( const ApplicationLifecycle & TheState, 
+                         const Address TheLifecycleTopic );
+
   // --------------------------------------------------------------------------
   // SLO violations
   // --------------------------------------------------------------------------
@@ -295,54 +363,6 @@ private:
 
   const Address TheSolverManager;
 
-  // After the sending of the application's excution context, one should not 
-  // initiate another reconfiguration because the state may the possibly be 
-  // inconsistent with the SLO Violation Detector belieivng that the old 
-  // configuration is still in effect while the new configuration is being 
-  // enacted. It is therefore a flag that will be set by the SLO Violation 
-  // handler indicating that a reconfiguration is ongoing.
-
-  bool ReconfigurationInProgress;
-
-  // When a reconfiguration has been enacted by the Optimiser Controller and 
-  // a new configuration is confirmed to be running on the new platofrm, it 
-  // will send a message to inform all other components that the 
-  // reconfiguration has happened. The event is just the reception of the 
-  // message and its content will not be processed, so there are no keys for
-  // the JSON map received.
-
-  class ReconfigurationMessage
-  : public Theron::AMQ::JSONTopicMessage
-  { 
-  public:
-
-    // The topic for the reconfiguration finished messages is defined by the 
-    // optimiser as the sender.
-
-    static constexpr std::string_view AMQTopic
-                     = "eu.nebulouscloud.optimiser.controller.reconfiguration";
-
-    // Constructors
-
-    ReconfigurationMessage( void )
-    : JSONTopicMessage( AMQTopic )
-    {}
-
-    ReconfigurationMessage( const ReconfigurationMessage & Other )
-    : JSONTopicMessage( Other )
-    {}
-
-    virtual ~ReconfigurationMessage() = default;
-  };
-
-  // The handler for this message will actually not use its contents, but only
-  // note that the reconfiguration has been completed to reset the 
-  // reconfiguration in progress flag allowing future SLO Violation Events to 
-  // triger new reconfigurations.
-
-  void ReconfigurationDone( const ReconfigurationMessage & TheReconfiguraton, 
-                            const Address TheReconfigurationTopic );
-
   // --------------------------------------------------------------------------
   // Constructor and destructor
   // --------------------------------------------------------------------------