Changes to verify that the HSIEvent Sender is really ready to send messages before completing the 'start' transition

include/hsilibs/HSIEventSender.hpp

@@ -62,6 +62,7 @@ class HSIEventSender : public dunedaq::appfwk::DAQModule
   std::shared_ptr<hsievent_sender_ct> m_hsievent_sender;
 
   // push events to HSIEvent output queue
+  virtual bool ready_to_send(std::chrono::milliseconds timeout);
   virtual void send_hsi_event(dfmessages::HSIEvent& event);
   virtual void send_raw_hsi_data(const std::array<uint32_t, 7>& raw_data, raw_sender_ct* sender);
 

include/hsilibs/Issues.hpp

@@ -36,6 +36,13 @@ ERS_DECLARE_ISSUE_BASE(hsilibs,
                        ((std::string)name),
                        ((std::string)queueType))
 
+ERS_DECLARE_ISSUE_BASE(hsilibs,
+                       SenderReadyTimeout,
+                       appfwk::GeneralDAQModuleIssue,
+                       "Timeout waiting for the Sender for connection " << conn << " to be ready.",
+                       ((std::string)name),
+                       ((std::string)conn))
+
 ERS_DECLARE_ISSUE(hsilibs,                         ///< Namespace
                   UHALIssue,                          ///< Issue class name
                   " UHAL related issue: " << message, ///< Message

plugins/FakeHSIEventGenerator.cpp

@@ -141,6 +141,32 @@ FakeHSIEventGenerator::do_start(const nlohmann::json& obj)
   }
   m_run_number.store(start_params.run);
 
+  // 28-Sep-2023, KAB: added code to wait for the Sender connection to be ready.
+  // This code needs to come *before* the Sender connection is first used, and 
+  // before any threads that use the Sender connection are start, and it needs
+  // to come *after* any Receiver connections are created/started so that it
+  // doesn't block other modules that are trying to connect to this one.
+  // We retry for 10 seconds.  That seems like it should be plenty long enough
+  // for the connection to be established but short enough so that it doesn't
+  // annoy users if/when the connection readiness times out.
+  if (! ready_to_send(std::chrono::milliseconds(1))) {
+    bool ready = false;
+    for (int loop_counter = 0; loop_counter < 10; ++loop_counter) {
+      TLOG() << get_name() << " Waiting for the Sender for the " <<  m_hsievent_send_connection
+             << " connection to be ready to send messages, loop_count=" << (loop_counter+1);
+      if (ready_to_send(std::chrono::milliseconds(1000))) {
+        ready = true;
+        break;
+      }
+    }
+    if (ready) {
+      TLOG() << get_name() << " The Sender for the " <<  m_hsievent_send_connection
+             << " connection is now ready.";
+    } else {
+      throw(SenderReadyTimeout(ERS_HERE, get_name(), m_hsievent_send_connection));
+    }
+  }
+
   m_thread.start_working_thread("fake-tsd-gen");
   TLOG() << get_name() << " successfully started";
   TLOG_DEBUG(TLVL_ENTER_EXIT_METHODS) << get_name() << ": Exiting do_start() method";

src/HSIEventSender.cpp

@@ -40,6 +40,13 @@ HSIEventSender::init(const nlohmann::json& init_data)
   m_hsievent_sender = get_iom_sender<dfmessages::HSIEvent>(m_hsievent_send_connection);
 }
 
+bool
+HSIEventSender::ready_to_send(std::chrono::milliseconds timeout)
+{
+  if (m_hsievent_sender == nullptr) {return false;}
+  return m_hsievent_sender->is_ready_for_sending(timeout);
+}
+
 void
 HSIEventSender::send_hsi_event(dfmessages::HSIEvent& event)
 {
@@ -50,7 +57,7 @@ HSIEventSender::send_hsi_event(dfmessages::HSIEvent& event)
   bool was_successfully_sent = false;
   while (!was_successfully_sent) {
     try {
-        dfmessages::HSIEvent event_copy(event);
+      dfmessages::HSIEvent event_copy(event);
       m_hsievent_sender->send(std::move(event_copy), m_queue_timeout);
       ++m_sent_counter;
       m_last_sent_timestamp.store(event.timestamp);