Remove startup delay in Services constructor

src/ServiceDiscovery/Services.cpp

@@ -27,21 +27,24 @@ bool Services::Init(Store &m_variables, zmq::context_t* context_in, SlowControlC
   if(!m_variables.Get("service_name",m_name)) m_name="test_service";
   if(!m_variables.Get("db_name",m_dbname)) m_dbname="daq";
 
-
-
   if(!m_backend_client.Initialise(m_variables)){
     std::clog<<"error initialising slowcontrol client"<<std::endl;
     return false;
   }
 
-  // TODO FIXME with better mechanism
-  // after Initilising the slow control client needs ~15 seconds for the middleman to connect
-  std::this_thread::sleep_for(std::chrono::seconds(15));
-  // hopefully the middleman has found us by now
+  // wait for the middleman to connect. ServiceDiscovery broadcasts are sent out intermittently,
+  // so we need to wait for the middleman to receive one & connect before we can communicate with it.
+  int pub_period=5;
+  m_variables.Get("service_publish_sec",pub_period);
+  Ready(pub_period*1000);
 
   return true;
 }
 
+bool Services::Ready(const unsigned int timeout){
+  return m_backend_client.Ready(timeout);
+}
+
 // ===========================================================================
 // Write Functions
 // ---------------

src/ServiceDiscovery/Services.h

@@ -38,6 +38,7 @@ namespace ToolFramework {
     Services();
     ~Services();
     bool Init(Store &m_variables, zmq::context_t* context_in, SlowControlCollection* sc_vars_in, bool new_service=false);
+    bool Ready(const unsigned int timeout=10000); // default service discovery broadcast period is 5s, middleman also checks intermittently, compound total time should be <10s...
 
     bool SQLQuery(const std::string& database, const std::string& query, std::vector<std::string>& responses, const unsigned int timeout=SERVICES_DEFAULT_TIMEOUT);
     bool SQLQuery(const std::string& database, const std::string& query, std::string& response, const unsigned int timeout=SERVICES_DEFAULT_TIMEOUT);

src/ServiceDiscovery/ServicesBackend.cpp

@@ -936,3 +936,30 @@ bool ServicesBackend::Receive(zmq::socket_t* sock, std::vector<zmq::message_t>&
 	return true;
 }
 
+bool ServicesBackend::Ready(int timeout){
+
+	// poll the output sockets for listeners
+	// only poll dealer socket, pub sockets always return true immediately so ignore the timeout
+	// polling the input socket checks for a message, so don't do that.
+	int ret;
+	try {
+		dlr_socket_mutex.lock();
+		ret = zmq::poll(&out_polls.at(1), 1, timeout);
+		dlr_socket_mutex.unlock();
+	} catch (zmq::error_t& err){
+		std::cerr<<"ServicesBackend::Ready caught "<<err.what()<<std::endl;
+		return false;
+	}
+	if(ret<0){
+		// error polling - is the socket closed?
+		std::cerr<<"ServicesBackend::Ready error: "<<zmq_strerror(errno)<<std::endl;
+		return false;
+	} else if(ret==0){
+		// 'resource temoprarily unavailable' - no-one connected.
+	} else if(out_polls.at(1).revents & ZMQ_POLLOUT){
+		return true;
+	}
+
+	return false;
+
+}

src/ServiceDiscovery/ServicesBackend.h

@@ -51,6 +51,7 @@ class ServicesBackend {
 	ServicesBackend(){};
 	~ServicesBackend(){};
 	void SetUp(zmq::context_t* in_context, std::function<void(std::string msg, int msg_verb, int verbosity)> log=nullptr); // possibly move to constructor
+	bool Ready(int timeout); // check if zmq sockets have connections
 	bool Initialise(std::string configfile);
 	bool Initialise(Store &varaibles_in);
 	bool Finalise();