Fix histserv signal handling

services/histserv/app/Application.cxx

@@ -42,7 +42,9 @@ using cbm::services::histserv::Application;
 
 // ---------------------------------------------------------------------------------------------------------------------
 //
-Application::Application(ProgramOptions const& opt) : fOpt(opt)
+Application::Application(ProgramOptions const& opt, volatile sig_atomic_t* signalStatus)
+  : fOpt(opt)
+  , fSignalStatus(signalStatus)
 {
   /// Read options from executable
   LOG(info) << "Options for Application:";
@@ -84,12 +86,6 @@ Application::Application(ProgramOptions const& opt) : fOpt(opt)
     fServer->Restrict("/Stop_Server", "allow=admin");
   }
 
-  // Provide signal handling for external interruptions
-  // NOTE: SZh 02.04.2024:
-  //    This function is needed for ZMQ to throw an exception (zmq::error_t) on the interrupt signal. It seems, that
-  //    the actual body of the function does not matter. This behaviour is not understood.
-  signal(SIGINT, [](int) {});
-
   LOG(info) << "JSROOT location: " << jsrootsys;
 }
 
@@ -100,7 +96,7 @@ void Application::Exec()
   fStopThread = false;
   fThread     = std::thread(&Application::UpdateHttpServer, this);
   LOG(info) << "Listening to ZMQ messages ...";
-  while (!(fUiCmdActor->GetServerStop())) {  //
+  while (!(fUiCmdActor->GetServerStop()) && *fSignalStatus == 0) {
     try {
       /// Infinite loop, this is a service which should survive until told otherwise after all
       /// FIXME: Start listening to <SOMETHING?!?> to receive histograms and configuration
@@ -111,27 +107,23 @@ void Application::Exec()
       if (!ret) continue;
 
       std::lock_guard<std::mutex> lk(mtx);
-      if (*ret > 3) {  //
+      if (*ret > 3) {
         ReceiveConfigAndData(vMsg);
       }
-      else if (*ret == 1) {  //
+      else if (*ret == 1) {
         ReceiveData(vMsg[0]);
       }
-      else {  //
+      else {
         LOG(error) << "Invalid number of message parts received: should be either 1 or more than 3 vs " << *ret;
       }
     }
     catch (const zmq::error_t& err) {
-      if (err.num() == EINTR) {
-        // FIXME: SZh: Are the socket and the context finished properly?
-        LOG(info) << "Histogram server execution was interrupted by user. Finishing application";
-        break;
-      }
-      else {
-        throw err;
+      if (err.num() != EINTR) {
+        throw;
       }
     }
   }
+  // FIXME: SZh: Are the socket and the context finished properly?
 }
 
 // ---------------------------------------------------------------------------------------------------------------------

services/histserv/app/Application.h

@@ -25,7 +25,7 @@ namespace cbm::services::histserv
   public:
     /** @brief Standard constructor, initialises the application
      ** @param opt  **/
-    explicit Application(ProgramOptions const& opt);
+    explicit Application(ProgramOptions const& opt, volatile sig_atomic_t* signalStatus);
 
     /** @brief Copy constructor forbidden **/
     Application(const Application&) = delete;
@@ -84,6 +84,7 @@ namespace cbm::services::histserv
 
   private:
     ProgramOptions const& fOpt;      ///< Program options object
+    volatile sig_atomic_t* fSignalStatus; ///< Global signal status
     THttpServer* fServer = nullptr;  ///< ROOT Histogram server (JSroot)
     std::thread fThread;
     bool fStopThread = false;

services/histserv/app/main.cxx

@@ -5,15 +5,25 @@
 
 #include "Application.h"
 #include "ProgramOptions.h"
+#include <csignal>
+
+namespace {
+volatile sig_atomic_t signal_status = 0;
+}
+
+static void signal_handler(int sig) { signal_status = sig; }
 
 using namespace cbm::services::histserv;
 
 int main(int argc, char* argv[])
 {
+  std::signal(SIGINT, signal_handler);
+  std::signal(SIGTERM, signal_handler);
+
   LOG(info) << "*****   Histogram server without FairMQ   *****";
   try {
     ProgramOptions opt(argc, argv);
-    Application app(opt);
+    Application app(opt, &signal_status);
     app.Exec();
   }
   catch (std::exception const& e) {