Revert "Fix delay between receiving signal in separate thread and handling it"

This reverts commit e14e3586e1.

Until I find what's wrong with it...

src/main.cpp

@@ -146,12 +146,6 @@ static void GenerateHelp(const char* appname) {
 class CSignalHandler {
   public:
     CSignalHandler(CZNC* pZNC) {
-        if (pipe(m_iPipe)) {
-            DEBUG("Ouch, can't open pipe for signal handler: "
-                  << strerror(errno));
-            exit(1);
-        }
-        pZNC->GetManager().MonitorFD(new CSignalHandlerMonitorFD(m_iPipe[0]));
         sigset_t signals;
         sigfillset(&signals);
         pthread_sigmask(SIG_SETMASK, &signals, nullptr);
@@ -163,21 +157,6 @@ class CSignalHandler {
     }
 
   private:
-    class CSignalHandlerMonitorFD : public CSMonitorFD {
-        // This class just prevents the pipe buffer from filling by clearing it
-      public:
-        CSignalHandlerMonitorFD(int fd) { Add(fd, CSockManager::ECT_Read); }
-
-        bool FDsThatTriggered(
-            const std::map<int, short>& miiReadyFds) override {
-            for (const auto& it : miiReadyFds) {
-                int sig;
-                read(it.first, &sig, sizeof(sig));
-            }
-            return true;
-        }
-    };
-
     void HandleSignals(CZNC* pZNC) {
         sigset_t signals;
         sigemptyset(&signals);
@@ -197,7 +176,6 @@ class CSignalHandler {
             // Such cancel will be the only way to finish this thread.
             if (sigwait(&signals, &sig) == -1) continue;
             pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, nullptr);
-            // TODO probably move switch() to CSignalHandlerMonitorFD?
             switch (sig) {
                 case SIGHUP:
                     pZNC->SetConfigState(CZNC::ECONFIG_NEED_REHASH);
@@ -221,23 +199,10 @@ class CSignalHandler {
                 default:
                     break;
             }
-            // This write() must succeed because POSIX guarantees that writes of
-            // less than PIPE_BUF are atomic (and PIPE_BUF is at least 512).
-            size_t w = write(m_iPipe[1], &sig, sizeof(sig));
-            if (w != sizeof(sig)) {
-                DEBUG(
-                    "Something bad happened during write() to a pipe for "
-                    "signal handler, wrote "
-                    << w << " bytes: " << strerror(errno));
-                exit(1);
-            }
         }
     }
 
     std::thread m_thread;
-
-    // pipe for waking up the main thread
-    int m_iPipe[2];
 };
 
 static bool isRoot() {