Workaround for the svr_writer thread (of DOOCS) to block location mutexes for...

Workaround for the svr_writer thread (of DOOCS) to block location mutexes for a very long time if many big D_spectrum are written. The write is now only done if necessary (i.e. after a modification) and the lock is released for a short period of time to make sure RPC calls don't get blocked for too long.

include/DoocsSpectrum.h

@@ -71,6 +71,8 @@ namespace ChimeraTK {
 
     void setMacroPulseNumberSource(boost::shared_ptr<ChimeraTK::NDRegisterAccessor<int64_t>> macroPulseNumberSource);
 
+    void write(fstream& fptr) override;
+
     boost::shared_ptr<ChimeraTK::NDRegisterAccessor<float>> _processArray;
     boost::shared_ptr<ChimeraTK::NDRegisterAccessor<float>> _startAccessor;
     boost::shared_ptr<ChimeraTK::NDRegisterAccessor<float>> _incrementAccessor;
@@ -85,6 +87,9 @@ namespace ChimeraTK {
     // the ChimeraTK ProcessArray and calls the send method. Factored out to allow
     // unit testing.
     void sendToDevice();
+
+    // Flag whether the value has been modified since the content has been saved to disk the last time (see write()).
+    bool modified{false};
   };
 
 } // namespace ChimeraTK

src/DoocsSpectrum.cc

@@ -57,6 +57,7 @@ namespace ChimeraTK {
 
   void DoocsSpectrum::set(EqAdr* eqAdr, EqData* data1, EqData* data2, EqFct* eqFct) {
     D_spectrum::set(eqAdr, data1, data2, eqFct);
+    modified = true;
     sendToDevice();
   }
 
@@ -71,11 +72,24 @@ namespace ChimeraTK {
 
     // send the current value to the device
     D_spectrum::read();
+    modified = false;
     if(_processArray->isWriteable()) {
       sendToDevice();
     }
   }
 
+  void DoocsSpectrum::write(fstream& fptr) {
+    // DOOCS is normally keeping the location lock until everything is written for that location: all D_spectrum and all
+    // other properties. This can take too long (like seconds), which leads to noticable freezes of the UI. As a
+    // work-around we release the lock here, wait some time and acquire the lock again. Since this happens in a separate
+    // thread (svr_writer), this slow-down should not be of any harm.
+    efp_->unlock();
+    usleep(1000);
+    efp_->lock();
+    if(!modified) return;
+    D_spectrum::write(fptr);
+  }
+
   void DoocsSpectrum::updateDoocsBuffer(TransferElementID transferElementId) {
     // Note: we already own the location lock by specification of the DoocsUpdater