queue.take possible race, send thread does not wait for read anymore

src/remote/codec.cpp

@@ -1214,7 +1214,7 @@ namespace epics {
     void BlockingAbstractCodec::sendThread(void *param)
     {
 
-        BlockingAbstractCodec *bac = static_cast<BlockingAbstractCodec *>(param);
+      BlockingAbstractCodec *bac = static_cast<BlockingAbstractCodec *>(param);
       Transport::shared_pointer ptr = bac->shared_from_this();
 
       bac->setSenderThread();
@@ -1241,16 +1241,17 @@ namespace epics {
         }
       }
 
+      /*
       // wait read thread to die
-      // TODO rewise
+      // TODO rewise if this is really needed
       // this timeout is needed where close() is initiated from the send thread,
       // and not from the read thread as usualy - recv() does not exit until socket is not destroyed,
       // which is done the internalDestroy() call below
       bac->_shutdownEvent.wait(3.0);
+      */
 
       // call internal destroy
       bac->internalDestroy();
-
     }
 
 

src/remote/codec.h

@@ -71,6 +71,7 @@ namespace epics {
     };
 
 
+    // TODO replace this queue with lock-free implementation
     template<typename T> 
     class queue {
     public:
@@ -119,6 +120,7 @@ namespace epics {
       }
 
 
+      // TODO very sub-optimal (locks and empty() - pop() sequence; at least 2 locks!)
       T take(int timeOut) 
       { 
         while (true)
@@ -161,6 +163,8 @@ namespace epics {
           else
           {
             epics::pvData::Lock lock(_queueMutex);
+            if (_queue.empty())
+                return T();
             T sender = _queue.front();
             _queue.pop_front();
             return sender;
@@ -179,7 +183,6 @@ namespace epics {
       epics::pvData::Event _queueEvent;
       epics::pvData::Mutex _queueMutex;
       AtomicValue<bool> _wakeup;
-      epics::pvData::Mutex _stdMutex;
     };
 
 

src/remoteClient/clientContextImpl.cpp

@@ -4515,6 +4515,15 @@ TODO
                 // stop UDPs
                 m_searchTransport->close();
                 m_broadcastTransport->close();
+
+                // wait for all transports to cleanly exit
+                int tries = 40;
+                epics::pvData::int32 transportCount;
+                while ((transportCount = m_transportRegistry->numberOfActiveTransports()) && tries--)
+                    epicsThreadSleep(0.025);
+
+                if (transportCount)
+                    LOG(logLevelDebug, "PVA client context destroyed with %d transport(s) active.", transportCount);
             }
 
             void destroyAllChannels() {