siptransportbroker: avoid deadlock when stopping daemon

SipTransportBroker::shutdown triggers pjsip_transport_shutdown
that can call transportStateChanged synchronously. In this case,
transportMapMutex_ is locked, causing a deadlock on a single thread.
We don't care about the transport's map at this point as we are
destroying the transportbroker, so we can just ignore the state
changed here.

Change-Id: I180ff1807fe87d1c48d72851f17e94ae2f892823

src/sip/siptransport.cpp

@@ -206,7 +206,7 @@ SipTransportBroker::transportStateChanged(pjsip_transport* tp,
 
     std::shared_ptr<SipTransport> sipTransport;
 
-    {
+    if (!isDestroying_) {
         std::lock_guard<std::mutex> lock(transportMapMutex_);
         auto key = transports_.find(tp);
         if (key == transports_.end())
@@ -269,6 +269,7 @@ void
 SipTransportBroker::shutdown()
 {
     std::unique_lock<std::mutex> lock(transportMapMutex_);
+    isDestroying_ = true;
     for (auto& t : transports_) {
         if (auto transport = t.second.lock()) {
             pjsip_transport_shutdown(transport->get());

src/sip/siptransport.h

@@ -197,6 +197,7 @@ private:
     std::map<IpAddr, pjsip_transport*> udpTransports_;
 
     pjsip_endpoint* endpt_;
+    std::atomic_bool isDestroying_ {false};
 };
 
 } // namespace jami