call service: synchronize state change

Change-Id: I50426174a6441aa53cb042890ae42233bdc73d8a

ring-android/libringclient/src/main/java/cx/ring/services/CallService.java

@@ -453,11 +453,14 @@ public class CallService {
     }
 
     public void removeCallForId(String callId) {
+        synchronized (currentCalls) {
             currentCalls.remove(callId);
             currentConferences.remove(callId);
         }
+    }
 
     private SipCall addCall(String accountId, String callId, String from, SipCall.Direction direction) {
+        synchronized (currentCalls) {
             SipCall call = currentCalls.get(callId);
             if (call == null) {
                 Account account = mAccountService.getAccount(accountId);
@@ -471,6 +474,7 @@ public class CallService {
             }
             return call;
         }
+    }
 
     private Conference addConference(SipCall call) {
         String confId = call.getConfId();
@@ -537,6 +541,7 @@ public class CallService {
     void callStateChanged(String callId, String newState, int detailCode) {
         Log.d(TAG, "call state changed: " + callId + ", " + newState + ", " + detailCode);
         try {
+            synchronized (currentCalls) {
                 SipCall call = parseCallState(callId, newState);
                 if (call != null) {
                     callSubject.onNext(call);
@@ -546,6 +551,7 @@ public class CallService {
                         updateConnectionCount();
                     }
                 }
+            }
         } catch (Exception e) {
             Log.w(TAG, "Exception during state change: ", e);
         }