Improve WebRTC Stability

Improve the stability of the WebRTC IceCandidate negotiation when the
round trip time to the Rendezvous server is large (> 400ms) which can be
the case when the Rendezvous server is on the other side of the planet!

Change-Id: I7a8883d30696ada2ea13393fde82f1d8f49bbc0c

appinventor/blocklyeditor/src/msg/en/_messages.js

@@ -1446,6 +1446,8 @@ Blockly.Msg.en.switch_language_to_english = {
     Blockly.Msg.REPL_YOUR_CODE_IS = "Your code is";
     Blockly.Msg.REPL_DO_YOU_REALLY_Q = "Do You Really?";
     Blockly.Msg.REPL_FACTORY_RESET = 'This will attempt to reset your Emulator to its "factory" state. If you had previously updated the Companion installed in the Emulator, you will likely have to do this again.';
+    Blockly.Msg.REPL_WEBRTC_CONNECTION_ERROR = "Companion Connection Error";
+
 
 // Messages from Blockly.js
     Blockly.Msg.WARNING_DELETE_X_BLOCKS = "Are you sure you want to delete all %1 of these blocks?";

appinventor/blocklyeditor/src/replmgr.js

@@ -334,6 +334,24 @@ Blockly.ReplMgr.putYail = (function() {
             var offer;
             var key = rs.replcode;
             var haveoffer = false;
+            var connectionstate = "none";
+            var webrtcerror = function(doalert, msg) {
+              webrtcdata = null;
+              webrtcstarting = false;
+              webrtcrunning = false;
+              webrtcforcestop = true;
+              top.BlocklyPanel_indicateDisconnect();
+              top.ConnectProgressBar_hide();
+              if (!webrtcpeer) {
+                webrtcpeer.close();
+              }
+              if (doalert) {
+                  var dialog = new Blockly.Util.Dialog(Blockly.Msg.REPL_NETWORK_ERROR, msg, Blockly.Msg.REPL_OK, false, null, 0,
+                      function() {
+                          dialog.hide();
+                      });
+              }
+            };
             webrtcisopen = false;
             webrtcforcestop = false;
             top.ConnectProgressBar_setProgress(20, Blockly.Msg.DIALOG_SECURE_ESTABLISHING);
@@ -348,11 +366,17 @@ Blockly.ReplMgr.putYail = (function() {
                                 var hunk = json[i];
                                 var candidate = hunk['candidate'];
                                 offer = hunk['offer'];
-                                if (candidate && haveoffer) {
+                                if (candidate && haveoffer && connectionstate != "none") {
                                     var nonce = hunk['nonce'];
                                     if (!seennonce[nonce]) {
                                         seennonce[nonce] = true;
-                                        webrtcpeer.addIceCandidate(candidate);
+                                        console.log("addIceCandidate: signalingState = " + webrtcpeer.signalingState +
+                                                    " iceConnectionState = " + webrtcpeer.iceConnectionState);
+                                        console.log("addIceCandidate: candidate = " + JSON.stringify(candidate));
+                                        webrtcpeer.addIceCandidate(candidate)["catch"](function(e) {
+                                            console.error(e);
+                                            webrtcerror(true, Bockly.Msg.REPL_WEBRTC_CONNECTION_ERROR + "\n" + e);
+                                        });
                                     } else {
                                         console.log("Seen nonce " + nonce);
                                     }
@@ -368,24 +392,24 @@ Blockly.ReplMgr.putYail = (function() {
                         if (!webrtcisopen && !webrtcforcestop) {
                             setTimeout(poll, 1000); // Try again in one second
                         }
+                    } else if (this.readyState == 4) { // Done, but didn't get a 200 back
+                        webrtcerror(true, Blockly.Msg.REPL_WEBRTC_CONNECTION_ERROR + "\n" + "Rendezvous Fail: " + this.status);
                     }
                 };
                 xhr.send();
             };
             webrtcpeer = new RTCPeerConnection(top.ReplState.iceservers);
             webrtcpeer.oniceconnectionstatechange = function(evt) {
-                console.log("oniceconnectionstatechange: evt.type = " + evt.type);
-                if (this.iceConnectionState == "disconnected" ||
-                    this.iceConnectionState == "failed") {
-                    webrtcdata = null;
-                    webrtcstarting = false;
-                    webrtcrunning = false;
-                    top.BlocklyPanel_indicateDisconnect();
-                    webrtcpeer.close();
+                console.log("oniceconnectionstatechange: evt.type = " + evt.type + " connection state = " + this.iceConnectionState);
+                connectionstate = this.iceConnectionState;
+                if (connectionstate == "disconnected" ||
+                    connectionstate == "failed") {
+                    webrtcerror(true, Blockly.Msg.REPL_WEBRTC_CONNECTION_ERROR + "\n" + "state = " + connectionstate);
                 }
             };
             webrtcpeer.onsignalingstatechange = function(evt) {
                 console.log("onsignalingstatechange: evt.type = " + evt.type);
+                console.log("onsignalingstatechange: signalingstate = " + this.signalingState);
             };
             webrtcpeer.onicecandidate = function(evt) {
                 if (evt.type == 'icecandidate') {

appinventor/components/src/com/google/appinventor/components/runtime/util/WebRTCNativeMgr.java

@@ -11,6 +11,7 @@ import android.util.Log;
 
 import com.google.appinventor.components.common.YaVersion;
 import com.google.appinventor.components.runtime.ReplForm;
+import com.google.appinventor.components.runtime.util.AsynchUtil;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -75,6 +76,7 @@ public class WebRTCNativeMgr {
   private boolean haveOffer = false;
   private String rCode;
   private volatile boolean keepPolling = true;
+  private volatile boolean haveLocalDescription = false;
   private boolean first = true; // This is used for logging in the Rendezvous server
   private Random random = new Random();
   private DataChannel dataChannel = null;
@@ -86,7 +88,11 @@ public class WebRTCNativeMgr {
 
   /* Callback that handles sdp offer/answers */
   SdpObserver sdpObserver = new SdpObserver() {
+
       public void onCreateFailure(String str) {
+        if (DEBUG) {
+          Log.d(LOG_TAG, "onCreateFailure: " + str);
+        }
       }
 
       public void onCreateSuccess(SessionDescription sessionDescription) {
@@ -97,9 +103,16 @@ public class WebRTCNativeMgr {
           }
           DataChannel.Init init = new DataChannel.Init();
           if (sessionDescription.type == SessionDescription.Type.OFFER) {
+            if (DEBUG) {
+              Log.d(LOG_TAG, "Got offer, about to set remote description (again?)");
+            }
             peerConnection.setRemoteDescription(sdpObserver, sessionDescription);
           } else if (sessionDescription.type == SessionDescription.Type.ANSWER) {
+            if (DEBUG) {
+              Log.d(LOG_TAG, "onCreateSuccess: type = ANSWER");
+            }
             peerConnection.setLocalDescription(sdpObserver, sessionDescription);
+            haveLocalDescription = true;
             /* Send to peer */
             JSONObject offer = new JSONObject();
             offer.put("type", "answer");
@@ -254,7 +267,7 @@ public class WebRTCNativeMgr {
     /* Create the peer connection using the iceServers we received in the constructor */
     peerConnection = factory.createPeerConnection(iceServers, new MediaConstraints(),
       observer);
-    timer.scheduleAtFixedRate(new TimerTask() {
+    timer.schedule(new TimerTask() {
         @Override
         public void run() {
           Poller();
@@ -343,6 +356,9 @@ public class WebRTCNativeMgr {
             Log.d(LOG_TAG, "type = " + type);
             Log.d(LOG_TAG, "About to set remote offer");
           }
+          if (DEBUG) {
+            Log.d(LOG_TAG, "Got offer, about to set remote description (maincode)");
+          }
           peerConnection.setRemoteDescription(sdpObserver,
             new SessionDescription(SessionDescription.Type.OFFER, sdp));
           peerConnection.createAnswer(sdpObserver, new MediaConstraints());
@@ -351,11 +367,29 @@ public class WebRTCNativeMgr {
           }
           i = -1;
         } else if (element.has("nonce")) {
-          if (element.isNull("candidate")) {
+          if (!haveLocalDescription) {
             if (DEBUG) {
-              Log.d(LOG_TAG, "Received a null candidate, skipping...");
+              Log.d(LOG_TAG, "Incoming candidate before local description set, punting");
             }
+            return;
+          }
+          if (element.has("offer")) { // Only take in the offer once!
             i++;
+            if (DEBUG) {
+              Log.d(LOG_TAG, "skipping offer, already processed");
+            }
+            continue;
+          }
+          if (element.isNull("candidate")) {
+            i++;
+            String nonce = element.optString("nonce");
+            if (!seenNonces.contains(nonce)) {
+              if (DEBUG) {
+                Log.d(LOG_TAG, "Received a null candidate, done?");
+              }
+              peerConnection.addIceCandidate(new IceCandidate("", 0, ""));
+              seenNonces.add(nonce);
+            }
             continue;
           }
           String nonce = element.optString("nonce");
@@ -363,13 +397,11 @@ public class WebRTCNativeMgr {
           String sdpcandidate = candidate.optString("candidate");
           String sdpMid = candidate.optString("sdpMid");
           int sdpMLineIndex = candidate.optInt("sdpMLineIndex");
-          if (DEBUG) {
-            Log.d(LOG_TAG, "candidate = " + sdpcandidate);
-          }
           if (!seenNonces.contains(nonce)) {
             seenNonces.add(nonce);
             if (DEBUG) {
               Log.d(LOG_TAG, "new nonce, about to add candidate!");
+              Log.d(LOG_TAG, "candidate = " + sdpcandidate);
             }
             IceCandidate iceCandidate = new IceCandidate(sdpMid, sdpMLineIndex, sdpcandidate);
             peerConnection.addIceCandidate(iceCandidate);
@@ -392,29 +424,34 @@ public class WebRTCNativeMgr {
     }
   }
 
-  private void sendRendezvous(JSONObject data) {
-    try {
-      data.put("first", first);
-      data.put("webrtc", true);
-      data.put("key", rCode + "-r");
-      if (first) {
-        first = false;
-        data.put("apiversion", SdkLevel.getLevel());
-      }
-      HttpClient client = new DefaultHttpClient();
-      HttpPost post = new HttpPost("http://" + rendezvousServer2 + "/rendezvous2/");
-      try {
-        if (DEBUG) {
-          Log.d(LOG_TAG, "About to send = " + data.toString());
+  private void sendRendezvous(final JSONObject data) {
+    AsynchUtil.runAsynchronously(new Runnable() {
+        @Override
+        public void run() {
+          try {
+            data.put("first", first);
+            data.put("webrtc", true);
+            data.put("key", rCode + "-r");
+            if (first) {
+              first = false;
+              data.put("apiversion", SdkLevel.getLevel());
+            }
+            HttpClient client = new DefaultHttpClient();
+            HttpPost post = new HttpPost("http://" + rendezvousServer2 + "/rendezvous2/");
+            try {
+              if (DEBUG) {
+                Log.d(LOG_TAG, "About to send = " + data.toString());
+              }
+              post.setEntity(new StringEntity(data.toString()));
+              client.execute(post);
+            } catch (IOException e) {
+              Log.e(LOG_TAG, "sendRedezvous IOException", e);
+            }
+          } catch (Exception e) {
+            Log.e(LOG_TAG, "Exception in sendRendezvous", e);
+          }
         }
-        post.setEntity(new StringEntity(data.toString()));
-        client.execute(post);
-      } catch (IOException e) {
-        Log.e(LOG_TAG, "sendRedezvous IOException", e);
-      }
-    } catch (Exception e) {
-      Log.e(LOG_TAG, "Exception in sendRendezvous", e);
-    }
+      });
   }
 
   public void send(String output) {