Rework concurrency in the signaling logic.

// FREEBIE

Podfile

@@ -5,7 +5,8 @@ target 'Signal' do
     pod 'SocketRocket',               :git => 'https://github.com/facebook/SocketRocket.git'
     pod 'AxolotlKit',                 git: 'https://github.com/WhisperSystems/SignalProtocolKit.git'
     #pod 'AxolotlKit',                 path: '../SignalProtocolKit'
-    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', branch: 'mkirk/webrtc'
+    #pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', branch: 'mkirk/webrtc'
+    pod 'SignalServiceKit',           git: 'https://github.com/WhisperSystems/SignalServiceKit.git', branch: 'charlesmchen/webrtc/threadSafety'
     #pod 'SignalServiceKit',           path: '../SignalServiceKit'
     pod 'OpenSSL'
     pod 'PastelogKit',                '~> 1.3'

Podfile.lock

@@ -123,7 +123,7 @@ DEPENDENCIES:
   - PastelogKit (~> 1.3)
   - PureLayout
   - SCWaveformView (~> 1.0)
-  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`, branch `mkirk/webrtc`)
+  - SignalServiceKit (from `https://github.com/WhisperSystems/SignalServiceKit.git`, branch `charlesmchen/webrtc/threadSafety`)
   - SocketRocket (from `https://github.com/facebook/SocketRocket.git`)
   - ZXingObjC
 
@@ -131,7 +131,7 @@ EXTERNAL SOURCES:
   AxolotlKit:
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :branch: mkirk/webrtc
+    :branch: charlesmchen/webrtc/threadSafety
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :git: https://github.com/facebook/SocketRocket.git
@@ -141,7 +141,7 @@ CHECKOUT OPTIONS:
     :commit: 919d541d6b8a8802a94f943026b8f68394e2c0b8
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :commit: 6521a80c44d3db20a0bd5acc6af2e30a9dbcbd6b
+    :commit: ddbc4819f1aa10e0164c1591dfc12cba49e04ed0
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 41b57bb2fc292a814f758441a05243eb38457027
@@ -173,6 +173,6 @@ SPEC CHECKSUMS:
   YapDatabase: b1e43555a34a5298e23a045be96817a5ef0da58f
   ZXingObjC: bf15b3814f7a105b6d99f47da2333c93a063650a
 
-PODFILE CHECKSUM: 9f2e2cf6d4db276e3d0280343260503d09c72979
+PODFILE CHECKSUM: beb37f2fe7d11b6d2a8124b03b20f903908fd8aa
 
 COCOAPODS: 1.0.1

Signal/src/Signal-Bridging-Header.h

@@ -13,6 +13,7 @@
 #import "OWSContactAvatarBuilder.h"
 #import "OWSContactsManager.h"
 #import "OWSDispatch.h"
+#import "OWSError.h"
 #import "OWSLogger.h"
 #import "OWSWebRTCDataProtos.pb.h"
 #import "PhoneNumber.h"

Signal/src/call/CallService.swift

@@ -635,10 +635,10 @@ protocol CallServiceObserver: class {
         callRecord.save()
 
         let message = DataChannelMessage.forConnected(callId: call.signalingId)
-        if peerConnectionClient.sendDataChannelMessage(data: message.asData()) {
-            Logger.debug("\(TAG) sendDataChannelMessage returned true")
-        } else {
-            Logger.warn("\(TAG) sendDataChannelMessage returned false")
+        peerConnectionClient.sendDataChannelMessage(data: message.asData()).then { _ in
+            Logger.debug("\(self.TAG) sendDataChannelMessage succeeded")
+            }.catch(on: DispatchQueue.main) { _ in
+                Logger.warn("\(self.TAG) sendDataChannelMessage failed")
         }
 
         handleConnectedCall(call)
@@ -737,10 +737,10 @@ protocol CallServiceObserver: class {
 
         // If the call is connected, we can send the hangup via the data channel.
         let message = DataChannelMessage.forHangup(callId: call.signalingId)
-        if peerConnectionClient.sendDataChannelMessage(data: message.asData()) {
-            Logger.debug("\(TAG) sendDataChannelMessage returned true")
-        } else {
-            Logger.warn("\(TAG) sendDataChannelMessage returned false")
+        peerConnectionClient.sendDataChannelMessage(data: message.asData()).then { _ in
+            Logger.debug("\(self.TAG) sendDataChannelMessage succeeded")
+            }.catch(on: DispatchQueue.main) { _ in
+                Logger.warn("\(self.TAG) sendDataChannelMessage failed")
         }
 
         // If the call hasn't started yet, we don't have a data channel to communicate the hang up. Use Signal Service Message.
@@ -1075,10 +1075,10 @@ protocol CallServiceObserver: class {
         self.peerConnectionClient?.setLocalVideoEnabled(enabled: shouldHaveLocalVideoTrack)
 
         let message = DataChannelMessage.forVideoStreamingStatus(callId: call.signalingId, enabled:shouldHaveLocalVideoTrack)
-        if peerConnectionClient.sendDataChannelMessage(data: message.asData()) {
-            Logger.debug("\(self.TAG) sendDataChannelMessage returned true")
-        } else {
-            Logger.warn("\(self.TAG) sendDataChannelMessage returned false")
+        peerConnectionClient.sendDataChannelMessage(data: message.asData()).then { _ in
+            Logger.debug("\(self.TAG) sendDataChannelMessage succeeded")
+            }.catch(on: DispatchQueue.main) { _ in
+                Logger.warn("\(self.TAG) sendDataChannelMessage failed")
         }
     }
 

Signal/src/call/PeerConnectionClient.swift

@@ -80,7 +80,7 @@ class PeerConnectionClient: NSObject, RTCPeerConnectionDelegate, RTCDataChannelD
     private weak var delegate: PeerConnectionClientDelegate!
 
     func setDelegate(delegate: PeerConnectionClientDelegate?) {
-        PeerConnectionClient.signalingQueue.sync {
+        PeerConnectionClient.signalingQueue.async {
             self.delegate = delegate
         }
     }
@@ -112,6 +112,8 @@ class PeerConnectionClient: NSObject, RTCPeerConnectionDelegate, RTCDataChannelD
     private var cameraConstraints: RTCMediaConstraints
 
     init(iceServers: [RTCIceServer], delegate: PeerConnectionClientDelegate) {
+        AssertIsOnMainThread()
+
         self.iceServers = iceServers
         self.delegate = delegate
 
@@ -140,6 +142,8 @@ class PeerConnectionClient: NSObject, RTCPeerConnectionDelegate, RTCDataChannelD
     // MARK: - Media Streams
 
     public func createSignalingDataChannel() {
+        AssertIsOnMainThread()
+        
         PeerConnectionClient.signalingQueue.sync {
             let dataChannel = peerConnection.dataChannel(forLabel: Identifiers.dataChannelSignaling.rawValue,
                                                          configuration: RTCDataChannelConfiguration())
@@ -400,23 +404,26 @@ class PeerConnectionClient: NSObject, RTCPeerConnectionDelegate, RTCDataChannelD
 
     // MARK: - Data Channel
 
-    public func sendDataChannelMessage(data: Data) -> Bool {
+    public func sendDataChannelMessage(data: Data) -> Promise<Bool> {
         AssertIsOnMainThread()
+        
+        return Promise { fulfill, reject in
+            AssertIsOnMainThread()
+            
+            PeerConnectionClient.signalingQueue.async {
+                self.assertOnSignalingQueue()
 
-        var result = false
-        PeerConnectionClient.signalingQueue.sync {
-            assertOnSignalingQueue()
-
-            guard let dataChannel = self.dataChannel else {
-                Logger.error("\(self.TAG) in \(#function) ignoring sending \(data) for nil dataChannel")
-                result = false
-                return
+                guard let dataChannel = self.dataChannel else {
+                    Logger.error("\(self.TAG) in \(#function) ignoring sending \(data) for nil dataChannel")
+                    reject(OWSErrorMakeWebRTCMissingDataChannelError())
+                    return
+                }
+                
+                let buffer = RTCDataBuffer(data: data, isBinary: false)
+                let result = dataChannel.sendData(buffer)
+                fulfill(result)
             }
-
-            let buffer = RTCDataBuffer(data: data, isBinary: false)
-            result = dataChannel.sendData(buffer)
         }
-        return result
     }
 
     // MARK: RTCDataChannelDelegate

Signal/translations/en.lproj/Localizable.strings

@@ -250,6 +250,9 @@
 /* Error message when attempting to send message */
 "ERROR_DESCRIPTION_UNREGISTERED_RECIPIENT" = "Recipient is no longer a Signal user.";
 
+/* Missing data channel while trying to sending message */
+"ERROR_DESCRIPTION_WEBRTC_MISSING_DATA_CHANNEL" = "Missing connection";
+
 /* No comment provided by engineer. */
 "ERROR_MESSAGE_DUPLICATE_MESSAGE" = "Received a duplicated message.";