Merge pull request #68 from pusher/more-robust-reconnect

More robust reconnect

Author: hamchapman

Example/Main.storyboard

@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="7702" systemVersion="14D136" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="yEm-Wa-8Rj">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="10117" systemVersion="15F34" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="yEm-Wa-8Rj">
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="7701"/>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="10085"/>
     </dependencies>
     <scenes>
         <!--View Controller-->
@@ -13,14 +14,39 @@
                         <viewControllerLayoutGuide type="bottom" id="r12-OR-bkP"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="y96-ws-RaM">
-                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
+                        <rect key="frame" x="0.0" y="0.0" width="320" height="568"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="pak-HB-Rmg">
+                                <rect key="frame" x="122" y="132" width="78" height="30"/>
+                                <state key="normal" title="Disconnect"/>
+                                <connections>
+                                    <action selector="disconnectButton:" destination="yEm-Wa-8Rj" eventType="touchUpInside" id="DIg-Tc-6e2"/>
+                                </connections>
+                            </button>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="zrh-9X-Fym">
+                                <rect key="frame" x="122" y="38" width="78" height="30"/>
+                                <state key="normal" title="Connect"/>
+                                <connections>
+                                    <action selector="connectButton:" destination="yEm-Wa-8Rj" eventType="touchUpInside" id="Hla-Ru-KoR"/>
+                                </connections>
+                            </button>
+                        </subviews>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
+                        <constraints>
+                            <constraint firstItem="pak-HB-Rmg" firstAttribute="width" secondItem="zrh-9X-Fym" secondAttribute="width" id="4lR-eK-ZIZ"/>
+                            <constraint firstItem="pak-HB-Rmg" firstAttribute="centerX" secondItem="y96-ws-RaM" secondAttribute="centerX" constant="1" id="55L-vA-Tvc"/>
+                            <constraint firstItem="zrh-9X-Fym" firstAttribute="centerX" secondItem="y96-ws-RaM" secondAttribute="centerX" constant="1" id="BgE-CD-tkr"/>
+                            <constraint firstItem="pak-HB-Rmg" firstAttribute="height" secondItem="zrh-9X-Fym" secondAttribute="height" id="VhG-sC-yO0"/>
+                            <constraint firstItem="pak-HB-Rmg" firstAttribute="top" secondItem="fji-4t-sKP" secondAttribute="bottom" constant="112" id="aX3-md-844"/>
+                            <constraint firstItem="zrh-9X-Fym" firstAttribute="top" secondItem="fji-4t-sKP" secondAttribute="bottom" constant="18" id="goe-io-Zww"/>
+                        </constraints>
                     </view>
+                    <simulatedScreenMetrics key="simulatedDestinationMetrics" type="retina4"/>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="weS-V8-jg5" userLabel="First Responder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="3746" y="98"/>
+            <point key="canvasLocation" x="3745.5" y="97.5"/>
         </scene>
     </scenes>
 </document>

Example/ViewController.swift

@@ -10,14 +10,23 @@ import UIKit
 import PusherSwift
 
 class ViewController: UIViewController, ConnectionStateChangeDelegate {
+    var pusher: Pusher! = nil
+
+    @IBAction func connectButton(sender: AnyObject) {
+        pusher.connect()
+    }
+
+    @IBAction func disconnectButton(sender: AnyObject) {
+        pusher.disconnect()
+    }
 
     override func viewDidLoad() {
         super.viewDidLoad()
 
         // Only use your secret here for testing or if you're sure that there's
         // no security risk
         let pusherClientOptions = PusherClientOptions(authMethod: .Internal(secret: "YOUR_APP_SECRET"))
-        let pusher = Pusher(key: "YOUR_APP_KEY", options: pusherClientOptions)
+        pusher = Pusher(key: "YOUR_APP_KEY", options: pusherClientOptions)
 
         // remove the debugLogger from the client options if you want to remove the
         // debug logging, or just change the function below
@@ -44,7 +53,7 @@ class ViewController: UIViewController, ConnectionStateChangeDelegate {
 
         chan.bind("test-event", callback: { (data: AnyObject?) -> Void in
             print(data)
-            pusher.subscribe("presence-channel", onMemberAdded: onMemberAdded)
+            self.pusher.subscribe("presence-channel", onMemberAdded: onMemberAdded)
 
             if let data = data as? [String : AnyObject] {
                 if let testVal = data["test"] as? String {

README.md

@@ -17,6 +17,8 @@ What else would you want? Head over to the example app [ViewController.swift](ht
 * [Installation](#installation)
 * [Configuration](#configuration)
 * [Connection](#connection)
+  * [Connection state changes](#connection-state-changes)
+  * [Reconnection](#reconnection)
 * [Subscribing to channels](#subscribing)
 * [Binding to events](#binding-to-events)
   * [Globally](#global-events)
@@ -204,6 +206,39 @@ class ViewController: UIViewController, ConnectionStateChangeDelegate {
 }
 ```
 
+The different states that the connection can be in are:
+
+* `Connecting` - the connection is about to attempt to be made
+* `Connected` - the connection has been successfully made
+* `Disconnecting` - the connection has been instructed to disconnect and it is just about to do so
+* `Disconnected` - the connection has disconnected and no attempt will be made to reconnect automatically
+* `Reconnecting` - an attempt is going to be made to try and re-establish the connection
+* `ReconnectingWhenNetworkBecomesReachable` - when the network becomes reachable an attempt will be made to reconnect
+
+
+### Reconnection
+
+There are three main ways in which a disconnection can occur:
+
+  * The client explicitly calls disconnect and a close frame is sent over the websocket connection
+  * The client experiences some form of network degradation which leads to a heartbeat (ping/pong) message being missed and thus the client disconnects
+  * The Pusher server closes the websocket connection; typically this will only occur during a restart of the Pusher socket servers and an almost immediate reconnection should occur
+
+In the case of the first type of disconnection the library will (as you'd hope) not attempt a reconnection.
+
+If there is network degradation that leads to a disconnection then the library has the [Reachability](https://github.com/ashleymills/Reachability.swift) library embedded and will be able to automatically determine when to attempt a reconnect based on the changing network conditions.
+
+If the Pusher servers close the websocket then the library will attempt to reconnect (by default) a maximum of 6 times, with an exponential backoff. The value of `reconnectAttemptsMax` is a public property on the `PusherConnection` and so can be changed if you wish.
+
+All of this is the case if you have the client option of `autoReconnect` set as `true`, which it is by default. If the reconnection strategies are not suitable for your use case then you can set `autoReconnect` to `false` and implement your own reconnection strategy based on the connection state changes.
+
+There are a couple of properties on the connection (`PusherConnection`) that you can set that affect how the reconnection behaviour works. These are:
+
+* `public var reconnectAttemptsMax: Int? = 6` - if you set this to `nil` then there is no maximum number of reconnect attempts and so attempts will continue to be made with an exponential backoff (based on number of attempts), otherwise only as many attempts as this property's value will be made before the connection's state moves to `.Disconnected`
+* `public var maxReconnectGapInSeconds: Double? = nil` - if you want to set a maximum length of time (in seconds) between reconnect attempts then set this property appropriately
+
+Note that the number of reconnect attempts gets reset to 0 as soon as a successful connection is made.
+
 ## Subscribing
 
 ### Public channels

Source/PusherConnection.swift

@@ -22,19 +22,21 @@ public class PusherConnection {
     public var userDataFetcher: (() -> PusherUserData)?
     public var debugLogger: ((String) -> ())?
     public weak var stateChangeDelegate: ConnectionStateChangeDelegate?
-    internal var reconnectOperation: NSOperation?
+    public var reconnectAttemptsMax: Int? = 6
+    public var reconnectAttempts: Int = 0
+    public var maxReconnectGapInSeconds: Double? = nil
+    internal var reconnectTimer: NSTimer? = nil
 
     public lazy var reachability: Reachability? = {
         let reachability = try? Reachability.reachabilityForInternetConnection()
         reachability?.whenReachable = { [unowned self] reachability in
-            self.reconnectOperation?.cancel()
-            if self.connectionState == .Disconnected {
-                self.socket.connect()
+            self.debugLogger?("[PUSHER DEBUG] Network reachable")
+            if self.connectionState == .Disconnected || self.connectionState == .ReconnectingWhenNetworkBecomesReachable {
+                self.attemptReconnect()
             }
         }
         reachability?.whenUnreachable = { [unowned self] reachability in
-            self.reconnectOperation?.cancel()
-            print("Network unreachable")
+            self.debugLogger?("[PUSHER DEBUG] Network unreachable")
         }
         return reachability
     }()
@@ -178,13 +180,14 @@ public class PusherConnection {
     /**
         Establish a websocket connection
     */
-    public func connect() {
+    @objc public func connect() {
         if self.connectionState == .Connected {
             return
         } else {
             updateConnectionState(.Connecting)
             self.socket.connect()
             if self.options.autoReconnect {
+                // can call this multiple times and only one notifier will be started
                 _ = try? reachability?.startNotifier()
             }
         }
@@ -278,6 +281,9 @@ public class PusherConnection {
                 updateConnectionState(.Connected)
                 self.socketId = socketId
 
+                self.reconnectAttempts = 0
+                self.reconnectTimer?.invalidate()
+
                 for (_, channel) in self.channels.channels {
                     if !channel.subscribed {
                         if !self.authorize(channel) {
@@ -356,7 +362,6 @@ public class PusherConnection {
             if let jsonData = data, jsonObject = try NSJSONSerialization.JSONObjectWithData(jsonData, options: []) as? [String : AnyObject] {
                 return jsonObject
             } else {
-                // TODO: Move below
                 print("Unable to parse string from WebSocket: \(string)")
             }
         } catch let error as NSError {
@@ -663,6 +668,8 @@ public enum ConnectionState {
     case Connected
     case Disconnecting
     case Disconnected
+    case Reconnecting
+    case ReconnectingWhenNetworkBecomesReachable
 }
 
 public protocol ConnectionStateChangeDelegate: class {

Source/PusherWebsocketDelegate.swift

@@ -7,7 +7,6 @@
 //
 
 extension PusherConnection: WebSocketDelegate {
-    // MARK: WebSocketDelegate Implementation
 
     /**
         Delegate method called when a message is received over a websocket
@@ -31,36 +30,75 @@ extension PusherConnection: WebSocketDelegate {
         - parameter error: The error, if one exists, when disconnected
     */
     public func websocketDidDisconnect(ws: WebSocket, error: NSError?) {
-
-        updateConnectionState(.Disconnected)
-        for (_, channel) in self.channels.channels {
-            channel.subscribed = false
+        // Handles setting channel subscriptions to unsubscribed wheter disconnection
+        // is intentional or not
+        if connectionState == .Disconnecting || connectionState == .Connected {
+            for (_, channel) in self.channels.channels {
+                channel.subscribed = false
+            }
         }
 
         // Handle error (if any)
         guard let error = error where error.code != Int(WebSocket.CloseCode.Normal.rawValue) else {
-            return
+            self.debugLogger?("[PUSHER DEBUG] Deliberate disconnection - skipping reconnect attempts")
+            return updateConnectionState(.Disconnected)
         }
 
         print("Websocket is disconnected. Error: \(error.localizedDescription)")
+        // Attempt reconnect if possible
 
-        // Reconnect if possible
-        if self.options.autoReconnect {
-            if let reachability = self.reachability where reachability.isReachable() {
-                let operation = NSBlockOperation {
-                    self.socket.connect()
-                }
+        guard self.options.autoReconnect else {
+            return updateConnectionState(.Disconnected)
+        }
 
-                dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(NSEC_PER_SEC)), dispatch_get_main_queue()) {
-                    NSOperationQueue.mainQueue().addOperation(operation)
-                }
+        guard reconnectAttemptsMax == nil || reconnectAttempts < reconnectAttemptsMax! else {
+            self.debugLogger?("[PUSHER DEBUG] Max reconnect attempts reached")
+            return updateConnectionState(.Disconnected)
+        }
 
-                self.reconnectOperation?.cancel()
-                self.reconnectOperation = operation
-            }
+        guard let reachability = self.reachability where reachability.isReachable() else {
+            self.debugLogger?("[PUSHER DEBUG] Network unreachable so waiting to attempt reconnect")
+            return updateConnectionState(.ReconnectingWhenNetworkBecomesReachable)
         }
+
+        if connectionState != .Reconnecting {
+            updateConnectionState(.Reconnecting)
+        }
+        self.debugLogger?("[PUSHER DEBUG] Network reachable so will setup reconnect attempt")
+
+        attemptReconnect()
     }
 
+    /**
+        Attempt to reconnect triggered by a disconnection
+    */
+    internal func attemptReconnect() {
+        guard connectionState != .Connected else {
+            return
+        }
+
+        guard reconnectAttemptsMax == nil || reconnectAttempts < reconnectAttemptsMax! else {
+            return
+        }
+
+        let reconnectInterval = Double(reconnectAttempts * reconnectAttempts)
+
+        let timeInterval = maxReconnectGapInSeconds != nil ? min(reconnectInterval, maxReconnectGapInSeconds!)
+                                                           : reconnectInterval
+
+        self.debugLogger?("[PUSHER DEBUG] Waiting \(timeInterval) seconds before attempting to reconnect (attempt \(reconnectAttempts + 1) of \(reconnectAttemptsMax!))")
+
+        reconnectTimer = NSTimer.scheduledTimerWithTimeInterval(
+            timeInterval,
+            target: self,
+            selector: #selector(connect),
+            userInfo: nil,
+            repeats: false
+        )
+        reconnectAttempts += 1
+    }
+
+
     public func websocketDidConnect(ws: WebSocket) {}
     public func websocketDidReceiveData(ws: WebSocket, data: NSData) {}
 }

Tests/PusherIncomingEventHandlingTests.swift

@@ -104,7 +104,11 @@ class HandlingIncomingEventsSpec: QuickSpec {
             }
 
             it("should pass incoming messages to the debugLogger if one is set") {
-                let debugLogger = { (text: String) in socket.appendToCallbackCheckString(text) }
+                let debugLogger = { (text: String) in
+                    if text.rangeOfString("websocketDidReceiveMessage") != nil {
+                        socket.appendToCallbackCheckString(text)
+                    }
+                }
                 pusher = Pusher(key: key)
                 pusher.connection.debugLogger = debugLogger
                 socket.delegate = pusher.connection