Add network logging tool

Only available in Debug configuration.

Author: Clément Le Provost

Source/Network.swift

@@ -41,3 +41,159 @@ protocol URLSession {
 extension NSURLSession: URLSession {
 }
 
+
+#if DEBUG
+
+import CoreTelephony
+import SystemConfiguration
+
+/// Wrapper around an `NSURLSession`, adding logging facilities.
+///
+class URLSessionLogger: NSObject, URLSession {
+    static var epoch: NSDate!
+    
+    struct RequestStat {
+        // TODO: Log network type.
+        let startTime: NSDate
+        let host: String
+        var networkType: String?
+        var responseTime: NSTimeInterval?
+        var cancelled: Bool = false
+        var dataSize: Int?
+        var statusCode: Int?
+        
+        init(startTime: NSDate, host: String) {
+            self.startTime = startTime
+            self.host = host
+        }
+        
+        var description: String {
+            var description = "@\(Int(startTime.timeIntervalSinceDate(URLSessionLogger.epoch) * 1000))ms; \(host); \(networkType != nil ? networkType! : "?")"
+            if let responseTime = responseTime, dataSize = dataSize, statusCode = statusCode {
+                description += "; \(Int(responseTime * 1000))ms; \(dataSize)B; \(statusCode)"
+            }
+            return description
+        }
+    }
+    
+    /// The wrapped session.
+    let session: NSURLSession
+    
+    /// Stats.
+    private(set) var stats: [RequestStat] = []
+    
+    /// Queue used to serialize concurrent accesses to this object.
+    private let queue = dispatch_queue_create(nil, DISPATCH_QUEUE_SERIAL)
+    
+    /// Temporary stats under construction (ongoing requests).
+    private var tmpStats: [NSURLSessionTask: RequestStat] = [:]
+    
+    /// Used to determine overall network type.
+    private let defaultRouteReachability: SCNetworkReachability
+    
+    /// Used to get the mobile data network type.
+    private let networkInfo = CTTelephonyNetworkInfo()
+    
+    init(session: NSURLSession) {
+        self.session = session
+        var zeroAddress = sockaddr_in()
+        zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
+        zeroAddress.sin_family = sa_family_t(AF_INET)
+        defaultRouteReachability = withUnsafePointer(&zeroAddress) {
+            SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))!
+        }
+        
+        // Reset the (global) epoch for logging.
+        URLSessionLogger.epoch = NSDate()
+    }
+    
+    func dataTaskWithRequest(request: NSURLRequest, completionHandler: (NSData?, NSURLResponse?, NSError?) -> Void) -> NSURLSessionDataTask {
+        var task: NSURLSessionDataTask!
+        let startTime = NSDate()
+        let networkType = getNetworkType()
+        task = session.dataTaskWithRequest(request, completionHandler: completionHandler)
+        dispatch_sync(self.queue) {
+            self.tmpStats[task] = RequestStat(startTime: startTime, host: request.URL!.host!)
+            self.tmpStats[task]?.networkType = networkType
+        }
+        task.addObserver(self, forKeyPath: "state", options: .New, context: nil)
+        return task
+    }
+    
+    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
+        if let task = object as? NSURLSessionTask {
+            if keyPath == "state" {
+                if task.state == .Canceling {
+                    dispatch_sync(self.queue) {
+                        self.tmpStats[task]!.cancelled = true
+                    }
+                }
+                if task.state == .Completed {
+                    let stopTime = NSDate()
+                    dispatch_sync(self.queue) {
+                        var stat = self.tmpStats[task]!
+                        stat.responseTime = stopTime.timeIntervalSinceDate(stat.startTime)
+                        stat.dataSize = Int(task.countOfBytesReceived)
+                        if let response = task.response as? NSHTTPURLResponse {
+                            stat.statusCode = response.statusCode
+                        } else if let error = task.error {
+                            stat.statusCode = error.code
+                        }
+                        self.stats.append(stat)
+                        self.tmpStats.removeValueForKey(task)
+                    }
+                    task.removeObserver(self, forKeyPath: "state")
+                    dump()
+                }
+            }
+        }
+    }
+    
+    func dump() {
+        dispatch_sync(self.queue) {
+            for stat in self.stats {
+                print("[NET] \(stat.description)")
+            }
+            self.stats.removeAll()
+        }
+    }
+    
+    // MARK: Network status
+    
+    /// Return the current network type as a human-friendly string.
+    ///
+    private func getNetworkType() -> String? {
+        var flags = SCNetworkReachabilityFlags()
+        if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
+            if flags.contains(.IsWWAN) {
+                if let technology = networkInfo.currentRadioAccessTechnology {
+                    return URLSessionLogger.radioAccessTechnologyDescription(technology)
+                }
+            } else {
+                return "WIFI"
+            }
+        }
+        return nil
+    }
+
+    /// Convert one of the enum-like `CTRadioAccessTechnology*` constants into a human-friendly string.
+    ///
+    static func radioAccessTechnologyDescription(radioAccessTechnology: String) -> String {
+        switch (radioAccessTechnology) {
+        case CTRadioAccessTechnologyGPRS: return "GPRS"
+        case CTRadioAccessTechnologyEdge: return "EDGE"
+        case CTRadioAccessTechnologyWCDMA: return "WCDMA"
+        case CTRadioAccessTechnologyHSDPA: return "HSDPA"
+        case CTRadioAccessTechnologyHSUPA: return "HSUPA"
+        case CTRadioAccessTechnologyCDMA1x: return "CDMA(1x)"
+        case CTRadioAccessTechnologyCDMAEVDORev0: return "CDMA(EVDORev0)"
+        case CTRadioAccessTechnologyCDMAEVDORevA: return "CDMA(EVDORevA)"
+        case CTRadioAccessTechnologyCDMAEVDORevB: return "CDMA(EVDORevB)"
+        case CTRadioAccessTechnologyeHRPD: return "HRPD"
+        case CTRadioAccessTechnologyLTE: return "LTE"
+        default: return "?"
+        }
+    }
+}
+
+#endif // DBEUG