feat(buffer): let buffer timeout/silosMaxNumber can be configured

Author: alexyu1989

Example/Example/ViewController.swift

@@ -153,15 +153,15 @@ extension ViewController: CocoaMQTTDelegate {
     }
 
     func mqtt(_ mqtt: CocoaMQTT, didPublishMessage message: CocoaMQTTMessage, id: UInt16) {
-        print("didPublishMessage with message: \(message.string)")
+        print("didPublishMessage with message: \(message.string ?? "")")
     }
 
     func mqtt(_ mqtt: CocoaMQTT, didPublishAck id: UInt16) {
         print("didPublishAck with id: \(id)")
     }
 
     func mqtt(_ mqtt: CocoaMQTT, didReceiveMessage message: CocoaMQTTMessage, id: UInt16 ) {
-        print("didReceivedMessage: \(message.string) with id \(id)")
+        print("didReceivedMessage: \(message.string ?? "") with id \(id)")
         let name = NSNotification.Name(rawValue: "MQTTMessageNotification" + animal!)
         NotificationCenter.default.post(name: name, object: self, userInfo: ["message": message.string!, "topic": message.topic])
     }

Source/CocoaMQTT.swift

@@ -136,7 +136,15 @@ open class CocoaMQTT: NSObject, CocoaMQTTClient, CocoaMQTTFrameBufferProtocol {
     open var dispatchQueue = DispatchQueue.main
 
     // flow control
-    var buffer = CocoaMQTTFrameBuffer()
+    fileprivate var buffer = CocoaMQTTFrameBuffer()
+    open var bufferSilosTimeout: Double {
+        get { return buffer.timeout }
+        set { buffer.timeout = newValue }
+    }
+    open var bufferSilosMaxNumber: UInt {
+        get { return buffer.silosMaxNumber }
+        set { buffer.silosMaxNumber = newValue }
+    }
 
 
     // heart beat
@@ -192,6 +200,7 @@ open class CocoaMQTT: NSObject, CocoaMQTTClient, CocoaMQTTFrameBufferProtocol {
         socket.disconnect()
     }
 
+    // MARK: CocoaMQTTFrameBufferProtocol
     public func buffer(_ buffer: CocoaMQTTFrameBuffer, sendPublishFrame frame: CocoaMQTTFramePublish) {
         send(frame, tag: Int(frame.msgid!))
     }

Source/CocoaMQTTFrame.swift

@@ -427,16 +427,17 @@ open class CocoaMQTTFrameBuffer: NSObject {
 
     // flow control
     fileprivate var silos = [CocoaMQTTFramePublish]()
-    fileprivate var silosMaxNumber = 10
     fileprivate var buffer = [CocoaMQTTFramePublish]()
     fileprivate var bufferSize = 1000
+    var silosMaxNumber: UInt = 10
+    var timeout: Double = 60
     //TODO: bufferCapacity
     //fileprivate var bufferCapacity = 50.MB // unit: byte
 
     //
     var isBufferEmpty: Bool { get { return buffer.count == 0 }}
     var isBufferFull : Bool { get { return buffer.count > bufferSize }}
-    var isSilosFull  : Bool { get { return silos.count >= silosMaxNumber }}
+    var isSilosFull  : Bool { get { return silos.count >= Int(silosMaxNumber) }}
 
 
     // return false means the frame is rejected because of the buffer is full
@@ -460,7 +461,7 @@ open class CocoaMQTTFrameBuffer: NSObject {
 
         send(frame)
 
-        Timer.after(60.seconds) {
+        Timer.after(timeout.seconds) {
             let msgid = frame.msgid!
             if self.removeFrameFromSilos(withMsgid: msgid) {
                 printDebug("timeout of frame:\(msgid)")