Add optional write completion handler for emit's

Source/SocketIO/Client/SocketIOClient.swift

@@ -213,7 +213,26 @@ open class SocketIOClient : NSObject, SocketIOClientSpec {
     /// - parameter items: The items to send with this event. May be left out.
     open func emit(_ event: String, _ items: SocketData...) {
         do {
-            try emit(event, with: items.map({ try $0.socketRepresentation() }))
+            try emit(event, with: items.map({ try $0.socketRepresentation() }), completion: {})
+        } catch {
+            DefaultSocketLogger.Logger.error("Error creating socketRepresentation for emit: \(event), \(items)",
+                                             type: logType)
+
+            handleClientEvent(.error, data: [event, items, error])
+        }
+    }
+
+    /// Send an event to the server, with optional data items and write completion handler.
+    ///
+    /// If an error occurs trying to transform `items` into their socket representation, a `SocketClientEvent.error`
+    /// will be emitted. The structure of the error data is `[eventName, items, theError]`
+    ///
+    /// - parameter event: The event to send.
+    /// - parameter items: The items to send with this event. May be left out.
+    /// - parameter completion: Callback called on transport write completion.
+    open func emit(_ event: String, _ items: SocketData..., completion: @escaping () -> ())  {
+        do {
+            try emit(event, with: items.map({ try $0.socketRepresentation() }), completion: completion)
         } catch {
             DefaultSocketLogger.Logger.error("Error creating socketRepresentation for emit: \(event), \(items)",
                                              type: logType)
@@ -228,7 +247,17 @@ open class SocketIOClient : NSObject, SocketIOClientSpec {
     /// - parameter items: The items to send with this event. Send an empty array to send no data.
     @objc
     open func emit(_ event: String, with items: [Any]) {
-        emit([event] + items)
+        emit([event] + items, completion: {})
+    }
+
+    /// Same as emit, but meant for Objective-C
+    ///
+    /// - parameter event: The event to send.
+    /// - parameter items: The items to send with this event. Send an empty array to send no data.
+    /// - parameter completion: Callback called on transport write completion.
+    @objc
+    open func emit(_ event: String, with items: [Any], completion: @escaping () -> ()) {
+        emit([event] + items, completion: completion)
     }
 
     /// Sends a message to the server, requesting an ack.
@@ -284,8 +313,15 @@ open class SocketIOClient : NSObject, SocketIOClientSpec {
         return createOnAck([event] + items)
     }
 
-    func emit(_ data: [Any], ack: Int? = nil, binary: Bool = true, isAck: Bool = false) {
+    func emit(_ data: [Any], ack: Int? = nil, binary: Bool = true, isAck: Bool = false, completion: (() -> ())? = nil) {
+        // wrap the completion handler so it always runs async via handlerQueue
+        let wrappedCompletion = {[weak self] in
+            guard let this = self else { return }
+            this.manager?.handleQueue.async { completion?() }
+        }
+
         guard status == .connected else {
+            wrappedCompletion();
             handleClientEvent(.error, data: ["Tried emitting when not connected"])
             return
         }
@@ -295,7 +331,7 @@ open class SocketIOClient : NSObject, SocketIOClientSpec {
 
         DefaultSocketLogger.Logger.log("Emitting: \(str), Ack: \(isAck)", type: logType)
 
-        manager?.engine?.send(str, withData: packet.binary)
+        manager?.engine?.send(str, withData: packet.binary, completion: completion != nil ? wrappedCompletion : nil)
     }
 
     /// Call when you wish to tell the server that you've received the event for `ack`.

Source/SocketIO/Client/SocketIOClientSpec.swift

@@ -101,6 +101,16 @@ public protocol SocketIOClientSpec : AnyObject {
     /// - parameter items: The items to send with this event. May be left out.
     func emit(_ event: String, _ items: SocketData...)
 
+    /// Send an event to the server, with optional data items and write completion handler.
+    ///
+    /// If an error occurs trying to transform `items` into their socket representation, a `SocketClientEvent.error`
+    /// will be emitted. The structure of the error data is `[eventName, items, theError]`
+    ///
+    /// - parameter event: The event to send.
+    /// - parameter items: The items to send with this event. May be left out.
+    /// - parameter completion: Callback called on transport write completion.
+    func emit(_ event: String, _ items: SocketData..., completion: @escaping () -> ())
+
     /// Call when you wish to tell the server that you've received the event for `ack`.
     ///
     /// - parameter ack: The ack number.

Source/SocketIO/Engine/SocketEngine.swift

@@ -49,7 +49,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
     /// A queue of engine.io messages waiting for POSTing
     ///
     /// **You should not touch this directly**
-    public var postWait = [String]()
+    public var postWait = [Post]()
 
     /// `true` if there is an outstanding poll. Trying to poll before the first is done will cause socket.io to
     /// disconnect us.
@@ -340,15 +340,15 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
         if polling {
             disconnectPolling(reason: reason)
         } else {
-            sendWebSocketMessage("", withType: .close, withData: [])
+            sendWebSocketMessage("", withType: .close, withData: [], completion: {})
             closeOutEngine(reason: reason)
         }
     }
 
     // We need to take special care when we're polling that we send it ASAP
     // Also make sure we're on the emitQueue since we're touching postWait
     private func disconnectPolling(reason: String) {
-        postWait.append(String(SocketEnginePacketType.close.rawValue))
+        postWait.append((String(SocketEnginePacketType.close.rawValue), {}))
 
         doRequest(for: createRequestForPostWithPostWait()) {_, _, _ in }
         closeOutEngine(reason: reason)
@@ -366,7 +366,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
 
         DefaultSocketLogger.Logger.log("Switching to WebSockets", type: SocketEngine.logType)
 
-        sendWebSocketMessage("", withType: .upgrade, withData: [])
+        sendWebSocketMessage("", withType: .upgrade, withData: [], completion: {})
         polling = false
         fastUpgrade = false
         probing = false
@@ -384,7 +384,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
         DefaultSocketLogger.Logger.log("Flushing probe wait", type: SocketEngine.logType)
 
         for waiter in probeWait {
-            write(waiter.msg, withType: waiter.type, withData: waiter.data)
+            write(waiter.msg, withType: waiter.type, withData: waiter.data, completion:waiter.completion)
         }
 
         probeWait.removeAll(keepingCapacity: false)
@@ -398,7 +398,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
         guard let ws = self.ws else { return }
 
         for msg in postWait {
-            ws.write(string: msg)
+            ws.write(string: msg.msg, completion: msg.completion)
         }
 
         postWait.removeAll(keepingCapacity: false)
@@ -544,7 +544,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
         }
 
         pongsMissed += 1
-        write("", withType: .ping, withData: [])
+        write("", withType: .ping, withData: [], completion: {})
 
         engineQueue.asyncAfter(deadline: DispatchTime.now() + .milliseconds(pingInterval)) {[weak self, id = self.sid] in
             // Make sure not to ping old connections
@@ -600,7 +600,7 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
             DefaultSocketLogger.Logger.log("Upgrading transport to WebSockets", type: SocketEngine.logType)
 
             fastUpgrade = true
-            sendPollMessage("", withType: .noop, withData: [])
+            sendPollMessage("", withType: .noop, withData: [], completion: {})
             // After this point, we should not send anymore polling messages
         }
     }
@@ -610,23 +610,27 @@ open class SocketEngine : NSObject, URLSessionDelegate, SocketEnginePollable, So
     /// - parameter msg: The message to send.
     /// - parameter type: The type of this message.
     /// - parameter data: Any data that this message has.
-    open func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data]) {
+    /// - parameter completion: Callback called on transport write completion.
+    open func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data], completion: @escaping () -> ()) {
         engineQueue.async {
-            guard self.connected else { return }
+            guard self.connected else {
+                completion()
+                return
+            }
             guard !self.probing else {
-                self.probeWait.append((msg, type, data))
+                self.probeWait.append((msg, type, data, completion))
 
                 return
             }
 
             if self.polling {
                 DefaultSocketLogger.Logger.log("Writing poll: \(msg) has data: \(data.count != 0)",
                                                type: SocketEngine.logType)
-                self.sendPollMessage(msg, withType: type, withData: data)
+                self.sendPollMessage(msg, withType: type, withData: data, completion: completion)
             } else {
                 DefaultSocketLogger.Logger.log("Writing ws: \(msg) has data: \(data.count != 0)",
                                                type: SocketEngine.logType)
-                self.sendWebSocketMessage(msg, withType: type, withData: data)
+                self.sendWebSocketMessage(msg, withType: type, withData: data, completion: completion)
             }
         }
     }

Source/SocketIO/Engine/SocketEnginePollable.swift

@@ -34,7 +34,7 @@ public protocol SocketEnginePollable : SocketEngineSpec {
     /// A queue of engine.io messages waiting for POSTing
     ///
     /// **You should not touch this directly**
-    var postWait: [String] { get set }
+    var postWait: [Post] { get set }
 
     /// The URLSession that will be used for polling.
     var session: URLSession? { get }
@@ -65,7 +65,7 @@ public protocol SocketEnginePollable : SocketEngineSpec {
     /// - parameter message: The message to send.
     /// - parameter withType: The type of message to send.
     /// - parameter withData: The data associated with this message.
-    func sendPollMessage(_ message: String, withType type: SocketEnginePacketType, withData datas: [Data])
+    func sendPollMessage(_ message: String, withType type: SocketEnginePacketType, withData datas: [Data], completion: @escaping () -> ())
 
     /// Call to stop polling and invalidate the URLSession.
     func stopPolling()
@@ -74,12 +74,15 @@ public protocol SocketEnginePollable : SocketEngineSpec {
 // Default polling methods
 extension SocketEnginePollable {
     func createRequestForPostWithPostWait() -> URLRequest {
-        defer { postWait.removeAll(keepingCapacity: true) }
+        defer {
+            for packet in postWait { packet.completion() }
+            postWait.removeAll(keepingCapacity: true)
+        }
 
         var postStr = ""
 
         for packet in postWait {
-            postStr += "\(packet.utf16.count):\(packet)"
+            postStr += "\(packet.msg.utf16.count):\(packet.msg)"
         }
 
         DefaultSocketLogger.Logger.log("Created POST string: \(postStr)", type: "SocketEnginePolling")
@@ -209,14 +212,17 @@ extension SocketEnginePollable {
     /// - parameter message: The message to send.
     /// - parameter withType: The type of message to send.
     /// - parameter withData: The data associated with this message.
-    public func sendPollMessage(_ message: String, withType type: SocketEnginePacketType, withData datas: [Data]) {
+    /// - parameter completion: Callback called on transport write completion.
+    public func sendPollMessage(_ message: String, withType type: SocketEnginePacketType, withData datas: [Data], completion: @escaping () -> ()) {
         DefaultSocketLogger.Logger.log("Sending poll: \(message) as type: \(type.rawValue)", type: "SocketEnginePolling")
 
-        postWait.append(String(type.rawValue) + message)
+        postWait.append((String(type.rawValue) + message, completion))
 
         for data in datas {
             if case let .right(bin) = createBinaryDataForSend(using: data) {
-                postWait.append(bin)
+                // completion handler will be called on initial message write
+                //     TODO: call completion after last message in batch
+                postWait.append((bin, {}))
             }
         }
 

Source/SocketIO/Engine/SocketEngineSpec.swift

@@ -137,7 +137,8 @@ import Starscream
     /// - parameter msg: The message to send.
     /// - parameter type: The type of this message.
     /// - parameter data: Any data that this message has.
-    func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data])
+    /// - parameter completion: Callback called on transport write completion.
+    func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data], completion: @escaping () -> ())
 }
 
 extension SocketEngineSpec {
@@ -162,7 +163,7 @@ extension SocketEngineSpec {
         if !cookiesToAdd.isEmpty {
             req.allHTTPHeaderFields = HTTPCookie.requestHeaderFields(with: cookiesToAdd)
         }
-        
+
         if let extraHeaders = extraHeaders {
             for (headerName, value) in extraHeaders {
                 req.setValue(value, forHTTPHeaderField: headerName)
@@ -179,7 +180,7 @@ extension SocketEngineSpec {
     }
 
     /// Send an engine message (4)
-    func send(_ msg: String, withData datas: [Data]) {
-        write(msg, withType: .message, withData: datas)
+    func send(_ msg: String, withData datas: [Data], completion: (() -> ())? = nil) {
+        write(msg, withType: .message, withData: datas, completion: completion ?? {})
     }
 }

Source/SocketIO/Engine/SocketEngineWebsocket.swift

@@ -37,14 +37,15 @@ public protocol SocketEngineWebsocket : SocketEngineSpec {
     /// - parameter message: The message to send.
     /// - parameter withType: The type of message to send.
     /// - parameter withData: The data associated with this message.
-    func sendWebSocketMessage(_ str: String, withType type: SocketEnginePacketType, withData datas: [Data])
+    /// - parameter completion: Callback called on transport write completion.
+    func sendWebSocketMessage(_ str: String, withType type: SocketEnginePacketType, withData datas: [Data], completion: @escaping () -> ())
 }
 
 // WebSocket methods
 extension SocketEngineWebsocket {
     func probeWebSocket() {
         if ws?.isConnected ?? false {
-            sendWebSocketMessage("probe", withType: .ping, withData: [])
+            sendWebSocketMessage("probe", withType: .ping, withData: [], completion: {})
         }
     }
 
@@ -55,14 +56,15 @@ extension SocketEngineWebsocket {
     /// - parameter message: The message to send.
     /// - parameter withType: The type of message to send.
     /// - parameter withData: The data associated with this message.
-    public func sendWebSocketMessage(_ str: String, withType type: SocketEnginePacketType, withData datas: [Data]) {
+    /// - parameter completion: Callback called on transport write completion.
+    public func sendWebSocketMessage(_ str: String, withType type: SocketEnginePacketType, withData datas: [Data], completion: @escaping () -> ()) {
         DefaultSocketLogger.Logger.log("Sending ws: \(str) as type: \(type.rawValue)", type: "SocketEngineWebSocket")
 
         ws?.write(string: "\(type.rawValue)\(str)")
 
         for data in datas {
             if case let .left(bin) = createBinaryDataForSend(using: data) {
-                ws?.write(data: bin)
+                ws?.write(data: bin, completion: completion)
             }
         }
     }

Source/SocketIO/Manager/SocketManager.swift

@@ -290,7 +290,7 @@ open class SocketManager : NSObject, SocketManagerSpec, SocketParsable, SocketDa
     /// - parameter items: The data to send with this event.
     open func emitAll(_ event: String, withItems items: [Any]) {
         forAll {socket in
-            socket.emit(event, with: items)
+            socket.emit(event, with: items, completion: {})
         }
     }
 

Source/SocketIO/Util/SocketTypes.swift

@@ -73,8 +73,11 @@ public typealias AckCallback = ([Any]) -> ()
 /// A typealias for a normal callback.
 public typealias NormalCallback = ([Any], SocketAckEmitter) -> ()
 
+/// A typealias for a queued POST
+public typealias Post = (msg: String, completion: (() -> ()))
+
 typealias JSON = [String: Any]
-typealias Probe = (msg: String, type: SocketEnginePacketType, data: [Data])
+typealias Probe = (msg: String, type: SocketEnginePacketType, data: [Data], completion: (() -> ()))
 typealias ProbeWaitQueue = [Probe]
 
 enum Either<E, V> {

Tests/TestSocketIO/SocketMangerTest.swift

@@ -188,7 +188,7 @@ public class TestSocket : SocketIOClient {
         super.didDisconnect(reason: reason)
     }
 
-    public override func emit(_ event: String, with items: [Any]) {
+    public override func emit(_ event: String, with items: [Any], completion: @escaping () -> ()) {
         expectations[ManagerExpectation.emitAllEventCalled]?.fulfill()
         expectations[ManagerExpectation.emitAllEventCalled] = nil
 

Tests/TestSocketIO/SocketSideEffectTest.swift

@@ -27,6 +27,11 @@ class SocketSideEffectTest: XCTestCase {
         XCTAssertEqual(socket.currentAck, 1)
     }
 
+    func testEmitCompletionSyntax() {
+        socket.emit("test", completion: {})
+        socket.emit("test", "thing", completion: {})
+    }
+
     func testHandleAck() {
         let expect = expectation(description: "handled ack")
         socket.emitWithAck("test").timingOut(after: 0) {data in
@@ -506,5 +511,5 @@ class TestEngine : SocketEngineSpec {
     func flushWaitingForPostToWebSocket() { }
     func parseEngineData(_ data: Data) { }
     func parseEngineMessage(_ message: String) { }
-    func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data]) { }
+    func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data], completion: @escaping () -> ()) { }
 }

Tests/TestSocketIOObjc/SocketObjectiveCTest.m

@@ -67,6 +67,20 @@ - (void)testEmitSyntax {
     [self.socket emit:@"testEmit" with:@[@YES]];
 }
 
+- (void)testEmitWriteCompletionSyntax {
+    [self.socket emit:@"testEmit" with:@[@YES] completion:^{}];
+}
+
+- (void)testEmitWriteCompletion {
+    XCTestExpectation* expect = [self expectationWithDescription:@"Write completion should be called"];
+
+    [self.socket emit:@"testEmit" with:@[@YES] completion:^{
+        [expect fulfill];
+    }];
+
+    [self waitForExpectationsWithTimeout:0.3 handler:nil];
+}
+
 - (void)testRawEmitSyntax {
     [[self.socket rawEmitView] emit:@"myEvent" with:@[@1]];
 }