Refactor Request Event Management (Alamofire#2796)

* Update Request event management and add tests.

* DRY up state switch.

* Add additional test for actions from multiple queues.

Alamofire.xcodeproj/project.pbxproj

@@ -372,7 +372,6 @@
 		319917A4209CDAC400103A19 /* RequestTaskMap.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RequestTaskMap.swift; sourceTree = "<group>"; };
 		319917A9209CDCB000103A19 /* HTTPHeaders.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HTTPHeaders.swift; sourceTree = "<group>"; };
 		319917B8209CE53A00103A19 /* OperationQueue+Alamofire.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "OperationQueue+Alamofire.swift"; sourceTree = "<group>"; };
-		31B2CA9421AA24F5005B371A /* [email protected] */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "[email protected]"; sourceTree = "<group>"; };
 		31B2CA9521AA25CD005B371A /* Package.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Package.swift; sourceTree = "<group>"; };
 		31D83FCD20D5C29300D93E47 /* URLConvertible+URLRequestConvertible.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "URLConvertible+URLRequestConvertible.swift"; sourceTree = "<group>"; };
 		31DADDFA224811ED0051390F /* AlamofireExtended.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlamofireExtended.swift; sourceTree = "<group>"; };
@@ -431,7 +430,6 @@
 		4CE292321EF4A393008DA555 /* CHANGELOG.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = CHANGELOG.md; sourceTree = "<group>"; };
 		4CE292331EF4A393008DA555 /* CONTRIBUTING.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = CONTRIBUTING.md; sourceTree = "<group>"; };
 		4CE292391EF4B12B008DA555 /* Alamofire.podspec */ = {isa = PBXFileReference; lastKnownFileType = text; path = Alamofire.podspec; sourceTree = "<group>"; };
-		4CE2923A1EF4B12B008DA555 /* [email protected] */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "[email protected]"; sourceTree = "<group>"; };
 		4CF3B4281F5FC7900075BE59 /* LICENSE */ = {isa = PBXFileReference; lastKnownFileType = text; path = LICENSE; sourceTree = "<group>"; };
 		4CF626EF1BA7CB3E0011A099 /* Alamofire.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Alamofire.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		4CF626F81BA7CB3E0011A099 /* Alamofire tvOS Tests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = "Alamofire tvOS Tests.xctest"; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -762,8 +760,6 @@
 				4CE292391EF4B12B008DA555 /* Alamofire.podspec */,
 				4CF3B4281F5FC7900075BE59 /* LICENSE */,
 				31B2CA9521AA25CD005B371A /* Package.swift */,
-				31B2CA9421AA24F5005B371A /* [email protected] */,
-				4CE2923A1EF4B12B008DA555 /* [email protected] */,
 			);
 			name = Deployment;
 			sourceTree = "<group>";

Source/EventMonitor.swift

@@ -130,12 +130,21 @@ public protocol EventMonitor {
     /// Event called when a `Request` receives a `resume` call.
     func requestDidResume(_ request: Request)
 
+    /// Event called when a `Request`'s associated `URLSessionTask` is resumed.
+    func request(_ request: Request, didResumeTask task: URLSessionTask)
+
     /// Event called when a `Request` receives a `suspend` call.
     func requestDidSuspend(_ request: Request)
 
+    /// Event called when a `Request`'s associated `URLSessionTask` is suspended.
+    func request(_ request: Request, didSuspendTask task: URLSessionTask)
+
     /// Event called when a `Request` receives a `cancel` call.
     func requestDidCancel(_ request: Request)
 
+    /// Event called when a `Request`'s associated `URLSessionTask` is cancelled.
+    func request(_ request: Request, didCancelTask task: URLSessionTask)
+
     // MARK: DataRequest Events
 
     /// Event called when a `DataRequest` calls a `Validation`.
@@ -242,8 +251,11 @@ extension EventMonitor {
     public func requestIsRetrying(_ request: Request) { }
     public func requestDidFinish(_ request: Request) { }
     public func requestDidResume(_ request: Request) { }
+    public func request(_ request: Request, didResumeTask task: URLSessionTask) { }
     public func requestDidSuspend(_ request: Request) { }
+    public func request(_ request: Request, didSuspendTask task: URLSessionTask) { }
     public func requestDidCancel(_ request: Request) { }
+    public func request(_ request: Request, didCancelTask task: URLSessionTask) { }
     public func request(_ request: DataRequest,
                         didValidateRequest urlRequest: URLRequest?,
                         response: HTTPURLResponse,
@@ -424,14 +436,26 @@ public final class CompositeEventMonitor: EventMonitor {
         performEvent { $0.requestDidResume(request) }
     }
 
+    public func request(_ request: Request, didResumeTask task: URLSessionTask) {
+        performEvent { $0.request(request, didResumeTask: task) }
+    }
+
     public func requestDidSuspend(_ request: Request) {
         performEvent { $0.requestDidSuspend(request) }
     }
 
+    public func request(_ request: Request, didSuspendTask task: URLSessionTask) {
+        performEvent { $0.request(request, didSuspendTask: task) }
+    }
+
     public func requestDidCancel(_ request: Request) {
         performEvent { $0.requestDidCancel(request) }
     }
 
+    public func request(_ request: Request, didCancelTask task: URLSessionTask) {
+        performEvent { $0.request(request, didCancelTask: task) }
+    }
+
     public func request(_ request: DataRequest,
                         didValidateRequest urlRequest: URLRequest?,
                         response: HTTPURLResponse,
@@ -571,12 +595,21 @@ open class ClosureEventMonitor: EventMonitor {
     /// Closure called on the `requestDidResume(_:)` event.
     open var requestDidResume: ((Request) -> Void)?
 
+    /// Closure called on the `request(_:didResumeTask:)` event.
+    open var requestDidResumeTask: ((Request, URLSessionTask) -> Void)?
+
     /// Closure called on the `requestDidSuspend(_:)` event.
     open var requestDidSuspend: ((Request) -> Void)?
 
+    /// Closure called on the `request(_:didSuspendTask:)` event.
+    open var requestDidSuspendTask: ((Request, URLSessionTask) -> Void)?
+
     /// Closure called on the `requestDidCancel(_:)` event.
     open var requestDidCancel: ((Request) -> Void)?
 
+    /// Closure called on the `request(_:didCancelTask:)` event.
+    open var requestDidCancelTask: ((Request, URLSessionTask) -> Void)?
+
     /// Closure called on the `request(_:didValidateRequest:response:data:withResult:)` event.
     open var requestDidValidateRequestResponseDataWithResult: ((DataRequest, URLRequest?, HTTPURLResponse, Data?, Request.ValidationResult) -> Void)?
 
@@ -722,14 +755,26 @@ open class ClosureEventMonitor: EventMonitor {
         requestDidResume?(request)
     }
 
+    public func request(_ request: Request, didResumeTask task: URLSessionTask) {
+        requestDidResumeTask?(request, task)
+    }
+
     open func requestDidSuspend(_ request: Request) {
         requestDidSuspend?(request)
     }
 
+    public func request(_ request: Request, didSuspendTask task: URLSessionTask) {
+        requestDidSuspendTask?(request, task)
+    }
+
     open func requestDidCancel(_ request: Request) {
         requestDidCancel?(request)
     }
 
+    public func request(_ request: Request, didCancelTask task: URLSessionTask) {
+        requestDidCancelTask?(request, task)
+    }
+
     open func request(_ request: DataRequest,
                       didValidateRequest urlRequest: URLRequest?,
                       response: HTTPURLResponse,

Source/Protector.swift

@@ -128,3 +128,19 @@ extension Protector where T == Data? {
         }
     }
 }
+
+extension Protector where T == Request.MutableState {
+    /// Attempts to transition to the passed `State`.
+    ///
+    /// - Parameter state: The `State` to attempt transition to.
+    /// - Returns:         Whether the transtion occured.
+    func attemptToTransitionTo(_ state: Request.State) -> Bool {
+        return lock.around {
+            guard value.state.canTransitionTo(state) else { return false }
+
+            value.state = state
+
+            return true
+        }
+    }
+}

Source/Request.swift

@@ -66,12 +66,12 @@ open class Request {
     /// The `Request`'s interceptor.
     public let interceptor: RequestInterceptor?
     /// The `Request`'s delegate.
-    public weak var delegate: RequestDelegate?
+    public private(set) weak var delegate: RequestDelegate?
 
     // MARK: - Updated State
 
     /// Type encapsulating all mutable state that may need to be accessed from anything other than the `underlyingQueue`.
-    private struct MutableState {
+    struct MutableState {
         /// State of the `Request`.
         var state: State = .initialized
         /// `ProgressHandler` and `DispatchQueue` provided for upload progress callbacks.
@@ -303,18 +303,33 @@ open class Request {
         eventMonitor?.requestDidResume(self)
     }
 
+    /// Called when a `URLSessionTask` is resumed on behalf of the instance.
+    func didResumeTask(_ task: URLSessionTask) {
+        eventMonitor?.request(self, didResumeTask: task)
+    }
+
     /// Called when suspension is completed.
     func didSuspend() {
         eventMonitor?.requestDidSuspend(self)
     }
 
+    /// Callend when a `URLSessionTask` is suspended on behalf of the instance.
+    func didSuspendTask(_ task: URLSessionTask) {
+        eventMonitor?.request(self, didSuspendTask: task)
+    }
+
     /// Called when cancellation is completed, sets `error` to `AFError.explicitlyCancelled`.
     func didCancel() {
         error = AFError.explicitlyCancelled
 
         eventMonitor?.requestDidCancel(self)
     }
 
+    /// Called when a `URLSessionTask` is cancelled on behalf of the instance.
+    func didCancelTask(_ task: URLSessionTask) {
+        eventMonitor?.request(self, didCancelTask: task)
+    }
+
     /// Called when a `URLSessionTaskMetrics` value is gathered on behalf of the `Request`.
     func didGatherMetrics(_ metrics: URLSessionTaskMetrics) {
         protectedMutableState.write { $0.metrics.append(metrics) }
@@ -465,9 +480,7 @@ open class Request {
     /// - Returns: The `Request`.
     @discardableResult
     open func cancel() -> Self {
-        guard state.canTransitionTo(.cancelled) else { return self }
-
-        state = .cancelled
+        guard protectedMutableState.attemptToTransitionTo(.cancelled) else { return self }
 
         delegate?.cancelRequest(self)
 
@@ -479,9 +492,7 @@ open class Request {
     /// - Returns: The `Request`.
     @discardableResult
     open func suspend() -> Self {
-        guard state.canTransitionTo(.suspended) else { return self }
-
-        state = .suspended
+        guard protectedMutableState.attemptToTransitionTo(.suspended) else { return self }
 
         delegate?.suspendRequest(self)
 
@@ -494,9 +505,7 @@ open class Request {
     /// - Returns: The `Request`.
     @discardableResult
     open func resume() -> Self {
-        guard state.canTransitionTo(.resumed) else { return self }
-
-        state = .resumed
+        guard protectedMutableState.attemptToTransitionTo(.resumed) else { return self }
 
         delegate?.resumeRequest(self)
 
@@ -877,12 +886,12 @@ open class DownloadRequest: Request {
 
     // MARK: Updated State
 
-    private struct MutableState {
+    private struct DownloadRequestMutableState {
         var resumeData: Data?
         var fileURL: URL?
     }
 
-    private let protectedMutableState: Protector<MutableState> = Protector(MutableState())
+    private let protectedMutableState: Protector<DownloadRequestMutableState> = Protector(DownloadRequestMutableState())
 
     public var resumeData: Data? { return protectedMutableState.directValue.resumeData }
     public var fileURL: URL? { return protectedMutableState.directValue.fileURL }