[Tracing] Further try to simplify availaabilty woes for call-sites

Author: ktoso

Sources/AsyncHTTPClient/AsyncAwait/Transaction.swift

@@ -36,10 +36,6 @@ final class Transaction:
     let preferredEventLoop: EventLoop
     let requestOptions: RequestOptions
 
-    #if TracingSupport
-    let span: (any Span)?
-    #endif
-
     private let state: NIOLockedValueBox<StateMachine>
 
     #if TracingSupport
@@ -57,7 +53,6 @@ final class Transaction:
         self.logger = logger
         self.connectionDeadline = connectionDeadline
         self.preferredEventLoop = preferredEventLoop
-        self.span = span
         self.state = NIOLockedValueBox(StateMachine(responseContinuation))
     }
     #endif  // TracingSupport
@@ -70,23 +65,17 @@ final class Transaction:
         preferredEventLoop: EventLoop,
         responseContinuation: CheckedContinuation<HTTPClientResponse, Error>
     ) {
-        print("[swift] new transaction = \(request)")
         self.request = request
         self.requestOptions = requestOptions
         self.logger = logger
         self.connectionDeadline = connectionDeadline
         self.preferredEventLoop = preferredEventLoop
-        self.span = nil
         self.state = NIOLockedValueBox(StateMachine(responseContinuation))
     }
 
     func cancel() {
         let error = CancellationError()
         self.fail(error)
-        #if TracingSupport
-        self.span?.recordError(error)
-        self.span?.end()
-        #endif
     }
 
     // MARK: Request body helpers

Sources/AsyncHTTPClient/HTTPClient.swift

@@ -808,7 +808,7 @@ public final class HTTPClient: Sendable {
             }
         }()
 
-        let task: HTTPClient.Task<Delegate.Response> 
+        let task: HTTPClient.Task<Delegate.Response>
         #if TracingSupport
         if #available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) {
             task = Task<Delegate.Response>(
@@ -825,7 +825,7 @@ public final class HTTPClient: Sendable {
             )
         }
         #else
-        let task = Task<Delegate.Response>(
+        task = Task<Delegate.Response>(
             eventLoop: taskEL,
             logger: logger,
             makeOrGetFileIOThreadPool: self.makeOrGetFileIOThreadPool

Sources/AsyncHTTPClient/HTTPHandler.swift

@@ -929,12 +929,11 @@ extension HTTPClient {
         public let logger: Logger  // We are okay to store the logger here because a Task is for only one request.
 
         #if TracingSupport
-        let anyTracer: Optional<any Sendable>  // Ok to store the tracer here because a Task is for only one request.
+        let anyTracer: (any Sendable)? = nil  // Ok to store the tracer here because a Task is for only one request.
 
         @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
         public var tracer: (any Tracer)? {
             get {
-                print("[swift][\(#fileID):\(#line)] _tracer = \(anyTracer)")
                 return anyTracer as! (any Tracer)?
             }
         }
@@ -973,7 +972,6 @@ extension HTTPClient {
             self.eventLoop = eventLoop
             self.promise = eventLoop.makePromise()
             self.logger = logger
-            self.anyTracer = nil
             self.makeOrGetFileIOThreadPool = makeOrGetFileIOThreadPool
             self.state = NIOLockedValueBox(State(isCancelled: false, taskDelegate: nil))
         }
@@ -1004,7 +1002,6 @@ extension HTTPClient {
             self.eventLoop = eventLoop
             self.promise = eventLoop.makePromise()
             self.logger = logger
-            print("[swift] set any tracer on TASK = \(tracer)")
             self.anyTracer = tracer
             self.makeOrGetFileIOThreadPool = makeOrGetFileIOThreadPool
             self.state = NIOLockedValueBox(State(isCancelled: false, taskDelegate: nil))

Sources/AsyncHTTPClient/RequestBag.swift

@@ -69,13 +69,21 @@ final class RequestBag<Delegate: HTTPClientResponseDelegate & Sendable>: Sendabl
         self.task.logger
     }
 
+    // Available unconditionally, so we can simplify callsites which can just try to pass this value
+    // regardless if the real tracer exists or not.
     var anyTracer: (any Sendable)? {
+        #if TracingSupport
         self.task.anyTracer
+        #else
+        nil
+        #endif
     }
+    #if TracingSupport
     @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
     var tracer: (any Tracer)? {
         self.task.tracer
     }
+    #endif // TracingSupport
 
     let connectionDeadline: NIODeadline
 
@@ -101,8 +109,6 @@ final class RequestBag<Delegate: HTTPClientResponseDelegate & Sendable>: Sendabl
         self.eventLoopPreference = eventLoopPreference
         self.task = task
 
-        assert(task.anyTracer != nil, "tracer was nil!") 
-
         let loopBoundState = LoopBoundState(
             request: request,
             state: StateMachine(redirectHandler: redirectHandler),
@@ -134,7 +140,6 @@ final class RequestBag<Delegate: HTTPClientResponseDelegate & Sendable>: Sendabl
 
     private func willExecuteRequest0(_ executor: HTTPRequestExecutor) {
         // Immediately start a span for the "whole" request
-        print("[swift] WILL EXECUTE \(self.anyTracer)")
         self.loopBoundState.value.startRequestSpan(tracer: self.anyTracer)
 
         let action = self.loopBoundState.value.state.willExecuteRequest(executor)

Sources/AsyncHTTPClient/TracingSupport.swift

@@ -46,7 +46,7 @@ protocol _TracingSupportOperations {
     // associatedtype TracerType
 
     /// Starts the "overall" Span that encompases the beginning of a request until receipt of the head part of the response.
-    mutating func startRequestSpan(tracer: Any?)
+    mutating func startRequestSpan<T>(tracer: T?)
 
     /// Fails the active overall span given some internal error, e.g. timeout, pool shutdown etc.
     /// This is not to be used for failing a span given a failure status coded HTTPResponse.
@@ -64,13 +64,14 @@ extension RequestBag.LoopBoundState: _TracingSupportOperations {}
 #if !TracingSupport
 /// Operations used to start/end spans at apropriate times from the Request lifecycle.
 extension RequestBag.LoopBoundState {
-    typealias TracerType = HTTPClientTracingSupportTracerType
-
     @inlinable
-    mutating func startRequestSpan(tracer: Any?) {}
+    mutating func startRequestSpan<T>(tracer: T?) {}
 
     @inlinable
     mutating func failRequestSpan(error: any Error) {}
+    
+    @inlinable
+    mutating func failRequestSpanAsCancelled() {}
 
     @inlinable
     mutating func endRequestSpan(response: HTTPResponseHead) {}
@@ -81,12 +82,9 @@ extension RequestBag.LoopBoundState {
 extension RequestBag.LoopBoundState {
     // typealias TracerType = Tracer
 
-    mutating func startRequestSpan(tracer: Any?) {
+    mutating func startRequestSpan<T>(tracer: T?) {
         guard #available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *), 
-            let tracer = tracer as? (any Tracer)?,
-            let tracer else {
-            // print("[swift][\(#fileID):\(#line)] MISSING TRACER: \(tracer)")
-            fatalError("[swift][\(#fileID):\(#line)] MISSING TRACER: \(tracer)")
+            let tracer = tracer as! (any Tracer)? else {
             return
         }