Added telemetry injection point for Ask<T> (#5297)

Looking for a way to help trace timeouts inside `Ask<T>` operations - needed some way to tap into the `TaskCompletionSource` and to create an active `ISpan` before the operation begins.

Author: Aaronontheweb

src/contrib/cluster/Akka.Cluster.Metrics/ClusterMetricsStrategy.cs

@@ -8,7 +8,6 @@
 using System;
 using Akka.Actor;
 using Akka.Configuration;
-using Akka.Configuration;
 
 namespace Akka.Cluster.Metrics
 {

src/core/Akka.API.Tests/CoreAPISpec.ApproveCore.approved.txt

@@ -968,6 +968,8 @@ namespace Akka.Actor
         Akka.Actor.IInternalActorRef TempContainer { get; }
         System.Threading.Tasks.Task TerminationTask { get; }
         Akka.Actor.IInternalActorRef ActorOf(Akka.Actor.Internal.ActorSystemImpl system, Akka.Actor.Props props, Akka.Actor.IInternalActorRef supervisor, Akka.Actor.ActorPath path, bool systemService, Akka.Actor.Deploy deploy, bool lookupDeploy, bool async);
+        [Akka.Annotations.InternalApiAttribute()]
+        Akka.Actor.FutureActorRef<T> CreateFutureRef<T>(System.Threading.Tasks.TaskCompletionSource<T> tcs);
         Akka.Actor.Address GetExternalAddressFor(Akka.Actor.Address address);
         void Init(Akka.Actor.Internal.ActorSystemImpl system);
         void RegisterTempActor(Akka.Actor.IInternalActorRef actorRef, Akka.Actor.ActorPath path);
@@ -1279,6 +1281,7 @@ namespace Akka.Actor
         public Akka.Actor.IInternalActorRef TempContainer { get; }
         public System.Threading.Tasks.Task TerminationTask { get; }
         public Akka.Actor.IInternalActorRef ActorOf(Akka.Actor.Internal.ActorSystemImpl system, Akka.Actor.Props props, Akka.Actor.IInternalActorRef supervisor, Akka.Actor.ActorPath path, bool systemService, Akka.Actor.Deploy deploy, bool lookupDeploy, bool async) { }
+        public Akka.Actor.FutureActorRef<T> CreateFutureRef<T>(System.Threading.Tasks.TaskCompletionSource<T> tcs) { }
         public Akka.Actor.Address GetExternalAddressFor(Akka.Actor.Address address) { }
         public void Init(Akka.Actor.Internal.ActorSystemImpl system) { }
         public void RegisterExtraName(string name, Akka.Actor.IInternalActorRef actor) { }

src/core/Akka.API.Tests/CoreAPISpec.ApproveRemote.approved.txt

@@ -202,6 +202,7 @@ namespace Akka.Remote
         public System.Threading.Tasks.Task TerminationTask { get; }
         public Akka.Remote.RemoteTransport Transport { get; }
         public Akka.Actor.IInternalActorRef ActorOf(Akka.Actor.Internal.ActorSystemImpl system, Akka.Actor.Props props, Akka.Actor.IInternalActorRef supervisor, Akka.Actor.ActorPath path, bool systemService, Akka.Actor.Deploy deploy, bool lookupDeploy, bool async) { }
+        public Akka.Actor.FutureActorRef<T> CreateFutureRef<T>(System.Threading.Tasks.TaskCompletionSource<T> tcs) { }
         protected virtual Akka.Actor.IActorRef CreateRemoteDeploymentWatcher(Akka.Actor.Internal.ActorSystemImpl system) { }
         protected virtual Akka.Actor.IInternalActorRef CreateRemoteRef(Akka.Actor.ActorPath actorPath, Akka.Actor.Address localAddress) { }
         protected virtual Akka.Actor.IInternalActorRef CreateRemoteRef(Akka.Actor.Props props, Akka.Actor.IInternalActorRef supervisor, Akka.Actor.Address localAddress, Akka.Actor.ActorPath rpath, Akka.Actor.Deploy deployment) { }

src/core/Akka.Cluster/ClusterDaemon.cs

@@ -1561,8 +1561,9 @@ public void StopSeedNodeProcess()
         /// Received `Join` message and replies with `Welcome` message, containing
         /// current gossip state, including the new joining member.
         /// </summary>
-        /// <param name="node">TBD</param>
-        /// <param name="roles">TBD</param>
+        /// <param name="node">The unique address of the joining node.</param>
+        /// <param name="roles">The roles, if any, of the joining node.</param>
+        /// <param name="appVersion">The software version of the joining node.</param>
         public void Joining(UniqueAddress node, ImmutableHashSet<string> roles, AppVersion appVersion)
         {
             var selfStatus = LatestGossip.GetMember(SelfUniqueAddress).Status;

src/core/Akka.Remote/RemoteActorRefProvider.cs

@@ -235,6 +235,12 @@ public void UnregisterTempActor(ActorPath path)
             _local.UnregisterTempActor(path);
         }
 
+        /// <inheritdoc/>
+        public FutureActorRef<T> CreateFutureRef<T>(TaskCompletionSource<T> tcs)
+        {
+            return _local.CreateFutureRef(tcs);
+        }
+
         private IActorRef _remotingTerminator;        
         private IActorRef _remoteWatcher;
 

src/core/Akka/Actor/ActorRefProvider.cs

@@ -91,6 +91,18 @@ public interface IActorRefProvider
         /// <param name="path">A path returned by <see cref="TempPath"/>. Do NOT pass in any other path!</param>
         void UnregisterTempActor(ActorPath path);
 
+        /// <summary>
+        /// Automatically generates a <see cref="FutureActorRef{T}"/> with a temporary path.
+        /// </summary>
+        /// <remarks>
+        /// Does not call <see cref="RegisterTempActor"/> or <see cref="UnregisterTempActor"/>.
+        /// </remarks>
+        /// <param name="tcs">A typed <see cref="TaskCompletionSource{T}"/></param>
+        /// <typeparam name="T">The type of output this <see cref="FutureActorRef{T}"/> expects.</typeparam>
+        /// <returns>A new, single-use <see cref="FutureActorRef{T}"/> instance.</returns>
+        [InternalApi]
+        FutureActorRef<T> CreateFutureRef<T>(TaskCompletionSource<T> tcs);
+
         /// <summary>
         /// Actor factory with create-only semantics: will create an actor as
         /// described by <paramref name="props"/> with the given <paramref name="supervisor"/> and <paramref name="path"/> (may be different
@@ -386,6 +398,16 @@ public void UnregisterTempActor(ActorPath path)
             _tempContainer.RemoveChild(path.Name);
         }
 
+        /// <inheritdoc cref="IActorRefProvider.CreateFutureRef{T}"/>
+        public FutureActorRef<T> CreateFutureRef<T>(TaskCompletionSource<T> tcs)
+        {
+            //create a new tempcontainer path
+            var path = TempPath();
+
+            var future = new FutureActorRef<T>(tcs, path, this);
+            return future;
+        }
+
         /// <summary>
         /// Initializes the ActorRefProvider
         /// </summary>

src/core/Akka/Actor/Futures.cs

@@ -148,10 +148,8 @@ public static Task<T> Ask<T>(this ICanTell self, Func<IActorRef, object> message
                 ctr2 = cancellationToken.Register(() => result.TrySetCanceled());
             }
 
-            //create a new tempcontainer path
-            var path = provider.TempPath();
-
-            var future = new FutureActorRef<T>(result, path, provider);
+            var future = provider.CreateFutureRef(result);
+            var path = future.Path;
 
             //The future actor needs to be unregistered in the temp container
             _ = result.Task.ContinueWith(t =>