Expose ChannelDiagnosticsListener (#28)

Author: Mpdreamz

src/Elastic.Channels/BufferedChannelBase.cs

@@ -61,7 +61,9 @@ public abstract class BufferedChannelBase<TChannelOptions, TEvent, TResponse>
 	private readonly CountdownEvent? _signal;
 
 	private readonly ChannelCallbackInvoker<TEvent, TResponse> _callbacks;
-	private readonly IChannelDiagnosticsListener? _diagnosticsListener;
+
+	/// <inheritdoc cref="IChannelDiagnosticsListener"/>
+	public IChannelDiagnosticsListener? DiagnosticsListener { get; }
 
 	/// <inheritdoc cref="BufferedChannelBase{TChannelOptions,TEvent,TResponse}"/>
 	protected BufferedChannelBase(TChannelOptions options) : this(options, null) { }
@@ -73,14 +75,14 @@ protected BufferedChannelBase(TChannelOptions options, ICollection<IChannelCallb
 		Options = options;
 
 		var listeners = callbackListeners == null ? new[] { Options } : callbackListeners.Concat(new[] { Options }).ToArray();
-		_diagnosticsListener = listeners
+		DiagnosticsListener = listeners
 			.Select(l => (l is IChannelDiagnosticsListener c) ? c : null)
 			.FirstOrDefault(e=> e != null);
-		if (_diagnosticsListener == null && !options.DisableDiagnostics)
+		if (DiagnosticsListener == null && !options.DisableDiagnostics)
 		{
 			// if no debug listener was already provided but was requested explicitly create one.
 			var l =  new ChannelDiagnosticsListener<TEvent, TResponse>(GetType().Name);
-			_diagnosticsListener = l;
+			DiagnosticsListener = l;
 			listeners = listeners.Concat(new[] { l }).ToArray();
 		}
 		_callbacks = new ChannelCallbackInvoker<TEvent, TResponse>(listeners);
@@ -326,7 +328,7 @@ async Task<bool> AsyncSlowPath(IOutboundBuffer<TEvent> b)
 
 	/// <inheritdoc cref="object.ToString"/>>
 	public override string ToString() =>
-		_diagnosticsListener != null ? _diagnosticsListener.ToString() : base.ToString();
+		DiagnosticsListener != null ? DiagnosticsListener.ToString() : base.ToString();
 
 	/// <inheritdoc cref="IDisposable.Dispose"/>
 	public virtual void Dispose()

src/Elastic.Channels/Diagnostics/ChannelDiagnosticsListener.cs

@@ -10,10 +10,18 @@
 namespace Elastic.Channels.Diagnostics;
 
 /// <summary>
-/// Marker interface used by <see cref="BufferedChannelBase{TChannelOptions,TEvent,TResponse}"/> to improve
-/// its to string if a <see cref="ChannelDiagnosticsListener{TEvent,TResponse}"/> gets injected.
+/// Active Diagnostics listener used by <see cref="BufferedChannelBase{TChannelOptions,TEvent,TResponse}"/>
 /// </summary>
-internal interface IChannelDiagnosticsListener {}
+public interface IChannelDiagnosticsListener
+{
+	/// <summary>
+	/// Keeps track of the first observed exception to calls to <see cref="BufferedChannelBase{TChannelOptions,TEvent,TResponse}.Export"/>
+	/// </summary>
+	public Exception? ObservedException { get; }
+
+	/// <summary> Indicates if the overall publishing thus far was successful</summary>
+	bool PublishSuccess { get; }
+}
 
 /// <summary>
 /// A very rudimentary diagnostics object tracking various important metrics to provide insights into the
@@ -62,12 +70,10 @@ public ChannelDiagnosticsListener(string? name = null)
 		ExportRetryableCountCallback = i => _returnedRetryableObjects = true;
 	}
 
-	/// <summary>
-	/// Keeps track of the first observed exception to calls to <see cref="BufferedChannelBase{TChannelOptions,TEvent,TResponse}.Export"/>
-	/// </summary>
+	/// <inheritdoc cref="IChannelDiagnosticsListener.ObservedException"/>
 	public Exception? ObservedException { get; private set; }
 
-	/// <summary> Indicates if the overall publishing was successful</summary>
+	/// <inheritdoc cref="IChannelDiagnosticsListener.PublishSuccess"/>
 	public bool PublishSuccess => !_returnedRetryableObjects && ObservedException == null && _exportedBuffers > 0 && _maxRetriesExceeded == 0 && _items > 0;
 
 	/// <inheritdoc cref="IChannelCallbacks{TEvent,TResponse}.ExportExceptionCallback"/>