Added event hook for document not found in storage. (#7596)

Author: michaelstaib

src/HotChocolate/Core/src/Execution/Instrumentation/AggregateExecutionDiagnosticEvents.cs

@@ -308,6 +308,16 @@ public void RetrievedDocumentFromStorage(IRequestContext context)
         }
     }
 
+    public void DocumentNotFoundInStorage(
+        IRequestContext context,
+        OperationDocumentId documentId)
+    {
+        for (var i = 0; i < _listeners.Length; i++)
+        {
+            _listeners[i].DocumentNotFoundInStorage(context, documentId);
+        }
+    }
+
     public void AddedOperationToCache(IRequestContext context)
     {
         for (var i = 0; i < _listeners.Length; i++)

src/HotChocolate/Core/src/Execution/Instrumentation/ExecutionDiagnosticEventListener.cs

@@ -164,6 +164,13 @@ public virtual void RetrievedDocumentFromStorage(IRequestContext context)
     {
     }
 
+    /// <inheritdoc />
+    public virtual void DocumentNotFoundInStorage(
+        IRequestContext context,
+        OperationDocumentId documentId)
+    {
+    }
+
     /// <inheritdoc />
     public virtual void AddedOperationToCache(IRequestContext context)
     {

src/HotChocolate/Core/src/Execution/Instrumentation/IExecutionDiagnosticEvents.cs

@@ -352,6 +352,19 @@ public interface IExecutionDiagnosticEvents
     /// <param name="context"></param>
     void RetrievedDocumentFromStorage(IRequestContext context);
 
+    /// <summary>
+    /// Called when the document for a persisted operation could not be found in the
+    /// operation document storage.
+    /// </summary>
+    /// <param name="context">
+    /// The request context encapsulates all GraphQL-specific information
+    /// about an individual GraphQL request.
+    /// </param>
+    /// <param name="documentId">
+    /// The document id that was not found in the storage.
+    /// </param>
+    void DocumentNotFoundInStorage(IRequestContext context, OperationDocumentId documentId);
+
     /// <summary>
     /// A compiled operation was added to the operation cache.
     /// </summary>

src/HotChocolate/Core/src/Execution/Instrumentation/NoopExecutionDiagnosticEvents.cs

@@ -101,6 +101,10 @@ public void RetrievedDocumentFromStorage(IRequestContext context)
     {
     }
 
+    public void DocumentNotFoundInStorage(IRequestContext context, OperationDocumentId documentId)
+    {
+    }
+
     public void AddedOperationToCache(IRequestContext context)
     {
     }

src/HotChocolate/Core/src/Execution/Pipeline/PersistedOperationNotFoundMiddleware.cs

@@ -27,15 +27,16 @@ public ValueTask InvokeAsync(IRequestContext context)
             return _next(context);
         }
 
+        // we know that the key is not null since otherwise the request would have
+        // failed already since no operation is specified.
         var requestedKey =
-            context.Request.DocumentId ??
+            (context.Request.DocumentId ??
             context.DocumentId ??
             context.DocumentHash ??
-            context.Request.DocumentHash;
+            context.Request.DocumentHash)!.Value;
 
-        // we know that the key is not null since otherwise the request would have
-        // failed already since no operation is specified.
-        var error = ErrorHelper.PersistedOperationNotFound(requestedKey!.Value);
+        _diagnosticEvents.DocumentNotFoundInStorage(context, requestedKey);
+        var error = ErrorHelper.PersistedOperationNotFound(requestedKey);
         _diagnosticEvents.RequestError(context, new GraphQLException(error));
         context.Result = OperationResultBuilder.CreateError(error, _statusCode);