Tapeti/Tapeti/Default/PublishResultBinding.cs

108 lines
4.6 KiB
C#

using System;
using System.Diagnostics;
using System.Reflection;
using System.Threading.Tasks;
using Tapeti.Annotations;
using Tapeti.Config;
using Tapeti.Helpers;
namespace Tapeti.Default
{
/// <summary>
/// Attempts to publish a return value for Controller methods as a response to the incoming message.
/// </summary>
public class PublishResultBinding : IControllerBindingMiddleware
{
/// <inheritdoc />
public void Handle(IControllerBindingContext context, Action next)
{
next();
if (context.Result.HasHandler)
return;
var hasClassResult = context.Result.Info.ParameterType.IsTypeOrTaskOf(t => t.IsClass, out var taskType, out var actualType);
var request = context.MessageClass?.GetCustomAttribute<RequestAttribute>();
var expectedClassResult = request?.Response;
// Verify the return type matches with the Request attribute of the message class. This is a backwards incompatible change in
// Tapeti 1.2: if you just want to publish another message as a result of the incoming message, explicitly call IPublisher.Publish.
// ReSharper disable once ConvertIfStatementToSwitchStatement
if (!hasClassResult && expectedClassResult != null || hasClassResult && expectedClassResult != actualType)
throw new ArgumentException($"Message handler for non-request message type {context.MessageClass?.FullName} must return type {expectedClassResult?.FullName ?? "void"} in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}, found: {actualType.FullName ?? "void"}");
if (!hasClassResult)
return;
switch (taskType)
{
case TaskType.None:
context.Result.SetHandler((messageContext, value) => Reply(value, messageContext));
break;
case TaskType.Task:
var handler = GetType().GetMethod(nameof(PublishGenericTaskResult), BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
Debug.Assert(handler != null, nameof(handler) + " != null");
context.Result.SetHandler((messageContext, value) =>
{
var result = handler.Invoke(null, new[] { messageContext, value });
return result != null ? (ValueTask)result : ValueTask.CompletedTask;
});
break;
case TaskType.ValueTask:
var valueTaskHandler = GetType().GetMethod(nameof(PublishGenericValueTaskResult), BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
Debug.Assert(valueTaskHandler != null, nameof(handler) + " != null");
context.Result.SetHandler((messageContext, value) =>
{
var result = valueTaskHandler.Invoke(null, new[] { messageContext, value });
return result != null ? (ValueTask)result : ValueTask.CompletedTask;
});
break;
default:
throw new ArgumentOutOfRangeException();
}
}
private static async ValueTask PublishGenericTaskResult<T>(IMessageContext messageContext, object value) where T : class
{
var message = await (Task<T>)value;
await Reply(message, messageContext);
}
private static async ValueTask PublishGenericValueTaskResult<T>(IMessageContext messageContext, object value) where T : class
{
var message = await (ValueTask<T>)value;
await Reply(message, messageContext);
}
private static async ValueTask Reply(object? message, IMessageContext messageContext)
{
if (message == null)
throw new ArgumentException("Return value of a request message handler must not be null");
var publisher = (IInternalPublisher)messageContext.Config.DependencyResolver.Resolve<IPublisher>();
var properties = new MessageProperties
{
CorrelationId = messageContext.Properties.CorrelationId
};
if (!string.IsNullOrEmpty(messageContext.Properties.ReplyTo))
await publisher.PublishDirect(message, messageContext.Properties.ReplyTo, properties, messageContext.Properties.Persistent.GetValueOrDefault(true));
else
await publisher.Publish(message, properties, false);
}
}
}