using System;
using System.Threading.Tasks;
using RabbitMQ.Client;
using Tapeti.Default;
namespace Tapeti.Connection
{
///
/// Called to report the result of a consumed message back to RabbitMQ.
///
/// The connection reference on which the consumed message was received
/// The delivery tag of the consumed message
/// The result which should be sent back
public delegate Task ResponseFunc(long expectedConnectionReference, ulong deliveryTag, ConsumeResult result);
///
///
/// Implements the bridge between the RabbitMQ Client consumer and a Tapeti Consumer
///
internal class TapetiBasicConsumer : DefaultBasicConsumer
{
private readonly IConsumer consumer;
private readonly long connectionReference;
private readonly ResponseFunc onRespond;
///
public TapetiBasicConsumer(IConsumer consumer, long connectionReference, ResponseFunc onRespond)
{
this.consumer = consumer;
this.connectionReference = connectionReference;
this.onRespond = onRespond;
}
///
public override void HandleBasicDeliver(string consumerTag,
ulong deliveryTag,
bool redelivered,
string exchange,
string routingKey,
IBasicProperties properties,
ReadOnlyMemory body)
{
// RabbitMQ.Client 6+ re-uses the body memory. Unfortunately Newtonsoft.Json does not support deserializing
// from Span/ReadOnlyMemory yet so we still need to use ToArray and allocate heap memory for it. When support
// is implemented we need to rethink the way the body is passed around and maybe deserialize it sooner
// (which changes exception handling, which is now done in TapetiConsumer exclusively).
//
// See also: https://github.com/JamesNK/Newtonsoft.Json/issues/1761
var bodyArray = body.ToArray();
Task.Run(async () =>
{
try
{
var response = await consumer.Consume(exchange, routingKey, new RabbitMQMessageProperties(properties), bodyArray);
await onRespond(connectionReference, deliveryTag, response);
}
catch
{
await onRespond(connectionReference, deliveryTag, ConsumeResult.Error);
}
});
}
}
}