/// <summary>高级消费消息。消息处理成功后，自动确认并删除消息体</summary>
/// <remarks>
/// Publish 必须跟 ConsumeAsync 配对使用。
/// </remarks>
/// <param name="func"></param>
/// <param name="timeout"></param>
/// <returns></returns>
public async Task <TResult> ConsumeAsync <TResult>(Func <T, Task <TResult> > func, Int32 timeout = 0)
{
#if NET4
throw new NotSupportedException();
#else
RetryAck();
// 取出消息键
var msgId = (timeout < 0) ?
await ExecuteAsync(rc => rc.ExecuteAsync <String>("RPOPLPUSH", Key, AckKey), true) :
await ExecuteAsync(rc => rc.ExecuteAsync <String>("BRPOPLPUSH", Key, AckKey, timeout), true);
// 取出消息。如果重复消费，或者业务层已经删除消息，此时将拿不到
//var message = Redis.Get<T>(msgId);
//if (Equals(message, default)) return 0;
if (!Redis.TryGet(msgId, out T messge))
{
// 拿不到消息体，直接确认消息键
Acknowledge(msgId);
return(default);