dont track offsets when consumer tag is generated

spec/stream_queue_spec.cr

@@ -348,5 +348,28 @@ describe LavinMQ::StreamQueue do
       msg_store.last_offset_by_consumer_tag(tag_prefix + 0.to_s).should eq offsets[0]
       msg_store.close
     end
+
+    it "does not track offset if c-tag is auto-generated" do
+      queue_name = Random::Secure.hex
+      StreamQueueSpecHelpers.publish(queue_name, 1)
+      args = {"x-queue-type": "stream"}
+      c_tag = ""
+      with_channel do |ch|
+        ch.prefetch 1
+        q = ch.queue(queue_name, args: AMQP::Client::Arguments.new(args))
+        msgs = Channel(AMQP::Client::DeliverMessage).new
+        c_tag = q.subscribe(no_ack: false) do |msg|
+          msgs.send msg
+          msg.ack
+        end
+        msg = msgs.receive
+      end
+
+      sleep 0.1
+      vhost = Server.vhosts["/"]
+      data_dir = File.join(vhost.data_dir, Digest::SHA1.hexdigest queue_name)
+      msg_store = LavinMQ::StreamQueue::StreamQueueMessageStore.new(data_dir, nil)
+      msg_store.last_offset_by_consumer_tag(c_tag).should eq nil
+    end
   end
 end

src/lavinmq/client/channel/stream_consumer.cr

@@ -12,9 +12,9 @@ module LavinMQ
         @track_offset = false
 
         def initialize(@channel : Client::Channel, @queue : StreamQueue, frame : AMQP::Frame::Basic::Consume)
+          @tag = frame.consumer_tag
           validate_preconditions(frame)
           offset = frame.arguments["x-stream-offset"]?
-          @tag = frame.consumer_tag
           @offset, @segment, @pos = stream_queue.find_offset(offset, @tag)
           super
         end
@@ -37,7 +37,7 @@ module LavinMQ
           end
           case frame.arguments["x-stream-offset"]?
           when Nil
-            @track_offset = true
+            @track_offset = true unless @tag.starts_with?("amq.ctag-")
           when Int, Time, "first", "next", "last"
             @track_offset = false
           else raise Error::PreconditionFailed.new("x-stream-offset must be an integer, a timestamp, 'first', 'next' or 'last'")