Preserve channel id allocator after recovery

lib/bunny/session.rb

@@ -975,7 +975,11 @@ def open_connection
       @logger.debug "Heartbeat interval negotiation: client = #{@client_heartbeat}, server = #{connection_tune.heartbeat}, result = #{@heartbeat}"
       @logger.info "Heartbeat interval used (in seconds): #{@heartbeat}"
 
-      @channel_id_allocator = ChannelIdAllocator.new(@channel_max)
+      # if there are existing channels we've just recovered from
+      # a network failure and need to fix the allocated set. See issue 205. MK.
+      if @channels.empty?
+        @channel_id_allocator = ChannelIdAllocator.new(@channel_max)
+      end
 
       @transport.send_frame(AMQ::Protocol::Connection::TuneOk.encode(@channel_max, @frame_max, @heartbeat))
       @logger.debug "Sent connection.tune-ok with heartbeat interval = #{@heartbeat}, frame_max = #{@frame_max}, channel_max = #{@channel_max}"

spec/higher_level_api/integration/connection_recovery_spec.rb

@@ -186,4 +186,26 @@ def ensure_exchange_binding_recovery(ch, source, destination, routing_key = "")
       ensure_exchange_binding_recovery(ch, x, x2)
     end
   end
+
+  it "recovers allocated channel ids" do
+    with_open do |c|
+      q = "queue#{Time.now.to_i}"
+      10.times { c.create_channel }
+      c.queue_exists?(q).should be_false
+      close_all_connections!
+      sleep 0.1
+      c.should_not be_open
+
+      wait_for_recovery
+      c.queue_exists?(q).should be_false
+      # make sure the connection isn't closed shortly after
+      # due to "second 'channel.open' seen". MK.
+      c.should be_open
+      sleep 0.1
+      c.should be_open
+      sleep 0.1
+      c.should be_open
+    end
+  end
 end
+