--- a/src/luan/modules/lucene/Lucene.luan	Tue Jun 18 16:27:03 2019 -0600
+++ b/src/luan/modules/lucene/Lucene.luan	Tue Jun 18 21:56:53 2019 -0600
@@ -10,10 +10,16 @@
 local uri = Io.uri or error()
 local String = require "luan:String.luan"
 local matches = String.matches or error()
+local Thread = require "luan:Thread.luan"
+local schedule = Thread.schedule or error()
+local run_for_backup = Thread.run_for_backup or error()
+local Time = require "luan:Time.luan"
 local Rpc = require "luan:Rpc.luan"
 local LuceneIndex = require "java:luan.modules.lucene.LuceneIndex"
 local NumberFieldParser = require "java:luan.lib.queryparser.NumberFieldParser"
 local SaneQueryParser = require "java:luan.lib.queryparser.SaneQueryParser"
+local Logging = require "luan:logging/Logging.luan"
+local logger = Logging.logger "Lucene"
 
 
 local Lucene = {}
@@ -138,6 +144,23 @@
 		end )
 	end
 
+	function index.schedule_backups_to(backup_dir,repeating_delay)
+		local lucene_dir = uri("file:"..index.dir)
+		local function backup()
+			if backup_dir.last_modified() < lucene_dir.last_modified() then
+				run_for_backup(function()
+					index.backup_to(backup_dir)
+					logger.info "backup"
+				end)
+			end
+		end
+		schedule( backup, {
+			repeating_delay = repeating_delay or Time.period{minutes=10}
+			run_on_close = true
+			daemon = true
+		} )
+	end
+
 	function index.zip(zip_file)
 		index.snapshot( function(dir_path,file_names)
 			zip_file.delete()