prefill: fix timer restart

event.reschedule() is not a good idea for long-running downloads and in
general I have a bad feeling that it did not work as intended even for
retries after errors.

diff --git a/modules/prefill/prefill.lua b/modules/prefill/prefill.lua
index 9ad19ec358de76a5626234700e5763192a838816..773162bd796ec4eb63f0db68f32f446d36884d41 100644 (file)
--- a/modules/prefill/prefill.lua
+++ b/modules/prefill/prefill.lua
@@ -13,8 +13,27 @@ local rz_interval_randomizator_limit = 10
 local rz_interval_threshold = 5
 local rz_interval_min = 3600
 
-local prefill = {
-}
+local prefill = {}
+
+-- hack for circular depedency between timer() and fill_cache()
+local forward_references = {}
+
+local function stop_timer()
+       if rz_event_id then
+               event.cancel(rz_event_id)
+               rz_event_id = nil
+       end
+end
+
+local function timer()
+       stop_timer()
+       worker.bg_worker.cq:wrap(forward_references.fill_cache)
+end
+
+local function restart_timer(after)
+       stop_timer()
+       rz_event_id = event.after(after * sec, timer)
+end
 
 local function display_delay(time)
        local days = math.floor(time / 86400)
@@ -77,7 +96,7 @@ local function import(fname)
        end
 end
 
-local function fill_cache()
+function forward_references.fill_cache()
        local file_ttl = get_file_ttl(rz_local_fname)
 
        if file_ttl > rz_interval_threshold then
@@ -91,7 +110,7 @@ local function fill_cache()
                        log("[prefill] cannot download new zone (%s), "
                                .. "will retry root zone download in %s",
                                errmsg, display_delay(rz_cur_interval))
-                       event.reschedule(rz_event_id, rz_cur_interval * sec)
+                       restart_timer(rz_cur_interval)
                        return
                end
                file_ttl = rz_default_interval
@@ -111,11 +130,7 @@ local function fill_cache()
                log("[prefill] root zone refresh in %s",
                        display_delay(rz_cur_interval))
        end
-       event.reschedule(rz_event_id, rz_cur_interval * sec)
-end
-
-local function timer()
-       worker.bg_worker.cq:wrap(fill_cache)
+       restart_timer(rz_cur_interval)
 end
 
 function prefill.init()
@@ -123,10 +138,7 @@ function prefill.init()
 end
 
 function prefill.deinit()
-       if rz_event_id then
-               event.cancel(rz_event_id)
-               rz_event_id = nil
-       end
+       stop_timer()
 end
 
 -- process one item from configuration table
@@ -179,9 +191,7 @@ function prefill.config(config)
                        .. 'for root zone')
        end
 
-       -- ability to change intervals
-       prefill.deinit()
-       rz_event_id = event.after(0, timer)
+       restart_timer(0)  -- start now
 end
 
 return prefill