[PATCH master 5/7] First part of confd timer changes

[Iustin Pop]

This patch changes the resolution of the timers: the watcher timer
goes from 60s to 17s, and the polling-mode timer goes from 2 seconds
to 250ms. The code changes a bit more due to the changes in the units
of the various constants.

Signed-off-by: Iustin Pop <ius...@google.com>
---
 lib/constants.py           |   18 ++++++++++--------
 src/Ganeti/Confd/Server.hs |   16 +++++++++-------
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/lib/constants.py b/lib/constants.py
index d62834b..c32a492 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -1,7 +1,7 @@
 #
 #
 
-# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Google Inc.
+# Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Google Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -2184,14 +2184,16 @@ CONFD_ERROR_ARGUMENT = 3
 # TODO: make this a default and allow the value to be more configurable
 CONFD_MAX_CLOCK_SKEW = 2 * NODE_MAX_CLOCK_SKEW
 
-# When we haven't reloaded the config for more than this amount of seconds, we
-# force a test to see if inotify is betraying us.
-CONFD_CONFIG_RELOAD_TIMEOUT = 60
+# When we haven't reloaded the config for more than this amount of
+# seconds, we force a test to see if inotify is betraying us. Using a
+# prime number to ensure we get less chance of 'same wakeup' with
+# other processes.
+CONFD_CONFIG_RELOAD_TIMEOUT = 17
 
-# If we receive more than one update in this amount of seconds, we move to
-# polling every RATELIMIT seconds, rather than relying on inotify, to be able
-# to serve more requests.
-CONFD_CONFIG_RELOAD_RATELIMIT = 2
+# If we receive more than one update in this amount of microseconds,
+# we move to polling every RATELIMIT seconds, rather than relying on
+# inotify, to be able to serve more requests.
+CONFD_CONFIG_RELOAD_RATELIMIT = 250000
 
 # Magic number prepended to all confd queries.
 # This allows us to distinguish different types of confd protocols and handle
diff --git a/src/Ganeti/Confd/Server.hs b/src/Ganeti/Confd/Server.hs
index 46f7226..7d69213 100644
--- a/src/Ganeti/Confd/Server.hs
+++ b/src/Ganeti/Confd/Server.hs
@@ -84,7 +84,7 @@ data ReloadModel = ReloadNotify      -- ^ We are using 
notifications
 -- | Server state data type.
 data ServerState = ServerState
   { reloadModel  :: ReloadModel
-  , reloadTime   :: Integer
+  , reloadTime   :: Integer      -- ^ Reload time (epoch) in microseconds
   , reloadFStat  :: FStat
   }
 
@@ -98,11 +98,11 @@ configReloadTimeout = C.confdConfigReloadTimeout * 1000000
 
 -- | Ratelimit timeout in microseconds.
 configReloadRatelimit :: Int
-configReloadRatelimit = C.confdConfigReloadRatelimit * 1000000
+configReloadRatelimit = C.confdConfigReloadRatelimit
 
--- | Ratelimit timeout in seconds, as an 'Integer'.
-reloadRatelimitSec :: Integer
-reloadRatelimitSec = fromIntegral C.confdConfigReloadRatelimit
+-- | Ratelimit timeout in microseconds, as an 'Integer'.
+reloadRatelimit :: Integer
+reloadRatelimit = fromIntegral C.confdConfigReloadRatelimit
 
 -- | Initial poll round.
 initialPoll :: ReloadModel
@@ -351,6 +351,7 @@ needsReload oldstat path = do
 onTimeoutTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()
 onTimeoutTimer inotiaction path cref state = do
   threadDelay configReloadTimeout
+  logDebug "Watcher timer fired"
   modifyMVar_ state (onTimeoutInner path cref)
   _ <- inotiaction
   onTimeoutTimer inotiaction path cref state
@@ -372,6 +373,7 @@ onTimeoutInner path cref state  = do
 -- notification.
 onReloadTimer :: IO Bool -> FilePath -> CRef -> MVar ServerState -> IO ()
 onReloadTimer inotiaction path cref state = do
+  logDebug "Reload timer fired"
   continue <- modifyMVar state (onReloadInner inotiaction path cref)
   when continue $
     do threadDelay configReloadRatelimit
@@ -440,10 +442,10 @@ onInotify inotify path cref mstate _ =
   modifyMVar_ mstate $ \state ->
     if reloadModel state == ReloadNotify
        then do
-         ctime <- getCurrentTime
+         ctime <- getCurrentTimeUSec
          (newfstat, _) <- safeUpdateConfig path (reloadFStat state) cref
          let state' = state { reloadFStat = newfstat, reloadTime = ctime }
-         if abs (reloadTime state - ctime) < reloadRatelimitSec
+         if abs (reloadTime state - ctime) < reloadRatelimit
            then do
              mode <- moveToPolling "too many reloads" inotify path cref mstate
              return state' { reloadModel = mode }
-- 
1.7.10.4