Move FStat related function to Utils

In this way, the functions to to decide, based on fstat, whether
a file needs to be reloaded can used by other parts as well,
in particular to monitor progress in the job queue.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

src/Ganeti/ConfigReader.hs

@@ -32,10 +32,8 @@ module Ganeti.ConfigReader
 
 import Control.Concurrent
 import Control.Exception
-import Control.Monad (liftM, unless)
+import Control.Monad (unless)
 import Data.IORef
-import System.Posix.Files
-import System.Posix.Types
 import System.INotify
 
 import Ganeti.BasicTypes
@@ -51,12 +49,6 @@ import Ganeti.Utils
 -- executed.
 type ConfigReader = IO (Result ConfigData)
 
--- | File stat identifier.
-type FStat = (EpochTime, FileID, FileOffset)
-
--- | Null 'FStat' value.
-nullFStat :: FStat
-nullFStat = (-1, -1, -1)
 
 -- | Reload model data type.
 data ReloadModel = ReloadNotify      -- ^ We are using notifications
@@ -151,27 +143,6 @@ safeUpdateConfig path oldfstat save_fn =
              return (nullFStat, ConfigIOError)
           )
 
--- | Computes the file cache data from a FileStatus structure.
-buildFileStatus :: FileStatus -> FStat
-buildFileStatus ofs =
-    let modt = modificationTime ofs
-        inum = fileID ofs
-        fsize = fileSize ofs
-    in (modt, inum, fsize)
-
--- | Wrapper over 'buildFileStatus'. This reads the data from the
--- filesystem and then builds our cache structure.
-getFStat :: FilePath -> IO FStat
-getFStat p = liftM buildFileStatus (getFileStatus p)
-
--- | Check if the file needs reloading
-needsReload :: FStat -> FilePath -> IO (Maybe FStat)
-needsReload oldstat path = do
-  newstat <- getFStat path
-  return $ if newstat /= oldstat
-             then Just newstat
-             else Nothing
-
 -- ** Watcher threads
 
 -- $watcher

src/Ganeti/Utils.hs

@@ -64,6 +64,9 @@ module Ganeti.Utils
   , atomicWriteFile
   , tryAndLogIOError
   , lockFile
+  , FStat
+  , nullFStat
+  , needsReload
   ) where
 
 import Control.Exception (try)
@@ -74,6 +77,7 @@ import qualified Data.Map as M
 import Control.Monad (foldM, liftM)
 import System.Directory (renameFile)
 import System.FilePath.Posix (takeDirectory, takeBaseName)
+import System.Posix.Types
 
 import Debug.Trace
 import Network.Socket
@@ -528,3 +532,31 @@ lockFile path = do
   fd <- handleToFd handle
   Control.Monad.liftM (either (Bad . show) Ok)
     (try (setLock fd (WriteLock, AbsoluteSeek, 0, 0)) :: IO (Either IOError ()))
+
+-- | File stat identifier.
+type FStat = (EpochTime, FileID, FileOffset)
+
+-- | Null 'FStat' value.
+nullFStat :: FStat
+nullFStat = (-1, -1, -1)
+
+-- | Computes the file cache data from a FileStatus structure.
+buildFileStatus :: FileStatus -> FStat
+buildFileStatus ofs =
+    let modt = modificationTime ofs
+        inum = fileID ofs
+        fsize = fileSize ofs
+    in (modt, inum, fsize)
+
+-- | Wrapper over 'buildFileStatus'. This reads the data from the
+-- filesystem and then builds our cache structure.
+getFStat :: FilePath -> IO FStat
+getFStat p = liftM buildFileStatus (getFileStatus p)
+
+-- | Check if the file needs reloading
+needsReload :: FStat -> FilePath -> IO (Maybe FStat)
+needsReload oldstat path = do
+  newstat <- getFStat path
+  return $ if newstat /= oldstat
+             then Just newstat
+             else Nothing