[PATCH master 4/8] Factor out lv info gathering function

[Michele Tartara]

The buildJsonReport function will soon have to perform the coupling of
instance data with LVInfo data. In preparation for that, in order to make
it more readable, the instructions for obtaining LVInfos are factored out
in a separate function.

Signed-off-by: Michele Tartara <mtart...@google.com>
---
 src/Ganeti/DataCollectors/Lv.hs | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/Ganeti/DataCollectors/Lv.hs b/src/Ganeti/DataCollectors/Lv.hs
index 938530a..5c4abcd 100644
--- a/src/Ganeti/DataCollectors/Lv.hs
+++ b/src/Ganeti/DataCollectors/Lv.hs
@@ -48,6 +48,7 @@ import Ganeti.Common
 import Ganeti.DataCollectors.CLI
 import Ganeti.DataCollectors.Types
 import Ganeti.Storage.Lvm.LVParser
+import Ganeti.Storage.Lvm.Types
 import Ganeti.Utils
 
 
@@ -94,9 +95,10 @@ options =
 arguments :: [ArgCompletion]
 arguments = [ArgCompletion OptComplFile 0 (Just 0)]
 
--- | This function computes the JSON representation of the LV status
-buildJsonReport :: Maybe FilePath -> IO J.JSValue
-buildJsonReport inputFile = do
+-- | Get information about logical volumes from file (if specified) or
+-- by actually running the command to get it from a live cluster.
+getLvInfo :: Maybe FilePath -> IO [LVInfo]
+getLvInfo inputFile = do
   let cmd = lvCommand
       params = lvParams
       fromLvs =
@@ -106,12 +108,16 @@ buildJsonReport inputFile = do
     maybe fromLvs (\fn -> ((E.try $ readFile fn) :: IO (Either IOError String))
       >>= exitIfBad "reading from file" . either (BT.Bad . show) BT.Ok)
       inputFile
-  lvInfo <-
-    case A.parse lvParser $ pack contents of
-      A.Fail unparsedText contexts errorMessage -> exitErr $
-        show (Prelude.take defaultCharNum $ unpack unparsedText) ++ "\n"
-          ++ show contexts ++ "\n" ++ errorMessage
-      A.Done _ lvinfoD -> return lvinfoD
+  case A.parse lvParser $ pack contents of
+    A.Fail unparsedText contexts errorMessage -> exitErr $
+      show (Prelude.take defaultCharNum $ unpack unparsedText) ++ "\n"
+        ++ show contexts ++ "\n" ++ errorMessage
+    A.Done _ lvinfoD -> return lvinfoD
+
+-- | This function computes the JSON representation of the LV status
+buildJsonReport :: Maybe FilePath -> IO J.JSValue
+buildJsonReport inputFile = do
+  lvInfo <- getLvInfo inputFile
   return $ J.showJSON lvInfo
 
 -- | This function computes the DCReport for the logical volumes.
-- 
1.8.3