Change the Container.findByName function

This patch changes the signature and implementation of the function;
returning the item makes more sense (saves a lookup later again in the
container, and applying idx is cheap), and the previous implementation
was ugly.

Ganeti/HTools/Container.hs

@@ -105,14 +105,10 @@ maxNameLen = maximum . map (length . T.nameOf) . elems
 
 -- | Find an element by name in a Container; this is a very slow function.
 findByName :: (T.Element a, Monad m) =>
-              Container a -> String -> m Key
+              Container a -> String -> m a
 findByName c n =
     let all_elems = elems c
         result = filter ((== n) . T.nameOf) all_elems
-        nems = length result
-    in
-      if nems /= 1 then
-          fail $ "Wrong number of elems (" ++ show nems ++
-                   ") found with name " ++ n
-      else
-          return $ T.idxOf $ head result
+    in case result of
+         [item] -> return item
+         _ -> fail $ "Wrong number of elems found with name " ++ n

Ganeti/HTools/IAlloc.hs

@@ -126,7 +126,7 @@ parseData body = do
               ex_nodes <- fromObj "relocate_from" request
               let ex_nodes' = map (stripSuffix $ length csf) ex_nodes
               ex_idex <- mapM (Container.findByName map_n) ex_nodes'
-              return $ Relocate ridx req_nodes ex_idex
+              return $ Relocate ridx req_nodes (map Node.idx ex_idex)
         other -> fail ("Invalid request type '" ++ other ++ "'")
   return $ Request rqtype map_n map_i csf
 

Ganeti/HTools/Loader.hs

@@ -139,10 +139,9 @@ mergeData :: [(String, DynUtil)]  -- ^ Instance utilisation data
 mergeData um (nl, il) = do
   let il2 = Container.fromAssocList il
   il3 <- foldM (\im (name, n_util) -> do
-                  idx <- Container.findByName im name
-                  let inst = Container.find idx im
-                      new_i = inst { Instance.util = n_util }
-                  return $ Container.add idx new_i im
+                  inst <- Container.findByName im name
+                  let new_i = inst { Instance.util = n_util }
+                  return $ Container.add (Instance.idx inst) new_i im
                ) il2 um
   let nl2 = foldl' fixNodes nl (Container.elems il3)
   let nl3 = Container.fromAssocList