Simplify the Cluster.tryAlloc structures

Currently the tryAlloc function calls the
allocateOnSingle/allocateOnPair and the builds a new tuple with those
functions's result plus the new node list. This is however suboptimal
in two respects:
  - the new nodes added are the 'old' versions of the respective nodes,
    so even though we don't use more than their names, it's logically
    broken
  - we do an extra unpack/repack of the result, while we could simply
    pass it through if allocateOnX returned the correct result

This patch makes the allocateOnX functions return the node list too and
also removes them and applyMove from the export list, as these are only
used within Cluster.hs.

diff --git a/Ganeti/HTools/Cluster.hs b/Ganeti/HTools/Cluster.hs
index d97ff5d..c4dba4c 100644 (file)
--- a/Ganeti/HTools/Cluster.hs
+++ b/Ganeti/HTools/Cluster.hs
@@ -45,13 +45,10 @@ module Ganeti.HTools.Cluster
     , formatCmds
     , printNodes
     -- * Balacing functions
-    , applyMove
     , checkMove
     , compCV
     , printStats
     -- * IAllocator functions
-    , allocateOnSingle
-    , allocateOnPair
     , tryAlloc
     , tryReloc
     ) where
@@ -335,17 +332,17 @@ applyMove nl inst (FailoverAndReplace new_sdx) =
 
 -- | Tries to allocate an instance on one given node.
 allocateOnSingle :: Node.List -> Instance.Instance -> Node.Node
-                 -> OpResult (Node.List, Instance.Instance)
+                 -> OpResult (Node.List, Instance.Instance, [Node.Node])
 allocateOnSingle nl inst p =
     let new_pdx = Node.idx p
         new_inst = Instance.setBoth inst new_pdx Node.noSecondary
         new_nl = Node.addPri p inst >>= \new_p ->
-                 return (Container.add new_pdx new_p nl, new_inst)
+                 return (Container.add new_pdx new_p nl, new_inst, [new_p])
     in new_nl
 
 -- | Tries to allocate an instance on a given pair of nodes.
 allocateOnPair :: Node.List -> Instance.Instance -> Node.Node -> Node.Node
-               -> OpResult (Node.List, Instance.Instance)
+               -> OpResult (Node.List, Instance.Instance, [Node.Node])
 allocateOnPair nl inst tgt_p tgt_s =
     let new_pdx = Node.idx tgt_p
         new_sdx = Node.idx tgt_s
@@ -353,7 +350,8 @@ allocateOnPair nl inst tgt_p tgt_s =
           new_p <- Node.addPri tgt_p inst
           new_s <- Node.addSec tgt_s inst new_pdx
           let new_inst = Instance.setBoth inst new_pdx new_sdx
-          return (Container.addTwo new_pdx new_p new_sdx new_s nl, new_inst)
+          return (Container.addTwo new_pdx new_p new_sdx new_s nl, new_inst,
+                 [new_p, new_s])
     in new_nl
 
 -- | Tries to perform an instance move and returns the best table
@@ -447,18 +445,12 @@ tryAlloc nl _ inst 2 =
     let all_nodes = getOnline nl
         all_pairs = liftM2 (,) all_nodes all_nodes
         ok_pairs = filter (\(x, y) -> Node.idx x /= Node.idx y) all_pairs
-        sols = map (\(p, s) -> do
-                      (mnl, i) <- allocateOnPair nl inst p s
-                      return (mnl, i, [p, s]))
-               ok_pairs
+        sols = map (uncurry $ allocateOnPair nl inst) ok_pairs
     in return sols
 
 tryAlloc nl _ inst 1 =
     let all_nodes = getOnline nl
-        sols = map (\p -> do
-                      (mnl, i) <- allocateOnSingle nl inst p
-                      return (mnl, i, [p]))
-               all_nodes
+        sols = map (allocateOnSingle nl inst) all_nodes
     in return sols
 
 tryAlloc _ _ _ reqn = fail $ "Unsupported number of alllocation \