From c8db97e5ff3640a07e782a6e6bd192820718919d Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Fri, 30 Oct 2009 12:07:28 +0100
Subject: [PATCH] Add support for shrinking instance specs
This patch adds a function that, for some given failure modes, shrinks a
given instance in the hope that allocation will succeed when retried
with the new spec.
---
Ganeti/HTools/Instance.hs | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/Ganeti/HTools/Instance.hs b/Ganeti/HTools/Instance.hs
index 0ec0644d3..72b27dadc 100644
--- a/Ganeti/HTools/Instance.hs
+++ b/Ganeti/HTools/Instance.hs
@@ -36,6 +36,7 @@ module Ganeti.HTools.Instance
, setPri
, setSec
, setBoth
+ , shrinkByType
) where
import qualified Ganeti.HTools.Types as T
@@ -62,6 +63,16 @@ instance T.Element Instance where
setName = setName
setIdx = setIdx
+-- | Base memory unit.
+unitMem :: Int
+unitMem = 64
+-- | Base disk unit.
+unitDsk :: Int
+unitDsk = 256
+-- | Base vcpus unit.
+unitCpu :: Int
+unitCpu = 1
+
-- | A simple name for the int, instance association list.
type AssocList = [(T.Idx, Instance)]
@@ -124,3 +135,20 @@ setBoth :: Instance -- ^ the original instance
-> T.Ndx -- ^ new secondary node index
-> Instance -- ^ the modified instance
setBoth t p s = t { pNode = p, sNode = s }
+
+-- | Try to shrink the instance based on the reason why we can't
+-- allocate it.
+shrinkByType :: Instance -> T.FailMode -> T.Result Instance
+shrinkByType inst T.FailMem = let v = mem inst - unitMem
+ in if v < unitMem
+ then T.Bad "out of memory"
+ else T.Ok inst { mem = v }
+shrinkByType inst T.FailDisk = let v = dsk inst - unitDsk
+ in if v < unitDsk
+ then T.Bad "out of disk"
+ else T.Ok inst { dsk = v }
+shrinkByType inst T.FailCPU = let v = vcpus inst - unitCpu
+ in if v < unitCpu
+ then T.Bad "out of vcpus"
+ else T.Ok inst { vcpus = v }
+shrinkByType _ f = T.Bad $ "Unhandled failure mode " ++ show f
--
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