From 41c3b292188e3c8cebe6cb03b5001620865752ea Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Mon, 6 Jul 2009 23:13:15 +0200
Subject: [PATCH] Simplify Cluster.computeMoves
This patch changes the function Cluster.computeMoves to use guards and a
couple of subexpressions in order to greatly simplify it.
---
Ganeti/HTools/Cluster.hs | 53 +++++++++++++++++-----------------------
1 file changed, 22 insertions(+), 31 deletions(-)
diff --git a/Ganeti/HTools/Cluster.hs b/Ganeti/HTools/Cluster.hs
index 1afbc0ce6..dc766a88d 100644
--- a/Ganeti/HTools/Cluster.hs
+++ b/Ganeti/HTools/Cluster.hs
@@ -446,38 +446,29 @@ computeMoves :: String -- ^ The instance name
-- either @/f/@ for failover or @/r:name/@ for replace
-- secondary, while the command list holds gnt-instance
-- commands (without that prefix), e.g \"@failover instance1@\"
-computeMoves i a b c d =
- if c == a then {- Same primary -}
- if d == b then {- Same sec??! -}
- ("-", [])
+computeMoves i a b c d
+ -- same primary
+ | c == a =
+ if d == b
+ then {- Same sec??! -} ("-", [])
else {- Change of secondary -}
- (printf "r:%s" d,
- [printf "replace-disks -n %s %s" d i])
- else
- if c == b then {- Failover and ... -}
- if d == a then {- that's all -}
- ("f", [printf "migrate -f %s" i])
- else
- (printf "f r:%s" d,
- [printf "migrate -f %s" i,
- printf "replace-disks -n %s %s" d i])
- else
- if d == a then {- ... and keep primary as secondary -}
- (printf "r:%s f" c,
- [printf "replace-disks -n %s %s" c i,
- printf "migrate -f %s" i])
- else
- if d == b then {- ... keep same secondary -}
- (printf "f r:%s f" c,
- [printf "migrate -f %s" i,
- printf "replace-disks -n %s %s" c i,
- printf "migrate -f %s" i])
-
- else {- Nothing in common -}
- (printf "r:%s f r:%s" c d,
- [printf "replace-disks -n %s %s" c i,
- printf "migrate -f %s" i,
- printf "replace-disks -n %s %s" d i])
+ (printf "r:%s" d, [rep d])
+ -- failover and ...
+ | c == b =
+ if d == a
+ then {- that's all -} ("f", [mig])
+ else (printf "f r:%s" d, [mig, rep d])
+ -- ... and keep primary as secondary
+ | d == a =
+ (printf "r:%s f" c, [rep c, mig])
+ -- ... keep same secondary
+ | d == b =
+ (printf "f r:%s f" c, [mig, rep c, mig])
+ -- nothing in common -
+ | otherwise =
+ (printf "r:%s f r:%s" c d, [rep c, mig, rep d])
+ where mig = printf "migrate -f %s" i::String
+ rep n = printf "replace-disks -n %s %s" n i
-- | Converts a placement to string format.
printSolutionLine :: Node.List -- ^ The node list
--
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