Commit 7fe8baad authored by Klaus Aehlig's avatar Klaus Aehlig
Browse files

Provide an extensional representation of LockWaiting



The internal representation of the lock waiting structure contains
some arbitrariness---pending requests are arbitrarily keyed by one
of the lock owners that blocks them. Therefore, LockWaiting is not
an instance of Eq. To allow some meaningful form of comparison
nevertheless (in particular for testing), provide some representation
of LockWaiting where equality on the representation is observable
equivalence.
Signed-off-by: default avatarKlaus Aehlig <aehlig@google.com>
Reviewed-by: default avatarPetr Pudlak <pudlak@google.com>
parent cb39314f
......@@ -25,6 +25,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
module Ganeti.Locking.Waiting
( LockWaiting
, ExtWaiting
, emptyWaiting
, updateLocks
, updateLocksWaiting
......@@ -33,8 +34,10 @@ module Ganeti.Locking.Waiting
, removePendingRequest
, releaseResources
, getPendingRequests
, extRepr
) where
import Control.Arrow ((&&&))
import qualified Data.Map as M
import Data.Maybe (fromMaybe)
import qualified Data.Set as S
......@@ -99,6 +102,15 @@ getPendingRequests :: (Ord a, Ord b, Ord c)
=> LockWaiting a b c -> S.Set (c, b, [L.LockRequest a])
getPendingRequests = S.unions . M.elems . lwPending
-- | Type of the extensional representation of a LockWaiting.
type ExtWaiting a b c = (L.LockAllocation a b, S.Set (c, b, [L.LockRequest a]))
-- | Get a representation, comparable by (==), that captures the extensional
-- behaviour. In other words, @(==) `on` extRepr@ is a bisumlation.
extRepr :: (Ord a, Ord b, Ord c)
=> LockWaiting a b c -> ExtWaiting a b c
extRepr = getAllocation &&& getPendingRequests
-- | Internal function to fulfill one request if possible, and keep track of
-- the owners to be notified. The type is chosen to be suitable as fold
-- operation.
......
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