Safe Haskell  None 

Implementation of lock allocation.
Synopsis
 data OwnerState
 data LockAllocation a b
 emptyAllocation :: (Ord a, Ord b) => LockAllocation a b
 lockOwners :: Ord b => LockAllocation a b > [b]
 listLocks :: Ord b => b > LockAllocation a b > Map a OwnerState
 listAllLocks :: Ord b => LockAllocation a b > [a]
 listAllLocksOwners :: LockAllocation a b > [(a, [(b, OwnerState)])]
 holdsLock :: (Ord a, Ord b) => b > a > OwnerState > LockAllocation a b > Bool
 data LockRequest a = LockRequest {
 lockAffected :: a
 lockRequestType :: Maybe OwnerState
 requestExclusive :: a > LockRequest a
 requestShared :: a > LockRequest a
 requestRelease :: a > LockRequest a
 updateLocks :: (Lock a, Ord b) => b > [LockRequest a] > LockAllocation a b > (LockAllocation a b, Result (Set b))
 freeLocks :: (Lock a, Ord b) => LockAllocation a b > b > LockAllocation a b
Documentation
data OwnerState Source #
Data type describing the way a lock can be owned.
Instances
Eq OwnerState #  
Defined in Ganeti.Locking.Allocation (==) :: OwnerState > OwnerState > Bool (/=) :: OwnerState > OwnerState > Bool  
Ord OwnerState #  
Defined in Ganeti.Locking.Allocation compare :: OwnerState > OwnerState > Ordering (<) :: OwnerState > OwnerState > Bool (<=) :: OwnerState > OwnerState > Bool (>) :: OwnerState > OwnerState > Bool (>=) :: OwnerState > OwnerState > Bool max :: OwnerState > OwnerState > OwnerState min :: OwnerState > OwnerState > OwnerState  
Show OwnerState #  
Defined in Ganeti.Locking.Allocation showsPrec :: Int > OwnerState > ShowS show :: OwnerState > String showList :: [OwnerState] > ShowS  
JSON OwnerState #  Serializaiton of Lock Allocations To serialize a lock allocation, we only remember which owner holds which locks at which level (shared or exclusive). From this information, everything else can be reconstructed, simply using updateLocks. 
Defined in Ganeti.Locking.Allocation readJSON :: JSValue > Result OwnerState showJSON :: OwnerState > JSValue readJSONs :: JSValue > Result [OwnerState] showJSONs :: [OwnerState] > JSValue  
Arbitrary OwnerState  
Defined in Test.Ganeti.Locking.Allocation arbitrary :: Gen OwnerState shrink :: OwnerState > [OwnerState] 
data LockAllocation a b Source #
Representation of a Lock allocation
To keep queries for locks efficient, we keep two associations, with the invariant that they fit together: the association from locks to their allocation state, and the association from an owner to the set of locks owned. As we do not export the constructor, the problem of keeping this invariant reduces to only exporting functions that keep the invariant.
Instances
(Eq a, Eq b) => Eq (LockAllocation a b) #  
Defined in Ganeti.Locking.Allocation (==) :: LockAllocation a b > LockAllocation a b > Bool (/=) :: LockAllocation a b > LockAllocation a b > Bool  
(Show a, Show b) => Show (LockAllocation a b) #  
Defined in Ganeti.Locking.Allocation showsPrec :: Int > LockAllocation a b > ShowS show :: LockAllocation a b > String showList :: [LockAllocation a b] > ShowS  
(Lock a, JSON a, Ord b, JSON b, Show b) => JSON (LockAllocation a b) #  
Defined in Ganeti.Locking.Allocation readJSON :: JSValue > Result (LockAllocation a b) showJSON :: LockAllocation a b > JSValue readJSONs :: JSValue > Result [LockAllocation a b] showJSONs :: [LockAllocation a b] > JSValue  
(Arbitrary a, Lock a, Arbitrary b, Ord b, Show b) => Arbitrary (LockAllocation a b)  
Defined in Test.Ganeti.Locking.Allocation arbitrary :: Gen (LockAllocation a b) shrink :: LockAllocation a b > [LockAllocation a b] 
emptyAllocation :: (Ord a, Ord b) => LockAllocation a b Source #
A state with all locks being free.
lockOwners :: Ord b => LockAllocation a b > [b] Source #
Obtain the list of all owners holding at least a single lock.
listLocks :: Ord b => b > LockAllocation a b > Map a OwnerState Source #
Obtain the locks held by a given owner. The locks are reported as a map from the owned locks to the form of ownership (OwnShared or OwnExclusive).
listAllLocks :: Ord b => LockAllocation a b > [a] Source #
List all locks currently (directly or indirectly) owned by someone.
listAllLocksOwners :: LockAllocation a b > [(a, [(b, OwnerState)])] Source #
List all locks currently (directly of indirectly) in use together with the direct owners.
holdsLock :: (Ord a, Ord b) => b > a > OwnerState > LockAllocation a b > Bool Source #
Returns True
if the given owner holds the given lock at the given
ownership level or higher. This means that querying for a shared lock
returns True
of the owner holds the lock in shared or exlusive mode.
data LockRequest a Source #
Data Type describing a change request on a single lock.
LockRequest  

Instances
requestExclusive :: a > LockRequest a Source #
Lock request for an exclusive lock.
requestShared :: a > LockRequest a Source #
Lock request for a shared lock.
requestRelease :: a > LockRequest a Source #
Request to release a lock.
updateLocks :: (Lock a, Ord b) => b > [LockRequest a] > LockAllocation a b > (LockAllocation a b, Result (Set b)) Source #
Update the locks of an owner according to the given request. Return the pair of the new state and the result of the operation, which is the the set of owners on which the operation was blocked on. so an empty set is success, and the state is updated if, and only if, the returned set is emtpy. In that way, it can be used in atomicModifyIORef.
freeLocks :: (Lock a, Ord b) => LockAllocation a b > b > LockAllocation a b Source #
Compute the state after an onwer releases all its locks.