Simpoole

Documentation

data Pool m a

Pool of resources

Since: 0.0.0

mapPool :: (forall x. m x -> n x) -> Pool m a -> Pool n a

Lift a natural transformation m ~> n to Pool m ~> Pool n.

Since: 0.0.0

newUnlimitedPool

Arguments

:: (MonadConc m, MonadIO m)

=> m a

Resource creation

-> (a -> m ())

Resource destruction

-> Settings

Pool settings

-> m (Pool m a)

Create a new pool that has no limit on how many resources it may create and hold.

Since: 0.1.0

newPool

Arguments

:: (MonadConc m, MonadIO m, MonadFail m)

=> m a

Resource creation

-> (a -> m ())

Resource destruction

-> Int

Maximum number of resources to exist at the same time

-> Settings

Pool settings

-> m (Pool m a)

Similar to newUnlimitedPool but allows you to limit the number of resources that will exist at the same time. When all resources are currently in use, further resource acquisition will block until one is no longer in use.

Since: 0.1.0

withResource :: MonadMask m => Pool m a -> (a -> m r) -> m r

Use a resource from the pool. Once the continuation returns, the resource will be returned to the pool. If the given continuation throws an error then the acquired resource will be destroyed instead.

Since: 0.0.0

acquireResource :: Pool m a -> m a

Acquire a resource.

Since: 0.1.0

returnResource :: Pool m a -> a -> m ()

Return a resource to the pool.

Since: 0.1.0

destroyResource :: Pool m a -> a -> m ()

Destroy a resource.

Since: 0.1.0

poolMetrics :: Pool m a -> m (Metrics Natural)

Fetch pool metrics.

Since: 0.0.0

data Settings

Lets you configure certain behaviours of the pool

Since: 0.1.0

Constructors

PoolSettings

Fields

• settings_idleTimeout :: NominalDiffTime

  Maximum idle time after which a resource is destroyed

  Since: 0.1.0

• settings_returnPolicy :: ReturnPolicy

defaultSettings :: Settings

Default pool settings

Since: 0.1.0

data ReturnPolicy

Strategy to use when returning resources to the pool

Since: 0.1.0

Constructors

ReturnToFront

Return resources to the front. Resources that have been used recently are more likely to be reused again quicker. This strategy is good if you want to scale down the pool more quickly in case resources are not needed.

Since: 0.1.0

ReturnToBack

Return resources to the back. Resources that have been used recently are less likely to be used again quicker. Use this strategy if you want to keep more resources in the pool fresh, or when maintaining the pool in order to be ready for burst workloads. This strategy can lead to no resources ever been freed when all resources are used within the idle timeout.

Since: 0.1.0

ReturnToMiddle

Return resources to the middle. This offers a middleground between ReturnToFront and ReturnToBack. By ensuring that the starting sub-sequence of resources is reused quicker but the trailing sub-sequence is not and therefore released more easily.

Since: 0.1.0

Instances

Bounded ReturnPolicy

Defined in Simpoole

Methods

minBound :: ReturnPolicy

maxBound :: ReturnPolicy

Enum ReturnPolicy

Defined in Simpoole

Methods

succ :: ReturnPolicy -> ReturnPolicy

pred :: ReturnPolicy -> ReturnPolicy

toEnum :: Int -> ReturnPolicy

fromEnum :: ReturnPolicy -> Int

enumFrom :: ReturnPolicy -> [ReturnPolicy]

enumFromThen :: ReturnPolicy -> ReturnPolicy -> [ReturnPolicy]

enumFromTo :: ReturnPolicy -> ReturnPolicy -> [ReturnPolicy]

enumFromThenTo :: ReturnPolicy -> ReturnPolicy -> ReturnPolicy -> [ReturnPolicy]

Eq ReturnPolicy

Defined in Simpoole

Methods

(==) :: ReturnPolicy -> ReturnPolicy -> Bool

(/=) :: ReturnPolicy -> ReturnPolicy -> Bool

Ord ReturnPolicy

Defined in Simpoole

Methods

compare :: ReturnPolicy -> ReturnPolicy -> Ordering

(<) :: ReturnPolicy -> ReturnPolicy -> Bool

(<=) :: ReturnPolicy -> ReturnPolicy -> Bool

(>) :: ReturnPolicy -> ReturnPolicy -> Bool

(>=) :: ReturnPolicy -> ReturnPolicy -> Bool

max :: ReturnPolicy -> ReturnPolicy -> ReturnPolicy

min :: ReturnPolicy -> ReturnPolicy -> ReturnPolicy

Read ReturnPolicy

Defined in Simpoole

Methods

readsPrec :: Int -> ReadS ReturnPolicy

readList :: ReadS [ReturnPolicy]

readPrec :: ReadPrec ReturnPolicy

readListPrec :: ReadPrec [ReturnPolicy]

Show ReturnPolicy

Defined in Simpoole

Methods

showsPrec :: Int -> ReturnPolicy -> ShowS

show :: ReturnPolicy -> String

showList :: [ReturnPolicy] -> ShowS

data Metrics a

Pool metrics

Since: 0.0.0

Constructors

Metrics

Fields

• metrics_createdResources :: a

  Total number of resources created

  Since: 0.0.0

• metrics_destroyedResources :: a

  Total number of resources destroyed

  Since: 0.0.0

• metrics_maxLiveResources :: a

  Maximum number of resources that were alive simultaneously

  Since: 0.0.0

• metrics_idleResources :: a

  Number of resources currently idle

  Since: 0.1.0

Instances

Functor Metrics

Defined in Simpoole

Methods

fmap :: (a -> b) -> Metrics a -> Metrics b

(<$) :: a -> Metrics b -> Metrics a

Foldable Metrics

Defined in Simpoole

Methods

fold :: Monoid m => Metrics m -> m

foldMap :: Monoid m => (a -> m) -> Metrics a -> m

foldMap' :: Monoid m => (a -> m) -> Metrics a -> m

foldr :: (a -> b -> b) -> b -> Metrics a -> b

foldr' :: (a -> b -> b) -> b -> Metrics a -> b

foldl :: (b -> a -> b) -> b -> Metrics a -> b

foldl' :: (b -> a -> b) -> b -> Metrics a -> b

foldr1 :: (a -> a -> a) -> Metrics a -> a

foldl1 :: (a -> a -> a) -> Metrics a -> a

toList :: Metrics a -> [a]

null :: Metrics a -> Bool

length :: Metrics a -> Int

elem :: Eq a => a -> Metrics a -> Bool

maximum :: Ord a => Metrics a -> a

minimum :: Ord a => Metrics a -> a

sum :: Num a => Metrics a -> a

product :: Num a => Metrics a -> a

Traversable Metrics

Defined in Simpoole

Methods

traverse :: Applicative f => (a -> f b) -> Metrics a -> f (Metrics b)

sequenceA :: Applicative f => Metrics (f a) -> f (Metrics a)

mapM :: Monad m => (a -> m b) -> Metrics a -> m (Metrics b)

sequence :: Monad m => Metrics (m a) -> m (Metrics a)

Eq a => Eq (Metrics a)

Defined in Simpoole

Methods

(==) :: Metrics a -> Metrics a -> Bool

(/=) :: Metrics a -> Metrics a -> Bool

Ord a => Ord (Metrics a)

Defined in Simpoole

Methods

compare :: Metrics a -> Metrics a -> Ordering

(<) :: Metrics a -> Metrics a -> Bool

(<=) :: Metrics a -> Metrics a -> Bool

(>) :: Metrics a -> Metrics a -> Bool

(>=) :: Metrics a -> Metrics a -> Bool

max :: Metrics a -> Metrics a -> Metrics a

min :: Metrics a -> Metrics a -> Metrics a

Read a => Read (Metrics a)

Defined in Simpoole

Methods

readsPrec :: Int -> ReadS (Metrics a)

readList :: ReadS [Metrics a]

readPrec :: ReadPrec (Metrics a)

readListPrec :: ReadPrec [Metrics a]

Show a => Show (Metrics a)

Defined in Simpoole

Methods

showsPrec :: Int -> Metrics a -> ShowS

show :: Metrics a -> String

showList :: [Metrics a] -> ShowS