Safe Haskell	Safe-Inferred
Language	GHC2021

Hydra.Events

Contents

State change events as used by Hydra.Node

Description

This module defines the types and functions for creating EventSource and EventSink instances and is intended to be used as an extension point.

A single EventSource and zero or more EventSink handles are used by the main HydraNode handle to load and send out events.

See FileBased for an example implementation and FileBasedSpec for the corresponding test suite.

Custom implementations should be located under Hydra.Events to avoid conflicts.

Synopsis

type EventId = Word64
class HasEventId a where
- getEventId :: a -> EventId
newtype EventSource e m = EventSource {
- sourceEvents :: HasEventId e => ConduitT () e (ResourceT m) ()
}
getEvents :: (HasEventId e, MonadUnliftIO m) => EventSource e m -> m [e]
newtype EventSink e m = EventSink {
- putEvent :: HasEventId e => e -> m ()
}
putEventsToSinks :: (Monad m, HasEventId e) => [EventSink e m] -> [e] -> m ()
data StateEvent tx = StateEvent {
- eventId :: EventId
- stateChanged :: StateChanged tx
- time :: UTCTime
}
genStateEvent :: StateChanged tx -> Gen (StateEvent tx)

Documentation

type EventId = Word64 Source #

class HasEventId a where Source #

Methods

getEventId :: a -> EventId Source #

Instances

Instances details

HasEventId (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods getEventId :: StateEvent tx -> EventId Source #

newtype EventSource e m Source #

Constructors

EventSource
Fields sourceEvents :: HasEventId e => ConduitT () e (ResourceT m) () Stream all events from the event source.

getEvents :: (HasEventId e, MonadUnliftIO m) => EventSource e m -> m [e] Source #

Retrieve all events from the event source as a list.

newtype EventSink e m Source #

Constructors

EventSink
Fields putEvent :: HasEventId e => e -> m () Send a single event to the event sink.

putEventsToSinks :: (Monad m, HasEventId e) => [EventSink e m] -> [e] -> m () Source #

Put a list of events to a list of event sinks in a round-robin fashion.

State change events as used by Hydra.Node

data StateEvent tx Source #

A state change event with an event id that is the common entity to be loaded from an EventSource and sent to EventSinks.

Constructors

StateEvent
Fields eventId :: EventId stateChanged :: StateChanged tx time :: UTCTime

Instances

Instances details

(ArbitraryIsTx tx, IsChainState tx) => Arbitrary (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods arbitrary :: Gen (StateEvent tx) shrink :: StateEvent tx -> [StateEvent tx]
IsChainState tx => FromJSON (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods parseJSON :: Value -> Parser (StateEvent tx) parseJSONList :: Value -> Parser [StateEvent tx] omittedField :: Maybe (StateEvent tx)
IsChainState tx => ToJSON (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods toJSON :: StateEvent tx -> Value toEncoding :: StateEvent tx -> Encoding toJSONList :: [StateEvent tx] -> Value toEncodingList :: [StateEvent tx] -> Encoding omitField :: StateEvent tx -> Bool
Generic (StateEvent tx) Source #
Instance details Defined in Hydra.Events Associated Types type Rep (StateEvent tx) :: Type -> Type Source # Methods from :: StateEvent tx -> Rep (StateEvent tx) x Source # to :: Rep (StateEvent tx) x -> StateEvent tx Source #
IsChainState tx => Show (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods showsPrec :: Int -> StateEvent tx -> ShowS Source # show :: StateEvent tx -> String Source # showList :: [StateEvent tx] -> ShowS Source #
IsChainState tx => Eq (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods (==) :: StateEvent tx -> StateEvent tx -> Bool Source # (/=) :: StateEvent tx -> StateEvent tx -> Bool Source #
HasEventId (StateEvent tx) Source #
Instance details Defined in Hydra.Events Methods getEventId :: StateEvent tx -> EventId Source #
type Rep (StateEvent tx) Source #
Instance details Defined in Hydra.Events type Rep (StateEvent tx) = D1 ('MetaData "StateEvent" "Hydra.Events" "hydra-node-0.21.0-4ibc00B6CCmF4EmjGjxvGm" 'False) (C1 ('MetaCons "StateEvent" 'PrefixI 'True) (S1 ('MetaSel ('Just "eventId") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 EventId) :: (S1 ('MetaSel ('Just "stateChanged") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (StateChanged tx)) :: S1 ('MetaSel ('Just "time") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 UTCTime))))

genStateEvent :: StateChanged tx -> Gen (StateEvent tx) Source #