Safe Haskell | None |
---|---|
Language | Haskell2010 |
Primary module containing everything needed to create stateful functions with Flink.
All stateful functions should have a single record type that represents the entire internal state
of the function. Stateful functions API provides many "slots" to store state, but for the purposes of this library
that is hardcoded to the single key flink_state
which you can see in the example module.yaml
.
The Serde typeclass abstracts serialization away from the library so that users can decide how
state should be serialized. Aeson is very convenient so I use it in the example, but protobuf or any other
binary format is also acceptable. Flink essentially stores function state as an opaque ByteString
regardless.
When running your program don't forget to pass +RTS -N
to your binary to run on all cores.
Synopsis
- class MonadIO m => StatefulFunc s m | m -> s where
- insideCtx :: (s -> a) -> m a
- getCtx :: m s
- setCtx :: s -> m ()
- modifyCtx :: (s -> s) -> m ()
- sendMsg :: Message a => (Text, Text, Text) -> a -> m ()
- sendMsgDelay :: Message a => (Text, Text, Text) -> Int -> a -> m ()
- sendEgressMsg :: Message a => (Text, Text) -> a -> m ()
- sendByteMsg :: Serde a => (Text, Text, Text) -> a -> m ()
- sendByteMsgDelay :: Serde a => (Text, Text, Text) -> Int -> a -> m ()
- flinkWrapper :: Serde s => (Any -> Function s ()) -> ByteString -> Env -> ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString))
- createApp :: FunctionTable -> Application
- flinkServer :: FunctionTable -> Server FlinkApi
- flinkApi :: Proxy FlinkApi
- class Serde a where
- deserializeBytes :: ByteString -> Either String a
- serializeBytes :: a -> ByteString
- type FunctionTable = Map (Text, Text) (ByteString, ByteString -> Env -> ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString)))
- newtype JsonSerde a = JsonSerde {
- getJson :: a
- newtype ProtoSerde a = ProtoSerde {
- getMessage :: a
- jsonState :: Json s => (a -> Function s ()) -> a -> Function (JsonSerde s) ()
- protoState :: Message s => (a -> Function s ()) -> a -> Function (ProtoSerde s) ()
- serdeInput :: (Serde s, Serde a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b
- protoInput :: (Serde s, Message a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b
- jsonInput :: (Serde s, Json a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b
Documentation
class MonadIO m => StatefulFunc s m | m -> s where Source #
Used to represent all Flink stateful function capabilities.
Contexts are received from Flink and deserializeBytesd into s
all modifications to state are shipped back to Flink at the end of the
batch to be persisted.
Message passing is also queued up and passed back at the end of the current batch.
setInitialCtx, insideCtx, getCtx, setCtx, modifyCtx, sendMsg, sendMsgDelay, sendEgressMsg, sendByteMsg, sendByteMsgDelay
insideCtx :: (s -> a) -> m a Source #
modifyCtx :: (s -> s) -> m () Source #
:: Message a | |
=> (Text, Text, Text) | Function address (namespace, type, id) |
-> a | protobuf message to send |
-> m () |
:: Message a | |
=> (Text, Text, Text) | Function address (namespace, type, id) |
-> Int | delay before message send |
-> a | protobuf message to send |
-> m () |
Instances
StatefulFunc s (Function s) Source # | |
Defined in Network.Flink.Internal.Stateful setInitialCtx :: s -> Function s () insideCtx :: (s -> a) -> Function s a Source # getCtx :: Function s s Source # setCtx :: s -> Function s () Source # modifyCtx :: (s -> s) -> Function s () Source # sendMsg :: Message a => (Text, Text, Text) -> a -> Function s () Source # sendMsgDelay :: Message a => (Text, Text, Text) -> Int -> a -> Function s () Source # sendEgressMsg :: Message a => (Text, Text) -> a -> Function s () Source # sendByteMsg :: Serde a => (Text, Text, Text) -> a -> Function s () Source # sendByteMsgDelay :: Serde a => (Text, Text, Text) -> Int -> a -> Function s () Source # |
flinkWrapper :: Serde s => (Any -> Function s ()) -> ByteString -> Env -> ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString)) Source #
Takes a function taking an arbitrary state type and converts it to take ByteString
s.
This allows each function in the FunctionTable
to take its own individual type of state and just expose
a function accepting ByteString
to the library code.
createApp :: FunctionTable -> Application Source #
Takes function table and creates a wai Application
to serve flink requests
flinkServer :: FunctionTable -> Server FlinkApi Source #
Takes function table and creates a servant Server
to serve flink requests
deserializeBytes :: ByteString -> Either String a Source #
decodes types from strict ByteString
s
serializeBytes :: a -> ByteString Source #
encodes types to strict ByteString
s
Instances
Serde () Source # | |
Defined in Network.Flink.Internal.Stateful deserializeBytes :: ByteString -> Either String () Source # serializeBytes :: () -> ByteString Source # | |
Serde ByteString Source # | |
Defined in Network.Flink.Internal.Stateful | |
Serde ByteString Source # | |
Defined in Network.Flink.Internal.Stateful | |
Json a => Serde (JsonSerde a) Source # | |
Defined in Network.Flink.Internal.Stateful deserializeBytes :: ByteString -> Either String (JsonSerde a) Source # serializeBytes :: JsonSerde a -> ByteString Source # | |
Message a => Serde (ProtoSerde a) Source # | |
Defined in Network.Flink.Internal.Stateful deserializeBytes :: ByteString -> Either String (ProtoSerde a) Source # serializeBytes :: ProtoSerde a -> ByteString Source # |
type FunctionTable = Map (Text, Text) (ByteString, ByteString -> Env -> ToFunction'InvocationBatchRequest -> IO (Either FlinkError (FunctionState ByteString))) Source #
Instances
Functor JsonSerde Source # | |
Json a => Serde (JsonSerde a) Source # | |
Defined in Network.Flink.Internal.Stateful deserializeBytes :: ByteString -> Either String (JsonSerde a) Source # serializeBytes :: JsonSerde a -> ByteString Source # |
newtype ProtoSerde a Source #
ProtoSerde | |
|
Instances
Functor ProtoSerde Source # | |
Defined in Network.Flink.Internal.Stateful fmap :: (a -> b) -> ProtoSerde a -> ProtoSerde b # (<$) :: a -> ProtoSerde b -> ProtoSerde a # | |
Message a => Serde (ProtoSerde a) Source # | |
Defined in Network.Flink.Internal.Stateful deserializeBytes :: ByteString -> Either String (ProtoSerde a) Source # serializeBytes :: ProtoSerde a -> ByteString Source # |
jsonState :: Json s => (a -> Function s ()) -> a -> Function (JsonSerde s) () Source #
Convenience function for wrapping state in newtype for JSON serialization
protoState :: Message s => (a -> Function s ()) -> a -> Function (ProtoSerde s) () Source #
Convenience function for wrapping state in newtype for Protobuf serialization
serdeInput :: (Serde s, Serde a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b Source #
Deserializes input messages as arbitrary bytes by extracting them out of the protobuf Any and ignoring the type since that's protobuf specific
protoInput :: (Serde s, Message a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b Source #
Deserializes input messages by unpacking the protobuf Any into the expected type.
If you are passing messages via protobuf, this is much more typesafe than serdeInput
jsonInput :: (Serde s, Json a, StatefulFunc s m, MonadError FlinkError m, MonadReader Env m) => (a -> m b) -> Any -> m b Source #
Deserializes input messages as arbitrary bytes by extracting them out of the protobuf Any and ignoring the type since that's protobuf specific