| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Data.Store.Streaming
Contents
Description
For efficiency reasons, Store does not provide facilities for
incrementally consuming input. In order to avoid partial input, this
module introduces Messages that wrap values of instances of Store.
In addition to the serialisation of a value, the serialised message also contains the length of the serialisation. This way, instead of consuming input incrementally, more input can be demanded before serialisation is attempted in the first place.
Each message starts with a fixed magic number, in order to detect (randomly) invalid data.
- newtype Message a = Message {
- fromMessage :: a
- encodeMessage :: Store a => Message a -> ByteString
- type PeekMessage i m a = FT ((->) i) m a
- type FillByteBuffer i m = ByteBuffer -> Int -> i -> m ()
- peekMessage :: (MonadIO m, Store a) => FillByteBuffer i m -> ByteBuffer -> PeekMessage i m (Message a)
- decodeMessage :: (Store a, MonadIO m) => FillByteBuffer i m -> ByteBuffer -> m (Maybe i) -> m (Maybe (Message a))
- peekMessageBS :: (MonadIO m, Store a) => ByteBuffer -> PeekMessage ByteString m (Message a)
- decodeMessageBS :: (MonadIO m, Store a) => ByteBuffer -> m (Maybe ByteString) -> m (Maybe (Message a))
- data ReadMoreData = ReadMoreData
- peekMessageFd :: (MonadIO m, Store a) => ByteBuffer -> Fd -> PeekMessage ReadMoreData m (Message a)
- decodeMessageFd :: (MonadIO m, Store a) => ByteBuffer -> Fd -> m (Message a)
- conduitEncode :: (Monad m, Store a) => Conduit (Message a) m ByteString
- conduitDecode :: (MonadResource m, Store a) => Maybe Int -> Conduit ByteString m (Message a)
Messages to stream data using Store for serialisation.
If a is an instance of Store, Message a can be serialised
and deserialised in a streaming fashion.
Constructors
| Message | |
Fields
| |
Encoding Messages
encodeMessage :: Store a => Message a -> ByteString Source #
Encode a Message to a ByteString.
Decoding Messages
type PeekMessage i m a = FT ((->) i) m a Source #
The result of peeking at the next message can either be a successfully deserialised object, or a request for more input.
type FillByteBuffer i m = ByteBuffer -> Int -> i -> m () Source #
Given some sort of input, fills the ByteBuffer with it.
The Int is how many bytes we'd like: this is useful when the filling
function is fillFromFd, where we can specify a max size.
peekMessage :: (MonadIO m, Store a) => FillByteBuffer i m -> ByteBuffer -> PeekMessage i m (Message a) Source #
Decode some object from a ByteBuffer, by first reading its
header, and then the actual data.
decodeMessage :: (Store a, MonadIO m) => FillByteBuffer i m -> ByteBuffer -> m (Maybe i) -> m (Maybe (Message a)) Source #
Decode a Message from a ByteBuffer and an action that can get
additional inputs to refill the buffer when necessary.
The only conditions under which this function will give Nothing,
is when the ByteBuffer contains zero bytes, and refilling yields
Nothing. If there is some data available, but not enough to
decode the whole Message, a PeekException will be thrown.
peekMessageBS :: (MonadIO m, Store a) => ByteBuffer -> PeekMessage ByteString m (Message a) Source #
Decode some Message from a ByteBuffer, by first reading its
header, and then the actual Message.
decodeMessageBS :: (MonadIO m, Store a) => ByteBuffer -> m (Maybe ByteString) -> m (Maybe (Message a)) Source #
data ReadMoreData Source #
We use this type as a more descriptive unit to signal that more input should be read from the Fd.
This data-type is only available on POSIX systems (essentially, non-windows)
Constructors
| ReadMoreData |
Instances
peekMessageFd :: (MonadIO m, Store a) => ByteBuffer -> Fd -> PeekMessage ReadMoreData m (Message a) Source #
Peeks a message from a _non blocking_ Fd.
This function is only available on POSIX systems (essentially, non-windows)
decodeMessageFd :: (MonadIO m, Store a) => ByteBuffer -> Fd -> m (Message a) Source #
Decodes all the message using registerFd to find out when a Socket is
ready for reading.
This function is only available on POSIX systems (essentially, non-windows)
Conduits for encoding and decoding
conduitEncode :: (Monad m, Store a) => Conduit (Message a) m ByteString Source #
Conduit for encoding Messages to ByteStrings.
Arguments
| :: (MonadResource m, Store a) | |
| => Maybe Int | Initial length of the |
| -> Conduit ByteString m (Message a) |
Conduit for decoding Messages from ByteStrings.