happstack-state-0.4.1: Event-based distributed state. Source code Contents Index

Happstack.State

Contents ACID monad Types Misc utilities Random numbers TH helpers Serialization Unsafe things

Synopsis

data Ev m t type AnyEv a = forall t. (Monad (t STM), MonadTrans t) => Ev (t STM) a data TxControl query :: (MonadIO m, QueryEvent ev res) => ev -> m res update :: (MonadIO m, UpdateEvent ev res) => ev -> m res type Update state = Ev (StateT state STM) type Query state = Ev (ReaderT state STM) type TxId = Int64 type EpochMilli = Int64 data Saver = NullSaver | FileSaver String | Queue Saver | Memory (MVar Store) setUpdateType :: Proxy t -> Update t () proxyUpdate :: Update t b -> Proxy t -> Update t b setQueryType :: Proxy t -> Query t () proxyQuery :: Query t b -> Proxy t -> Query t b asUpdate :: Update t a -> Proxy t -> Update t a asQuery :: Query t a -> Proxy t -> Query t a askState :: Query st st getState :: Update st st putState :: st -> Update st () liftSTM :: STM a -> AnyEv a class CatchEv m where catchEv :: Ev m a -> (SomeException -> a) -> Ev m a sel :: (Env -> b) -> AnyEv b localState :: (outer -> inner) -> (inner -> outer -> outer) -> Ev (StateT inner STM) a -> Ev (StateT outer STM) a localStateReader :: (outer -> inner) -> Ev (ReaderT inner STM) a -> Ev (ReaderT outer STM) a runQuery :: Query st a -> Update st a getEventId :: Integral txId => AnyEv txId getTime :: Integral epochTime => AnyEv epochTime getEventClockTime :: AnyEv ClockTime getEventStream :: IO (IO EventItem) data EventItem = EventItem { eventContext :: TxContext eventData :: Dynamic } getRandom :: Random a => AnyEv a getRandomR :: Random a => (a, a) -> AnyEv a inferRecordUpdaters :: Name -> Q [Dec] module Happstack.Data.Serialize module Happstack.Data.SerializeTH module Happstack.State.Control module Happstack.State.ComponentTH module Happstack.State.ComponentSystem runTxSystem :: (Methods st, Component st) => Saver -> Proxy st -> IO (MVar TxControl) createCheckpoint :: MVar TxControl -> IO () shutdownSystem :: MVar TxControl -> IO () unsafeIOToEv :: IO a -> AnyEv a

ACID monad

data Ev m t Source

Monad for ACID event handlers. Instances Monad m => Monad (Ev m) Monad m => Functor (Ev m) MonadPlus m => MonadPlus (Ev m) (Typeable state, Typeable t) => Typeable (Ev (StateT state STM) t) (Typeable state, Typeable t) => Typeable (Ev (ReaderT state STM) t)

type AnyEv a = forall t. (Monad (t STM), MonadTrans t) => Ev (t STM) a Source

ACID computations that work with any state and event types.

data TxControl Source

query :: (MonadIO m, QueryEvent ev res) => ev -> m res Source

Emit a state query and wait for the result.

update :: (MonadIO m, UpdateEvent ev res) => ev -> m res Source

Schedule an update and wait for it to complete. When this function returns, you're guaranteed the update will be persistent.

type Update state = Ev (StateT state STM) Source

type Query state = Ev (ReaderT state STM) Source

Types

type TxId = Int64 Source

type EpochMilli = Int64 Source

data Saver Source

Constructors NullSaver A saver that discards all output FileSaver String A saver that operates on files. The parameter is the prefix for the files. Queue Saver Enable queueing. Memory (MVar Store)

Misc utilities

setUpdateType :: Proxy t -> Update t () Source

Use a proxy to force the type of an update action.

proxyUpdate :: Update t b -> Proxy t -> Update t b Source

Forces the type of the proxy and update to match

setQueryType :: Proxy t -> Query t () Source

Use a proxy to force the type of a query action.

proxyQuery :: Query t b -> Proxy t -> Query t b Source

Forces the type of proxy and query to match

asUpdate :: Update t a -> Proxy t -> Update t a Source

Currying version of setUpdateType.

asQuery :: Query t a -> Proxy t -> Query t a Source

Currying version of setQueryType.

askState :: Query st st Source

Specialized version of ask

getState :: Update st st Source

Specialized version of get

putState :: st -> Update st () Source

Specialized version of put.

liftSTM :: STM a -> AnyEv a Source

Lift an STM action into Ev.

class CatchEv m where Source

Methods catchEv :: Ev m a -> (SomeException -> a) -> Ev m a Source Instances CatchEv (StateT st STM) CatchEv (ReaderT st STM)

sel :: (Env -> b) -> AnyEv b Source

Select a part of the environment.

localState :: (outer -> inner) -> (inner -> outer -> outer) -> Ev (StateT inner STM) a -> Ev (StateT outer STM) a Source

Run a computation with local state. Changes to state will be visible to outside.

localStateReader :: (outer -> inner) -> Ev (ReaderT inner STM) a -> Ev (ReaderT outer STM) a Source

Run a computation with local state.

runQuery :: Query st a -> Update st a Source

Execute a Query action in the Update monad.

getEventId :: Integral txId => AnyEv txId Source

getTime :: Integral epochTime => AnyEv epochTime Source

getEventClockTime :: AnyEv ClockTime Source

getEventStream :: IO (IO EventItem) Source

data EventItem Source

Constructors EventItem eventContext :: TxContext eventData :: Dynamic

Random numbers

getRandom :: Random a => AnyEv a Source

Get a random number.

getRandomR :: Random a => (a, a) -> AnyEv a Source

Get a random number inside the range.

TH helpers

inferRecordUpdaters :: Name -> Q [Dec] Source

Infer updating functions for a record. Given a data declaration of data Foo = Foo {bar :: String, baz :: Int} then $(inferRecordUpdaters ''Foo) will define functions a_bar :: String -> Foo -> Foo, withBar :: Update String a -> Update Foo a, etc. that can be used as convenience updaters.

Serialization

module Happstack.Data.Serialize

module Happstack.Data.SerializeTH

module Happstack.State.Control

module Happstack.State.ComponentTH

module Happstack.State.ComponentSystem

runTxSystem :: (Methods st, Component st) => Saver -> Proxy st -> IO (MVar TxControl) Source

Run the MACID system without multimaster support and with the given Saver.

createCheckpoint :: MVar TxControl -> IO () Source

shutdownSystem :: MVar TxControl -> IO () Source

Shuts down a transaction system

Unsafe things

unsafeIOToEv :: IO a -> AnyEv a Source

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