happstack-state-0.3.4: 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 TxConfig = TxConfig { txcCheckpointSeconds :: Seconds txcOperationMode :: OperationMode txcClusterSize :: Int txcClusterPort :: Int txcCommitFrequency :: Int } nullTxConfig :: TxConfig 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 runTxSystem :: (Methods st, Component st) => Saver -> Proxy st -> IO (MVar TxControl) runTxSystem' :: (Methods st, Component st) => Bool -> Saver -> Proxy st -> IO (MVar TxControl) shutdownSystem :: MVar TxControl -> IO () module Happstack.State.ComponentTH module Happstack.State.ComponentSystem closeTxControl :: MVar TxControl -> IO () createCheckpoint :: MVar TxControl -> IO () unsafeIOToEv :: IO a -> AnyEv a

ACID monad

data Ev m t Source

Monad for ACID event handlers. Instances MonadReader st (Update st) MonadReader st (Query st) MonadState st (Update st) 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 TxConfig Source

Constructors TxConfig txcCheckpointSeconds :: Seconds Perform checkpoint at least every N seconds. txcOperationMode :: OperationMode txcClusterSize :: Int Number of active nodes in the cluster (not counting this node). txcClusterPort :: Int txcCommitFrequency :: Int Commits per second. Only applies to cluster mode.

nullTxConfig :: TxConfig 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

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

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

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

Run the MACID system with multimaster support turned on if the first argument is True.

shutdownSystem :: MVar TxControl -> IO () Source

Shuts down a transaction system

module Happstack.State.ComponentTH

module Happstack.State.ComponentSystem

closeTxControl :: MVar TxControl -> IO () Source

Saves the state and closes the serialization

createCheckpoint :: MVar TxControl -> IO () Source

Creates a checkpoint using the provided TxControl. This checkpoint may be used as a safe state with which to start the system, e.g. one may delete all the serialized events that took place after the last checkpoint and start the application fresh from the checkpoint. Calling this function manually is the only way to create checkpoints.

Unsafe things

unsafeIOToEv :: IO a -> AnyEv a Source

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