Control.Concurrent.STM.Firehose

Documentation

data Firehose a

data Subscription a

newFirehose :: STM (Firehose a)

Creates a new Firehose item.

writeEvent :: Firehose a -> a -> STM ()

Sends a piece of data in the fire hose.

subscribe

Arguments

:: Int

Number of elements buffered. If set too high, it will increase memory usage. If set too low, activity spikes will result in message loss.

-> Firehose a

-> STM (Subscription a)

Get a subscription from the fire hose, that will be used to read events.

unsubscribe :: Subscription a -> STM ()

Unsubscribe from the fire hose. Subsequent calls to readEvent will return Nothing. This runs in O(n), where n is the current number of subscriptions.

readEvent :: Subscription a -> STM (Maybe a)

Read an event from a Subscription. This will return Nothing if the firehose is shut, or the subscription removed.

getQueue :: Subscription a -> TBMQueue a

Gets the underlying queue from a subscription.