Control.Concurrent.STM.Broadcast

A Broadcast variable is a mechanism for communication between threads. Multiple reader threads can wait until a broadcaster thread writes a signal. The readers retry until the signal is received. When the broadcaster sends the signal all readers are woken.

This module is designed to be imported qualified. We suggest importing it like:

 import           Control.Concurrent.STM.Broadcast ( Broadcast )
 import qualified Control.Concurrent.STM.Broadcast as Broadcast ( ... )

Documentation

data Broadcast α

A broadcast variable. It can be thought of as a box, which may be empty of full.

Instances

Typeable1 Broadcast

Eq (Broadcast α)

new :: STM (Broadcast α)

Create a new empty Broadcast variable.

newWritten :: α -> STM (Broadcast α)

Create a new Broadcast variable containing an initial value.

read :: Broadcast α -> STM α

Read the value of a Broadcast variable.

If the Broadcast variable contains a value it will be returned immediately, otherwise it will retry until another thread writes a value to the Broadcast variable.

tryRead :: Broadcast α -> STM (Maybe α)

Try to read the value of a Broadcast variable; non blocking.

Like read but doesn't retry. Returns Just the contents of the Broadcast if it wasn't empty, Nothing otherwise.

write :: Broadcast α -> α -> STM ()

Write a new value into a Broadcast variable.

If the variable is empty any threads that are reading from the variable will be woken. If the variable is full its contents will simply be overwritten.

clear :: Broadcast α -> STM ()

Clear the contents of a Broadcast variable.