TMQueue is an abstract type representing a closeable FIFO
queue.
Modulestm-chans-3.0.0.9Haskell2010
Control.Concurrent.STM.TMQueue
A version of Control.Concurrent.STM.TQueue where the queue is
closeable. This is similar to a TQueue (Maybe a) with a
monotonicity guarantee that once there's a Nothing there will
always be Nothing.
Since: 2.0.0
- 1 type
- 11 values
- Packagestm-chans-3.0.0.9
- Exports12
- LanguageHaskell2010
- LicenceBSD-3-Clause
- SourceTMQueue.hs
The TMQueue type
1 declarationCreating TMQueues
Build and returns a new instance of TMQueue.
IO version of newTMQueue. This is useful for creating
top-level TMQueues using unsafePerformIO,
because using atomically inside
unsafePerformIO isn't possible.
Reading from TMQueues
Read the next value from the TMQueue, retrying if the queue
is empty (and not closed). We return Nothing immediately if
the queue is closed and empty.
A version of readTMQueue which does not retry. Instead it
returns Just Nothing if the queue is open but no value is
available; it still returns Nothing if the queue is closed
and empty.
Get the next value from the TMQueue without removing it,
retrying if the queue is empty.
A version of peekTMQueue which does not retry. Instead it
returns Just Nothing if the queue is open but no value is
available; it still returns Nothing if the queue is closed
and empty.
Writing to TMQueues
Write a value to a TMQueue. If the queue is closed then the
value is silently discarded. Use isClosedTMQueue to determine
if the queue is closed before writing, as needed.
Put a data item back onto a queue, where it will be the next item read. If the queue is closed then the value is silently discarded; you can use peekTMQueue to circumvent this in certain circumstances.
Closing TMQueues
Closes the TMQueue, preventing any further writes.
Predicates
Returns True if the supplied TMQueue has been closed.
Returns True if the supplied TMQueue is empty.