| Copyright | (c) The University of Glasgow 2012 |
|---|---|
| License | BSD-style (see the file libraries/base/LICENSE) |
| Maintainer | libraries@haskell.org |
| Stability | experimental |
| Portability | non-portable (requires STM) |
| Safe Haskell | Trustworthy |
| Language | Haskell2010 |
Control.Concurrent.STM.TQueue
Contents
Description
A TQueue is like a TChan, with two important differences:
- it has faster throughput than both
TChanandChan(although the costs are amortised, so the cost of individual operations can vary a lot). - it does not provide equivalents of the
dupTChanandcloneTChanoperations.
The implementation is based on the traditional purely-functional queue representation that uses two lists to obtain amortised O(1) enqueue and dequeue operations.
Since: 2.4
Synopsis
- data TQueue a
- newTQueue :: STM (TQueue a)
- newTQueueIO :: IO (TQueue a)
- readTQueue :: TQueue a -> STM a
- tryReadTQueue :: TQueue a -> STM (Maybe a)
- flushTQueue :: TQueue a -> STM [a]
- peekTQueue :: TQueue a -> STM a
- tryPeekTQueue :: TQueue a -> STM (Maybe a)
- writeTQueue :: TQueue a -> a -> STM ()
- unGetTQueue :: TQueue a -> a -> STM ()
- isEmptyTQueue :: TQueue a -> STM Bool
TQueue
TQueue is an abstract type representing an unbounded FIFO channel.
Since: 2.4
newTQueueIO :: IO (TQueue a) Source #
IO version of newTQueue. This is useful for creating top-level
TQueues using unsafePerformIO, because using
atomically inside unsafePerformIO isn't
possible.
tryReadTQueue :: TQueue a -> STM (Maybe a) Source #
A version of readTQueue which does not retry. Instead it
returns Nothing if no value is available.
flushTQueue :: TQueue a -> STM [a] Source #
Efficiently read the entire contents of a TQueue into a list. This
function never retries.
Since: 2.4.5
peekTQueue :: TQueue a -> STM a Source #
Get the next value from the TQueue without removing it,
retrying if the channel is empty.
tryPeekTQueue :: TQueue a -> STM (Maybe a) Source #
A version of peekTQueue which does not retry. Instead it
returns Nothing if no value is available.
unGetTQueue :: TQueue a -> a -> STM () Source #
Put a data item back onto a channel, where it will be the next item read.