| 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.TBQueue
Contents
Description
TBQueue
is a bounded version of
TQueue
. The queue has a maximum
capacity set when it is created. If the queue already contains the
maximum number of elements, then
writeTBQueue
blocks until an
element is removed from the queue.
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 TBQueue a
- newTBQueue :: Natural -> STM ( TBQueue a)
- newTBQueueIO :: Natural -> IO ( TBQueue a)
- readTBQueue :: TBQueue a -> STM a
- tryReadTBQueue :: TBQueue a -> STM ( Maybe a)
- flushTBQueue :: TBQueue a -> STM [a]
- peekTBQueue :: TBQueue a -> STM a
- tryPeekTBQueue :: TBQueue a -> STM ( Maybe a)
- writeTBQueue :: TBQueue a -> a -> STM ()
- unGetTBQueue :: TBQueue a -> a -> STM ()
- lengthTBQueue :: TBQueue a -> STM Natural
- isEmptyTBQueue :: TBQueue a -> STM Bool
- isFullTBQueue :: TBQueue a -> STM Bool
TBQueue
TBQueue
is an abstract type representing a bounded FIFO channel.
Since: 2.4
Builds and returns a new instance of
TBQueue
.
newTBQueueIO :: Natural -> IO ( TBQueue a) Source #
IO
version of
newTBQueue
. This is useful for creating top-level
TBQueue
s using
unsafePerformIO
, because using
atomically
inside
unsafePerformIO
isn't
possible.
tryReadTBQueue :: TBQueue a -> STM ( Maybe a) Source #
A version of
readTBQueue
which does not retry. Instead it
returns
Nothing
if no value is available.
flushTBQueue :: TBQueue a -> STM [a] Source #
Efficiently read the entire contents of a
TBQueue
into a list. This
function never retries.
Since: 2.4.5
peekTBQueue :: TBQueue a -> STM a Source #
Get the next value from the
TBQueue
without removing it,
retrying if the channel is empty.
tryPeekTBQueue :: TBQueue a -> STM ( Maybe a) Source #
A version of
peekTBQueue
which does not retry. Instead it
returns
Nothing
if no value is available.
writeTBQueue :: TBQueue a -> a -> STM () Source #
Write a value to a
TBQueue
; blocks if the queue is full.
unGetTBQueue :: TBQueue a -> a -> STM () Source #
Put a data item back onto a channel, where it will be the next item read. Blocks if the queue is full.