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/Haskell 8

Control.Concurrent.STM.TBQueue

Copyright (c) The University of Glasgow 2012
License BSD-style (see the file libraries/base/LICENSE)
Maintainer [email protected]
Stability experimental
Portability non-portable (requires STM)
Safe Haskell Trustworthy
Language Haskell2010

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: stm-2.4

TBQueue

data TBQueue a Source

TBQueue is an abstract type representing a bounded FIFO channel.

Since: stm-2.4

Instances
Eq (TBQueue a)
Instance details

Defined in Control.Concurrent.STM.TBQueue

Methods

(==) :: TBQueue a -> TBQueue a -> Bool

(/=) :: TBQueue a -> TBQueue a -> Bool

newTBQueue Source

Arguments

:: Natural

maximum number of elements the queue can hold

-> STM (TBQueue a)

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 TBQueues using unsafePerformIO, because using atomically inside unsafePerformIO isn't possible.

readTBQueue :: TBQueue a -> STM a Source

Read the next value from the TBQueue.

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: stm-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.

lengthTBQueue :: TBQueue a -> STM Natural Source

Return the length of a TBQueue.

Since: stm-2.5.0.0

isEmptyTBQueue :: TBQueue a -> STM Bool Source

Returns True if the supplied TBQueue is empty.

isFullTBQueue :: TBQueue a -> STM Bool Source

Returns True if the supplied TBQueue is full.

Since: stm-2.4.3

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.6.1/docs/html/libraries/stm-2.5.0.0/Control-Concurrent-STM-TBQueue.html