atomic-counter-0.1.2.4: Mutable counters that can be modified with atomic operatinos

Copyright | (c) Sergey Vinokurov 2022
License | Apache-2.0 (see LICENSE)
Maintainer | serg.foo@gmail.com
Safe Haskell | None
Language | Haskell2010

Control.Concurrent.Counter.Lifted.ST

Contents

- Create
- Read/write
- Arithmetic operations
- Bitwise operations

Description

Counters that support some atomic operations. Safe to use from multiple threads and likely faster than using IORef or TVar for the same operation (terms and conditions apply).

Synopsis

- data Counter s
- new :: Int -> ST s (Counter s)
- get :: Counter s -> ST s Int
- set :: Counter s -> Int -> ST s ()
- cas :: Counter s -> Int -> Int -> ST s Int
- add :: Counter s -> Int -> ST s Int
- sub :: Counter s -> Int -> ST s Int
- and :: Counter s -> Int -> ST s Int
- or :: Counter s -> Int -> ST s Int
- xor :: Counter s -> Int -> ST s Int
- nand :: Counter s -> Int -> ST s Int

# Documentation

data Counter s Source #

Memory location that supports select few atomic operations.

Isomorphic to `STRef s Int`.

#### Instances

Instances details

Eq (Counter s) Source # | Pointer equality
Instance details Defined in Control.Concurrent.Counter.Lifted.ST Methods (==) :: Counter s -> Counter s -> Bool Source # (/=) :: Counter s -> Counter s -> Bool Source #

# Create

new :: Int -> ST s (Counter s) Source #

Create new counter with initial value.

# Read/write

get :: Counter s -> ST s Int Source #

Atomically read the counter's value.

set :: Counter s -> Int -> ST s () Source #

Atomically assign new value to the counter.

cas Source #

Arguments

:: Counter s |
-> Int | Expected old value
-> Int | New value
-> ST s Int |

Atomic compare and swap, i.e. write the new value if the current value matches the provided old value. Returns the value of the element before the operation

Since: 0.1.2

# Arithmetic operations

add :: Counter s -> Int -> ST s Int Source #

Atomically add an amount to the counter and return its old value.

sub :: Counter s -> Int -> ST s Int Source #

Atomically subtract an amount from the counter and return its old value.

# Bitwise operations

and :: Counter s -> Int -> ST s Int Source #

Atomically combine old value with a new one via bitwise and. Returns old counter value.

or :: Counter s -> Int -> ST s Int Source #

Atomically combine old value with a new one via bitwise or. Returns old counter value.

xor :: Counter s -> Int -> ST s Int Source #

Atomically combine old value with a new one via bitwise xor. Returns old counter value.

nand :: Counter s -> Int -> ST s Int Source #

Atomically combine old value with a new one via bitwise nand. Returns old counter value.