NAME

Concurrent::PriorityQueue - provide a thread-safe priority queue

SYNOPSIS

use Concurrent::PriorityQueue;

my @a is Concurrent::PriorityQueue;

@a.push(666);
@a.push(42);

say @a.shift;  # 42
say @a.shift;  # 666

@a.push(666 => "bar");
@a.push(42  => "foo");

say @a.shift;  # foo
say @a.shift;  # bar

DESCRIPTION

Concurrent::PriorityQueue provides a customizable role to create an ordered queue to which one can .push values to, and <.shift> or .pop values from. By default, the underlying order of values pushed, is in ascending order, using infix:<cmp> semantics.

If a Pair was .pushed, then the .key will determine the position in the underlying order. And .shift and .pop will produce the associated .value.

If any other value was .pushed, then it will both serve as key as well as value.

METHODS

push

@a.push(42);          # key and value same

@a.push(42 => "foo")  # key and value different

Adds a key or a key/value pair to the queue.

pop

say @a.pop;  # value associated with highest key

Produces the value associated with the highest key, and removes that entry from the queue. Or produces a Failure if there were no values in the queue.

shift

say @a.shift;  # value associated with lowest key

Produces the value associated with the lowest key, and removes that entry from the queue. Or produces a Failure if there were no values in the queue.

elems

say @a.elems;  # number of items remaining in queue

Produces the current number of items in the queue.

List

@a.List;  # representation for

Produces the queue as a List of Pairs. Intended to be used to provide more permanent storage for the queue, to later re-initialize a new queue with.

PARAMETERIZATION

# only allow Int as key
class IntQueue does Concurrent::PriorityQueue[Int] { }
my @b is IntQueue;

By default, Any defined value can serve as key. This can be parameterized by specifying a type, e.g. Int to only allow integers as keys.

# only allow Int as key with <=> order semantics
class NumericQueue does Concurrent::PriorityQueue[Int, :cmp(&[<=>])] { }
my @b is NumericQueue;

By default the infix:<cmp> comparator is used to determine the order in which values will be produced, This can be parameterized with the :cmp named argument, e.g. :cmp(&infix«<=>») to use numerical comparisons only.

INSPIRATION

This module was inspired by Rob Hoelz's PriorityQueue module.

AUTHOR

Elizabeth Mattijsen liz@raku.rocks

Source can be located at: https://github.com/lizmat/Concurrent::PriorityQueue Comments and Pull Requests are welcome.

If you like this module, or what I’m doing more generally, committing to a small sponsorship would mean a great deal to me!

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.