pqueue

Documentation

Overview

This package provides a priority queue implementation and scaffold interfaces.

Copyright (C) 2011 by Krzysztof Kowalik <chris@nu7hat.ch>

Index

• type Interface
• type Queue
  • func New(max int) (q *Queue)
  • func (q *Queue) ChangeLimit(newLimit int)
  • func (q *Queue) Dequeue() (item Interface)
  • func (q *Queue) Enqueue(item Interface) (err error)
  • func (q *Queue) Heapify()
  • func (q *Queue) IsEmpty() bool
  • func (q *Queue) Len() int
  • func (q *Queue) Peek() Interface
• type Sorter
  • func (s *Sorter) Len() int
  • func (s *Sorter) Less(i, j int) bool
  • func (s *Sorter) Pop() (x interface{})
  • func (s *Sorter) Push(i interface{})
  • func (s *Sorter) Swap(i, j int)

Types

type Interface

type Interface interface {
	Less(other interface{}) bool
}

Only Items implementing this interface can be enqueued on the priority queue.

type Queue

type Queue struct {
	Limit int
	Items *Sorter
	// contains filtered or unexported fields
}

Queue is a threadsafe priority queue exchange. Here's a trivial example of usage:

q := pqueue.New(0)
go func() {
    for {
        task := q.Dequeue()
        println(task.(*CustomTask).Name)
    }
}()
for i := 0; i < 100; i := 1 {
    task := CustomTask{Name: "foo", priority: rand.Intn(10)}
    q.Enqueue(&task)
}

func New

func New(max int) (q *Queue)

New creates and initializes a new priority queue, taking a limit as a parameter. If 0 given, then queue will be unlimited.

func (*Queue) ChangeLimit

func (q *Queue) ChangeLimit(newLimit int)

Safely changes enqueued Items limit. When limit is set to 0, then queue is unlimited.

func (*Queue) Dequeue

func (q *Queue) Dequeue() (item Interface)

Dequeue takes an item from the queue. If queue is empty then should block waiting for at least one item.

func (*Queue) Enqueue

func (q *Queue) Enqueue(item Interface) (err error)

Enqueue puts given item to the queue.

func (*Queue) Heapify

func (q *Queue) Heapify()

func (*Queue) IsEmpty

func (q *Queue) IsEmpty() bool

IsEmpty returns true if queue is empty.

func (*Queue) Len

func (q *Queue) Len() int

Len returns number of enqueued elemnents.

func (*Queue) Peek

func (q *Queue) Peek() Interface

type Sorter

type Sorter []Interface

func (*Sorter) Len

func (s *Sorter) Len() int

func (*Sorter) Less

func (s *Sorter) Less(i, j int) bool

func (*Sorter) Pop

func (s *Sorter) Pop() (x interface{})

func (*Sorter) Push

func (s *Sorter) Push(i interface{})

func (*Sorter) Swap

func (s *Sorter) Swap(i, j int)