boltqueue

-- import "github.com/alaska/boltqueue"

Package boltqueue provides a persistent queue or priority queue based on boltdb (https://github.com/boltdb/bolt)

Priority Queue

boltqueue's PQueue type represents a priority queue. Messages may be inserted into the queue at a numeric priority between 0(highest) and 255(lowest). Messages are dequeued following priority order, then time ordering, with the oldest messages of the highest priority emerging first.

Usage

type Message

type Message struct {
}

Message represents a message in the priority queue

func NewMessage

func NewMessage(value string) *Message

NewMessage generates a new priority queue message

func (*Message) Priority

func (m *Message) Priority() int

Priority returns the priority the message had in the queue in the range of 0-255 or -1 if the message is new.

func (*Message) ToString

func (m *Message) ToString() string

ToString outputs the string representation of the message's value

type PQueue

type PQueue struct {
}

PQueue is a priority queue backed by a Bolt database on disk

func NewPQueue

func NewPQueue(filename string) (*PQueue, error)

NewPQueue loads or creates a new PQueue with the given filename

func (*PQueue) Close

func (b *PQueue) Close() error

Close closes the queue and releases all resources

func (*PQueue) Dequeue

func (b *PQueue) Dequeue() (*Message, error)

Dequeue removes the oldest, highest priority message from the queue and returns it

func (*PQueue) Enqueue

func (b *PQueue) Enqueue(priority int, message *Message) error

Enqueue adds a message to the queue

func (*PQueue) Requeue

func (b *PQueue) Requeue(priority int, message *Message) error

Requeue adds a message back into the queue, keeping its precedence. If added at the same priority, it should be among the first to dequeue. If added at a different priority, it will dequeue before newer messages of that priority.

func (*PQueue) Size

func (b *PQueue) Size(priority int) (int, error)

Size returns the number of entries of a given priority from 1 to 5