tickque v0.1.3

tickque

A queue that auto shift itself based on the given interval.

• You might not want to create timer for each incoming request.
• The queue is designed to align those requests into time slots.
• When each time slot is shifted, process requests in the slot in batch.

Get started

const Queue = require('tickque')

let queue = new Queue(1, 10, true)
queue.onShift(itemsIterator => { ... })

queue.add('shifted after 10 sec'))
queue.add('shifted after 2 sec'), 2)

API

Queue(interval = 1, limit = 0, preAlloc = false)

• interval: auto shifting interval in second
• limit: maximum ttl (queue length), which make it fixed length
• preAlloc: alloc slots during construction if limit > 0

Note: It's possible to set interval to float point but the queue uses setInterval which cannot guarantee pricise timers. There will be ms delays (depending on CPU usage) before each onShift callback due to single thread JS model. It's roughly 1 second error every 8 minutes

onShift(cb)

• cb will be invoked with the items iterator in the shifted time slot

add(item, ttl)

• item: the object to be inserted into the ttl specified time slot
• ttl: tick to live -- time slot offset (positive integer)

The queue grows automatically until limit, if ttl is larger than current queue length. This is one time O(n) operation, n equals the length of queue. When queue is contructred with preAlloc, complexity is always O(1). If ttl is omitted, item is added to the end of queue.

peek(ttl)

Returns the items in the given time slot in O(1).

remove(item)

Remove the given item in O(1).

has(item)

Check if the item is in the queue in O(1).

length

Returns the queue length in O(1).

items()

Returns iterator of all items in O(1).

count()

Returns number of all items in O(1).

start(immediate = false)

• immediate: tick at once if true, otherwise tick after interval

Start queue shifting. Note the queue starts automatically when item is added.

stop()

Stop queue shifting. Note the queue stops automatically once it's empty.