@logeshdas21/channel-queue
v0.0.1
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A queue management library with channels
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channel-queue
A queue management library with channels.
About
This library provides a queue system, organised by channels (or "topics"), that allows for finer-grain control over asynchronous method execution. It allows for queuing tasks by channels (string-based names) - tasks executing sequentially when the previous task is done. It also allows for 3 priority levels : normal, high and tail.
Check out the API documentation.
Installation
Simply run:
npm install @buttercup/channel-queue --save
Usage
The simplest usage is to just queue some tasks:
const ChannelQueue = require("@buttercup/channel-queue");
const queue = new ChannelQueue();
const work = queue.channel("myChannel").enqueue(() => 123);
// 'work' will resolve with 123
const someChannel = queue.channel("someChannel");
someChannel.enqueue(job1);
someChannel.enqueue(job2);
someChannel.enqueue(job3);
You can push tasks above others by setting them as high-priority:
const ChannelQueue = require("@buttercup/channel-queue");
const { TASK_TYPE_HIGH_PRIORITY } = ChannelQueue.Task;
const queue = new ChannelQueue();
const workChannel = queue.channel("work");
// some other tasks added to the queue...
workChannel.enqueue(importantJobMethod, TASK_TYPE_HIGH_PRIORITY).then(result => {
// 'result' is the resolved result from the 'importantJobMethod' function
});
Tasks can also be run as "low" priority or at the tail end of the queue:
const ChannelQueue = require("@buttercup/channel-queue");
const { TASK_TYPE_TAIL } = ChannelQueue.Task;
const queue = new ChannelQueue();
const workChannel = queue.channel("work");
// some other tasks added to the queue...
workChannel.enqueue(runNearEnd, TASK_TYPE_TAIL);
Stacking
Items can be "stacked", meaning that if specified, items can be limited to only 1 pending item in queue. All items of the same stack name would simply queue on the same item and not create more tasks. The stack can be specified when enqueuing:
const ChannelQueue = require("@buttercup/channel-queue");
const queue = new ChannelQueue();
const workChannel = queue.channel("work");
const promise1 = workChannel.enqueue(saveWorkFn, undefined, /* Stack ID */ "save");
// work start
const promise2 = workChannel.enqueue(saveWorkFn, undefined, "save");
const promise3 = workChannel.enqueue(saveWorkFn, undefined, "save");
// promise2 and promise3 will be equal, as promise2 was still in the queue when promise3
Parallel Execution
Tasks can be run in parallel using the ParallelChannel
class. You can create a parallel channel, in place of a regular channel, by calling ChannelQueue#createParallelChannel
:
const ChannelQueue = require("@buttercup/channel-queue");
const queue = new ChannelQueue();
const workChannel = queue.createParallelChannel("work");
workChannel.enqueue(someTask);
// The same channel can be fetched later using the familiar channel() method:
queue.channel("work"); // The parallel channel
Parallel channels, like their name implies, can run tasks in parallel. Instead of running them head-to-tail like regular channels, parallel channels can execute many tasks side-by-side. You can also limit them to a certain number of threads (default is 2) by calling queue.createParallelChannel("name", 5)
(where 5
is the maximum number of simultaneous tasks).
Parallel channels by default do not run tasks of different priorities simultaneously. This means that if the current running tasks are high-priority, no normal priority tasks will be started. This feature can be disabled by running parallelChannel.canRunAcrossTaskTypes = true
.
Clearing
You can clear all enqueued items in a Channel
by calling clear()
:
queue.channel("myChannel").clear();
Development & Supported Node Versions
This library is intended to be used with NodeJS version 6 and later.
To contribute, clone this project and run npm install
before beginning development.
To test, simply run npm test
.