Vizidrix - LibRingBufferJS

Goals

Provide a low level mechanism which avoids allocation and garbage collection overhead.

By enforcing ring counts as 2s compliments the wrapping mechanism is simplified from variable size rings, where head and tail index must be tracked in order to provide looping characteristics, down to a simple binary AND (&).

The goal of this library is to provide low level features that can be used to build higher order structures such as Queues and Pub/Sub that can take advantage of it's internal structure.

Inspired by ideas around mechanical sympathy:

• Mechanical Sympathy
• LMAX Disruptor

Pre-allocated structures, data element which could be size aligned to optimize for cache lines

Changelog

ringbuffer.ts

/**
 * IRingBuffer provides access methods to interact with the ring buffer structure
 */
export interface IRingBuffer<T> {
  /** returns a DataView of the current position and moves the position forward */
  claim: () => T
  /** returns the current bounded position used to index the ring internally */
  getIndex: () => number
  /** returns the current, perpetually incrementing, cursor position of the ring buffer */
  getPosition: () => number
  /** returns the ring's initialization data */
  getRingSize: () => number
  /** returns a slice cursor to the slice at the specified index within the ring */
  peek: (index: number) => T
}

// example using BianryRingBuffer
import { BinaryRingBuffer } from 'libringbufferjs'

// make a binary ring buffer
let rb = BinaryRingBuffer(4, 16)

// claim a slot - gives a reference to the DataView in the current slot and moves the pointer
let writer = rb.claim()

// put binary data into the slice you claimed
writer.setInt8(0, 10)

// grab a slice cursor at a specified position
let reader = rb.peek(0)

// read the data out of the slice you previously wrote to
let value = reader.getInt8(0)

// example using RingBuffer
import { RingBuffer } from 'libringbufferjs'

// make a basic object ring buffer with a structure defined inline
let rb = RingBuffer(4, () => {return { value: 0 }})

// claim a slot = gives a reference to the object in the current slot and moves the pointer
let writer = rb.claim()

// update properties of your object
writer.value = 20

// grab an object reference at a specified position
let reader = rb.peek(0)

// read the data out of the object property
let value = reader.value

todo: implement non-binary ring buffer that can pre-fill object instances using a factory (optionally a reset function?) and claim returns a reference that can be mutated

Usefull libraries

JavaScript typed arrays

ArrayBuffer

DataView

StringView

ArrayBuffer Playground

Library

This library depends on TypeScript to compile:

Tips for setting up repo for NPM: Authoring NPM Modules with TypeScript

npm install -g typescript

Useful NPM Commands

Initializes a freshly cloned repo, downloading npm and typescript packages and other prep

Caution, this will delete files that aren't linked to Git

npm run setup

Builds the typescript command and generates the es5 compatible version

npm run compile

Runs the tslint utility which reports back any non-conforming instances

Helps to create a uniform code base by enforcing sytle and naming type of guidelines

npm run lint

Executes the 'tape' test suite and emits the results to the console

npm run test

Executes the benchmarkjs suite and emits the results to the console

npm run bench

Executes compile, lint and test functions and sets up a file watcher to trigger them on each file modification

npm run dev

Executes the typedoc utility which generates documentation for the project based upon the provided types, comments and structures

npm run docs

Hosted on GitLab

GitLab - Free Private Repos

View Project Runners

GitLab CI - gitlab.com/vizidrix/typescript_lib_boilerplate

Setup Private Runners

GitLab CI - Register Runner

Development Environment

• Typescript
  • Add static typing and related utility to JS IDE
• TSLint
  • TypeScript linter to enforce syntax and coding standards
• Tape / Blue-Tape
  • Async Unit Testing callable from node
• Istanbul
  • Test Coverage Report and Enforcement
• BenchmarkJS
  • JavaScript benchmarking library

Support for multiple targets (es5 and es6) is difficult due to es5 required polyfills

Documentation

TypeDoc

Keeping documentation up to date is hard, wherever possible keep it next to the item being documented so it stays live.

Documenting Comments

Setup a pre-commit step to trigger docs generation, need to check if it auto updates prior to commit

// Generate docs manually
npm run docs

Typescript Definitions

From DefiantlyTyped

• blue-tape
• es6-promise
• node
• tape

TSLint

TODO: Consider switching / implementing Standard JS

See TSLint - Github for more options and documentation

Excluded options:

"no-any": true,
"no-bitwise": true,
"no-conditional-assignment": true,
"no-constructor-vars": true,

BenchmarkJS

Bulletproof JavaScript Benchmarks

How it works

Publishing to NPM

Publishing TypeScript on NPM

Automating Publish with NPM

npm publish --access=public

Interesting Stuff

JavaScript Performance Dev - Volkan Özçelik

High Performance JavaScript Book

Roll your own CI with Node.js

Suppress NPM ERR!

NPM Installing from GitLab

Changelog Standard