versionbits

Track Bitcoin versionbits deployments (BIP9)

Usage

npm install versionbits

// import versionbits parameters for Bitcoin
var params = require('webcoin-bitcoin').versionbits

var VersionBits = require('versionbits')
var vbits = new VersionBits(params, db) // db is a LevelUp instance

// `chain` is a Blockchain instance from the `blockchain-spv` module
chain.createReadStream().pipe(vbits)

BIP9 is a specification that allows Bitcoin miners to use the version field in blocks as a bitfield in order to specify which soft-fork changes they support. Once a certain number of blocks have a certain bit set, the soft-fork change is activated and the new rules come into effect. This module checks the status of these soft-fork deployments.

var vbits = new VersionBits(params, db)

Creates a VersionBits instance which keeps track of the state of each versionbits deployment.

params should be the versionbits parameters for the blockchain you wish to use. Parameters for Bitcoin are available at require('webcoin-bitcoin').versionbits. For more info about params you can use, see the Parameters section.

db should be a LevelUp instance where state data will be stored. The db should not be shared.

vbits.get(id)

Returns the state of the deployment with the given id (e.g. 'csv' or 'segwit').

vbits.getDeployments()

Returns an array of all deployments currently being tracked.

vbits.getHash(cb)

Calls cb with the hash of the most recently processed block. Use this to figure out which block to start streaming from when piping blocks from a blockchain-spv Blockchain into vbits.

Event: status

Emitted when the status of a deployment changes (e.g. when a deployment goes from started to lockedIn).

Event: update

Emitted whenever the state of a deployment changes (e.g. when the bit count is incremented).

Event: error

Emitted when an error occurs.

Parameters

Parameters specify known versionbits deployments. Parameters should contain the following:

{
  // number of blocks for the confirmation period
  // usually the same as the retarget period (in Bitcoin it is 2016)
  confirmationWindow: Number,

  // number of blocks in the period that must set the bit for a deployment
  // to make it "lock in"
  activationThreshold: Number,

  // an array of deployments to track
  deployments: [
    {
      bit: 0,
      name: 'csv',
      start: 1462060800,
      timeout: 1493596800
    }
  ]
}

For some examples, see these parameter repos:

• webcoin-bitcoin
• webcoin-bitcoin-testnet