hypercore-multipart

Partition bytes into several Hypercore feeds

Installation

$ npm install hypercore-multipart

Example

const multipart = require('hypercore-multipart')
const Corestore = require('corestore')
const fs = require('fs')

const corestore = new Corestore(ram)

fs.open('/path/to/file', (err, fd) => {
  multipart({ read, pageSize: 5 * 1024 * 1024, bufferSize: 4096 }, (err, parts) => {
    // `parts` is an array of hypercores with a byteLength at most `pageSize`
  })

  function read(offset, length, callback) {
    const buffer = Buffer.alloc(length)
    fs.read(fd, buffer, 0, length, offset, (err) => callback(err, buffer))
  }
})

API

state = multipart(opts, callback)

Reads bytes from a source partitioning chunks into Hypercore feeds where calling callback(err, parts) with an error if one occurs or parts, an array of hypercore feeds. opts can be:

{
  bufferSize: 4096, // how big the read buffers should be
  pageSize: 10 * 1024 * 1024, // how big the hypercore feeds should be
  offset: 0, // the initial offset to start reading at

  corestore: null, // a corestore instance for hypercore creation
  masterKey: crypto.randomBytes(32), // the master key for key derivation
  namespace: 'multipart', // the namespace for key derivation

  read: null, // a function that accepts an offset, length, and callback to read bytes from a source
  stat: null, // a function that explicitly resolves the size of the source
  onpage(page, hypercore), // a function that is called upon cycling to a new page (hypercore)
}

state.bufferSize

The read buffer size for the multipart state.

state.pageSize

The size for each page (hypercore feed) for the multipart state.

state.offset

The current read offset for the multipart state.

state.blocks

The number of blocks in the multipart state.

state.page

The current page of the multipart state.

state.stats

Stats (if available) for the multipart state.

state.masterKey

The master key for the multipart state.

License

MIT