multi-random-access

An abstract-random-access compliant instance (API similar to random-access-file) that combines multiple other abstract-random-access instances into a single one.

npm install multi-random-access

Usage

In the below example we'll create a multi-random-access instance that writes to different instances of random-access-memory, each containing 10 bytes of data.

var multi = require('multi-random-access')
var ram = require('random-access-memory')

var storage = multi(function (offset, cb) {
  var index = Math.floor(offset / 10)

  console.log('Creating new underlying storage')

  cb(null, {
    start: index * 10,
    end: index * 10 + 10,
    storage: ram()
  })
})

storage.write(0, Buffer('hello world'), function (err) {
  if (err) throw err
  storage.read(0, 11, function (err, buf) {
    if (err) throw err
    console.log(buf.toString())
  })
})

API

var storage = multi([options], open)

Create a new instance. open is a function that is called when a new storage instance is needed. A new instance is needed when a read or write happens in a byte range that has not been opened yet.

The signature for open is (offset, cb). You should call the callback with an object containing the following properties:

function open (offset, cb) {
  cb(null, {
    start: startByteOffset,
    end: endByteOffset,
    storage: abstractRandomAccessInstance
  })
}

Options include:

{
  limit: 16 // start closes old stores after this many was opened
}

License

MIT