index.js

var hyperdrive = require('hyperdrive')
var pump = require('pump')
var fs = require('fs')
var storage = require('dat-storage')

var source = hyperdrive('./source')

source.ready(() => {
  var dest = hyperdrive(storage('./dest'), source.key, {
    latest: true, sparse: false
  })

  dest.on('syncing', () => {
    console.log('dest syncing')
    console.log('  dest version:', dest.version)
    console.log('  source version:', source.version)
  })

  dest.on('sync', () => {
    console.log('dest sync, version:', dest.version)
  })

  setInterval(() => {
    source.readFile('hi.txt', 'utf8', (err,data) => {
      if (!data) data = ''
      source.writeFile('hi.txt', data + new Date() + '\n')
    })
  }, 1000)

  var stream = dest.replicate({live: true})
  stream.pipe(source.replicate()).pipe(stream)
})

package.json

{
  "name": "latest-cpu",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "dat-storage": "^1.1.1",
    "hyperdrive": "^9.14.2",
    "pump": "^3.0.0"
  }
}

Run:

node index.js

With each import you'll see more syncing and sync outputs.

Example output:

dest syncing
  dest version: 10
  source version: 10
dest syncing
  dest version: 10
  source version: 10
dest sync, version: 10
dest sync, version: 10
dest syncing
  dest version: 11
  source version: 11
dest syncing
  dest version: 11
  source version: 11
dest syncing
  dest version: 11
  source version: 11
dest syncing
  dest version: 11
  source version: 11
dest sync, version: 11
dest sync, version: 11
dest sync, version: 11
dest sync, version: 11
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest syncing
  dest version: 12
  source version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest sync, version: 12
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest syncing
  dest version: 13
  source version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest sync, version: 13
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest syncing
  dest version: 14
  source version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14
dest sync, version: 14

If it helps the issue persists with random-access-memory as the storage backend.

Interesting enough, when I switched to the v10 branch and changed 'syncing' to 'update', things look okay:

dest syncing
  dest version: 290
  source version: 290
dest syncing
  dest version: 291
  source version: 291
dest syncing
  dest version: 292
  source version: 292
dest syncing
  dest version: 293
  source version: 293
dest syncing
  dest version: 294
  source version: 294
dest syncing
  dest version: 295
  source version: 295
dest syncing
  dest version: 296
  source version: 296
dest syncing
  dest version: 297
  source version: 297
dest syncing
  dest version: 298
  source version: 298
dest syncing
  dest version: 299
  source version: 299

It might be great to include this in the general hyperdrive tests

Hmmm @jedahan I still saw the same bug with node v10.

@allain, ya seems this is happening whenever latest: true regardless of storage.

_fetchVersion callback is called multiple times https://github.com/mafintosh/hyperdrive/blob/acf7d5416d4a189170a13073012176b5c5c4c0cd/index.js#L184

That should help narrow down the bug.

It happens on node v9, v10, and v11 for me.

@joehand @allain sorry, I meant node 11, but the v10 branch of hyperdrive