Edit

Wallet Rescans

With BIP157 you can cache block filters locally to use later for rescans in the case you need to restore your wallets. Our chain project gives us an API with the ability to query for filters.

You can rescan your wallet with filters with WalletApi.rescanNeutrinoWallet()

Example

To run this example you need to make sure you have access to a bitcoind binary. You can download this with bitcoin-s by doing sbt downloadBitcoind

//we need an actor system and app config to power this
implicit val system: ActorSystem = ActorSystem(s"wallet-rescan-example")
implicit val ec: ExecutionContext = system.dispatcher
implicit val appConfig: BitcoinSAppConfig = BitcoinSTestAppConfig.getNeutrinoTestConfig()

//ok now let's spin up a bitcoind and a bitcoin-s wallet with funds in it
val walletWithBitcoindF = for {
  w <- BitcoinSWalletTest.createWalletBitcoindNodeChainQueryApi()
} yield w

val walletF = walletWithBitcoindF.map(_.wallet)

val bitcoindF = walletWithBitcoindF.map(_.bitcoind)

//let's see what our initial wallet balance is
val initBalanceF = for {
  w <- walletF
  balance <- w.getBalance()
} yield {
  println(s"Initial wallet balance=${balance}")
  balance
}

//ok great! We have money in the wallet to start,
//now let's delete our internal tables that hold our utxos
//and addresses so that we end up with a 0 balance
val clearedWalletF = for {
  w <- walletF
  _ <- initBalanceF
  clearedWallet <- w.clearUtxosAndAddresses()
  zeroBalance <- clearedWallet.getBalance()
} yield {
  println(s"Balance after clearing utxos: ${zeroBalance}")
  clearedWallet
}

//we need to pick how many addresses we want to generate off of our keychain
//when doing a rescan, this means we are generating 100 addrsses
//and then looking for matches. If we find a match, we generate _another_
//100 fresh addresses and search those. We keep doing this until we find
//100 addresses that do not contain a match.
val addrBatchSize = 100
//ok now that we have a cleared wallet, we need to rescan and find our fudns again!
val rescannedBalanceF = for {
  w <- clearedWalletF
  _ <- w.fullRescanNeurinoWallet(addrBatchSize)
  balanceAfterRescan <- w.getBalance()
} yield {
  println(s"Wallet balance after rescan: ${balanceAfterRescan}")
  ()
}

//cleanup
val cleanupF = for {
  _ <- rescannedBalanceF
  walletWithBitcoind <- walletWithBitcoindF
  _ <- BitcoinSWalletTest.destroyWalletWithBitcoind(walletWithBitcoind)
} yield ()

Await.result(cleanupF, 60.seconds)