public async Task <IEnumerable <Coin> > FilterAsync(IList <Coin> coins)
{
var spentOutputs = new HashSet <OutPoint>(
(await _spentOutputRepository.GetSpentOutputsAsync(coins.Select(o => new Output(o.Outpoint))))
.Select(o => new OutPoint(uint256.Parse(o.TransactionHash), o.N)));
return(coins.Where(c => !spentOutputs.Contains(c.Outpoint)));
}
private async Task <IEnumerable <Coin> > FilterSpentCoinsAsync(IList <Coin> coins)
{
var spentOutputs = new HashSet <Output>(
(await _spentOutputRepository.GetSpentOutputsAsync(coins.Select(o => new Output(o.Reference)))),
Output.TransactionHashNComparer);
return(coins.Where(c => !spentOutputs.Contains(new Output(c.Reference))));
}
/// <summary>
/// Retrieves all utxos for a single address found in dcrdata's db + mempool.
/// Performs basic checking to prevent double-spending of mempool transactions.
/// </summary>
/// <param name="address"></param>
/// <returns></returns>
private async Task <IEnumerable <Transaction.Input> > GetUtxosForAddress(string address)
{
const uint sequence = uint.MaxValue;
// Grab transactions from dcrdata + the mempool.
var confirmedResults = await _txRepo.GetConfirmedUtxos(address);
var mempoolResults = await _txRepo.GetMempoolUtxos(address);
// Remove duplicate outpoints.
var allUtxos = confirmedResults.Concat(mempoolResults)
.OrderBy(r => r.BlockHeight)
.GroupBy(r => new { r.Hash, r.OutputIndex })
.Select(g => g.First())
.ToArray();
// Remove already spent outputs (based on db storage)
var spentoutputs = (await
_spentOutputRepository.GetSpentOutputsAsync(allUtxos.Select(p => new Output(p.Hash, p.OutputIndex)))).ToDictionary(p => p, Output.HashOutputIndexComparer);
var notSpentUtxos = allUtxos.Where(p => !spentoutputs.ContainsKey(new Output(p.Hash, p.OutputIndex))).ToList();
// Get all unspent transaction outputs to address
// and map as inputs to new transaction
return
(from output in notSpentUtxos
let txHash = new Blake256Hash(HexUtil.ToByteArray(output.Hash).Reverse().ToArray())
let outpoint = new Transaction.OutPoint(txHash, output.OutputIndex, output.Tree)
group new { outpoint, output }
by outpoint.ToString() into outpointGroup
let element = outpointGroup.First()
let outpoint = element.outpoint
let output = element.output
select new Transaction.Input(
outpoint,
sequence,
output.OutputValue,
output.BlockHeight,
output.BlockIndex,
output.PkScript
));
}