// Methods for how to add transactions to a block.
// Add transactions based on feerate including unconfirmed ancestors
// Increments nPackagesSelected / nDescendantsUpdated with corresponding
// statistics from the package selection (for logging statistics).
// This transaction selection algorithm orders the mempool based
// on feerate of a transaction including all unconfirmed ancestors.
// Since we don't remove transactions from the mempool as we select them
// for block inclusion, we need an alternate method of updating the feerate
// of a transaction with its not-yet-selected ancestors as we go.
// This is accomplished by walking the in-mempool descendants of selected
// transactions and storing a temporary modified state in mapModifiedTxs.
// Each time through the loop, we compare the best transaction in
// mapModifiedTxs with the next transaction in the mempool to decide what
// transaction package to work on next.
protected virtual void AddTransactions(int nPackagesSelected, int nDescendantsUpdated)
{
// mapModifiedTx will store sorted packages after they are modified
// because some of their txs are already in the block
var mapModifiedTx = new Dictionary <uint256, TxMemPoolModifiedEntry>();
//var mapModifiedTxRes = this.mempoolScheduler.ReadAsync(() => mempool.MapTx.Values).GetAwaiter().GetResult();
// mapModifiedTxRes.Select(s => new TxMemPoolModifiedEntry(s)).OrderBy(o => o, new CompareModifiedEntry());
// Keep track of entries that failed inclusion, to avoid duplicate work
TxMempool.SetEntries failedTx = new TxMempool.SetEntries();
// Start by adding all descendants of previously added txs to mapModifiedTx
// and modifying them for their already included ancestors
UpdatePackagesForAdded(inBlock, mapModifiedTx);
var ancestorScoreList =
this.mempoolScheduler.ReadAsync(() => mempool.MapTx.AncestorScore).GetAwaiter().GetResult().ToList();
TxMempoolEntry iter;
// Limit the number of attempts to add transactions to the block when it is
// close to full; this is just a simple heuristic to finish quickly if the
// mempool has a lot of entries.
int MAX_CONSECUTIVE_FAILURES = 1000;
int nConsecutiveFailed = 0;
while (ancestorScoreList.Any() || mapModifiedTx.Any())
{
var mi = ancestorScoreList.FirstOrDefault();
if (mi != null)
{
// Skip entries in mapTx that are already in a block or are present
// in mapModifiedTx (which implies that the mapTx ancestor state is
// stale due to ancestor inclusion in the block)
// Also skip transactions that we've already failed to add. This can happen if
// we consider a transaction in mapModifiedTx and it fails: we can then
// potentially consider it again while walking mapTx. It's currently
// guaranteed to fail again, but as a belt-and-suspenders check we put it in
// failedTx and avoid re-evaluation, since the re-evaluation would be using
// cached size/sigops/fee values that are not actually correct.
// First try to find a new transaction in mapTx to evaluate.
if (mapModifiedTx.ContainsKey(mi.TransactionHash) || inBlock.Contains(mi) || failedTx.Contains(mi))
{
ancestorScoreList.Remove(mi);
continue;
}
}
// Now that mi is not stale, determine which transaction to evaluate:
// the next entry from mapTx, or the best from mapModifiedTx?
bool fUsingModified = false;
TxMemPoolModifiedEntry modit;
var compare = new CompareModifiedEntry();
if (mi == null)
{
modit = mapModifiedTx.Values.OrderByDescending(o => o, compare).First();
iter = modit.iter;
fUsingModified = true;
}
else
{
// Try to compare the mapTx entry to the mapModifiedTx entry
iter = mi;
modit = mapModifiedTx.Values.OrderByDescending(o => o, compare).FirstOrDefault();
if (modit != null && compare.Compare(modit, new TxMemPoolModifiedEntry(iter)) > 0)
{
// The best entry in mapModifiedTx has higher score
// than the one from mapTx.
// Switch which transaction (package) to consider
iter = modit.iter;
fUsingModified = true;
}
else
{
// Either no entry in mapModifiedTx, or it's worse than mapTx.
// Increment mi for the next loop iteration.
ancestorScoreList.Remove(iter);
}
}
// We skip mapTx entries that are inBlock, and mapModifiedTx shouldn't
// contain anything that is inBlock.
Guard.Assert(!inBlock.Contains(iter));
var packageSize = iter.SizeWithAncestors;
var packageFees = iter.ModFeesWithAncestors;
var packageSigOpsCost = iter.SizeWithAncestors;
if (fUsingModified)
{
packageSize = modit.SizeWithAncestors;
packageFees = modit.ModFeesWithAncestors;
packageSigOpsCost = modit.SigOpCostWithAncestors;
}
if (packageFees < blockMinFeeRate.GetFee((int)packageSize))
{
// Everything else we might consider has a lower fee rate
return;
}
if (!TestPackage(packageSize, packageSigOpsCost))
{
if (fUsingModified)
{
// Since we always look at the best entry in mapModifiedTx,
// we must erase failed entries so that we can consider the
// next best entry on the next loop iteration
mapModifiedTx.Remove(modit.iter.TransactionHash);
failedTx.Add(iter);
}
++nConsecutiveFailed;
if (nConsecutiveFailed > MAX_CONSECUTIVE_FAILURES && blockWeight >
blockMaxWeight - 4000)
{
// Give up if we're close to full and haven't succeeded in a while
break;
}
continue;
}
TxMempool.SetEntries ancestors = new TxMempool.SetEntries();
long nNoLimit = long.MaxValue;
string dummy;
mempool.CalculateMemPoolAncestors(iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, out dummy, false);
OnlyUnconfirmed(ancestors);
ancestors.Add(iter);
// Test if all tx's are Final
if (!TestPackageTransactions(ancestors))
{
if (fUsingModified)
{
mapModifiedTx.Remove(modit.iter.TransactionHash);
failedTx.Add(iter);
}
continue;
}
// This transaction will make it in; reset the failed counter.
nConsecutiveFailed = 0;
// Package can be added. Sort the entries in a valid order.
// Sort package by ancestor count
// If a transaction A depends on transaction B, then A's ancestor count
// must be greater than B's. So this is sufficient to validly order the
// transactions for block inclusion.
var sortedEntries = ancestors.ToList().OrderBy(o => o, new CompareTxIterByAncestorCount()).ToList();
foreach (var sortedEntry in sortedEntries)
{
AddToBlock(sortedEntry);
// Erase from the modified set, if present
mapModifiedTx.Remove(sortedEntry.TransactionHash);
}
++nPackagesSelected;
// Update transactions that depend on each of these
nDescendantsUpdated += UpdatePackagesForAdded(ancestors, mapModifiedTx);
}
}
public void MempoolIndexingTest()
{
NodeSettings settings = NodeSettings.Default(KnownNetworks.TestNet);
var pool = new TxMempool(DateTimeProvider.Default, new BlockPolicyEstimator(new MempoolSettings(settings), settings.LoggerFactory, settings), settings.LoggerFactory, settings);
var entry = new TestMemPoolEntryHelper();
/* 3rd highest fee */
var tx1 = new Transaction();
tx1.AddOutput(new TxOut(new Money(10 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx1.GetHash(), entry.Fee(new Money(10000L)).Priority(10.0).FromTx(tx1));
/* highest fee */
var tx2 = new Transaction();
tx2.AddOutput(new TxOut(new Money(2 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx2.GetHash(), entry.Fee(new Money(20000L)).Priority(9.0).FromTx(tx2));
/* lowest fee */
var tx3 = new Transaction();
tx3.AddOutput(new TxOut(new Money(5 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx3.GetHash(), entry.Fee(new Money(0L)).Priority(100.0).FromTx(tx3));
/* 2nd highest fee */
var tx4 = new Transaction();
tx4.AddOutput(new TxOut(new Money(6 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx4.GetHash(), entry.Fee(new Money(15000L)).Priority(1.0).FromTx(tx4));
/* equal fee rate to tx1, but newer */
var tx5 = new Transaction();
tx5.AddOutput(new TxOut(new Money(11 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx5.GetHash(), entry.Fee(new Money(10000L)).Priority(10.0).Time(1).FromTx(tx5));
// assert size
Assert.Equal(5, pool.Size);
var sortedOrder = new List <string>(5);
sortedOrder.Insert(0, tx3.GetHash().ToString()); // 0
sortedOrder.Insert(1, tx5.GetHash().ToString()); // 10000
sortedOrder.Insert(2, tx1.GetHash().ToString()); // 10000
sortedOrder.Insert(3, tx4.GetHash().ToString()); // 15000
sortedOrder.Insert(4, tx2.GetHash().ToString()); // 20000
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
/* low fee but with high fee child */
/* tx6 -> tx7 -> tx8, tx9 -> tx10 */
var tx6 = new Transaction();
tx6.AddOutput(new TxOut(new Money(20 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx6.GetHash(), entry.Fee(new Money(0L)).FromTx(tx6));
// assert size
Assert.Equal(6, pool.Size);
// Check that at this point, tx6 is sorted low
sortedOrder.Insert(0, tx6.GetHash().ToString());
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
var setAncestors = new TxMempool.SetEntries();
setAncestors.Add(pool.MapTx.TryGet(tx6.GetHash()));
var tx7 = new Transaction();
tx7.AddInput(new TxIn(new OutPoint(tx6.GetHash(), 0), new Script(OpcodeType.OP_11)));
tx7.AddOutput(new TxOut(new Money(10 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
tx7.AddOutput(new TxOut(new Money(1 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
var setAncestorsCalculated = new TxMempool.SetEntries();
string dummy;
Assert.True(pool.CalculateMemPoolAncestors(entry.Fee(2000000L).FromTx(tx7), setAncestorsCalculated, 100, 1000000, 1000, 1000000, out dummy));
Assert.True(setAncestorsCalculated.Equals(setAncestors));
pool.AddUnchecked(tx7.GetHash(), entry.FromTx(tx7), setAncestors);
Assert.Equal(7, pool.Size);
// Now tx6 should be sorted higher (high fee child): tx7, tx6, tx2, ...
sortedOrder.RemoveAt(0);
sortedOrder.Add(tx6.GetHash().ToString());
sortedOrder.Add(tx7.GetHash().ToString());
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
/* low fee child of tx7 */
var tx8 = new Transaction();
tx8.AddInput(new TxIn(new OutPoint(tx7.GetHash(), 0), new Script(OpcodeType.OP_11)));
tx8.AddOutput(new TxOut(new Money(10 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
setAncestors.Add(pool.MapTx.TryGet(tx7.GetHash()));
pool.AddUnchecked(tx8.GetHash(), entry.Fee(0L).Time(2).FromTx(tx8), setAncestors);
// Now tx8 should be sorted low, but tx6/tx both high
sortedOrder.Insert(0, tx8.GetHash().ToString());
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
/* low fee child of tx7 */
var tx9 = new Transaction();
tx9.AddInput(new TxIn(new OutPoint(tx7.GetHash(), 1), new Script(OpcodeType.OP_11)));
tx9.AddOutput(new TxOut(new Money(1 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
pool.AddUnchecked(tx9.GetHash(), entry.Fee(0L).Time(3).FromTx(tx9), setAncestors);
// tx9 should be sorted low
Assert.Equal(9, pool.Size);
sortedOrder.Insert(0, tx9.GetHash().ToString());
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
List <string> snapshotOrder = sortedOrder.ToList();
setAncestors.Add(pool.MapTx.TryGet(tx8.GetHash()));
setAncestors.Add(pool.MapTx.TryGet(tx9.GetHash()));
/* tx10 depends on tx8 and tx9 and has a high fee*/
var tx10 = new Transaction();
tx10.AddInput(new TxIn(new OutPoint(tx8.GetHash(), 0), new Script(OpcodeType.OP_11)));
tx10.AddInput(new TxIn(new OutPoint(tx9.GetHash(), 0), new Script(OpcodeType.OP_11)));
tx10.AddOutput(new TxOut(new Money(10 * Money.COIN), new Script(OpcodeType.OP_11, OpcodeType.OP_EQUAL)));
setAncestorsCalculated.Clear();
Assert.True(pool.CalculateMemPoolAncestors(entry.Fee(200000L).Time(4).FromTx(tx10), setAncestorsCalculated, 100, 1000000, 1000, 1000000, out dummy));
Assert.True(setAncestorsCalculated.Equals(setAncestors));
pool.AddUnchecked(tx10.GetHash(), entry.FromTx(tx10), setAncestors);
/**
* tx8 and tx9 should both now be sorted higher
* Final order after tx10 is added:
*
* tx3 = 0 (1)
* tx5 = 10000 (1)
* tx1 = 10000 (1)
* tx4 = 15000 (1)
* tx2 = 20000 (1)
* tx9 = 200k (2 txs)
* tx8 = 200k (2 txs)
* tx10 = 200k (1 tx)
* tx6 = 2.2M (5 txs)
* tx7 = 2.2M (4 txs)
*/
sortedOrder.RemoveRange(0, 2); // take out tx9, tx8 from the beginning
sortedOrder.Insert(5, tx9.GetHash().ToString());
sortedOrder.Insert(6, tx8.GetHash().ToString());
sortedOrder.Insert(7, tx10.GetHash().ToString()); // tx10 is just before tx6
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), sortedOrder);
// there should be 10 transactions in the mempool
Assert.Equal(10, pool.Size);
// Now try removing tx10 and verify the sort order returns to normal
pool.RemoveRecursive(pool.MapTx.TryGet(tx10.GetHash()).Transaction);
this.CheckSort(pool, pool.MapTx.DescendantScore.ToList(), snapshotOrder);
pool.RemoveRecursive(pool.MapTx.TryGet(tx9.GetHash()).Transaction);
pool.RemoveRecursive(pool.MapTx.TryGet(tx8.GetHash()).Transaction);
/* Now check the sort on the mining score index.
* Final order should be:
*
* tx7 (2M)
* tx2 (20k)
* tx4 (15000)
* tx1/tx5 (10000)
* tx3/6 (0)
* (Ties resolved by hash)
*/
sortedOrder.Clear();
sortedOrder.Add(tx7.GetHash().ToString());
sortedOrder.Add(tx2.GetHash().ToString());
sortedOrder.Add(tx4.GetHash().ToString());
if (tx1.GetHash() < tx5.GetHash())
{
sortedOrder.Add(tx5.GetHash().ToString());
sortedOrder.Add(tx1.GetHash().ToString());
}
else
{
sortedOrder.Add(tx1.GetHash().ToString());
sortedOrder.Add(tx5.GetHash().ToString());
}
if (tx3.GetHash() < tx6.GetHash())
{
sortedOrder.Add(tx6.GetHash().ToString());
sortedOrder.Add(tx3.GetHash().ToString());
}
else
{
sortedOrder.Add(tx3.GetHash().ToString());
sortedOrder.Add(tx6.GetHash().ToString());
}
this.CheckSort(pool, pool.MapTx.MiningScore.ToList(), sortedOrder);
}
