// ProcessTransaction is the main workhorse for handling insertion of new
// free-standing transactions into the memory pool. It includes functionality
// such as rejecting duplicate transactions, ensuring transactions follow all
// rules, orphan transaction handling, and insertion into the memory pool.
//
// This function is safe for concurrent access.
func (mp *txMemPool) ProcessTransaction(tx *btcutil.Tx, allowOrphan, rateLimit bool) error {
// Protect concurrent access.
mp.Lock()
defer mp.Unlock()
txmpLog.Tracef("Processing transaction %v", tx.Sha())
// Potentially accept the transaction to the memory pool.
missingParents, err := mp.maybeAcceptTransaction(tx, true, rateLimit)
if err != nil {
return err
}
if len(missingParents) == 0 {
// Generate the inventory vector and relay it.
iv := btcwire.NewInvVect(btcwire.InvTypeTx, tx.Sha())
mp.server.RelayInventory(iv, tx)
// Accept any orphan transactions that depend on this
// transaction (they may no longer be orphans if all inputs
// are now available) and repeat for those accepted
// transactions until there are no more.
err := mp.processOrphans(tx.Sha())
if err != nil {
return err
}
} else {
// The transaction is an orphan (has inputs missing). Reject
// it if the flag to allow orphans is not set.
if !allowOrphan {
// Only use the first missing parent transaction in
// the error message.
//
// NOTE: RejectDuplicate is really not an accurate
// reject code here, but it matches the reference
// implementation and there isn't a better choice due
// to the limited number of reject codes. Missing
// inputs is assumed to mean they are already spent
// which is not really always the case.
str := fmt.Sprintf("orphan transaction %v references "+
"outputs of unknown or fully-spent "+
"transaction %v", tx.Sha(), missingParents[0])
return txRuleError(btcwire.RejectDuplicate, str)
}
// Potentially add the orphan transaction to the orphan pool.
err := mp.maybeAddOrphan(tx)
if err != nil {
return err
}
}
return nil
}
// BenchmarkMruInventoryList performs basic benchmarks on the most recently
// used inventory handling.
func BenchmarkMruInventoryList(b *testing.B) {
// Create a bunch of fake inventory vectors to use in benchmarking
// the mru inventory code.
b.StopTimer()
numInvVects := 100000
invVects := make([]*btcwire.InvVect, 0, numInvVects)
for i := 0; i < numInvVects; i++ {
hashBytes := make([]byte, btcwire.HashSize)
rand.Read(hashBytes)
hash, _ := btcwire.NewShaHash(hashBytes)
iv := btcwire.NewInvVect(btcwire.InvTypeBlock, hash)
invVects = append(invVects, iv)
}
b.StartTimer()
// Benchmark the add plus evicition code.
limit := 20000
mruInvMap := NewMruInventoryMap(uint(limit))
for i := 0; i < b.N; i++ {
mruInvMap.Add(invVects[i%numInvVects])
}
}
// processOrphans determines if there are any orphans which depend on the passed
// transaction hash (it is possible that they are no longer orphans) and
// potentially accepts them to the memory pool. It repeats the process for the
// newly accepted transactions (to detect further orphans which may no longer be
// orphans) until there are no more.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *txMemPool) processOrphans(hash *btcwire.ShaHash) error {
// Start with processing at least the passed hash.
processHashes := list.New()
processHashes.PushBack(hash)
for processHashes.Len() > 0 {
// Pop the first hash to process.
firstElement := processHashes.Remove(processHashes.Front())
processHash := firstElement.(*btcwire.ShaHash)
// Look up all orphans that are referenced by the transaction we
// just accepted. This will typically only be one, but it could
// be multiple if the referenced transaction contains multiple
// outputs. Skip to the next item on the list of hashes to
// process if there are none.
orphans, exists := mp.orphansByPrev[*processHash]
if !exists || orphans == nil {
continue
}
var enext *list.Element
for e := orphans.Front(); e != nil; e = enext {
enext = e.Next()
tx := e.Value.(*btcutil.Tx)
// Remove the orphan from the orphan pool. Current
// behavior requires that all saved orphans with
// a newly accepted parent are removed from the orphan
// pool and potentially added to the memory pool, but
// transactions which cannot be added to memory pool
// (including due to still being orphans) are expunged
// from the orphan pool.
//
// TODO(jrick): The above described behavior sounds
// like a bug, and I think we should investigate
// potentially moving orphans to the memory pool, but
// leaving them in the orphan pool if not all parent
// transactions are known yet.
orphanHash := tx.Sha()
mp.removeOrphan(orphanHash)
// Potentially accept the transaction into the
// transaction pool.
missingParents, err := mp.maybeAcceptTransaction(tx,
true, true)
if err != nil {
return err
}
if len(missingParents) == 0 {
// Generate and relay the inventory vector for the
// newly accepted transaction.
iv := btcwire.NewInvVect(btcwire.InvTypeTx, tx.Sha())
mp.server.RelayInventory(iv, tx)
} else {
// Transaction is still an orphan.
// TODO(jrick): This removeOrphan call is
// likely unnecessary as it was unconditionally
// removed above and maybeAcceptTransaction won't
// add it back.
mp.removeOrphan(orphanHash)
}
// Add this transaction to the list of transactions to
// process so any orphans that depend on this one are
// handled too.
//
// TODO(jrick): In the case that this is still an orphan,
// we know that any other transactions in the orphan
// pool with this orphan as their parent are still
// orphans as well, and should be removed. While
// recursively calling removeOrphan and
// maybeAcceptTransaction on these transactions is not
// wrong per se, it is overkill if all we care about is
// recursively removing child transactions of this
// orphan.
processHashes.PushBack(orphanHash)
}
}
return nil
}
