p2p: reconsider orphans when missing inputs are mined

src/node/txdownloadman_impl.cpp

@@ -100,6 +100,9 @@ void TxDownloadManagerImpl::BlockConnected(const std::shared_ptr<const CBlock>&
     m_orphanage->EraseForBlock(*pblock);
 
     for (const auto& ptx : pblock->vtx) {
+        // Reconsider potential child transactions.
+        m_orphanage->AddChildrenToWorkSet(*ptx, m_opts.m_rng);
+
         RecentConfirmedTransactionsFilter().insert(ptx->GetHash().ToUint256());
         if (ptx->HasWitness()) {
             RecentConfirmedTransactionsFilter().insert(ptx->GetWitnessHash().ToUint256());

src/node/txorphanage.cpp

@@ -531,6 +531,8 @@ void TxOrphanageImpl::LimitOrphans()
 
 std::vector<std::pair<Wtxid, NodeId>> TxOrphanageImpl::AddChildrenToWorkSet(const CTransaction& tx, FastRandomContext& rng)
 {
+    if (m_orphans.empty()) return {};
+
     std::vector<std::pair<Wtxid, NodeId>> ret;
     auto& index_by_wtxid = m_orphans.get<ByWtxid>();
     for (unsigned int i = 0; i < tx.vout.size(); i++) {

test/functional/p2p_orphan_handling.py

@@ -383,6 +383,31 @@ class OrphanHandlingTest(BitcoinTestFramework):
         assert tx_in_orphanage(node, orphan["tx"])
         peer.wait_for_parent_requests([int(missing_parent["txid"], 16)])
 
+    @cleanup
+    def test_orphan_parent_confirmed(self):
+        node = self.nodes[0]
+        peer = node.add_p2p_connection(PeerTxRelayer())
+
+        parent = self.wallet.create_self_transfer(fee_rate=0)
+        child = self.wallet.create_self_transfer(utxo_to_spend=parent["new_utxo"])
+
+        self.log.info("Test orphan reconsideration when its missing parent is confirmed")
+        self.relay_transaction(peer, child["tx"])
+        assert tx_in_orphanage(node, child["tx"])
+
+        # Withhold the requested parent so it can only become available through the block.
+        node.bumpmocktime(TXREQUEST_TIME_SKIP)
+        peer.wait_for_parent_requests([parent["tx"].txid_int])
+        assert_equal(node.getrawmempool(), [])
+
+        self.generateblock(
+            node,
+            output=self.wallet.get_address(),
+            transactions=[parent["hex"]],
+        )
+        self.wait_until(lambda: child["txid"] in node.getrawmempool())
+        assert not tx_in_orphanage(node, child["tx"])
+
     @cleanup
     def test_orphan_inherit_rejection(self):
         node = self.nodes[0]
@@ -826,6 +851,7 @@ class OrphanHandlingTest(BitcoinTestFramework):
         self.test_orphan_multiple_parents()
         self.test_orphans_overlapping_parents()
         self.test_orphan_of_orphan()
+        self.test_orphan_parent_confirmed()
         self.test_orphan_inherit_rejection()
         self.test_same_txid_orphan()
         self.test_same_txid_orphan_of_orphan()