chain(fix): conflict resolution for txs with same last_seen

Author: LagginTimes

crates/chain/src/tx_graph.rs

@@ -693,6 +693,26 @@ impl<A: Anchor> TxGraph<A> {
             if conflicting_tx.last_seen_unconfirmed > *last_seen {
                 return Ok(None);
             }
+            if conflicting_tx.last_seen_unconfirmed == *last_seen {
+                // Check if conflicting tx has higher absolute fee and fee rate
+                if let Ok(fee) = self.calculate_fee(tx) {
+                    if let Ok(conflicting_fee) = self.calculate_fee(&conflicting_tx) {
+                        let fee_rate = fee as f32 / tx.weight().to_vbytes_ceil() as f32;
+                        let conflicting_fee_rate = conflicting_fee as f32
+                            / conflicting_tx.weight().to_vbytes_ceil() as f32;
+
+                        if conflicting_fee > fee && conflicting_fee_rate > fee_rate {
+                            return Ok(None);
+                        }
+                    }
+                }
+
+                // If fee rates cannot be distinguished, then conflicting tx has priority if txid of
+                // conflicting tx > txid of original tx
+                if conflicting_tx.txid() > tx.txid() {
+                    return Ok(None);
+                }
+            }
         }
 
         Ok(Some(ChainPosition::Unconfirmed(*last_seen)))

crates/chain/tests/test_indexed_tx_graph.rs

@@ -7,12 +7,14 @@ use bdk_chain::{
     indexed_tx_graph::{self, IndexedTxGraph},
     keychain::{self, Balance, KeychainTxOutIndex},
     local_chain::LocalChain,
-    tx_graph, BlockId, ChainPosition, ConfirmationHeightAnchor,
+    tx_graph, BlockId, ChainPosition, ConfirmationHeightAnchor, SpkIterator,
 };
 use bitcoin::{
-    secp256k1::Secp256k1, BlockHash, OutPoint, Script, ScriptBuf, Transaction, TxIn, TxOut,
+    hashes::Hash, secp256k1::Secp256k1, BlockHash, OutPoint, Script, ScriptBuf, Transaction, TxIn,
+    TxOut,
 };
-use miniscript::Descriptor;
+use common::*;
+use miniscript::{Descriptor, DescriptorPublicKey};
 
 /// Ensure [`IndexedTxGraph::insert_relevant_txs`] can successfully index transactions NOT presented
 /// in topological order.
@@ -471,3 +473,127 @@ fn test_list_owned_txouts() {
         );
     }
 }
+
+#[allow(unused)]
+pub fn single_descriptor_setup() -> (
+    LocalChain,
+    IndexedTxGraph<ConfirmationHeightAnchor, KeychainTxOutIndex<()>>,
+    Descriptor<DescriptorPublicKey>,
+) {
+    let local_chain = (0..10)
+        .map(|i| (i as u32, BlockHash::hash(format!("Block {}", i).as_bytes())))
+        .collect::<BTreeMap<u32, BlockHash>>();
+    let local_chain = LocalChain::from(local_chain);
+
+    let (desc_1, _) = Descriptor::parse_descriptor(&Secp256k1::signing_only(), "tr(tprv8ZgxMBicQKsPd3krDUsBAmtnRsK3rb8u5yi1zhQgMhF1tR8MW7xfE4rnrbbsrbPR52e7rKapu6ztw1jXveJSCGHEriUGZV7mCe88duLp5pj/86'/1'/0'/0/*)").unwrap();
+
+    let mut graph = IndexedTxGraph::<ConfirmationHeightAnchor, KeychainTxOutIndex<()>>::default();
+
+    graph.index.add_keychain((), desc_1.clone());
+    graph.index.set_lookahead_for_all(100);
+
+    (local_chain, graph, desc_1)
+}
+
+#[allow(unused)]
+pub fn setup_conflicts(
+    spk_iter: &mut SpkIterator<&Descriptor<DescriptorPublicKey>>,
+) -> (Transaction, Transaction, Transaction) {
+    let tx1 = Transaction {
+        output: vec![TxOut {
+            script_pubkey: spk_iter.next().unwrap().1,
+            value: 40000,
+        }],
+        ..new_tx(0)
+    };
+
+    let tx_conflict_1 = Transaction {
+        input: vec![TxIn {
+            previous_output: OutPoint::new(tx1.txid(), 0),
+            ..Default::default()
+        }],
+        output: vec![TxOut {
+            script_pubkey: spk_iter.next().unwrap().1,
+            value: 20000,
+        }],
+        ..new_tx(0)
+    };
+
+    let tx_conflict_2 = Transaction {
+        input: vec![TxIn {
+            previous_output: OutPoint::new(tx1.txid(), 0),
+            ..Default::default()
+        }],
+        output: vec![TxOut {
+            script_pubkey: spk_iter.next().unwrap().1,
+            value: 30000,
+        }],
+        ..new_tx(0)
+    };
+
+    (tx1, tx_conflict_1, tx_conflict_2)
+}
+
+/// Test conflicts for two mempool tx, with same `seen_at` time.
+#[test]
+fn test_unconfirmed_conflicts_at_same_last_seen() {
+    let (local_chain, mut graph, desc) = single_descriptor_setup();
+    let mut spk_iter = SpkIterator::new(&desc);
+    let (parent_tx, tx_conflict_1, tx_conflict_2) = setup_conflicts(&mut spk_iter);
+
+    // Parent confirms at height 2.
+    let _ = graph.insert_relevant_txs(
+        [&parent_tx].iter().map(|tx| {
+            (
+                *tx,
+                [ConfirmationHeightAnchor {
+                    anchor_block: (2, *local_chain.blocks().get(&2).unwrap()).into(),
+                    confirmation_height: 2,
+                }],
+            )
+        }),
+        None,
+    );
+
+    // Both conflicts are in mempool at same `seen_at`
+    let _ = graph.insert_relevant_txs(
+        [&tx_conflict_1, &tx_conflict_2]
+            .iter()
+            .map(|tx| (*tx, None)),
+        Some(100),
+    );
+
+    let txouts = graph
+        .graph()
+        .filter_chain_txouts(
+            &local_chain,
+            local_chain.tip().unwrap().block_id(),
+            graph.index.outpoints().iter().cloned(),
+        )
+        .collect::<Vec<_>>();
+
+    let utxos = graph
+        .graph()
+        .filter_chain_unspents(
+            &local_chain,
+            local_chain.tip().unwrap().block_id(),
+            graph.index.outpoints().iter().cloned(),
+        )
+        .collect::<Vec<_>>();
+
+    assert_eq!(txouts.len(), 2);
+    assert_eq!(
+        txouts
+            .iter()
+            .filter(|(_, txout)| matches!(txout.chain_position, ChainPosition::Unconfirmed(100)))
+            .count(),
+        1
+    );
+    assert_eq!(
+        utxos
+            .iter()
+            .filter(|(_, txout)| matches!(txout.chain_position, ChainPosition::Unconfirmed(100)))
+            .count(),
+        1
+    );
+}