-use crate::collections::{hash_map, HashMap, HashSet, VecDeque};
+use crate::collections::{HashMap, HashSet, VecDeque};
use crate::tx_graph::{TxAncestors, TxDescendants};
use crate::{Anchor, ChainOracle, TxGraph};
use alloc::boxed::Box;
use alloc::collections::BTreeSet;
use alloc::sync::Arc;
+use alloc::vec::Vec;
use bdk_core::BlockId;
use bitcoin::{Transaction, Txid};
+type CanonicalMap<A> = HashMap<Txid, (Arc<Transaction>, CanonicalReason<A>)>;
+type NotCanonicalSet = HashSet<Txid>;
+
/// Iterates over canonical txs.
pub struct CanonicalIter<'g, A, C> {
tx_graph: &'g TxGraph<A>,
unprocessed_txs_with_last_seens: Box<dyn Iterator<Item = (Txid, Arc<Transaction>, u64)> + 'g>,
unprocessed_txs_left_over: VecDeque<(Txid, Arc<Transaction>, u32)>,
- canonical: HashMap<Txid, (Arc<Transaction>, CanonicalReason<A>)>,
- not_canonical: HashSet<Txid>,
+ canonical: CanonicalMap<A>,
+ not_canonical: NotCanonicalSet,
queue: VecDeque<Txid>,
}
Ok(())
}
- /// Marks a transaction and it's ancestors as canonical. Mark all conflicts of these as
+ /// Marks `tx` and it's ancestors as canonical and mark all conflicts of these as
/// `not_canonical`.
+ ///
+ /// The exception is when it is discovered that `tx` double spends itself (i.e. two of it's
+ /// inputs conflict with each other), then no changes will be made.
+ ///
+ /// The logic works by having two loops where one is nested in another.
+ /// * The outer loop iterates through ancestors of `tx` (including `tx`). We can transitively
+ /// assume that all ancestors of `tx` are also canonical.
+ /// * The inner loop loops through conflicts of ancestors of `tx`. Any descendants of conflicts
+ /// are also conflicts and are transitively considered non-canonical.
+ ///
+ /// If the inner loop ends up marking `tx` as non-canonical, then we know that it double spends
+ /// itself.
fn mark_canonical(&mut self, txid: Txid, tx: Arc<Transaction>, reason: CanonicalReason<A>) {
let starting_txid = txid;
- let mut is_root = true;
- TxAncestors::new_include_root(
+ let mut is_starting_tx = true;
+
+ // We keep track of changes made so far so that we can undo it later in case we detect that
+ // `tx` double spends itself.
+ let mut detected_self_double_spend = false;
+ let mut undo_not_canonical = Vec::<Txid>::new();
+
+ // `staged_queue` doubles as the `undo_canonical` data.
+ let staged_queue = TxAncestors::new_include_root(
self.tx_graph,
tx,
- |_: usize, tx: Arc<Transaction>| -> Option<()> {
+ |_: usize, tx: Arc<Transaction>| -> Option<Txid> {
let this_txid = tx.compute_txid();
- let this_reason = if is_root {
- is_root = false;
+ let this_reason = if is_starting_tx {
+ is_starting_tx = false;
reason.clone()
} else {
reason.to_transitive(starting_txid)
};
+
+ use crate::collections::hash_map::Entry;
let canonical_entry = match self.canonical.entry(this_txid) {
// Already visited tx before, exit early.
- hash_map::Entry::Occupied(_) => return None,
- hash_map::Entry::Vacant(entry) => entry,
+ Entry::Occupied(_) => return None,
+ Entry::Vacant(entry) => entry,
};
+
// Any conflicts with a canonical tx can be added to `not_canonical`. Descendants
// of `not_canonical` txs can also be added to `not_canonical`.
for (_, conflict_txid) in self.tx_graph.direct_conflicts(&tx) {
conflict_txid,
|_: usize, txid: Txid| -> Option<()> {
if self.not_canonical.insert(txid) {
+ undo_not_canonical.push(txid);
Some(())
} else {
None
)
.run_until_finished()
}
+
+ if self.not_canonical.contains(&this_txid) {
+ // Early exit if self-double-spend is detected.
+ detected_self_double_spend = true;
+ return None;
+ }
canonical_entry.insert((tx, this_reason));
- self.queue.push_back(this_txid);
- Some(())
+ Some(this_txid)
},
)
- .run_until_finished()
+ .collect::<Vec<Txid>>();
+
+ if detected_self_double_spend {
+ for txid in staged_queue {
+ self.canonical.remove(&txid);
+ }
+ for txid in undo_not_canonical {
+ self.not_canonical.remove(&txid);
+ }
+ } else {
+ self.queue.extend(staged_queue);
+ }
}
}
exp_chain_txouts: HashSet::from([("tx", 0)]),
exp_unspents: HashSet::from([("tx", 0)]),
exp_balance: Balance { trusted_pending: Amount::from_sat(9000), ..Default::default() }
- }
+ },
+ Scenario {
+ name: "tx spends from 2 conflicting transactions where a conflict spends another",
+ tx_templates: &[
+ TxTemplate {
+ tx_name: "A",
+ inputs: &[TxInTemplate::Bogus],
+ outputs: &[TxOutTemplate::new(10_000, None)],
+ last_seen: Some(1),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S1",
+ inputs: &[TxInTemplate::PrevTx("A", 0)],
+ outputs: &[TxOutTemplate::new(9_000, None)],
+ last_seen: Some(2),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S2",
+ inputs: &[TxInTemplate::PrevTx("A", 0), TxInTemplate::PrevTx("S1", 0)],
+ outputs: &[TxOutTemplate::new(17_000, None)],
+ last_seen: Some(3),
+ ..Default::default()
+ },
+ ],
+ exp_chain_txs: HashSet::from(["A", "S1"]),
+ exp_chain_txouts: HashSet::from([]),
+ exp_unspents: HashSet::from([]),
+ exp_balance: Balance::default(),
+ },
+ Scenario {
+ name: "tx spends from 2 conflicting transactions where the conflict is nested",
+ tx_templates: &[
+ TxTemplate {
+ tx_name: "A",
+ inputs: &[TxInTemplate::Bogus],
+ outputs: &[TxOutTemplate::new(10_000, Some(0))],
+ last_seen: Some(1),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S1",
+ inputs: &[TxInTemplate::PrevTx("A", 0)],
+ outputs: &[TxOutTemplate::new(9_000, Some(0))],
+ last_seen: Some(3),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "B",
+ inputs: &[TxInTemplate::PrevTx("S1", 0)],
+ outputs: &[TxOutTemplate::new(8_000, Some(0))],
+ last_seen: Some(2),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S2",
+ inputs: &[TxInTemplate::PrevTx("B", 0), TxInTemplate::PrevTx("A", 0)],
+ outputs: &[TxOutTemplate::new(17_000, Some(0))],
+ last_seen: Some(4),
+ ..Default::default()
+ },
+ ],
+ exp_chain_txs: HashSet::from(["A", "S1", "B"]),
+ exp_chain_txouts: HashSet::from([("A", 0), ("B", 0), ("S1", 0)]),
+ exp_unspents: HashSet::from([("B", 0)]),
+ exp_balance: Balance { trusted_pending: Amount::from_sat(8_000), ..Default::default() },
+ },
+ Scenario {
+ name: "tx spends from 2 conflicting transactions where the conflict is nested (different last_seens)",
+ tx_templates: &[
+ TxTemplate {
+ tx_name: "A",
+ inputs: &[TxInTemplate::Bogus],
+ outputs: &[TxOutTemplate::new(10_000, Some(0))],
+ last_seen: Some(1),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S1",
+ inputs: &[TxInTemplate::PrevTx("A", 0)],
+ outputs: &[TxOutTemplate::new(9_000, Some(0))],
+ last_seen: Some(4),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "B",
+ inputs: &[TxInTemplate::PrevTx("S1", 0)],
+ outputs: &[TxOutTemplate::new(8_000, Some(0))],
+ last_seen: Some(2),
+ ..Default::default()
+ },
+ TxTemplate {
+ tx_name: "S2",
+ inputs: &[TxInTemplate::PrevTx("A", 0), TxInTemplate::PrevTx("B", 0)],
+ outputs: &[TxOutTemplate::new(17_000, Some(0))],
+ last_seen: Some(3),
+ ..Default::default()
+ },
+ ],
+ exp_chain_txs: HashSet::from(["A", "S1", "B"]),
+ exp_chain_txouts: HashSet::from([("A", 0), ("B", 0), ("S1", 0)]),
+ exp_unspents: HashSet::from([("B", 0)]),
+ exp_balance: Balance { trusted_pending: Amount::from_sat(8_000), ..Default::default() },
+ },
];
for scenario in scenarios {
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