From 23af05ff856d1e59c242c7ba5a9d0bea6f6820b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BF=97=E5=AE=87?= <hello@evanlinjin.me>
Date: Tue, 24 Dec 2024 16:51:32 +1100
Subject: [PATCH] fix(chain,wallet): Provide unconfirmed spends to chain src
 sync request

Unconfirmed outputs can now be easily provided to the `SyncRequest` via
`SyncRequestExt::unconfirmed_spends`. This allows the chain src to
detect receiving txs being replaced/cancelled.

`Wallet::start_sync_with_revealed_spks` has been deprecated in favor of
`start_sync` which included unconfirmed spends.
---
 crates/chain/src/indexer/keychain_txout.rs | 47 +++++++++++++++++++++-
 crates/wallet/src/wallet/mod.rs            | 26 ++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/crates/chain/src/indexer/keychain_txout.rs b/crates/chain/src/indexer/keychain_txout.rs
index 80bd879d7..5de7e0f1e 100644
--- a/crates/chain/src/indexer/keychain_txout.rs
+++ b/crates/chain/src/indexer/keychain_txout.rs
@@ -7,11 +7,13 @@ use crate::{
     spk_client::{FullScanRequestBuilder, SyncRequestBuilder},
     spk_iter::BIP32_MAX_INDEX,
     spk_txout::SpkTxOutIndex,
-    DescriptorExt, DescriptorId, Indexed, Indexer, KeychainIndexed, SpkIterator,
+    Anchor, CanonicalIter, ChainOracle, DescriptorExt, DescriptorId, Indexed, Indexer,
+    KeychainIndexed, SpkIterator,
 };
 use alloc::{borrow::ToOwned, vec::Vec};
 use bitcoin::{Amount, OutPoint, ScriptBuf, SignedAmount, Transaction, TxOut, Txid};
 use core::{
+    convert::Infallible,
     fmt::Debug,
     ops::{Bound, RangeBounds},
 };
@@ -879,6 +881,18 @@ pub trait SyncRequestBuilderExt<K> {
 
     /// Add [`Script`](bitcoin::Script)s that are revealed by the `indexer` but currently unused.
     fn unused_spks_from_indexer(self, indexer: &KeychainTxOutIndex<K>) -> Self;
+
+    /// Add [`OutPoint`]s which are spent by unconfirmed transactions.
+    ///
+    /// This allows the chain source to detect transactions which are cancelled/replaced.
+    fn unconfirmed_outpoints<A, C>(
+        self,
+        canonical_iter: CanonicalIter<A, C>,
+        indexer: &KeychainTxOutIndex<K>,
+    ) -> Self
+    where
+        A: Anchor,
+        C: ChainOracle<Error = Infallible>;
 }
 
 impl<K: Clone + Ord + core::fmt::Debug> SyncRequestBuilderExt<K> for SyncRequestBuilder<(K, u32)> {
@@ -892,6 +906,37 @@ impl<K: Clone + Ord + core::fmt::Debug> SyncRequestBuilderExt<K> for SyncRequest
     fn unused_spks_from_indexer(self, indexer: &KeychainTxOutIndex<K>) -> Self {
         self.spks_with_indexes(indexer.unused_spks())
     }
+
+    fn unconfirmed_outpoints<A, C>(
+        self,
+        canonical_iter: CanonicalIter<A, C>,
+        indexer: &KeychainTxOutIndex<K>,
+    ) -> Self
+    where
+        A: Anchor,
+        C: ChainOracle<Error = Infallible>,
+    {
+        self.outpoints(
+            canonical_iter
+                .filter_map(|r| {
+                    let (_, tx, reason) = r.expect("infallible");
+                    match reason {
+                        crate::CanonicalReason::ObservedIn { .. }
+                            if indexer.is_tx_relevant(&tx) =>
+                        {
+                            Some(tx)
+                        }
+                        _ => None,
+                    }
+                })
+                .flat_map(|tx| {
+                    tx.input
+                        .iter()
+                        .map(|txin| txin.previous_output)
+                        .collect::<Vec<_>>()
+                }),
+        )
+    }
 }
 
 /// Trait to extend [`FullScanRequestBuilder`].
diff --git a/crates/wallet/src/wallet/mod.rs b/crates/wallet/src/wallet/mod.rs
index 2e068a95f..f703970ef 100644
--- a/crates/wallet/src/wallet/mod.rs
+++ b/crates/wallet/src/wallet/mod.rs
@@ -2445,6 +2445,10 @@ impl Wallet {
     /// This is the first step when performing a spk-based wallet partial sync, the returned
     /// [`SyncRequest`] collects all revealed script pubkeys from the wallet keychain needed to
     /// start a blockchain sync with a spk based blockchain client.
+    #[deprecated(
+        since = "1.1.0",
+        note = "start_sync_with_revealed_spks could not detect receiving transactions being replaced. Use start_sync instead"
+    )]
     pub fn start_sync_with_revealed_spks(&self) -> SyncRequestBuilder<(KeychainKind, u32)> {
         use bdk_chain::keychain_txout::SyncRequestBuilderExt;
         SyncRequest::builder()
@@ -2452,6 +2456,28 @@ impl Wallet {
             .revealed_spks_from_indexer(&self.indexed_graph.index, ..)
     }
 
+    /// Create a [`SyncRequest`] for this wallet.
+    ///
+    /// This assembles a request which initiates a sync against a spk-based chain source. This
+    /// request contains all revealed script pubkeys and unconfirmed spends.
+    ///
+    /// This request can detect when transactions get cancelled/replaced.
+    pub fn start_sync(&self) -> SyncRequestBuilder<(KeychainKind, u32)> {
+        use bdk_chain::keychain_txout::SyncRequestBuilderExt;
+
+        let chain = &self.chain;
+        let tx_graph = &self.indexed_graph.graph();
+        let tx_index = &self.indexed_graph.index;
+
+        SyncRequest::builder()
+            .chain_tip(chain.tip())
+            .revealed_spks_from_indexer(tx_index, ..)
+            .unconfirmed_outpoints(
+                tx_graph.canonical_iter(chain, chain.tip().block_id()),
+                tx_index,
+            )
+    }
+
     /// Create a [`FullScanRequest] for this wallet.
     ///
     /// This is the first step when performing a spk-based wallet full scan, the returned