refactor(chain)!: update ChainOracle and TxGraph methods to being infallible

Author: oleonardolima

crates/chain/src/canonical_iter.rs

@@ -90,14 +90,14 @@ impl<'g, A: Anchor, C: ChainOracle> CanonicalIter<'g, A, C> {
         txid: Txid,
         tx: Arc<Transaction>,
         anchors: &BTreeSet<A>,
-    ) -> Result<(), C::Error> {
+    ) {
         for anchor in anchors {
             let in_chain_opt = self
                 .chain
-                .is_block_in_chain(anchor.anchor_block(), self.chain_tip)?;
+                .is_block_in_chain(anchor.anchor_block(), self.chain_tip);
             if in_chain_opt == Some(true) {
                 self.mark_canonical(txid, tx, CanonicalReason::from_anchor(anchor.clone()));
-                return Ok(());
+                return;
             }
         }
         // cannot determine
@@ -112,7 +112,6 @@ impl<'g, A: Anchor, C: ChainOracle> CanonicalIter<'g, A, C> {
                 )
                 .confirmation_height_upper_bound(),
         ));
-        Ok(())
     }
 
     /// Marks `tx` and it's ancestors as canonical and mark all conflicts of these as
@@ -201,7 +200,7 @@ impl<'g, A: Anchor, C: ChainOracle> CanonicalIter<'g, A, C> {
 }
 
 impl<A: Anchor, C: ChainOracle> Iterator for CanonicalIter<'_, A, C> {
-    type Item = Result<(Txid, Arc<Transaction>, CanonicalReason<A>), C::Error>;
+    type Item = (Txid, Arc<Transaction>, CanonicalReason<A>);
 
     fn next(&mut self) -> Option<Self::Item> {
         loop {
@@ -211,7 +210,7 @@ impl<A: Anchor, C: ChainOracle> Iterator for CanonicalIter<'_, A, C> {
                     .get(&txid)
                     .cloned()
                     .expect("reason must exist");
-                return Some(Ok((txid, tx, reason)));
+                return Some((txid, tx, reason));
             }
 
             if let Some((txid, tx)) = self.unprocessed_assumed_txs.next() {
@@ -222,9 +221,7 @@ impl<A: Anchor, C: ChainOracle> Iterator for CanonicalIter<'_, A, C> {
 
             if let Some((txid, tx, anchors)) = self.unprocessed_anchored_txs.next() {
                 if !self.is_canonicalized(txid) {
-                    if let Err(err) = self.scan_anchors(txid, tx, anchors) {
-                        return Some(Err(err));
-                    }
+                    self.scan_anchors(txid, tx, anchors);
                 }
                 continue;
             }

crates/chain/src/chain_oracle.rs

@@ -7,19 +7,12 @@ use crate::BlockId;
 ///
 /// [`is_block_in_chain`]: Self::is_block_in_chain
 pub trait ChainOracle {
-    /// Error type.
-    type Error: core::fmt::Debug;
-
     /// Determines whether `block` of [`BlockId`] exists as an ancestor of `chain_tip`.
     ///
     /// If `None` is returned, it means the implementation cannot determine whether `block` exists
     /// under `chain_tip`.
-    fn is_block_in_chain(
-        &self,
-        block: BlockId,
-        chain_tip: BlockId,
-    ) -> Result<Option<bool>, Self::Error>;
+    fn is_block_in_chain(&self, block: BlockId, chain_tip: BlockId) -> Option<bool>;
 
     /// Get the best chain's chain tip.
-    fn get_chain_tip(&self) -> Result<BlockId, Self::Error>;
+    fn get_chain_tip(&self) -> BlockId;
 }

crates/chain/src/indexed_tx_graph.rs

@@ -1,7 +1,6 @@
 //! Contains the [`IndexedTxGraph`] and associated types. Refer to the
 //! [`IndexedTxGraph`] documentation for more.
 use core::{
-    convert::Infallible,
     fmt::{self, Debug},
     ops::RangeBounds,
 };
@@ -439,46 +438,21 @@ where
     ///
     /// The spk index range can be contrained with `range`.
     ///
-    /// # Error
-    ///
-    /// If the [`ChainOracle`] implementation (`chain`) fails, an error will be returned with the
-    /// returned item.
-    ///
-    /// If the [`ChainOracle`] is infallible,
-    /// [`list_expected_spk_txids`](Self::list_expected_spk_txids) can be used instead.
-    pub fn try_list_expected_spk_txids<'a, C, I>(
+    pub fn list_expected_spk_txids<'a, C, I>(
         &'a self,
         chain: &'a C,
         chain_tip: BlockId,
         spk_index_range: impl RangeBounds<I> + 'a,
-    ) -> impl Iterator<Item = Result<(ScriptBuf, Txid), C::Error>> + 'a
+    ) -> impl Iterator<Item = (ScriptBuf, Txid)> + 'a
     where
         C: ChainOracle,
         X: AsRef<SpkTxOutIndex<I>> + 'a,
         I: fmt::Debug + Clone + Ord + 'a,
     {
         self.graph
-            .try_list_expected_spk_txids(chain, chain_tip, &self.index, spk_index_range)
+            .list_expected_spk_txids(chain, chain_tip, &self.index, spk_index_range)
     }
 
-    /// List txids that are expected to exist under the given spks.
-    ///
-    /// This is the infallible version of
-    /// [`try_list_expected_spk_txids`](Self::try_list_expected_spk_txids).
-    pub fn list_expected_spk_txids<'a, C, I>(
-        &'a self,
-        chain: &'a C,
-        chain_tip: BlockId,
-        spk_index_range: impl RangeBounds<I> + 'a,
-    ) -> impl Iterator<Item = (ScriptBuf, Txid)> + 'a
-    where
-        C: ChainOracle<Error = Infallible>,
-        X: AsRef<SpkTxOutIndex<I>> + 'a,
-        I: fmt::Debug + Clone + Ord + 'a,
-    {
-        self.try_list_expected_spk_txids(chain, chain_tip, spk_index_range)
-            .map(|r| r.expect("infallible"))
-    }
 }
 
 impl<A, I> AsRef<TxGraph<A>> for IndexedTxGraph<A, I> {

crates/chain/src/local_chain.rs

@@ -1,6 +1,5 @@
 //! The [`LocalChain`] is a local implementation of [`ChainOracle`].
 
-use core::convert::Infallible;
 use core::fmt;
 use core::ops::RangeBounds;
 
@@ -70,27 +69,21 @@ impl<D> PartialEq for LocalChain<D> {
 }
 
 impl<D> ChainOracle for LocalChain<D> {
-    type Error = Infallible;
-
-    fn is_block_in_chain(
-        &self,
-        block: BlockId,
-        chain_tip: BlockId,
-    ) -> Result<Option<bool>, Self::Error> {
+    fn is_block_in_chain(&self, block: BlockId, chain_tip: BlockId) -> Option<bool> {
         let chain_tip_cp = match self.tip.get(chain_tip.height) {
             // we can only determine whether `block` is in chain of `chain_tip` if `chain_tip` can
             // be identified in chain
             Some(cp) if cp.hash() == chain_tip.hash => cp,
-            _ => return Ok(None),
+            _ => return None,
         };
         match chain_tip_cp.get(block.height) {
-            Some(cp) => Ok(Some(cp.hash() == block.hash)),
-            None => Ok(None),
+            Some(cp) => Some(cp.hash() == block.hash),
+            None => None,
         }
     }
 
-    fn get_chain_tip(&self) -> Result<BlockId, Self::Error> {
-        Ok(self.tip.block_id())
+    fn get_chain_tip(&self) -> BlockId {
+        self.tip.block_id()
     }
 }