adds a `spending_transaction_hash()` read fn for the new column family

zebra-state/src/service/finalized_state/zebra_db/transparent.rs

@@ -68,8 +68,7 @@ impl ZebraDb {
 
     /// Returns the [`TransactionLocation`] for a transaction that spent the output
     /// at the provided [`OutputLocation`], if it is in the finalized state.
-    #[allow(clippy::unwrap_in_result)]
-    pub fn tx_loc_by_spent_output_loc(
+    pub fn tx_location_by_spent_output_location(
         &self,
         output_location: &OutputLocation,
     ) -> Option<TransactionLocation> {
@@ -123,6 +122,15 @@ impl ZebraDb {
         self.utxo_by_location(output_location)
     }
 
+    /// Returns the [`transaction::Hash`] of the transaction that spent the given
+    /// [`transparent::OutPoint`], if it is unspent in the finalized state.
+    pub fn spending_tx_id(&self, outpoint: &transparent::OutPoint) -> Option<transaction::Hash> {
+        let output_location = self.output_location(outpoint)?;
+        let spending_tx_location = self.tx_location_by_spent_output_location(&output_location)?;
+
+        self.transaction_hash(spending_tx_location)
+    }
+
     /// Returns the transparent output for an [`OutputLocation`],
     /// if it is unspent in the finalized state.
     #[allow(clippy::unwrap_in_result)]

zebra-state/src/service/non_finalized_state/chain.rs

@@ -1256,11 +1256,15 @@ impl Chain {
     ///
     /// UTXOs are returned regardless of whether they have been spent.
     pub fn created_utxo(&self, outpoint: &transparent::OutPoint) -> Option<transparent::Utxo> {
-        if let Some(utxo) = self.created_utxos.get(outpoint) {
-            return Some(utxo.utxo.clone());
-        }
+        self.created_utxos
+            .get(outpoint)
+            .map(|utxo| utxo.utxo.clone())
+    }
 
-        None
+    /// Returns the [`transaction::Hash`] of the transaction that spent the given
+    /// [`transparent::OutPoint`], if it was spent by this chain.
+    pub fn spending_tx_id(&self, outpoint: &transparent::OutPoint) -> Option<transaction::Hash> {
+        self.spent_utxos.get(outpoint).cloned()
     }
 
     // Address index queries

zebra-state/src/service/read.rs

@@ -31,7 +31,8 @@ pub use address::{
     utxo::{address_utxos, AddressUtxos},
 };
 pub use block::{
-    any_utxo, block, block_header, mined_transaction, transaction_hashes_for_block, unspent_utxo,
+    any_utxo, block, block_header, mined_transaction, spending_transaction_hash,
+    transaction_hashes_for_block, unspent_utxo,
 };
 pub use find::{
     best_tip, block_locator, depth, finalized_state_contains_block_hash, find_chain_hashes,

zebra-state/src/service/read/block.rs

@@ -181,6 +181,22 @@ where
     }
 }
 
+/// Returns the [`Hash`](transaction::Hash) of the transaction that spent an output at
+/// the provided [`transparent::OutPoint`], if it exists and is spent in the non-finalized
+/// `chain` or finalized `db`.
+pub fn spending_transaction_hash<C>(
+    chain: Option<C>,
+    db: &ZebraDb,
+    outpoint: transparent::OutPoint,
+) -> Option<transaction::Hash>
+where
+    C: AsRef<Chain>,
+{
+    chain
+        .and_then(|chain| chain.as_ref().spending_tx_id(&outpoint))
+        .or_else(|| db.spending_tx_id(&outpoint))
+}
+
 /// Returns the [`Utxo`] for [`transparent::OutPoint`], if it exists in any chain
 /// in the `non_finalized_state`, or in the finalized `db`.
 ///