Adds a `TransactionIdForSpentOutPoint` ReadRequest and a `TransactionId` ReadResponse

zebra-state/src/request.rs

@@ -1020,6 +1020,12 @@ pub enum ReadRequest {
         height_range: RangeInclusive<block::Height>,
     },
 
+    /// Looks up a spending transaction id by its spent transparent input.
+    ///
+    /// Returns [`ReadResponse::TransactionId`] with the hash of the transaction
+    /// that spent the output at the provided [`transparent::OutPoint`].
+    TransactionIdForSpentOutPoint(transparent::OutPoint),
+
     /// Looks up utxos for the provided addresses.
     ///
     /// Returns a type with found utxos and transaction information.
@@ -1100,6 +1106,7 @@ impl ReadRequest {
             ReadRequest::OrchardSubtrees { .. } => "orchard_subtrees",
             ReadRequest::AddressBalance { .. } => "address_balance",
             ReadRequest::TransactionIdsByAddresses { .. } => "transaction_ids_by_addesses",
+            ReadRequest::TransactionIdForSpentOutPoint { .. } => "transaction_id_by_spent_outpoint",
             ReadRequest::UtxosByAddresses(_) => "utxos_by_addesses",
             ReadRequest::CheckBestChainTipNullifiersAndAnchors(_) => {
                 "best_chain_tip_nullifiers_anchors"

zebra-state/src/response.rs

@@ -175,6 +175,11 @@ pub enum ReadResponse {
     /// or `None` if the block was not found.
     TransactionIdsForBlock(Option<Arc<[transaction::Hash]>>),
 
+    /// Response to [`ReadRequest::TransactionIdForSpentOutPoint`],
+    /// with an list of transaction hashes in block order,
+    /// or `None` if the block was not found.
+    TransactionId(Option<transaction::Hash>),
+
     /// Response to [`ReadRequest::BlockLocator`] with a block locator object.
     BlockLocator(Vec<block::Hash>),
 
@@ -339,6 +344,7 @@ impl TryFrom<ReadResponse> for Response {
             | ReadResponse::OrchardSubtrees(_)
             | ReadResponse::AddressBalance(_)
             | ReadResponse::AddressesTransactionIds(_)
+            | ReadResponse::TransactionId(_)
             | ReadResponse::AddressUtxos(_) => {
                 Err("there is no corresponding Response for this ReadResponse")
             }

zebra-state/src/service.rs

@@ -1383,6 +1383,34 @@ impl Service<ReadRequest> for ReadStateService {
                 .wait_for_panics()
             }
 
+            ReadRequest::TransactionIdForSpentOutPoint(outpoint) => {
+                let state = self.clone();
+
+                tokio::task::spawn_blocking(move || {
+                    span.in_scope(move || {
+                        let spending_transaction_id = state
+                            .non_finalized_state_receiver
+                            .with_watch_data(|non_finalized_state| {
+                                read::spending_transaction_hash(
+                                    non_finalized_state.best_chain(),
+                                    &state.db,
+                                    outpoint,
+                                )
+                            });
+
+                        // The work is done in the future.
+                        timer.finish(
+                            module_path!(),
+                            line!(),
+                            "ReadRequest::TransactionIdForSpentOutPoint",
+                        );
+
+                        Ok(ReadResponse::TransactionId(spending_transaction_id))
+                    })
+                })
+                .wait_for_panics()
+            }
+
             ReadRequest::UnspentBestChainUtxo(outpoint) => {
                 let state = self.clone();