fix(dash-spv)!: leave the masternode engine untouched by a refused or interrupted QRInfo

dash-spv/src/sml_engine/helpers.rs

@@ -74,7 +74,7 @@ impl<H: BlockHeaderStorage> MasternodeListEngine<H> {
 
         let mut below_floor = BTreeSet::new();
         for cycle_hash in self.rotated_quorums_per_cycle.keys() {
-            if self.height_of(cycle_hash).await.is_some_and(|height| height < floor) {
+            if self.height_if_known(cycle_hash).await.is_some_and(|height| height < floor) {
                 below_floor.insert(*cycle_hash);
             }
         }
@@ -85,7 +85,8 @@ impl<H: BlockHeaderStorage> MasternodeListEngine<H> {
     /// chain has dropped them for another branch: the lists above it, and the
     /// rotated cycles whose base block left the chain or whose mining window
     /// ends above it, since their commitments may have been mined on the
-    /// dropped branch.
+    /// dropped branch. A cycle whose base block cannot be read goes too:
+    /// nothing shows it was mined below `height`.
     pub(crate) async fn truncate_above(&mut self, height: CoreBlockHeight) {
         if let Some(above) = height.checked_add(1) {
             self.masternode_lists.split_off(&above);
@@ -95,7 +96,7 @@ impl<H: BlockHeaderStorage> MasternodeListEngine<H> {
         let mut dropped = BTreeSet::new();
         for cycle_hash in self.rotated_quorums_per_cycle.keys() {
             let mined_below = self
-                .height_of(cycle_hash)
+                .height_if_known(cycle_hash)
                 .await
                 .is_some_and(|base| base.saturating_add(mining_window_end) <= height);
             if !mined_below {

dash-spv/src/sml_engine/rotated_quorum_construction.rs

@@ -39,7 +39,7 @@ impl<H: BlockHeaderStorage> MasternodeListEngine<H> {
                 quorum_hash,
                 index,
             };
-            let Some(height) = self.height_of(&quorum_hash).await else {
+            let Some(height) = self.height_if_known(&quorum_hash).await else {
                 members.push(Err(QuorumValidationError::RequiredBlockNotPresent(
                     quorum_hash,
                     "rotated quorum height".to_string(),

dash-spv/src/sml_engine/validation.rs

@@ -23,7 +23,7 @@ impl<H: BlockHeaderStorage> MasternodeListEngine<H> {
     ) -> Result<(), QuorumValidationError> {
         quorum.quorum_entry.validate_structure()?;
         let quorum_hash = quorum.quorum_entry.quorum_hash;
-        let height = self.height_of(&quorum_hash).await.ok_or_else(|| {
+        let height = self.height_if_known(&quorum_hash).await.ok_or_else(|| {
             QuorumValidationError::RequiredBlockNotPresent(quorum_hash, "quorum height".to_string())
         })?;
         let work_height = height.saturating_sub(QUORUM_MEMBER_LIST_OFFSET);

dash-spv/src/storage/masternode.rs

@@ -190,7 +190,7 @@ impl<H: BlockHeaderStorage> MessageLog<H> {
             };
             let mut newest_base = None;
             for base in message.base_hashes() {
-                newest_base = newest_base.max(engine.height_of(&base).await);
+                newest_base = newest_base.max(engine.height_if_known(&base).await);
             }
             plan.push((newest_base.unwrap_or(height), height, kind, path));
         }
@@ -201,8 +201,8 @@ impl<H: BlockHeaderStorage> MessageLog<H> {
         for (_, height, kind, path) in plan {
             if let Some(message) = self.read_entry(height, kind, path).await {
                 match message.apply(&mut engine).await {
-                    true => applied += 1,
-                    false => tracing::warn!("Masternode message at {height} does not apply"),
+                    Ok(()) => applied += 1,
+                    Err(e) => tracing::warn!("Masternode message at {height} does not apply: {e}"),
                 }
             }
             visit(&engine);
@@ -272,10 +272,16 @@ impl<H: BlockHeaderStorage> MessageLog<H> {
 }
 
 impl Message {
-    async fn apply<H: BlockHeaderStorage>(self, engine: &mut MasternodeListEngine<H>) -> bool {
+    /// Feeds the message to `engine`, failing with why it was not taken.
+    async fn apply<H: BlockHeaderStorage>(
+        self,
+        engine: &mut MasternodeListEngine<H>,
+    ) -> Result<(), String> {
         match self {
-            Message::QrInfo(qr_info) => engine.feed_qr_info(*qr_info).await.is_ok(),
-            Message::Diff(diff) => engine.apply_diff(*diff).await.is_ok(),
+            Message::QrInfo(qr_info) => {
+                engine.feed_qr_info(*qr_info).await.map(drop).map_err(|e| e.to_string())
+            }
+            Message::Diff(diff) => engine.apply_diff(*diff).await.map_err(|e| e.to_string()),
         }
     }
 

dash-spv/src/sync/masternodes/sync_manager.rs

@@ -119,8 +119,8 @@ impl<H: BlockHeaderStorage> SyncManager for MasternodesManager<H> {
                     }
                 };
 
-                let request_pairs = engine.missing_work_block_list_requests().await;
-                let tip_height = engine.height_of(&qr_info.mn_list_diff_tip.block_hash).await;
+                let request_pairs = engine.readable_missing_work_block_list_requests().await;
+                let tip_height = engine.height_if_known(&qr_info.mn_list_diff_tip.block_hash).await;
                 drop(engine);
 
                 if let Some(height) = tip_height {
@@ -191,7 +191,7 @@ impl<H: BlockHeaderStorage> SyncManager for MasternodesManager<H> {
                 tracing::debug!("Processing MnListDiff message for {}", diff.block_hash);
 
                 let mut engine = self.engine.write().await;
-                let Some(target_height) = engine.height_of(&diff.block_hash).await else {
+                let Some(target_height) = engine.height_if_known(&diff.block_hash).await else {
                     drop(engine);
                     tracing::warn!(
                         "Height not found for MnListDiff block {}, requeuing for retry",

dash-spv/src/test_utils/mod.rs

@@ -31,7 +31,7 @@ pub use wallet::{
 
 pub(crate) use node::DashCoreConfig;
 
-pub use crate::sml_engine::{MasternodeListEngine, WORK_DIFF_DEPTH};
+pub use crate::sml_engine::{FeedError, MasternodeListEngine, WORK_DIFF_DEPTH};
 
 /// Storage types for tests and benches that open the client's storage directly.
 pub use crate::storage::{

dash-spv/tests/dashd_masternode/tests_sync.rs

@@ -312,7 +312,8 @@ async fn test_masternode_list_sync_with_quorum_rotation() {
             let engine = client_handle.engine.read().await;
             let mut max_cycle = 0;
             for cycle_hash in engine.rotated_quorums_per_cycle().keys() {
-                max_cycle = max_cycle.max(engine.height_of(cycle_hash).await.unwrap_or(0));
+                let height = engine.height_of(cycle_hash).await.expect("the headers read");
+                max_cycle = max_cycle.max(height.unwrap_or(0));
             }
             max_cycle
         };
@@ -443,7 +444,7 @@ async fn test_rotated_quorums_stored_when_sync_starts_post_dkg() {
         assert_all_rotated_quorums_verified(&engine);
         let mut heights: Vec<u32> = Vec::new();
         for cycle_hash in engine.rotated_quorums_per_cycle().keys() {
-            heights.extend(engine.height_of(cycle_hash).await);
+            heights.extend(engine.height_of(cycle_hash).await.expect("the headers read"));
         }
         heights.sort_unstable();
         heights.dedup();