fix: ensures mutable MMR bitmaps are compressed

base_layer/core/src/base_node/sync/horizon_state_sync/synchronizer.rs

@@ -606,7 +606,6 @@ impl<'a, B: BlockchainBackend + 'static> HorizonStateSynchronization<'a, B> {
                     // in the output MMR
                     let bitmap = self.full_bitmap_mut();
                     bitmap.or_inplace(&diff_bitmap);
-                    bitmap.run_optimize();
 
                     let pruned_output_set = output_mmr.get_pruned_hash_set()?;
                     let output_mmr = MutablePrunedOutputMmr::new(pruned_output_set.clone(), bitmap.clone())?;

base_layer/core/src/chain_storage/blockchain_database.rs

@@ -1360,8 +1360,6 @@ pub fn calculate_mmr_roots<T: BlockchainBackend>(
         }
     }
 
-    output_mmr.compress();
-
     let block_height = block.header.height;
     let epoch_len = rules.consensus_constants(block_height).epoch_length();
     let validator_node_mr = if block_height % epoch_len == 0 {

base_layer/mmr/src/functions.rs

@@ -95,7 +95,6 @@ where
     for index in deletions {
         pruned_mmr.delete(index);
     }
-    pruned_mmr.compress();
     pruned_mmr.get_merkle_root()
 }
 

base_layer/mmr/src/mutable_mmr.rs

@@ -125,9 +125,18 @@ where
         // virtue of the fact that the underlying MMRs could be different, but all elements are marked as deleted in
         // both sets.
         let mmr_root = self.mmr.get_merkle_root()?;
+
+        // To avoid requiring mutability, we compress a clone of the bitmap
+        let mut bitmap = self.deleted.clone();
+        bitmap.run_optimize();
+        let bitmap_ser = bitmap.serialize();
+
+        // Include the compressed bitmap in the root hash
         let mut hasher = D::new();
         hasher.update(&mmr_root);
-        Ok(self.hash_deleted(hasher).finalize().to_vec())
+        hasher.update(&bitmap_ser);
+
+        Ok(hasher.finalize().to_vec())
     }
 
     /// Returns only the MMR merkle root without the compressed serialisation of the bitmap
@@ -197,13 +206,6 @@ where
         self.mmr.validate()
     }
 
-    /// Hash the roaring bitmap of nodes that are marked for deletion
-    fn hash_deleted(&self, mut hasher: D) -> D {
-        let bitmap_ser = self.deleted.serialize();
-        hasher.update(&bitmap_ser);
-        hasher
-    }
-
     // Returns a bitmap with only the deleted nodes for the specified region in the MMR.
     fn get_sub_bitmap(&self, leaf_index: LeafIndex, count: usize) -> Result<Bitmap, MerkleMountainRangeError> {
         let mut deleted = self.deleted.clone();