perf: batch UTXO set writes during IBD (issue #768)

consensus/src/consensus/mod.rs

@@ -25,7 +25,7 @@ use crate::{
             selected_chain::SelectedChainStore,
             statuses::StatusesStoreReader,
             tips::{TipsStore, TipsStoreReader},
-            utxo_set::{UtxoSetStore, UtxoSetStoreReader},
+            utxo_set::UtxoSetStoreReader,
             virtual_state::VirtualState,
             DB,
         },
@@ -1074,7 +1074,10 @@ impl ConsensusApi for Consensus {
 
     fn append_imported_pruning_point_utxos(&self, utxoset_chunk: &[(TransactionOutpoint, UtxoEntry)], current_multiset: &mut MuHash) {
         let mut pruning_meta_write = self.pruning_meta_stores.write();
-        pruning_meta_write.utxo_set.write_many(utxoset_chunk).unwrap();
+        let mut batch = WriteBatch::default();
+        pruning_meta_write.utxo_set.write_many_batch(&mut batch, utxoset_chunk).unwrap();
+        self.db.write(batch).unwrap();
+        drop(pruning_meta_write);
 
         // Parallelize processing using the context of an existing thread pool.
         let inner_multiset = self.virtual_processor.install(|| {

consensus/src/model/stores/utxo_set.rs

@@ -138,6 +138,15 @@ impl DbUtxoSetStore {
         self.access.write_many_without_cache(&mut writer, &mut utxos.into_iter().map(|(o, e)| (o.into(), e)))?;
         Ok(())
     }
+
+    /// Write many UTXOs using a WriteBatch (for better performance during IBD).
+    /// This method skips cache updates and writes directly to the batch.
+    /// NOTE: This action also clears the cache.
+    pub fn write_many_batch(&mut self, batch: &mut WriteBatch, utxos: &[(TransactionOutpoint, UtxoEntry)]) -> Result<(), StoreError> {
+        let mut writer = BatchDbWriter::new(batch);
+        self.access.write_many_without_cache(&mut writer, &mut utxos.iter().map(|(o, e)| ((*o).into(), Arc::new(e.clone()))))?;
+        Ok(())
+    }
 }
 
 impl UtxoView for DbUtxoSetStore {