fix(mempool): minor mempool improvements

core/lib/mempool/src/mempool_store.rs

@@ -1,4 +1,4 @@
-use std::collections::{hash_map, BTreeSet, HashMap, HashSet};
+use std::collections::{hash_map, BTreeSet, HashMap};
 
 use zksync_types::{
     l1::L1Tx, l2::L2Tx, Address, ExecuteTransactionCommon, Nonce, PriorityOpId, Transaction,
@@ -221,22 +221,57 @@ impl MempoolStore {
     }
 
     fn gc(&mut self) -> Vec<Address> {
-        if self.size >= self.capacity {
-            let index: HashSet<_> = self
+        if self.size > self.capacity {
+            let mut transactions = std::mem::take(&mut self.l2_transactions_per_account);
+            let mut possibly_kept: Vec<_> = self
                 .l2_priority_queue
                 .iter()
-                .map(|pointer| pointer.account)
+                .rev()
+                .filter_map(|pointer| {
+                    transactions
+                        .remove(&pointer.account)
+                        .map(|txs| (pointer.account, txs))
+                })
                 .collect();
-            let transactions = std::mem::take(&mut self.l2_transactions_per_account);
-            let (kept, drained) = transactions
+
+            let mut sum = 0;
+            let mut number_of_accounts_kept = 0;
+            for (_, txs) in &possibly_kept {
+                sum += txs.len();
+                if sum <= self.capacity as usize {
+                    number_of_accounts_kept += 1;
+                } else {
+                    break;
+                }
+            }
+            if number_of_accounts_kept == 0 && !possibly_kept.is_empty() {
+                tracing::warn!("mempool capacity is too low to handle txs from single account, consider increasing capacity");
+                // Keep at least one entry, otherwise mempool won't return any new L2 tx to process.
+                number_of_accounts_kept = 1;
+            }
+            let (kept, drained) = {
+                let mut drained: Vec<_> = transactions.into_keys().collect();
+                let also_drained = possibly_kept
+                    .split_off(number_of_accounts_kept)
+                    .into_iter()
+                    .map(|(address, _)| address);
+                drained.extend(also_drained);
+
+                (possibly_kept, drained)
+            };
+
+            let l2_priority_queue = std::mem::take(&mut self.l2_priority_queue);
+            self.l2_priority_queue = l2_priority_queue
                 .into_iter()
-                .partition(|(address, _)| index.contains(address));
-            self.l2_transactions_per_account = kept;
+                .rev()
+                .take(number_of_accounts_kept)
+                .collect();
+            self.l2_transactions_per_account = kept.into_iter().collect();
             self.size = self
                 .l2_transactions_per_account
                 .iter()
-                .fold(0, |agg, (_, tnxs)| agg + tnxs.len() as u64);
-            return drained.into_keys().collect();
+                .fold(0, |agg, (_, txs)| agg + txs.len() as u64);
+            return drained;
         }
         vec![]
     }

core/lib/mempool/src/tests.rs

@@ -321,32 +321,26 @@ fn stashed_accounts() {
 
 #[test]
 fn mempool_capacity() {
-    let mut mempool = MempoolStore::new(PriorityOpId(0), 5);
+    let mut mempool = MempoolStore::new(PriorityOpId(0), 4);
     let account0 = Address::random();
     let account1 = Address::random();
     let account2 = Address::random();
+    let account3 = Address::random();
     let transactions = vec![
         gen_l2_tx(account0, Nonce(0)),
         gen_l2_tx(account0, Nonce(1)),
         gen_l2_tx(account0, Nonce(2)),
-        gen_l2_tx(account1, Nonce(1)),
-        gen_l2_tx(account2, Nonce(1)),
+        gen_l2_tx_with_timestamp(account1, Nonce(0), unix_timestamp_ms() + 1),
+        gen_l2_tx_with_timestamp(account2, Nonce(0), unix_timestamp_ms() + 2),
+        gen_l2_tx(account3, Nonce(1)),
     ];
     mempool.insert(transactions, HashMap::new());
-    // the mempool is full. Accounts with non-sequential nonces got stashed
+    // Mempool is full. Accounts with non-sequential nonces and some accounts with lowest score should be purged.
     assert_eq!(
         HashSet::<_>::from_iter(mempool.get_mempool_info().purged_accounts),
-        HashSet::<_>::from_iter(vec![account1, account2]),
-    );
-    // verify that existing good-to-go transactions and new ones got picked
-    mempool.insert(
-        vec![gen_l2_tx_with_timestamp(
-            account1,
-            Nonce(0),
-            unix_timestamp_ms() + 1,
-        )],
-        HashMap::new(),
+        HashSet::from([account2, account3]),
     );
+    // verify that good-to-go transactions are kept.
     for _ in 0..3 {
         assert_eq!(
             mempool
@@ -363,6 +357,34 @@ fn mempool_capacity() {
             .initiator_account(),
         account1
     );
+    assert!(!mempool.has_next(&L2TxFilter::default()));
+}
+
+#[test]
+fn mempool_does_not_purge_all_accounts() {
+    let mut mempool = MempoolStore::new(PriorityOpId(0), 1);
+    let account0 = Address::random();
+    let account1 = Address::random();
+    let transactions = vec![
+        gen_l2_tx(account0, Nonce(0)),
+        gen_l2_tx(account0, Nonce(1)),
+        gen_l2_tx(account1, Nonce(1)),
+    ];
+    mempool.insert(transactions, HashMap::new());
+    // Mempool is full. Account 1 has tx with non-sequential nonce so it should be purged.
+    // Txs from account 0 have sequential nonces but their number is greater than capacity; they should be kept.
+    assert_eq!(mempool.get_mempool_info().purged_accounts, vec![account1]);
+    // verify that good-to-go transactions are kept.
+    for _ in 0..2 {
+        assert_eq!(
+            mempool
+                .next_transaction(&L2TxFilter::default())
+                .unwrap()
+                .initiator_account(),
+            account0
+        );
+    }
+    assert!(!mempool.has_next(&L2TxFilter::default()));
 }
 
 fn gen_l2_tx(address: Address, nonce: Nonce) -> Transaction {

core/node/state_keeper/src/mempool_actor.rs

@@ -89,20 +89,35 @@ impl MempoolFetcher {
                 .await
                 .context("failed getting pending protocol version")?;
 
-            let l2_tx_filter = l2_tx_filter(
-                self.batch_fee_input_provider.as_ref(),
-                protocol_version.into(),
-            )
-            .await
-            .context("failed creating L2 transaction filter")?;
+            let (fee_per_gas, gas_per_pubdata) = if let Some(unsealed_batch) = storage
+                .blocks_dal()
+                .get_unsealed_l1_batch()
+                .await
+                .context("failed getting unsealed batch")?
+            {
+                let (fee_per_gas, gas_per_pubdata) = derive_base_fee_and_gas_per_pubdata(
+                    unsealed_batch.fee_input,
+                    protocol_version.into(),
+                );
+                (fee_per_gas, gas_per_pubdata as u32)
+            } else {
+                let filter = l2_tx_filter(
+                    self.batch_fee_input_provider.as_ref(),
+                    protocol_version.into(),
+                )
+                .await
+                .context("failed creating L2 transaction filter")?;
+
+                (filter.fee_per_gas, filter.gas_per_pubdata)
+            };
 
             let transactions = storage
                 .transactions_dal()
                 .sync_mempool(
                     &mempool_info.stashed_accounts,
                     &mempool_info.purged_accounts,
-                    l2_tx_filter.gas_per_pubdata,
-                    l2_tx_filter.fee_per_gas,
+                    gas_per_pubdata,
+                    fee_per_gas,
                     self.sync_batch_size,
                 )
                 .await