Add a metric for blob transactions nonce gaps

crates/transaction-pool/src/metrics.rs

@@ -104,4 +104,6 @@ pub struct AllTransactionsMetrics {
     pub(crate) all_transactions_by_id: Gauge,
     /// Number of all transactions by all senders in the pool
     pub(crate) all_transactions_by_all_senders: Gauge,
+    /// Number of blob transactions nonce gaps.
+    pub(crate) blob_transactions_nonce_gaps: Counter,
 }

crates/transaction-pool/src/pool/txpool.rs

@@ -1335,11 +1335,13 @@ impl<T: PoolTransaction> AllTransactions<T> {
         if let Some(ancestor) = ancestor {
             let Some(ancestor_tx) = self.txs.get(&ancestor) else {
                 // ancestor tx is missing, so we can't insert the new blob
+                self.metrics.blob_transactions_nonce_gaps.increment(1);
                 return Err(InsertErr::BlobTxHasNonceGap { transaction: Arc::new(new_blob_tx) })
             };
             if ancestor_tx.state.has_nonce_gap() {
                 // the ancestor transaction already has a nonce gap, so we can't insert the new
                 // blob
+                self.metrics.blob_transactions_nonce_gaps.increment(1);
                 return Err(InsertErr::BlobTxHasNonceGap { transaction: Arc::new(new_blob_tx) })
             }
 

etc/grafana/dashboards/reth-mempool.json

@@ -1719,6 +1719,23 @@
           "range": true,
           "refId": "C",
           "useBackend": false
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "${DS_PROMETHEUS}"
+          },
+          "disableTextWrap": false,
+          "editorMode": "builder",
+          "expr": "reth_transaction_pool_blob_transactions_nonce_gaps{instance=~\"$instance\"}",
+          "fullMetaSearch": false,
+          "hide": false,
+          "includeNullMetadata": true,
+          "instant": false,
+          "legendFormat": "Blob transactions nonce gaps",
+          "range": true,
+          "refId": "D",
+          "useBackend": false
         }
       ],
       "title": "All Transactions metrics",