Add disable-balances config flag to driver

crates/driver/src/infra/api/mod.rs

@@ -40,6 +40,7 @@ pub struct Api {
     pub mempools: Mempools,
     pub addr: SocketAddr,
     pub bad_token_detector: risk_detector::bad_tokens::Detector,
+    pub disable_settlement_balance_fetcher: bool,
     /// If this channel is specified, the bound address will be sent to it. This
     /// allows the driver to bind to 0.0.0.0:0 during testing.
     pub addr_sender: Option<oneshot::Sender<SocketAddr>>,
@@ -61,7 +62,11 @@ impl Api {
             self.eth.current_block().clone(),
         );
 
-        let tokens = tokens::Fetcher::new(&self.eth);
+        let tokens = if self.disable_settlement_balance_fetcher {
+            tokens::Fetcher::disabled()
+        } else {
+            tokens::Fetcher::new(&self.eth)
+        };
         let fetcher = Arc::new(domain::competition::DataAggregator::new(
             self.eth.clone(),
             app_data_retriever.clone(),

crates/driver/src/infra/config/file/load.rs

@@ -391,5 +391,6 @@ pub async fn load(chain: Chain, path: &Path) -> infra::Config {
         simulation_bad_token_max_age: config.simulation_bad_token_max_age,
         app_data_fetching: config.app_data_fetching,
         tx_gas_limit: config.tx_gas_limit,
+        disable_settlement_balance_fetcher: config.disable_settlement_balance_fetcher,
     }
 }

crates/driver/src/infra/config/file/mod.rs

@@ -88,6 +88,12 @@ struct Config {
     #[serde(default)]
     flashloans_enabled: bool,
 
+    /// Skip settlement contract token balance fetching (background and
+    /// on-demand). Balances default to 0. Useful for local testing to
+    /// avoid RPC calls.
+    #[serde(default)]
+    disable_settlement_balance_fetcher: bool,
+
     #[serde_as(as = "HexOrDecimalU256")]
     tx_gas_limit: eth::U256,
 }

crates/driver/src/infra/config/mod.rs

@@ -32,4 +32,5 @@ pub struct Config {
     pub simulation_bad_token_max_age: Duration,
     pub app_data_fetching: AppDataFetching,
     pub tx_gas_limit: eth::U256,
+    pub disable_settlement_balance_fetcher: bool,
 }

crates/driver/src/infra/tokens.rs

@@ -25,22 +25,31 @@ pub struct Metadata {
 }
 
 #[derive(Clone)]
-pub struct Fetcher(Arc<Inner>);
+pub enum Fetcher {
+    /// Fetches token metadata and settlement contract balances from the node.
+    Rpc(Arc<Inner>),
+    /// Returns zero balances without making any RPC calls.
+    Disabled,
+}
 
 impl Fetcher {
     pub fn new(eth: &Ethereum) -> Self {
         let eth = eth.with_metric_label("tokenInfos".into());
-        let block_stream = eth.current_block().clone();
         let inner = Arc::new(Inner {
             eth,
             cache: RwLock::new(HashMap::new()),
             requests: BoxRequestSharing::labelled("token_info".into()),
         });
+        let block_stream = inner.eth.current_block().clone();
         tokio::task::spawn(
             update_task(block_stream, Arc::downgrade(&inner))
                 .instrument(tracing::info_span!("token_fetcher")),
         );
-        Self(inner)
+        Self::Rpc(inner)
+    }
+
+    pub fn disabled() -> Self {
+        Self::Disabled
     }
 
     /// Returns the `Metadata` for the given tokens. Note that the result will
@@ -50,7 +59,23 @@ impl Fetcher {
         &self,
         addresses: &[eth::TokenAddress],
     ) -> HashMap<eth::TokenAddress, Metadata> {
-        self.0.get(addresses).await
+        match self {
+            Self::Rpc(inner) => inner.get(addresses).await,
+            Self::Disabled => addresses
+                .iter()
+                .filter(|address| address.0.0 != BUY_ETH_ADDRESS)
+                .map(|address| {
+                    (
+                        *address,
+                        Metadata {
+                            decimals: None,
+                            symbol: None,
+                            balance: 0.into(),
+                        },
+                    )
+                })
+                .collect(),
+        }
     }
 }
 
@@ -120,7 +145,7 @@ async fn update_balances(inner: Arc<Inner>) -> Result<(), blockchain::Error> {
 }
 
 /// Provides metadata of tokens.
-struct Inner {
+pub struct Inner {
     eth: Ethereum,
     cache: RwLock<HashMap<eth::TokenAddress, Metadata>>,
     requests: BoxRequestSharing<eth::TokenAddress, Option<(eth::TokenAddress, Metadata)>>,

crates/driver/src/run.rs

@@ -97,6 +97,7 @@ async fn run_with(args: cli::Args, addr_sender: Option<oneshot::Sender<SocketAdd
             config.simulation_bad_token_max_age,
             &eth,
         ),
+        disable_settlement_balance_fetcher: config.disable_settlement_balance_fetcher,
         eth,
         addr: args.addr,
         addr_sender,