Bugfix: Add circuit breaker

common/client-core/src/client/base_client/mod.rs

@@ -801,7 +801,7 @@ where
             event_tx,
         );
 
-        let mix_tx = mix_traffic_controller.mix_rx();
+        let mix_tx = mix_traffic_controller.mix_tx();
         let client_tx = mix_traffic_controller.client_tx();
 
         shutdown_tracker.try_spawn_named(
@@ -1004,8 +1004,8 @@ where
         // Create a shutdown tracker for this client - either as a child of provided tracker
         // or get one from the registry
         let shutdown_tracker = match self.shutdown {
-            Some(parent_tracker) => parent_tracker.child_tracker(),
-            None => nym_task::get_sdk_shutdown_tracker()?,
+            Some(parent_tracker) => parent_tracker.clone(),
+            None => nym_task::create_sdk_shutdown_tracker()?,
         };
 
         Self::start_event_control(self.event_tx, event_receiver, &shutdown_tracker);
@@ -1044,7 +1044,7 @@ where
             self.user_agent.clone(),
             generate_client_stats_id(*self_address.identity()),
             input_sender.clone(),
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         );
 
         // needs to be started as the first thing to block if required waiting for the gateway
@@ -1054,7 +1054,7 @@ where
             shared_topology_accessor.clone(),
             self_address.gateway(),
             self.wait_for_gateway,
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         )
         .await?;
 
@@ -1074,15 +1074,15 @@ where
             stats_reporter.clone(),
             #[cfg(unix)]
             self.connection_fd_callback,
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         )
         .await?;
         let gateway_ws_fd = gateway_transceiver.ws_fd();
 
         let reply_storage = Self::setup_persistent_reply_storage(
             reply_storage_backend,
             key_rotation_config,
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         )
         .await?;
 
@@ -1093,7 +1093,7 @@ where
             reply_storage.key_storage(),
             reply_controller_sender.clone(),
             stats_reporter.clone(),
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         );
 
         // The message_sender is the transmitter for any component generating sphinx packets
@@ -1103,7 +1103,7 @@ where
 
         let (message_sender, client_request_sender) = Self::start_mix_traffic_controller(
             gateway_transceiver,
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
             EventSender(event_sender),
         );
 
@@ -1134,7 +1134,7 @@ where
             shared_lane_queue_lengths.clone(),
             client_connection_rx,
             stats_reporter.clone(),
-            &shutdown_tracker.child_tracker(),
+            &shutdown_tracker.clone(),
         );
 
         if !self
@@ -1150,7 +1150,7 @@ where
                 shared_topology_accessor.clone(),
                 message_sender,
                 stats_reporter.clone(),
-                &shutdown_tracker.child_tracker(),
+                &shutdown_tracker.clone(),
             );
         }
 

common/client-core/src/client/cover_traffic_stream.rs

@@ -205,7 +205,7 @@ impl LoopCoverTrafficStream<OsRng> {
                 TrySendError::Full(_) => {
                     // This isn't a problem, if the channel is full means we're already sending the
                     // max amount of messages downstream can handle.
-                    tracing::debug!("Failed to send cover message - channel full");
+                    tracing::trace!("Failed to send cover message - channel full");
                 }
                 TrySendError::Closed(_) => {
                     tracing::warn!("Failed to send cover message - channel closed");

common/client-core/src/client/mix_traffic/mod.rs

@@ -20,7 +20,10 @@ pub mod transceiver;
 
 // We remind ourselves that 32 x 32kb = 1024kb, a reasonable size for a network buffer.
 pub const MIX_MESSAGE_RECEIVER_BUFFER_SIZE: usize = 32;
-const MAX_FAILURE_COUNT: usize = 100;
+
+/// Reduced from 100 to 20 to fail fast (~1-2 seconds instead of ~6 seconds).
+/// If we can't send 20 packets in a row, the gateway is unreachable.
+const MAX_FAILURE_COUNT: usize = 20;
 
 // that's also disgusting.
 pub struct Empty;
@@ -84,7 +87,7 @@ impl MixTrafficController {
         self.client_tx.clone()
     }
 
-    pub fn mix_rx(&self) -> BatchMixMessageSender {
+    pub fn mix_tx(&self) -> BatchMixMessageSender {
         self.mix_tx.clone()
     }
 
@@ -156,6 +159,11 @@ impl MixTrafficController {
                             // Do we need to handle the embedded mixnet client case
                             // separately?
                             self.event_tx.send(MixnetClientEvent::Traffic(MixTrafficEvent::FailedSendingSphinx));
+                            // IMO it shouldn't be signalled from there but it is how it is
+                            // TODO : report the failure upwards and shutdown from upwards
+                            // Gateway is dead, we have to shut down currently
+                            error!("Signalling shutdown from the MixTrafficController");
+                            self.shutdown_token.cancel();
                             break;
                         }
                     }

common/client-core/src/client/real_messages_control/real_traffic_stream.rs

@@ -298,6 +298,8 @@ where
                         "failed to send mixnet packet due to closed channel (outside of shutdown!)"
                     );
                 }
+                // Early return to avoid further processing when channel is closed
+                return;
             }
             Ok(_) => {
                 let event = if fragment_id.is_some() {

common/task/src/lib.rs

@@ -24,6 +24,6 @@ pub use crate::runtime_registry::RegistryAccessError;
 
 /// Get or create a ShutdownTracker for SDK use.
 /// This provides automatic task management without requiring manual setup.
-pub fn get_sdk_shutdown_tracker() -> Result<ShutdownTracker, RegistryAccessError> {
-    Ok(runtime_registry::RuntimeRegistry::get_or_create_sdk()?.shutdown_tracker_owned())
+pub fn create_sdk_shutdown_tracker() -> Result<ShutdownTracker, RegistryAccessError> {
+    Ok(runtime_registry::RuntimeRegistry::create_sdk()?.shutdown_tracker_owned())
 }

common/task/src/runtime_registry.rs

@@ -19,32 +19,47 @@ pub(crate) struct RuntimeRegistry {
 pub enum RegistryAccessError {
     #[error("the runtime registry is poisoned")]
     Poisoned,
+
+    #[error("The SDK ShutdownManager already exists")]
+    ExistingShutdownManager,
+
+    #[error("No existing SDK ShutdownManager")]
+    MissingShutdownManager,
 }
 
 impl RuntimeRegistry {
-    /// Get or create a ShutdownManager for SDK use.
+    /// Create a ShutdownManager for SDK use.
     /// This manager doesn't listen to OS signals, making it suitable for library use.
-    pub(crate) fn get_or_create_sdk() -> Result<Arc<ShutdownManager>, RegistryAccessError> {
-        let guard = REGISTRY
-            .sdk_manager
-            .read()
-            .map_err(|_| RegistryAccessError::Poisoned)?;
-        if let Some(manager) = guard.as_ref() {
-            return Ok(manager.clone());
-        }
-        drop(guard);
-
+    /// This function overwrite any existing manager!
+    pub(crate) fn create_sdk() -> Result<Arc<ShutdownManager>, RegistryAccessError> {
         let mut guard = REGISTRY
             .sdk_manager
             .write()
             .map_err(|_| RegistryAccessError::Poisoned)?;
+
         Ok(guard
-            .get_or_insert_with(|| {
-                Arc::new(ShutdownManager::new_without_signals().with_cancel_on_panic())
-            })
+            .insert(Arc::new(
+                ShutdownManager::new_without_signals().with_cancel_on_panic(),
+            ))
             .clone())
     }
 
+    /// Get the  ShutdownManager for SDK use.
+    /// This manager doesn't listen to OS signals, making it suitable for library use.
+    /// Not yet used, but maybe in the future
+    #[allow(dead_code)]
+    pub(crate) fn get_sdk() -> Result<Arc<ShutdownManager>, RegistryAccessError> {
+        let guard = REGISTRY
+            .sdk_manager
+            .read()
+            .map_err(|_| RegistryAccessError::Poisoned)?;
+        if let Some(manager) = guard.as_ref() {
+            Ok(manager.clone())
+        } else {
+            Err(RegistryAccessError::MissingShutdownManager)
+        }
+    }
+
     /// Check if an SDK manager has been created.
     /// Useful for testing and debugging.
     #[allow(dead_code)]
@@ -85,10 +100,13 @@ mod tests {
 
         assert!(!RuntimeRegistry::has_sdk_manager().unwrap());
 
-        let manager1 = RuntimeRegistry::get_or_create_sdk().unwrap();
+        // Error if nothing was created
+        assert!(RuntimeRegistry::get_sdk().is_err());
+
+        let manager1 = RuntimeRegistry::create_sdk().unwrap();
         assert!(RuntimeRegistry::has_sdk_manager().unwrap());
 
-        let manager2 = RuntimeRegistry::get_or_create_sdk().unwrap();
+        let manager2 = RuntimeRegistry::get_sdk().unwrap();
         // Should return the same instance
         assert!(Arc::ptr_eq(&manager1, &manager2));
 

sdk/rust/nym-sdk/src/mixnet/client.rs

@@ -736,15 +736,11 @@ where
             base_builder = base_builder.with_topology_provider(topology_provider);
         }
 
-        // Use custom shutdown if provided, otherwise get from registry
-        let shutdown_tracker = match self.custom_shutdown {
-            Some(custom) => custom,
-            None => {
-                // Auto-create from registry for SDK use
-                nym_task::get_sdk_shutdown_tracker()?
-            }
-        };
-        base_builder = base_builder.with_shutdown(shutdown_tracker);
+        // Use custom shutdown if provided, otherwise the sdk one will be used later down the line
+        if let Some(shutdown_tracker) = self.custom_shutdown {
+            base_builder = base_builder.with_shutdown(shutdown_tracker);
+        }
+
         if let Some(event_tx) = self.event_tx {
             base_builder = base_builder.with_event_tx(event_tx);
         }
@@ -809,7 +805,7 @@ where
             client_output,
             client_state.clone(),
             nym_address,
-            started_client.shutdown_handle.child_tracker(),
+            started_client.shutdown_handle.clone(),
             packet_type,
         );