From 538157ec5d69d41ca3426ff45278032498c3a41e Mon Sep 17 00:00:00 2001
From: Naveed Jooma <naveed@viam.com>
Date: Wed, 30 Oct 2024 13:39:57 -0400
Subject: [PATCH] Improved error handling in sessions (#284)

---
 lib/src/robot/client.dart          |  1 +
 lib/src/robot/sessions_client.dart | 22 +++++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/lib/src/robot/client.dart b/lib/src/robot/client.dart
index 63d0dcdc506..27a08b849c1 100644
--- a/lib/src/robot/client.dart
+++ b/lib/src/robot/client.dart
@@ -111,6 +111,7 @@ class RobotClient {
     client._options = options;
     client._channel = await dial(url, options.dialOptions, () => client._sessionsClient.metadata());
     client._sessionsClient = SessionsClient(client._channel, options.enableSessions);
+    client._sessionsClient.start();
     client._client = rpb.RobotServiceClient(client._channel);
     client._streamManager = StreamManager(client._channel as WebRtcClientChannel);
     await client.refresh();
diff --git a/lib/src/robot/sessions_client.dart b/lib/src/robot/sessions_client.dart
index 1817183c5d8..e6956cdaacf 100644
--- a/lib/src/robot/sessions_client.dart
+++ b/lib/src/robot/sessions_client.dart
@@ -4,6 +4,7 @@ import 'package:grpc/grpc_connection_interface.dart';
 import 'package:logger/logger.dart';
 import 'package:viam_sdk/protos/robot/robot.dart';
 
+import '../gen/google/rpc/code.pbenum.dart';
 import '../resource/base.dart';
 
 final _logger = Logger();
@@ -32,7 +33,7 @@ class SessionsClient implements ResourceRPCClient {
 
   String _currentId = '';
   final bool _enabled;
-  bool _supported = false;
+  bool? _supported;
   late Duration _heartbeatInterval;
 
   SessionsClient(this.channel, this._enabled) {
@@ -42,6 +43,7 @@ class SessionsClient implements ResourceRPCClient {
   /// Retrieve metadata associated with the session (e.g. whether sessions are supported, the current ID of the session)
   String metadata() {
     if (!_enabled) return '';
+    if (_supported == false) return '';
 
     if (_currentId != '') return _currentId;
 
@@ -60,9 +62,14 @@ class SessionsClient implements ResourceRPCClient {
           microseconds: response.heartbeatWindow.nanos ~/ 1.8,
         );
 
-        _heartbeatTask();
-
         return _currentId;
+      }, onError: (error, _) {
+        if (error is GrpcError && error.code == Code.UNIMPLEMENTED.value) {
+          _supported = false;
+        } else {
+          _logger.e('Error starting session: $error');
+        }
+        return '';
       });
     } catch (e) {
       _logger.e('Error starting session: $e');
@@ -76,15 +83,16 @@ class SessionsClient implements ResourceRPCClient {
   void reset() {
     _logger.d('Resetting current session with ID: $_currentId');
     _currentId = '';
-    _supported = false;
+    _supported = null;
     metadata();
+    _heartbeatTask();
   }
 
   /// Stop the session client and heartbeat tasks
   void stop() {
     _logger.d('Stopping SessionClient');
     _currentId = '';
-    _supported = false;
+    _supported = null;
   }
 
   /// Start the session client
@@ -93,14 +101,14 @@ class SessionsClient implements ResourceRPCClient {
   }
 
   Future<void> _heartbeatTask() async {
-    while (_supported) {
+    while (_supported == true) {
       await _heartbeatTick();
       await Future.delayed(_heartbeatInterval);
     }
   }
 
   Future<void> _heartbeatTick() async {
-    if (!_supported) return;
+    if (_supported == false) return;
 
     final request = SendSessionHeartbeatRequest()..id = _currentId;