RSDK-6157 - add initial connection options (#347)

add initial connection options

Author: stuqdog

lib/src/robot/client.dart

@@ -126,7 +126,7 @@ class RobotClient {
     final client = RobotClient._();
     client._address = url;
     client._options = options;
-    client._channel = await dial(url, options.dialOptions, () => client._sessionsClient.metadata());
+    client._channel = await dialInitial(url, options.dialOptions, () => client._sessionsClient.metadata());
     client._sessionsClient = SessionsClient(client._channel, options.enableSessions, url);
     client._sessionsClient.start();
     client._client = rpb.RobotServiceClient(client._channel);

lib/src/rpc/dial.dart

@@ -61,6 +61,13 @@ class DialOptions {
   /// Whether the connection was made using mDNS
   bool _usingMdns = false;
 
+  /// The number of connection attempts to make when first dialing. If set to zero or a negative
+  /// integer, will attempt to reconnect forever.
+  int initialConnectionAttempts = 3;
+
+  // The timeout to use for initial connection attempts.
+  Duration initialConnectionAttemptTimeout = const Duration(seconds: 10);
+
   /// Timeout is the timeout for dial.
   Duration timeout = const Duration(seconds: 10);
 
@@ -123,6 +130,35 @@ class DialWebRtcOptions {
   String? signalingAccessToken;
 }
 
+/// {@category Viam SDK}
+/// Initial connection to a robot at the provided address with the given options, allowing for specifying of initial connection attempt count and timeout
+Future<ClientChannelBase> dialInitial(String address, DialOptions? options, String Function() sessionCallback) async {
+  final opts = options ?? DialOptions();
+
+  int numAttempts = opts.initialConnectionAttempts;
+  if (numAttempts == 0) {
+    numAttempts = -1;
+  }
+
+  final timeout = opts.timeout;
+  opts.timeout = opts.initialConnectionAttemptTimeout;
+
+  while (numAttempts != 0) {
+    try {
+      final channel = await dial(address, opts, sessionCallback);
+      opts.timeout = timeout;
+      return channel;
+    } catch (e) {
+      numAttempts -= 1;
+      if (numAttempts == 0) {
+        rethrow;
+      }
+    }
+  }
+
+  throw Exception('unreachable');
+}
+
 /// {@category Viam SDK}
 /// Connect to a robot at the provided address with the given options
 Future<ClientChannelBase> dial(String address, DialOptions? options, String Function() sessionCallback) async {