Added ability to set connectTimeout of socket (#575)

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## 3.1.1-dev
 
+* `ChannelOptions` now exposes `connectTimeout`, which is used on the 
+  socket connect. This is used to specify the maximum allowed time to wait
+  for a connection to be established. If `connectTime` is longer than the system
+  level timeout duration, a timeout may occur sooner than specified in
+  `connectTimeout`. On timeout, a `SocketException` is thrown.
 * Require Dart 2.17 or greater.
 * Fix issue [#51](https://github.com/grpc/grpc-dart/issues/51), add support for custom error handling.
 

lib/src/client/http2_connection.dart

@@ -334,7 +334,8 @@ class _SocketTransportConnector implements ClientTransportConnector {
   @override
   Future<ClientTransportConnection> connect() async {
     final securityContext = _options.credentials.securityContext;
-    _socket = await Socket.connect(_host, _port);
+    _socket =
+        await Socket.connect(_host, _port, timeout: _options.connectTimeout);
     // Don't wait for io buffers to fill up before sending requests.
     if (_socket.address.type != InternetAddressType.unix) {
       _socket.setOption(SocketOption.tcpNoDelay, true);

lib/src/client/options.dart

@@ -50,6 +50,11 @@ class ChannelOptions {
 
   /// The maximum time a single connection will be used for new requests.
   final Duration connectionTimeout;
+
+  /// The maximum allowed time to wait for a connection to be established.
+  /// If [connectTimeout] is longer than the system level timeout duration,
+  /// a timeout may occur sooner than specified in [connectTimeout].
+  final Duration? connectTimeout;
   final BackoffStrategy backoffStrategy;
   final String userAgent;
 
@@ -58,6 +63,7 @@ class ChannelOptions {
     this.idleTimeout = defaultIdleTimeout,
     this.userAgent = defaultUserAgent,
     this.backoffStrategy = defaultBackoffStrategy,
+    this.connectTimeout,
     this.connectionTimeout = defaultConnectionTimeOut,
     this.codecRegistry,
   });

test/src/client_utils.dart

@@ -69,6 +69,8 @@ class FakeChannelOptions implements ChannelOptions {
   @override
   Duration connectionTimeout = const Duration(seconds: 10);
   @override
+  Duration? connectTimeout;
+  @override
   String userAgent = 'dart-grpc/1.0.0 test';
   @override
   BackoffStrategy backoffStrategy = testBackoff;