Add support for per-address attributes (#1472)

Author: JamesNK

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "6.0.100-rc.1.21458.32",
+    "version": "6.0.100",
     "rollForward": "latestFeature"
   }
 }

src/Grpc.Net.Client/Balancer/BalancerAddress.cs

@@ -0,0 +1,71 @@
+#region Copyright notice and license
+
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+#if SUPPORT_LOAD_BALANCING
+using System.Net;
+
+namespace Grpc.Net.Client.Balancer
+{
+    /// <summary>
+    /// Represents a balancer address.
+    /// <para>
+    /// Note: Experimental API that can change or be removed without any prior notice.
+    /// </para>
+    /// </summary>
+    public sealed class BalancerAddress
+    {
+        private BalancerAttributes? _attributes;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BalancerAddress"/> class with the specified <see cref="DnsEndPoint"/>.
+        /// </summary>
+        /// <param name="endPoint">The end point.</param>
+        public BalancerAddress(DnsEndPoint endPoint)
+        {
+            EndPoint = endPoint;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BalancerAddress"/> class with the specified host and port.
+        /// </summary>
+        /// <param name="host">The host.</param>
+        /// <param name="port">The port.</param>
+        public BalancerAddress(string host, int port) : this(new DnsEndPoint(host, port))
+        {
+        }
+
+        /// <summary>
+        /// Gets the address <see cref="DnsEndPoint"/>.
+        /// </summary>
+        public DnsEndPoint EndPoint { get; }
+
+        /// <summary>
+        /// Gets the address attributes.
+        /// </summary>
+        public BalancerAttributes Attributes => _attributes ??= new BalancerAttributes();
+
+        /// <summary>
+        /// Returns a string that reprsents the address.
+        /// </summary>
+        public override string ToString()
+        {
+            return $"{EndPoint.Host}:{EndPoint.Port}";
+        }
+    }
+}
+#endif

src/Grpc.Net.Client/Balancer/ChannelState.cs

@@ -34,7 +34,7 @@ namespace Grpc.Net.Client.Balancer
     public sealed class ChannelState
     {
         [DebuggerStepThrough]
-        internal ChannelState(Status status, IReadOnlyList<DnsEndPoint>? addresses, LoadBalancingConfig? loadBalancingConfig, BalancerAttributes attributes)
+        internal ChannelState(Status status, IReadOnlyList<BalancerAddress>? addresses, LoadBalancingConfig? loadBalancingConfig, BalancerAttributes attributes)
         {
             Addresses = addresses;
             LoadBalancingConfig = loadBalancingConfig;
@@ -45,7 +45,7 @@ internal ChannelState(Status status, IReadOnlyList<DnsEndPoint>? addresses, Load
         /// <summary>
         /// Gets a collection of addresses. Will be <c>null</c> if <see cref="Status"/> has a non-OK value.
         /// </summary>
-        public IReadOnlyList<DnsEndPoint>? Addresses { get; }
+        public IReadOnlyList<BalancerAddress>? Addresses { get; }
 
         /// <summary>
         /// Gets an optional load balancing config.

src/Grpc.Net.Client/Balancer/CompletionContext.cs

@@ -32,9 +32,9 @@ namespace Grpc.Net.Client.Balancer
     public sealed class CompletionContext
     {
         /// <summary>
-        /// Gets or sets the <see cref="DnsEndPoint"/> a call was made with. Required.
+        /// Gets or sets the <see cref="BalancerAddress"/> a call was made with. Required.
         /// </summary>
-        public DnsEndPoint? Address { get; set; }
+        public BalancerAddress? Address { get; set; }
 
         /// <summary>
         /// Gets or sets the <see cref="Exception"/> thrown when making the call.

src/Grpc.Net.Client/Balancer/DnsResolver.cs

@@ -146,7 +146,7 @@ private async Task RefreshCoreAsync(CancellationToken cancellationToken)
                 DnsResolverLog.ReceivedDnsResults(_logger, addresses.Length, _address, addresses);
 
                 var resolvedPort = _address.Port == -1 ? 80 : _address.Port;
-                var endpoints = addresses.Select(a => new DnsEndPoint(a.ToString(), resolvedPort)).ToArray();
+                var endpoints = addresses.Select(a => new BalancerAddress(a.ToString(), resolvedPort)).ToArray();
                 var resolverResult = ResolverResult.ForResult(endpoints, serviceConfig: null);
                 _listener(resolverResult);
             }

src/Grpc.Net.Client/Balancer/Internal/BalancerAddressEqualityComparer.cs

@@ -0,0 +1,56 @@
+#region Copyright notice and license
+
+// Copyright 2019 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+#if SUPPORT_LOAD_BALANCING
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Grpc.Net.Client.Balancer.Internal
+{
+    internal class BalancerAddressEqualityComparer : IEqualityComparer<BalancerAddress>
+    {
+        internal static readonly BalancerAddressEqualityComparer Instance = new BalancerAddressEqualityComparer();
+
+        public bool Equals(BalancerAddress? x, BalancerAddress? y)
+        {
+            if (ReferenceEquals(x, y))
+            {
+                return true;
+            }
+
+            if (x == null || y == null)
+            {
+                return false;
+            }
+
+            if (!x.EndPoint.Equals(y.EndPoint))
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        public int GetHashCode([DisallowNull] BalancerAddress obj)
+        {
+            throw new NotSupportedException();
+        }
+    }
+}
+#endif

src/Grpc.Net.Client/Balancer/Internal/BalancerHttpHandler.cs

@@ -77,15 +77,16 @@ protected override async Task<HttpResponseMessage> SendAsync(
             var pickContext = new PickContext { Request = request };
             var result = await _manager.PickAsync(pickContext, waitForReady, cancellationToken).ConfigureAwait(false);
             var address = result.Address!;
+            var addressEndpoint = address.EndPoint;
 
             // Update request host if required.
             if (!request.RequestUri.IsAbsoluteUri ||
-                request.RequestUri.Host != address.Host ||
-                request.RequestUri.Port != address.Port)
+                request.RequestUri.Host != addressEndpoint.Host ||
+                request.RequestUri.Port != addressEndpoint.Port)
             {
                 var uriBuilder = new UriBuilder(request.RequestUri);
-                uriBuilder.Host = address.Host;
-                uriBuilder.Port = address.Port;
+                uriBuilder.Host = addressEndpoint.Host;
+                uriBuilder.Port = addressEndpoint.Port;
                 request.RequestUri = uriBuilder.Uri;
             }
 

src/Grpc.Net.Client/Balancer/Internal/ConnectionManager.cs

@@ -290,7 +290,7 @@ public void UpdateState(BalancerState state)
 
         public async
 #if !NETSTANDARD2_0
-            ValueTask<(Subchannel Subchannel, DnsEndPoint Address, Action<CompletionContext> OnComplete)>
+            ValueTask<(Subchannel Subchannel, BalancerAddress Address, Action<CompletionContext> OnComplete)>
 #else
             Task<(Subchannel Subchannel, DnsEndPoint Address, Action<CompleteContext> OnComplete)>
 #endif
@@ -316,7 +316,7 @@ public async
 
                         if (address != null)
                         {
-                            ConnectionManagerLog.PickResultSuccessful(Logger, subchannel.Id, address);
+                            ConnectionManagerLog.PickResultSuccessful(Logger, subchannel.Id, address.EndPoint);
                             return (subchannel, address, result.Complete);
                         }
                         else

src/Grpc.Net.Client/Balancer/Internal/ISubchannelTransport.cs

@@ -33,7 +33,7 @@ namespace Grpc.Net.Client.Balancer.Internal
     internal interface ISubchannelTransport : IDisposable
     {
         void OnRequestComplete(CompletionContext context);
-        DnsEndPoint? CurrentEndPoint { get; }
+        BalancerAddress? CurrentAddress { get; }
 
 #if NET5_0_OR_GREATER
         ValueTask<Stream> GetStreamAsync(DnsEndPoint endPoint, CancellationToken cancellationToken);

src/Grpc.Net.Client/Balancer/Internal/PassiveSubchannelTransport.cs

@@ -35,22 +35,22 @@ namespace Grpc.Net.Client.Balancer.Internal
     internal class PassiveSubchannelTransport : ISubchannelTransport, IDisposable
     {
         private readonly Subchannel _subchannel;
-        private DnsEndPoint? _currentEndPoint;
+        private BalancerAddress? _currentAddress;
 
         public PassiveSubchannelTransport(Subchannel subchannel)
         {
             _subchannel = subchannel;
         }
 
-        public DnsEndPoint? CurrentEndPoint => _currentEndPoint;
+        public BalancerAddress? CurrentAddress => _currentAddress;
 
         public void OnRequestComplete(CompletionContext context)
         {
         }
 
         public void Disconnect()
         {
-            _currentEndPoint = null;
+            _currentAddress = null;
             _subchannel.UpdateConnectivityState(ConnectivityState.Idle, "Disconnected.");
         }
 
@@ -63,12 +63,12 @@ public void Disconnect()
             TryConnectAsync(CancellationToken cancellationToken)
         {
             Debug.Assert(_subchannel._addresses.Count == 1);
-            Debug.Assert(CurrentEndPoint == null);
+            Debug.Assert(CurrentAddress == null);
 
-            var currentEndPoint = _subchannel._addresses[0];
+            var currentAddress = _subchannel._addresses[0];
 
             _subchannel.UpdateConnectivityState(ConnectivityState.Connecting, "Passively connecting.");
-            _currentEndPoint = currentEndPoint;
+            _currentAddress = currentAddress;
             _subchannel.UpdateConnectivityState(ConnectivityState.Ready, "Passively connected.");
 
 #if !NETSTANDARD2_0
@@ -80,7 +80,7 @@ public void Disconnect()
 
         public void Dispose()
         {
-            _currentEndPoint = null;
+            _currentAddress = null;
         }
 
 #if NET5_0_OR_GREATER