feat: Add Spanner request ID header

Author: robertvoinescu-work

apis/Google.Cloud.Spanner.V1/Google.Cloud.Spanner.V1.Tests/RequestIdTests.cs

@@ -0,0 +1,215 @@
+// Copyright 2025 Google LLC
+//
+// 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
+//
+//     https://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.
+
+using Grpc.Core;
+using Google.Api.Gax.Grpc;
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Xunit;
+using System.Collections.Generic;
+
+namespace Google.Cloud.Spanner.V1.Tests;
+
+public class RequestIdTests
+{
+    private const string SampleDatabaseName = "projects/proj/instances/inst/databases/db";
+    private const string SampleSessionName = "projects/proj/instances/inst/databases/db/sessions/sess";
+
+    [Fact]
+    public void RequestId_Format()
+    {
+        var invoker = new RetryFakeCallInvoker();
+        var client = new SpannerClientBuilder { CallInvoker = invoker }.Build();
+
+        client.CreateSession(new CreateSessionRequest { Database = SampleDatabaseName });
+
+        // The expected format is 6 parts that break down as such:
+        // {VersionId}.{s_processId}.{ClientId}.{ChannelId}.{RequestSequence}.{AttemptNum}
+        Metadata headerMetadata = invoker.CapturedMetadata[0];
+        // We can't access RequestId.HeaderKey anymore, so use the string literal.
+        var idString = headerMetadata.Get("x-goog-spanner-request-id").Value;
+
+        var parts = idString.Split('.');
+
+        Assert.Equal(6, parts.Length);
+        var versionId = parts[0];
+        var processId = parts[1];
+        var clientId = parts[2];
+        var channelId = parts[3];
+        var requestSequence = parts[4];
+        var attemptNum = parts[5];
+
+        Assert.Equal("1", versionId);
+        Assert.True(ulong.TryParse(processId, out ulong processIdLong));
+        // We want to make sure the random generation ran. The default value for ulong is 0
+        // and with a very high probability this should not be 0 after generation.
+        Assert.NotEqual(0UL, processIdLong);
+        Assert.True(int.TryParse(clientId, out _));
+        Assert.Equal("1", channelId);
+        Assert.True(int.TryParse(requestSequence, out _));
+        Assert.Equal("1", attemptNum);
+    }
+
+    [Fact]
+    public void RequestIdSource_ProcessId_OverwritingBehavior() =>
+        // The process ID should only ever be set once per process.
+        Assert.Throws<InvalidOperationException>(() =>
+            {
+                // Note in the case of test re-runs within the same process the
+                // "first_override" may cause the exception to be thrown as it was
+                // set prior.
+                SpannerClientImpl.ProcessId = 1UL;
+                SpannerClientImpl.ProcessId = 2UL;
+            });
+
+    // Tests for header injection
+    public static TheoryData<Action<SpannerClient>> SpannerClientActions { get; } = new TheoryData<Action<SpannerClient>>
+    {
+        client => client.ExecuteSql(new ExecuteSqlRequest { Session = SampleSessionName, Sql = "SELECT 1" }),
+        client => client.GetSession(new GetSessionRequest { Name = SampleSessionName }),
+        client => client.ListSessions(new ListSessionsRequest { Database = SampleDatabaseName }).AsRawResponses().First(),
+        client => client.DeleteSession(new DeleteSessionRequest { Name = SampleSessionName }),
+        client => client.ExecuteSql(new ExecuteSqlRequest { Session = SampleSessionName }),
+        client => client.ExecuteBatchDml(new ExecuteBatchDmlRequest { Session = SampleSessionName }),
+        client => client.Read(new ReadRequest { Session = SampleSessionName }),
+        client => client.BeginTransaction(new BeginTransactionRequest { Session = SampleSessionName }),
+        client => client.Commit(new CommitRequest { Session = SampleSessionName }),
+        client => client.Rollback(new RollbackRequest { Session = SampleSessionName }),
+        client => client.PartitionQuery(new PartitionQueryRequest { Session = SampleSessionName }),
+        client => client.PartitionRead(new PartitionReadRequest { Session = SampleSessionName })
+    };
+
+    [Theory]
+    [MemberData(nameof(SpannerClientActions))]
+    public void SetsHeaderOnRpcCalls(Action<SpannerClient> action)
+    {
+        var invoker = new RetryFakeCallInvoker();
+        var client = new SpannerClientBuilder { CallInvoker = invoker }.Build();
+        action(client);
+        Metadata.Entry entry = Assert.Single(invoker.CapturedMetadata[0], e => e.Key == "x-goog-spanner-request-id");
+        Assert.NotNull(entry.Value);
+    }
+
+    [Fact]
+    public void IncrementsRequestIdOnRetry()
+    {
+        var invoker = new RetryFakeCallInvoker(failCount: 1);
+        var settings = new SpannerSettings
+        {
+            // Configure the CreateSession call to retry on Unavailable errors.
+            CallSettings = CallSettings.FromRetry(RetrySettings.FromExponentialBackoff(
+                maxAttempts: 3,
+                initialBackoff: TimeSpan.FromMilliseconds(1),
+                maxBackoff: TimeSpan.FromMilliseconds(1),
+                backoffMultiplier: 1.0,
+                retryFilter: RetrySettings.FilterForStatusCodes(StatusCode.Unavailable)))
+        };
+        var client = new SpannerClientBuilder { CallInvoker = invoker, Settings = settings }.Build();
+
+        client.CreateSession(new CreateSessionRequest { Database = SampleDatabaseName });
+        client.CreateSession(new CreateSessionRequest { Database = SampleDatabaseName });
+        client.CreateSession(new CreateSessionRequest { Database = SampleDatabaseName });
+
+        // Assert that the invoker was called four times for the three client calls.
+        // The first call should have failed the first time and succeeded on retry.
+        Assert.Equal(4, invoker.CapturedMetadata.Count);
+
+        var requestIds = invoker.CapturedMetadata
+            .Select(m => m.Single(e => e.Key == "x-goog-spanner-request-id").Value)
+            .Select(id => new SpannerRequestIdParts(id))
+            .ToList();
+
+        Assert.Equal((1, 1), (requestIds[0].RequestSequence, requestIds[0].AttemptNum));
+        Assert.Equal((1, 2), (requestIds[1].RequestSequence, requestIds[1].AttemptNum));
+        Assert.Equal((2, 1), (requestIds[2].RequestSequence, requestIds[2].AttemptNum));
+        Assert.Equal((3, 1), (requestIds[3].RequestSequence, requestIds[3].AttemptNum));
+    }
+
+    /// <summary>
+    /// A fake call invoker that fails the first time it's called with an "Unavailable" status,
+    /// and succeeds on subsequent calls. It captures the metadata for every call.
+    /// </summary>
+    private class RetryFakeCallInvoker : CallInvoker
+    {
+        private int _callCount = 0;
+        private readonly int _failCount;
+        public List<Metadata> CapturedMetadata { get; } = new List<Metadata>();
+
+        public RetryFakeCallInvoker(int failCount = 0) => _failCount = failCount;
+
+        public override TResponse BlockingUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
+        {
+            CapturedMetadata.Add(options.Headers);
+            _callCount++;
+
+            if (_callCount <= _failCount)
+            {
+                // Fail the first time with a retryable error.
+                throw new RpcException(new Status(StatusCode.Unavailable, "Transient error"));
+            }
+
+            // Succeed on the second attempt.
+            return (TResponse)Activator.CreateInstance(typeof(TResponse));
+        }
+
+        public override AsyncClientStreamingCall<TRequest, TResponse> AsyncClientStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options) =>
+            throw new NotImplementedException();
+
+        public override AsyncDuplexStreamingCall<TRequest, TResponse> AsyncDuplexStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options) =>
+            throw new NotImplementedException();
+
+        public override AsyncServerStreamingCall<TResponse> AsyncServerStreamingCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request) =>
+            throw new NotImplementedException();
+
+        public override AsyncUnaryCall<TResponse> AsyncUnaryCall<TRequest, TResponse>(Method<TRequest, TResponse> method, string host, CallOptions options, TRequest request)
+        {
+            CapturedMetadata.Add(options.Headers);
+            _callCount++;
+
+            if (_callCount <= _failCount)
+            {
+                // Fail the first time with a retryable error.
+                throw new RpcException(new Status(StatusCode.Unavailable, "Transient error"));
+            }
+
+            // Succeed on the second attempt.
+            var response = (TResponse)Activator.CreateInstance(typeof(TResponse));
+            return new AsyncUnaryCall<TResponse>(Task.FromResult(response), Task.FromResult(new Metadata()), () => Status.DefaultSuccess, () => new Metadata(), () => { });
+        }
+    }
+
+    private struct SpannerRequestIdParts
+    {
+        public int VersionId { get; }
+        public ulong ProcessId { get; }
+        public int ClientId { get; }
+        public int ChannelId { get; }
+        public int RequestSequence { get; }
+        public int AttemptNum { get; }
+
+        public SpannerRequestIdParts(string requestId)
+        {
+            var parts = requestId.Split('.');
+            Assert.Equal(6, parts.Length);
+
+            VersionId = int.Parse(parts[0]);
+            ProcessId = ulong.Parse(parts[1]);
+            ClientId = int.Parse(parts[2]);
+            ChannelId = int.Parse(parts[3]);
+            RequestSequence = int.Parse(parts[4]);
+            AttemptNum = int.Parse(parts[5]);
+        }
+    }
+}

apis/Google.Cloud.Spanner.V1/Google.Cloud.Spanner.V1/SpannerClientBuilderPartial.cs

@@ -25,6 +25,15 @@ namespace Google.Cloud.Spanner.V1
 {
     public partial class SpannerClientBuilder
     {
+        /// <summary>
+        /// The process ID, assigned to each outgoing RPC to identify the request source. This can be overridden,
+        /// but only before the process has made its first Spanner request.
+        /// </summary>
+        public static ulong ProcessId
+        {
+            set => SpannerClientImpl.ProcessId = value;
+        }
+
         /// <summary>
         /// The Grpc.Gcp method configurations for pool options.
         /// </summary>

apis/Google.Cloud.Spanner.V1/Google.Cloud.Spanner.V1/SpannerClientPartial.RequestId.cs

@@ -0,0 +1,102 @@
+// Copyright 2025 Google LLC
+//
+// 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
+//
+//     https://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.
+
+using Grpc.Core;
+
+namespace Google.Cloud.Spanner.V1;
+
+public partial class SpannerClientImpl
+{
+    /// <summary>
+    /// The header key used for Spanner request IDs.
+    /// </summary>
+    internal const string RequestIdHeaderKey = "x-goog-spanner-request-id";
+
+    /// <summary>
+    /// Represents a structured request ID for Spanner RPCs, formatted as:
+    /// {version}.{process}.{client}.{channel}.{request}.{attempt}
+    /// </summary>
+    private sealed class RequestId
+    {
+        /// <summary>
+        /// The version number of the request ID format.
+        /// </summary>
+        private const int FormatVersion = 1;
+
+        /// <summary>
+        /// A unique ID for the user application process. This can be overridden, but only before it has been accessed.
+        /// </summary>
+        private readonly ulong _processId;
+
+        /// <summary>
+        /// A unique ID for the gRPC channel being used. This is hardcoded to 1 for now.
+        /// See: b/459445539
+        /// </summary>
+        private readonly int _channelId = 1;
+
+        /// <summary>
+        /// A unique ID for the <see cref="SpannerClient"/> instance that generated the request.
+        /// </summary>
+        private readonly int _clientId;
+
+        /// <summary>
+        /// A unique ID for the logical request made using the current <see cref="SpannerClient"/>.
+        /// </summary>
+        private readonly int _requestId;
+
+        /// <summary>
+        /// The attempt count of the request, incremented before each RPC attempt.
+        /// </summary>
+        private int _attemptCount;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RequestId"/> class
+        /// with a specified client and logical request identifier.
+        /// </summary>
+        /// <param name="clientId">The ID for the <see cref="SpannerClient"/> associated with the request.</param>
+        /// <param name="processId">The ID for the user application process.</param>
+        /// <param name="requestId">The ID of the logical request within the client.</param>
+        internal RequestId(ulong processId, int clientId, int requestId)
+        {
+            _processId = processId;
+            _clientId = clientId;
+            _requestId = requestId;
+        }
+
+        /// <summary>
+        /// Increments the request's attempt number and then returns the request ID.
+        /// </summary>
+        private RequestId IncrementAttempt()
+        {
+            // Retry attempts are expected to be sequential so we can safely
+            // increment without first acquiring a lock.
+            _attemptCount++;
+            return this;
+        }
+
+        /// <summary>
+        /// Add a request ID header. The header mutation increments the attempt each time the header is populated which
+        /// happens right before a call. This allows us to increment the attempt num and assign a unique request id in the
+        /// case of retries.
+        /// </summary>
+        internal void AddHeader(Metadata metadata) => metadata.Add(RequestIdHeaderKey, IncrementAttempt().ToString());
+
+        /// <summary>
+        /// Returns the string representation of the Spanner request ID.
+        /// </summary>
+        public override string ToString() => $"{FormatVersion}.{_processId}.{_clientId}.{_channelId}.{_requestId}.{_attemptCount}";
+
+    }
+}