[otlp] Replace the current trace implementation with the new one (#6003)

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/ProtobufOtlpHttpExportClient.cs

@@ -11,7 +11,7 @@ namespace OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.ExportClie
 /// <summary>Class for sending OTLP trace export request over HTTP.</summary>
 internal sealed class ProtobufOtlpHttpExportClient : ProtobufOtlpExportClient
 {
-    private static readonly MediaTypeHeaderValue MediaHeaderValue = new("application/x-protobuf");
+    internal static readonly MediaTypeHeaderValue MediaHeaderValue = new("application/x-protobuf");
     private static readonly ExportClientHttpResponse SuccessExportResponse = new(success: true, deadlineUtc: default, response: null, exception: null);
 
     internal ProtobufOtlpHttpExportClient(OtlpExporterOptions options, HttpClient httpClient, string signalPath)

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptionsExtensions.cs

@@ -16,7 +16,6 @@
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Transmission;
 using LogOtlpCollector = OpenTelemetry.Proto.Collector.Logs.V1;
 using MetricsOtlpCollector = OpenTelemetry.Proto.Collector.Metrics.V1;
-using TraceOtlpCollector = OpenTelemetry.Proto.Collector.Trace.V1;
 
 namespace OpenTelemetry.Exporter;
 
@@ -99,42 +98,6 @@ public static THeaders GetHeaders<THeaders>(this OtlpExporterOptions options, Ac
         return headers;
     }
 
-    public static OtlpExporterTransmissionHandler<TraceOtlpCollector.ExportTraceServiceRequest> GetTraceExportTransmissionHandler(this OtlpExporterOptions options, ExperimentalOptions experimentalOptions)
-    {
-        var exportClient = GetTraceExportClient(options);
-
-        // `HttpClient.Timeout.TotalMilliseconds` would be populated with the correct timeout value for both the exporter configuration cases:
-        // 1. User provides their own HttpClient. This case is straightforward as the user wants to use their `HttpClient` and thereby the same client's timeout value.
-        // 2. If the user configures timeout via the exporter options, then the timeout set for the `HttpClient` initialized by the exporter will be set to user provided value.
-        double timeoutMilliseconds = exportClient is OtlpHttpTraceExportClient httpTraceExportClient
-            ? httpTraceExportClient.HttpClient.Timeout.TotalMilliseconds
-            : options.TimeoutMilliseconds;
-
-        if (experimentalOptions.EnableInMemoryRetry)
-        {
-            return new OtlpExporterRetryTransmissionHandler<TraceOtlpCollector.ExportTraceServiceRequest>(exportClient, timeoutMilliseconds);
-        }
-        else if (experimentalOptions.EnableDiskRetry)
-        {
-            Debug.Assert(!string.IsNullOrEmpty(experimentalOptions.DiskRetryDirectoryPath), $"{nameof(experimentalOptions.DiskRetryDirectoryPath)} is null or empty");
-
-            return new OtlpExporterPersistentStorageTransmissionHandler<TraceOtlpCollector.ExportTraceServiceRequest>(
-                exportClient,
-                timeoutMilliseconds,
-                (byte[] data) =>
-                {
-                    var request = new TraceOtlpCollector.ExportTraceServiceRequest();
-                    request.MergeFrom(data);
-                    return request;
-                },
-                Path.Combine(experimentalOptions.DiskRetryDirectoryPath, "traces"));
-        }
-        else
-        {
-            return new OtlpExporterTransmissionHandler<TraceOtlpCollector.ExportTraceServiceRequest>(exportClient, timeoutMilliseconds);
-        }
-    }
-
     public static ProtobufOtlpExporterTransmissionHandler GetProtobufExportTransmissionHandler(this OtlpExporterOptions options, ExperimentalOptions experimentalOptions, OtlpSignalType otlpSignalType)
     {
         var exportClient = GetProtobufExportClient(options, otlpSignalType);
@@ -169,6 +132,11 @@ public static IProtobufExportClient GetProtobufExportClient(this OtlpExporterOpt
     {
         var httpClient = options.HttpClientFactory?.Invoke() ?? throw new InvalidOperationException("OtlpExporterOptions was missing HttpClientFactory or it returned null.");
 
+        if (options.Protocol != OtlpExportProtocol.Grpc && options.Protocol != OtlpExportProtocol.HttpProtobuf)
+        {
+            throw new NotSupportedException($"Protocol {options.Protocol} is not supported.");
+        }
+
         return otlpSignalType switch
         {
             OtlpSignalType.Traces => options.Protocol == OtlpExportProtocol.Grpc
@@ -255,16 +223,6 @@ public static IProtobufExportClient GetProtobufExportClient(this OtlpExporterOpt
         }
     }
 
-    public static IExportClient<TraceOtlpCollector.ExportTraceServiceRequest> GetTraceExportClient(this OtlpExporterOptions options) =>
-        options.Protocol switch
-        {
-            OtlpExportProtocol.Grpc => new OtlpGrpcTraceExportClient(options),
-            OtlpExportProtocol.HttpProtobuf => new OtlpHttpTraceExportClient(
-                options,
-                options.HttpClientFactory?.Invoke() ?? throw new InvalidOperationException("OtlpExporterOptions was missing HttpClientFactory or it returned null.")),
-            _ => throw new NotSupportedException($"Protocol {options.Protocol} is not supported."),
-        };
-
     public static IExportClient<MetricsOtlpCollector.ExportMetricsServiceRequest> GetMetricsExportClient(this OtlpExporterOptions options) =>
         options.Protocol switch
         {

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpTraceExporter.cs

@@ -1,11 +1,12 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+using System.Buffers.Binary;
 using System.Diagnostics;
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation;
+using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Serializer;
 using OpenTelemetry.Exporter.OpenTelemetryProtocol.Implementation.Transmission;
-using OtlpCollector = OpenTelemetry.Proto.Collector.Trace.V1;
-using OtlpResource = OpenTelemetry.Proto.Resource.V1;
+using OpenTelemetry.Resources;
 
 namespace OpenTelemetry.Exporter;
 
@@ -16,9 +17,15 @@ namespace OpenTelemetry.Exporter;
 public class OtlpTraceExporter : BaseExporter<Activity>
 {
     private readonly SdkLimitOptions sdkLimitOptions;
-    private readonly OtlpExporterTransmissionHandler<OtlpCollector.ExportTraceServiceRequest> transmissionHandler;
+    private readonly ProtobufOtlpExporterTransmissionHandler transmissionHandler;
+    private readonly int startWritePosition;
 
-    private OtlpResource.Resource? processResource;
+    private Resource? resource;
+
+    // Initial buffer size set to ~732KB.
+    // This choice allows us to gradually grow the buffer while targeting a final capacity of around 100 MB,
+    // by the 7th doubling to maintain efficient allocation without frequent resizing.
+    private byte[] buffer = new byte[750000];
 
     /// <summary>
     /// Initializes a new instance of the <see cref="OtlpTraceExporter"/> class.
@@ -40,31 +47,40 @@ internal OtlpTraceExporter(
         OtlpExporterOptions exporterOptions,
         SdkLimitOptions sdkLimitOptions,
         ExperimentalOptions experimentalOptions,
-        OtlpExporterTransmissionHandler<OtlpCollector.ExportTraceServiceRequest>? transmissionHandler = null)
+        ProtobufOtlpExporterTransmissionHandler? transmissionHandler = null)
     {
         Debug.Assert(exporterOptions != null, "exporterOptions was null");
         Debug.Assert(sdkLimitOptions != null, "sdkLimitOptions was null");
 
         this.sdkLimitOptions = sdkLimitOptions!;
-
-        this.transmissionHandler = transmissionHandler ?? exporterOptions!.GetTraceExportTransmissionHandler(experimentalOptions);
+        this.startWritePosition = exporterOptions!.Protocol == OtlpExportProtocol.Grpc ? 5 : 0;
+        this.transmissionHandler = transmissionHandler ?? exporterOptions!.GetProtobufExportTransmissionHandler(experimentalOptions, OtlpSignalType.Traces);
     }
 
-    internal OtlpResource.Resource ProcessResource => this.processResource ??= this.ParentProvider.GetResource().ToOtlpResource();
+    internal Resource Resource => this.resource ??= this.ParentProvider.GetResource();
 
     /// <inheritdoc/>
     public override ExportResult Export(in Batch<Activity> activityBatch)
     {
         // Prevents the exporter's gRPC and HTTP operations from being instrumented.
         using var scope = SuppressInstrumentationScope.Begin();
 
-        var request = new OtlpCollector.ExportTraceServiceRequest();
-
         try
         {
-            request.AddBatch(this.sdkLimitOptions, this.ProcessResource, activityBatch);
+            int writePosition = ProtobufOtlpTraceSerializer.WriteTraceData(this.buffer, this.startWritePosition, this.sdkLimitOptions, this.Resource, activityBatch);
+
+            if (this.startWritePosition == 5)
+            {
+                // Grpc payload consists of 3 parts
+                // byte 0 - Specifying if the payload is compressed.
+                // 1-4 byte - Specifies the length of payload in big endian format.
+                // 5 and above -  Protobuf serialized data.
+                Span<byte> data = new Span<byte>(this.buffer, 1, 4);
+                var dataLength = writePosition - 5;
+                BinaryPrimitives.WriteUInt32BigEndian(data, (uint)dataLength);
+            }
 
-            if (!this.transmissionHandler.TrySubmitRequest(request))
+            if (!this.transmissionHandler.TrySubmitRequest(this.buffer, writePosition))
             {
                 return ExportResult.Failure;
             }
@@ -74,17 +90,10 @@ public override ExportResult Export(in Batch<Activity> activityBatch)
             OpenTelemetryProtocolExporterEventSource.Log.ExportMethodException(ex);
             return ExportResult.Failure;
         }
-        finally
-        {
-            request.Return();
-        }
 
         return ExportResult.Success;
     }
 
     /// <inheritdoc />
-    protected override bool OnShutdown(int timeoutMilliseconds)
-    {
-        return this.transmissionHandler.Shutdown(timeoutMilliseconds);
-    }
+    protected override bool OnShutdown(int timeoutMilliseconds) => this.transmissionHandler.Shutdown(timeoutMilliseconds);
 }

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpTraceExporterHelperExtensions.cs

@@ -136,16 +136,7 @@ internal static BaseProcessor<Activity> BuildOtlpExporterProcessor(
 
         exporterOptions!.TryEnableIHttpClientFactoryIntegration(serviceProvider!, "OtlpTraceExporter");
 
-        BaseExporter<Activity> otlpExporter;
-
-        if (experimentalOptions != null && experimentalOptions.UseCustomProtobufSerializer)
-        {
-            otlpExporter = new ProtobufOtlpTraceExporter(exporterOptions!, sdkLimitOptions!, experimentalOptions!);
-        }
-        else
-        {
-            otlpExporter = new OtlpTraceExporter(exporterOptions!, sdkLimitOptions!, experimentalOptions!);
-        }
+        BaseExporter<Activity> otlpExporter = new OtlpTraceExporter(exporterOptions!, sdkLimitOptions!, experimentalOptions!);
 
         if (configureExporterInstance != null)
         {