[Tracing] sampling code cleanup (#5477)

tracer/missing-nullability-files.csv

@@ -24,8 +24,6 @@ src/Datadog.Trace/OSPlatformName.cs
 src/Datadog.Trace/ProcessArchitecture.cs
 src/Datadog.Trace/PropagationErrorTagValues.cs
 src/Datadog.Trace/ReadOnlySpanContext.cs
-src/Datadog.Trace/SamplingPriority.cs
-src/Datadog.Trace/SamplingPriorityValues.cs
 src/Datadog.Trace/Scope.cs
 src/Datadog.Trace/Scope.IScope.cs
 src/Datadog.Trace/Span.cs
@@ -85,7 +83,6 @@ src/Datadog.Trace/Ci/IEvent.cs
 src/Datadog.Trace/ClrProfiler/AutomaticTracer.cs
 src/Datadog.Trace/ClrProfiler/CallTargetKind.cs
 src/Datadog.Trace/ClrProfiler/ClrNames.cs
-src/Datadog.Trace/ClrProfiler/CommonTracer.cs
 src/Datadog.Trace/ClrProfiler/DistributedTracer.cs
 src/Datadog.Trace/ClrProfiler/IAutomaticTracer.cs
 src/Datadog.Trace/ClrProfiler/ICommonTracer.cs
@@ -198,20 +195,14 @@ src/Datadog.Trace/RuntimeMetrics/PerformanceCounterWrapper.cs
 src/Datadog.Trace/RuntimeMetrics/RuntimeEventListener.cs
 src/Datadog.Trace/RuntimeMetrics/RuntimeMetricsWriter.cs
 src/Datadog.Trace/RuntimeMetrics/Timing.cs
-src/Datadog.Trace/Sampling/CustomSamplingRule.cs
-src/Datadog.Trace/Sampling/DefaultSamplingRule.cs
-src/Datadog.Trace/Sampling/GlobalSamplingRule.cs
 src/Datadog.Trace/Sampling/IRateLimiter.cs
-src/Datadog.Trace/Sampling/ISamplingRule.cs
 src/Datadog.Trace/Sampling/ISpanSamplingRule.cs
-src/Datadog.Trace/Sampling/ITraceSampler.cs
 src/Datadog.Trace/Sampling/OverheadController.cs
 src/Datadog.Trace/Sampling/RateLimiter.cs
 src/Datadog.Trace/Sampling/SamplingMechanism.cs
 src/Datadog.Trace/Sampling/SpanRateLimiter.cs
 src/Datadog.Trace/Sampling/SpanSamplingRule.cs
 src/Datadog.Trace/Sampling/TracerRateLimiter.cs
-src/Datadog.Trace/Sampling/TraceSampler.cs
 src/Datadog.Trace/ServiceFabric/ServiceRemotingConstants.cs
 src/Datadog.Trace/Tagging/AerospikeTags.cs
 src/Datadog.Trace/Tagging/AspNetCoreEndpointTags.cs

tracer/src/Datadog.Trace/Agent/MessagePack/SpanMessagePackFormatter.cs

@@ -5,7 +5,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Runtime.CompilerServices;
 using Datadog.Trace.ExtensionMethods;
 using Datadog.Trace.Processors;
@@ -228,19 +227,24 @@ private int Serialize(ref byte[] bytes, int offset, in SpanModel spanModel)
  private int WriteSpanLink(ref byte[] bytes, int offset, in SpanModel spanModel)
  {
  int originalOffset = offset;
+
  offset += MessagePackBinary.WriteStringBytes(ref bytes, offset, _spanLinkBytes);
  offset += MessagePackBinary.WriteArrayHeader(ref bytes, offset, spanModel.Span.SpanLinks.Count);
+
  foreach (var spanLink in spanModel.Span.SpanLinks)
  {
  var context = spanLink.Context;
  var samplingPriority = context.TraceContext?.SamplingPriority ?? context.SamplingPriority;
+
  var traceFlags = samplingPriority switch
  {
  null => 0u, // not set
  > 0 => 1u + (1u << 31), // keep
  <= 0 => 1u << 31, // drop
  };
+
  var len = 3;
+
  // check to serialize tracestate
  if (context.IsRemote)
  {

tracer/src/Datadog.Trace/Agent/MessagePack/TraceChunkModel.cs

@@ -10,7 +10,6 @@
 using System.Threading;
 using Datadog.Trace.Configuration;
 using Datadog.Trace.Tagging;
-using Datadog.Trace.Util;
 
 namespace Datadog.Trace.Agent.MessagePack;
 
@@ -62,7 +61,7 @@ internal readonly struct TraceChunkModel
  /// <param name="spans">The spans that will be within this <see cref="TraceChunkModel"/>.</param>
  /// <param name="samplingPriority">Optional sampling priority to override the <see cref="TraceContext"/> sampling priority.</param>
  public TraceChunkModel(in ArraySegment<Span> spans, int? samplingPriority = null)
- : this(spans, GetTraceContext(spans), samplingPriority)
+ : this(spans, TraceContext.GetTraceContext(spans), samplingPriority)
  {
  // since all we have is an array of spans, use the trace context from the first span
  // to get the other values we need (sampling priority, origin, trace tags, etc) for now.
@@ -78,19 +77,29 @@ private TraceChunkModel(in ArraySegment<Span> spans, TraceContext? traceContext,
 
  if (traceContext is not null)
  {
- DefaultServiceName = traceContext.Tracer?.DefaultServiceName;
  SamplingPriority ??= traceContext.SamplingPriority;
+
  Environment = traceContext.Environment;
  ServiceVersion = traceContext.ServiceVersion;
  Origin = traceContext.Origin;
  Tags = traceContext.Tags;
- IsRunningInAzureAppService = traceContext.Tracer?.Settings?.IsRunningInAzureAppService ?? false;
- AzureAppServiceSettings = traceContext.Tracer?.Settings?.AzureAppServiceMetadata ?? null;
- if (traceContext.Tracer?.GitMetadataTagsProvider?.TryExtractGitMetadata(out var gitMetadata) == true &&
- gitMetadata != GitMetadata.Empty)
+
+ if (traceContext.Tracer is { } tracer)
  {
- GitRepositoryUrl = gitMetadata.RepositoryUrl;
- GitCommitSha = gitMetadata.CommitSha;
+ DefaultServiceName = tracer.DefaultServiceName;
+
+ if (tracer.Settings is { } settings)
+ {
+ IsRunningInAzureAppService = settings.IsRunningInAzureAppService;
+ AzureAppServiceSettings = settings.AzureAppServiceMetadata ?? null;
+ }
+
+ if (tracer.GitMetadataTagsProvider?.TryExtractGitMetadata(out var gitMetadata) == true &&
+ gitMetadata != GitMetadata.Empty)
+ {
+ GitRepositoryUrl = gitMetadata.RepositoryUrl;
+ GitCommitSha = gitMetadata.CommitSha;
+ }
  }
  }
  }
@@ -121,16 +130,6 @@ internal TraceChunkModel(in ArraySegment<Span> spans, Span? localRootSpan)
  // used in tests
  internal bool HashSetInitialized => _hashSet?.IsValueCreated == true && _hashSet.Value.Count > 0;
 
- private static TraceContext? GetTraceContext(in ArraySegment<Span> spans)
- {
- if (spans.Count > 0)
- {
- return spans.Array![spans.Offset].Context.TraceContext;
- }
-
- return null;
- }
-
  public SpanModel GetSpanModel(int spanIndex)
  {
  if (spanIndex >= _spans.Count)

tracer/src/Datadog.Trace/Ci/Test.cs

@@ -51,7 +51,7 @@ internal Test(TestSuite suite, string name, DateTimeOffset? startDate, TraceId t
 
  scope.Span.Type = SpanTypes.Test;
  scope.Span.ResourceName = $"{suite.Name}.{name}";
- scope.Span.Context.TraceContext.SetSamplingPriority((int)SamplingPriority.AutoKeep, SamplingMechanism.Manual);
+ scope.Span.Context.TraceContext.SetSamplingPriority(SamplingPriorityValues.AutoKeep, SamplingMechanism.Manual);
  scope.Span.Context.TraceContext.Origin = TestTags.CIAppTestOriginName;
  TelemetryFactory.Metrics.RecordCountSpanCreated(MetricTags.IntegrationName.CiAppManual);
 

tracer/src/Datadog.Trace/Ci/TestModule.cs

@@ -172,7 +172,7 @@ internal TestModule(string name, string? framework, string? frameworkVersion, Da
 
  span.Type = SpanTypes.TestModule;
  span.ResourceName = name;
- span.Context.TraceContext.SetSamplingPriority((int)SamplingPriority.AutoKeep);
+ span.Context.TraceContext.SetSamplingPriority(SamplingPriorityValues.AutoKeep);
  span.Context.TraceContext.Origin = TestTags.CIAppTestOriginName;
 
  tags.ModuleId = span.SpanId;

tracer/src/Datadog.Trace/Ci/TestSession.cs

@@ -61,7 +61,7 @@ private TestSession(string? command, string? workingDirectory, string? framework
 
  span.Type = SpanTypes.TestSession;
  span.ResourceName = $"{span.OperationName}.{command}";
- span.Context.TraceContext.SetSamplingPriority((int)SamplingPriority.AutoKeep);
+ span.Context.TraceContext.SetSamplingPriority(SamplingPriorityValues.AutoKeep);
  span.Context.TraceContext.Origin = TestTags.CIAppTestOriginName;
 
  tags.SessionId = span.SpanId;

tracer/src/Datadog.Trace/Ci/TestSuite.cs

@@ -38,7 +38,7 @@ internal TestSuite(TestModule module, string name, DateTimeOffset? startDate)
 
  span.Type = SpanTypes.TestSuite;
  span.ResourceName = name;
- span.Context.TraceContext.SetSamplingPriority((int)SamplingPriority.AutoKeep);
+ span.Context.TraceContext.SetSamplingPriority(SamplingPriorityValues.AutoKeep);
  span.Context.TraceContext.Origin = TestTags.CIAppTestOriginName;
 
  tags.SuiteId = span.SpanId;

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/Grpc/GrpcLegacy/Client/GrpcLegacyClientCommon.cs

@@ -81,9 +81,9 @@ internal static class GrpcLegacyClientCommon
  span.SetHeaderTags(requestMetadataWrapper, tracer.Settings.GrpcTagsInternal, GrpcCommon.RequestMetadataTagPrefix);
  scope = tracer.ActivateSpan(span);
 
- if (setSamplingPriority && existingSpanContext?.SamplingPriority is not null)
+ if (setSamplingPriority && existingSpanContext?.SamplingPriority is { } samplingPriority)
  {
- span.Context.TraceContext?.SetSamplingPriority(existingSpanContext.SamplingPriority.Value);
+ span.Context.TraceContext?.SetSamplingPriority(samplingPriority);
  }
 
  GrpcCommon.RecordFinalStatus(span, receivedStatus.StatusCode, receivedStatus.Detail, receivedStatus.DebugException);
@@ -242,10 +242,10 @@ private static Span CreateInactiveSpan(Tracer tracer, string? methodFullName)
  var operationName = tracer.CurrentTraceSettings.Schema.Client.GetOperationNameForProtocol("grpc");
  var serviceName = tracer.CurrentTraceSettings.Schema.Client.GetServiceName(component: "grpc-client");
  var tags = tracer.CurrentTraceSettings.Schema.Client.CreateGrpcClientTags();
- var span = tracer.StartSpan(operationName, tags, serviceName: serviceName, addToTraceContext: false);
  tags.SetAnalyticsSampleRate(IntegrationId.Grpc, tracer.Settings, enabledWithGlobalSetting: false);
  tracer.CurrentTraceSettings.Schema.RemapPeerService(tags);
 
+ var span = tracer.StartSpan(operationName, tags, serviceName: serviceName, addToTraceContext: false);
  span.Type = SpanTypes.Grpc;
  span.ResourceName = methodFullName;
 

tracer/src/Datadog.Trace/ClrProfiler/CommonTracer.cs

@@ -3,7 +3,7 @@
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
 // </copyright>
 
-using Datadog.Trace.Sampling;
+#nullable enable
 
 namespace Datadog.Trace.ClrProfiler
 {

tracer/src/Datadog.Trace/Configuration/ConfigurationKeys.AzureAppService.cs

@@ -67,7 +67,7 @@ internal class AzureAppService
  internal const string OperatingSystemKey = "WEBSITE_OS";
 
  /// <summary>
- /// Used to force the loader to start the tracer agent (in case automatic instrumentation is disabled)
+ /// Used to force the loader to start the trace agent (in case automatic instrumentation is disabled)
  /// </summary>
  public const string AasEnableCustomTracing = "DD_AAS_ENABLE_CUSTOM_TRACING";
 

tracer/src/Datadog.Trace/Configuration/ConfigurationSources/DynamicConfigConfigurationSource.cs

@@ -15,7 +15,7 @@ namespace Datadog.Trace.Configuration.ConfigurationSources
 {
  internal class DynamicConfigConfigurationSource : JsonConfigurationSource
  {
- private static readonly IReadOnlyDictionary<string, string> Mapping = new Dictionary<string, string>
+ private static readonly Dictionary<string, string> Mapping = new()
  {
  { ConfigurationKeys.TraceEnabled, "tracing_enabled" },
  // { ConfigurationKeys.DebugEnabled, "tracing_debug" },
@@ -48,17 +48,17 @@ internal DynamicConfigConfigurationSource(string json, ConfigurationOrigins orig
  return jobject;
  }
 
- private static IDictionary<string, string> ReadHeaderTags(JToken token)
+ private static Dictionary<string, string> ReadHeaderTags(JToken token)
  {
  return ((JArray)token).ToDictionary(t => t["header"]!.Value<string>()!, t => t["tag_name"]!.Value<string>()!);
  }
 
- private static IDictionary<string, string> ReadServiceMapping(JToken token)
+ private static Dictionary<string, string> ReadServiceMapping(JToken token)
  {
  return ((JArray)token).ToDictionary(t => t["from_key"]!.Value<string>()!, t => t["to_name"]!.Value<string>()!);
  }
 
- private static IDictionary<string, string> ReadGlobalTags(JToken token)
+ private static Dictionary<string, string> ReadGlobalTags(JToken token)
  {
  var result = new Dictionary<string, string>();
 

tracer/src/Datadog.Trace/Configuration/PerTraceSettings.cs

@@ -52,16 +52,5 @@ internal string GetServiceName(Tracer tracer, string serviceName)
 
  return finalServiceName;
  }
-
- internal bool TryGetServiceName(string key, out string? serviceName)
- {
- if (ServiceNames.TryGetValue(key, out serviceName))
- {
- return true;
- }
-
- serviceName = null;
- return false;
- }
  }
 }

tracer/src/Datadog.Trace/Propagators/B3MultipleHeaderContextPropagator.cs

@@ -73,9 +73,11 @@ public bool TryExtract<TCarrier, TCarrierGetter>(TCarrier carrier, TCarrierGette
 
  internal static void CreateHeaders(SpanContext context, out string traceId, out string spanId, out string sampled)
  {
- var samplingPriority = context.TraceContext?.SamplingPriority ?? context.SamplingPriority;
- sampled = samplingPriority > 0 ? "1" : "0";
+ // BUG: we should fall back to SamplingPriorityValues.AutoKeep
+ var samplingPriority = context.TraceContext?.SamplingPriority ??
+ context.SamplingPriority; // should never happen in production, but some tests rely on this
 
+ sampled = SamplingPriorityValues.IsKeep(samplingPriority) ? "1" : "0";
  traceId = context.RawTraceId;
  spanId = context.RawSpanId;
  }

tracer/src/Datadog.Trace/Propagators/B3SingleHeaderContextPropagator.cs

@@ -139,8 +139,11 @@ public bool TryExtract<TCarrier, TCarrierGetter>(TCarrier carrier, TCarrierGette
 
  internal static string CreateHeader(SpanContext context)
  {
- var samplingPriority = context.TraceContext?.SamplingPriority ?? context.SamplingPriority;
- var sampled = samplingPriority > 0 ? "1" : "0";
+ // BUG: we should fall back to SamplingPriorityValues.AutoKeep
+ var samplingPriority = context.TraceContext?.SamplingPriority ??
+ context.SamplingPriority; // should never happen in production, but some tests rely on this
+
+ var sampled = SamplingPriorityValues.IsKeep(samplingPriority) ? "1" : "0";
 
 #if NET6_0_OR_GREATER
  return string.Create(null, stackalloc char[128], $"{context.RawTraceId}-{context.RawSpanId}-{sampled}");

tracer/src/Datadog.Trace/Propagators/DatadogContextPropagator.cs

@@ -36,19 +36,12 @@ public void Inject<TCarrier, TCarrierSetter>(SpanContext context, TCarrier carri
  carrierSetter.Set(carrier, HttpHeaderNames.Origin, context.Origin);
  }
 
- var samplingPriority = context.TraceContext?.SamplingPriority ?? context.SamplingPriority;
+ var samplingPriority = context.TraceContext?.SamplingPriority ??
+ context.SamplingPriority; // should never happen in production, but some tests rely on this
 
  if (samplingPriority != null)
  {
- var samplingPriorityString = samplingPriority.Value switch
- {
- -1 => "-1",
- 0 => "0",
- 1 => "1",
- 2 => "2",
- _ => samplingPriority.Value.ToString(invariantCulture)
- };
-
+ var samplingPriorityString = SamplingPriorityValues.ToString(samplingPriority);
  carrierSetter.Set(carrier, HttpHeaderNames.SamplingPriority, samplingPriorityString);
  }
 

tracer/src/Datadog.Trace/Propagators/SpanContextPropagator.cs

@@ -11,7 +11,6 @@
 using System.Linq;
 using Datadog.Trace.ExtensionMethods;
 using Datadog.Trace.Headers;
-using Datadog.Trace.Util;
 
 namespace Datadog.Trace.Propagators
 {

tracer/src/Datadog.Trace/Propagators/W3CTraceContextPropagator.cs

@@ -8,7 +8,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Text;
 using Datadog.Trace.SourceGenerators;
@@ -119,6 +118,7 @@ public void Inject<TCarrier, TCarrierSetter>(SpanContext context, TCarrier carri
  where TCarrierSetter : struct, ICarrierSetter<TCarrier>
  {
  TelemetryFactory.Metrics.RecordCountContextHeaderStyleInjected(MetricTags.ContextHeaderStyle.TraceContext);
+
  var traceparent = CreateTraceParentHeader(context);
  carrierSetter.Set(carrier, TraceParentHeaderName, traceparent);
 
@@ -132,8 +132,12 @@ public void Inject<TCarrier, TCarrierSetter>(SpanContext context, TCarrier carri
 
  internal static string CreateTraceParentHeader(SpanContext context)
  {
- var samplingPriority = context.TraceContext?.SamplingPriority ?? context.SamplingPriority ?? SamplingPriorityValues.AutoKeep;
- var sampled = samplingPriority > 0 ? "01" : "00";
+ var samplingPriority = context.TraceContext?.SamplingPriority ??
+ context.SamplingPriority ?? // should never happen in production, but some tests rely on this
+ SamplingPriorityValues.AutoKeep; // fallback
+
+ var sampled = SamplingPriorityValues.IsKeep(samplingPriority) ? "01" : "00";
+
 #if NET6_0_OR_GREATER
  return string.Create(null, stackalloc char[128], $"00-{context.RawTraceId}-{context.RawSpanId}-{sampled}");
 #else
@@ -150,11 +154,9 @@ internal static string CreateTraceStateHeader(SpanContext context)
  sb.Append("dd=");
 
  // sampling priority ("s:<value>")
- var samplingPriority = SamplingPriorityToString(context.TraceContext?.SamplingPriority);
-
- if (samplingPriority != null)
+ if (context.TraceContext?.SamplingPriority is { } samplingPriority)
  {
- sb.Append("s:").Append(samplingPriority).Append(TraceStateDatadogPairsSeparator);
+ sb.Append("s:").Append(SamplingPriorityValues.ToString(samplingPriority)).Append(TraceStateDatadogPairsSeparator);
  }
 
  // origin ("o:<value>")
@@ -563,20 +565,6 @@ internal static void SplitTraceStateValues(string header, out string? ddValues,
  }
  }
 
- [return: NotNullIfNotNull("samplingPriority")]
- private static string? SamplingPriorityToString(int? samplingPriority)
- {
- return samplingPriority switch
- {
- 2 => "2",
- 1 => "1",
- 0 => "0",
- -1 => "-1",
- null => null,
- not null => samplingPriority.Value.ToString(CultureInfo.InvariantCulture)
- };
- }
-
 #if NETCOREAPP
  private static int? SamplingPriorityToInt32(ReadOnlySpan<char> samplingPriority)
  {