feat: Tracing without performance

src/Sentry.AspNet/HttpContextExtensions.cs

@@ -55,6 +55,25 @@ public static class HttpContextExtensions
         }
     }
 
+    /// <summary>
+    /// Starts or continues a Sentry trace.
+    /// </summary>
+    public static void StartOrContinueTrace(this HttpContext httpContext)
+    {
+        var options = SentrySdk.CurrentOptions;
+
+        var traceHeader = TryGetSentryTraceHeader(httpContext, options);
+        var baggageHeader = TryGetBaggageHeader(httpContext, options);
+
+        var method = httpContext.Request.HttpMethod;
+        var path = httpContext.Request.Path;
+
+        var transactionName = $"{method} {path}";
+        const string operation = "http.server";
+
+        SentrySdk.ContinueTrace(traceHeader, baggageHeader, transactionName, operation);
+    }
+
     /// <summary>
     /// Starts a new Sentry transaction that encompasses the currently executing HTTP request.
     /// </summary>
@@ -65,13 +84,13 @@ public static ITransaction StartSentryTransaction(this HttpContext httpContext)
         var options = SentrySdk.CurrentOptions;
 
         var traceHeader = TryGetSentryTraceHeader(httpContext, options);
+        var baggageHeader = TryGetBaggageHeader(httpContext, options);
 
         var transactionName = $"{method} {path}";
         const string transactionOperation = "http.server";
 
-        var transactionContext = traceHeader is not null
-            ? new TransactionContext(transactionName, transactionOperation, traceHeader, TransactionNameSource.Url)
-            : new TransactionContext(transactionName, transactionOperation, TransactionNameSource.Url);
+        var transactionContext = SentrySdk.ContinueTrace(traceHeader, baggageHeader, transactionName, transactionOperation);
+        transactionContext.NameSource = TransactionNameSource.Url;
 
         var customSamplingContext = new Dictionary<string, object?>(3, StringComparer.Ordinal)
         {
@@ -81,10 +100,9 @@ public static ITransaction StartSentryTransaction(this HttpContext httpContext)
         };
 
         // Set the Dynamic Sampling Context from the baggage header, if it exists.
-        var baggageHeader = TryGetBaggageHeader(httpContext, options);
         var dynamicSamplingContext = baggageHeader?.CreateDynamicSamplingContext();
 
-        if (traceHeader is { } && baggageHeader is null)
+        if (traceHeader is not null && baggageHeader is null)
         {
             // We received a sentry-trace header without a baggage header, which indicates the request
             // originated from an older SDK that doesn't support dynamic sampling.

src/Sentry.AspNetCore/SentryMiddleware.cs

@@ -7,6 +7,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
+using Sentry.AspNetCore.Extensions;
 using Sentry.Extensibility;
 using Sentry.Reflection;
 
@@ -17,6 +18,10 @@ namespace Sentry.AspNetCore;
 /// </summary>
 internal class SentryMiddleware : IMiddleware
 {
+    internal static readonly object TraceHeaderItemKey = new();
+    internal static readonly object BaggageHeaderItemKey = new();
+    internal static readonly object TransactionContextItemKey = new();
+
     private readonly Func<IHub> _getHub;
     private readonly SentryAspNetCoreOptions _options;
     private readonly IHostingEnvironment _hostingEnvironment;
@@ -90,6 +95,15 @@ public async Task InvokeAsync(HttpContext context, RequestDelegate next)
                 context.Response.OnCompleted(() => hub.FlushAsync(_options.FlushTimeout));
             }
 
+            var traceHeader = context.TryGetSentryTraceHeader(_options);
+            var baggageHeader = context.TryGetBaggageHeader(_options);
+            var transactionContext = hub.ContinueTrace(traceHeader, baggageHeader);
+
+            // Adding the headers and the TransactionContext to the context to be picked up by the Sentry tracing middleware
+            context.Items.Add(TraceHeaderItemKey, traceHeader);
+            context.Items.Add(BaggageHeaderItemKey, baggageHeader);
+            context.Items.Add(TransactionContextItemKey, transactionContext);
+
             hub.ConfigureScope(scope =>
             {
                 // At the point lots of stuff from the request are not yet filled

src/Sentry.AspNetCore/SentryTracingMiddleware.cs

@@ -36,19 +36,19 @@ public SentryTracingMiddleware(
 
         try
         {
-            var hub = _getHub();
-
-            // Attempt to start a transaction from the trace header if it exists
-            var traceHeader = context.TryGetSentryTraceHeader(_options);
+            // The trace gets continued in the SentryMiddleware.
+            context.Items.TryGetValue(SentryMiddleware.TransactionContextItemKey, out var transactionContextObject);
+            if (transactionContextObject is not TransactionContext transactionContext)
+            {
+                throw new KeyNotFoundException($"Failed to retrieve the '{nameof(SentryMiddleware.TransactionContextItemKey)}' from the HttpContext items.");
+            }
 
             // It's important to try and set the transaction name to some value here so that it's available for use
             // in sampling.  At a later stage, we will try to get the transaction name again, to account for the
             // other middlewares that may have ran after ours.
-            var transactionName = context.TryGetTransactionName() ?? string.Empty;
-
-            var transactionContext = traceHeader is not null
-                ? new TransactionContext(transactionName, OperationName, traceHeader, TransactionNameSource.Route)
-                : new TransactionContext(transactionName, OperationName, TransactionNameSource.Route);
+            transactionContext.Name = context.TryGetTransactionName() ?? string.Empty;
+            transactionContext.Operation = OperationName;
+            transactionContext.NameSource = TransactionNameSource.Route;
 
             var customSamplingContext = new Dictionary<string, object?>(4, StringComparer.Ordinal)
             {
@@ -58,11 +58,14 @@ public SentryTracingMiddleware(
                 [SamplingExtensions.KeyForHttpContext] = context,
             };
 
-            // Set the Dynamic Sampling Context from the baggage header, if it exists.
-            var baggageHeader = context.TryGetBaggageHeader(_options);
+            var traceHeader = context.Items.TryGetValue(SentryMiddleware.TraceHeaderItemKey, out var traceHeaderObject)
+                ? traceHeaderObject as SentryTraceHeader : null;
+            var baggageHeader = context.Items.TryGetValue(SentryMiddleware.BaggageHeaderItemKey, out var baggageHeaderObject)
+                ? baggageHeaderObject as BaggageHeader : null;
+
             var dynamicSamplingContext = baggageHeader?.CreateDynamicSamplingContext();
 
-            if (traceHeader is { } && baggageHeader is null)
+            if (traceHeader is not null && baggageHeader is null)
             {
                 // We received a sentry-trace header without a baggage header, which indicates the request
                 // originated from an older SDK that doesn't support dynamic sampling.
@@ -73,7 +76,7 @@ public SentryTracingMiddleware(
                 dynamicSamplingContext = DynamicSamplingContext.Empty;
             }
 
-            var transaction = hub.StartTransaction(transactionContext, customSamplingContext, dynamicSamplingContext);
+            var transaction = _getHub().StartTransaction(transactionContext, customSamplingContext, dynamicSamplingContext);
 
             _options.LogInfo(
                 "Started transaction with span ID '{0}' and trace ID '{1}'.",
@@ -95,7 +98,6 @@ public SentryTracingMiddleware(
     public async Task InvokeAsync(HttpContext context)
     {
         var hub = _getHub();
-
         if (!hub.IsEnabled)
         {
             await _next(context).ConfigureAwait(false);

src/Sentry/BaggageHeader.cs

@@ -8,7 +8,7 @@ namespace Sentry;
 /// </summary>
 /// <seealso href="https://develop.sentry.dev/sdk/performance/dynamic-sampling-context"/>
 /// <seealso href="https://www.w3.org/TR/baggage"/>
-internal class BaggageHeader
+public class BaggageHeader
 {
     internal const string HttpHeaderName = "baggage";
     internal const string SentryKeyPrefix = "sentry-";
@@ -19,14 +19,14 @@ internal class BaggageHeader
     // "Uniqueness of keys between multiple list-members in a baggage-string is not guaranteed."
     // "The order of duplicate entries SHOULD be preserved when mutating the list."
 
-    public IReadOnlyList<KeyValuePair<string, string>> Members { get; }
+    internal IReadOnlyList<KeyValuePair<string, string>> Members { get; }
 
     private BaggageHeader(IEnumerable<KeyValuePair<string, string>> members) =>
         Members = members.ToList();
 
     // We can safely return a dictionary of Sentry members, as we are in control over the keys added.
     // Just to be safe though, we'll group by key and only take the first of each one.
-    public IReadOnlyDictionary<string, string> GetSentryMembers() =>
+    internal IReadOnlyDictionary<string, string> GetSentryMembers() =>
         Members
             .Where(kvp => kvp.Key.StartsWith(SentryKeyPrefix))
             .GroupBy(kvp => kvp.Key, kvp => kvp.Value)
@@ -59,7 +59,7 @@ public override string ToString()
     /// <returns>
     /// An object representing the members baggage header, or <c>null</c> if there are no members parsed.
     /// </returns>
-    public static BaggageHeader? TryParse(string baggage, bool onlySentry = false)
+    internal static BaggageHeader? TryParse(string baggage, bool onlySentry = false)
     {
         // Example from W3C baggage spec:
         // "key1=value1;property1;property2, key2 = value2, key3=value3; propertyKey=propertyValue"
@@ -107,7 +107,7 @@ public override string ToString()
         return members.Count == 0 ? null : new BaggageHeader(members);
     }
 
-    public static BaggageHeader Create(
+    internal static BaggageHeader Create(
         IEnumerable<KeyValuePair<string, string>> items,
         bool useSentryPrefix = false)
     {
@@ -121,7 +121,7 @@ public static BaggageHeader Create(
         return new BaggageHeader(members);
     }
 
-    public static BaggageHeader Merge(IEnumerable<BaggageHeader> baggageHeaders) =>
+    internal static BaggageHeader Merge(IEnumerable<BaggageHeader> baggageHeaders) =>
         new(baggageHeaders.SelectMany(x => x.Members));
 
     private static bool IsValidKey(string? key)

src/Sentry/DynamicSamplingContext.cs

@@ -23,7 +23,7 @@ private DynamicSamplingContext(
         SentryId traceId,
         string publicKey,
         bool? sampled,
-        double sampleRate,
+        double? sampleRate = null,
         string? release = null,
         string? environment = null,
         string? userSegment = null,
@@ -49,15 +49,19 @@ private DynamicSamplingContext(
         {
             ["trace_id"] = traceId.ToString(),
             ["public_key"] = publicKey,
-            ["sample_rate"] = sampleRate.ToString(CultureInfo.InvariantCulture)
         };
 
+        // Set optional values
         if (sampled.HasValue)
         {
             items.Add("sampled", sampled.Value ? "true" : "false");
         }
 
-        // Set optional values
+        if (sampleRate is not null)
+        {
+            items.Add("sample_rate", sampleRate.Value.ToString(CultureInfo.InvariantCulture));
+        }
+
         if (!string.IsNullOrWhiteSpace(release))
         {
             items.Add("release", release);
@@ -119,7 +123,7 @@ private DynamicSamplingContext(
     public static DynamicSamplingContext CreateFromTransaction(TransactionTracer transaction, SentryOptions options)
     {
         // These should already be set on the transaction.
-        var publicKey = Dsn.Parse(options.Dsn!).PublicKey;
+        var publicKey = options.ParsedDsn.PublicKey;
         var traceId = transaction.TraceId;
         var sampled = transaction.IsSampled;
         var sampleRate = transaction.SampleRate!.Value;
@@ -140,6 +144,21 @@ public static DynamicSamplingContext CreateFromTransaction(TransactionTracer tra
             userSegment,
             transactionName);
     }
+
+    public static DynamicSamplingContext CreateFromPropagationContext(SentryPropagationContext propagationContext, SentryOptions options)
+    {
+        var publicKey = options.ParsedDsn.PublicKey;
+        var traceId = propagationContext.TraceId;
+        var release = options.SettingLocator.GetRelease();
+        var environment = options.SettingLocator.GetEnvironment();
+
+        return new DynamicSamplingContext(
+            traceId,
+            publicKey,
+            null,
+            release: release,
+            environment:environment);
+    }
 }
 
 internal static class DynamicSamplingContextExtensions
@@ -149,4 +168,7 @@ internal static class DynamicSamplingContextExtensions
 
     public static DynamicSamplingContext CreateDynamicSamplingContext(this TransactionTracer transaction, SentryOptions options)
         => DynamicSamplingContext.CreateFromTransaction(transaction, options);
+
+    public static DynamicSamplingContext CreateDynamicSamplingContext(this SentryPropagationContext propagationContext, SentryOptions options)
+        => DynamicSamplingContext.CreateFromPropagationContext(propagationContext, options);
 }

src/Sentry/Extensibility/DisabledHub.cs

@@ -74,6 +74,29 @@ public void BindException(Exception exception, ISpan span)
     /// </summary>
     public SentryTraceHeader? GetTraceHeader() => null;
 
+    /// <summary>
+    /// Returns null.
+    /// </summary>
+    public SentryTraceHeader? GetTraceParent() => null;
+
+    /// <summary>
+    /// Returns null.
+    /// </summary>
+    public BaggageHeader? GetBaggage() => null;
+
+    /// <summary>
+    /// Returns null.
+    /// </summary>
+    public TransactionContext ContinueTrace(
+        SentryTraceHeader? traceHeader,
+        BaggageHeader? baggageHeader,
+        string? name = null,
+        string? operation = null)
+    {
+        // Transactions from DisabledHub are always sampled out
+        return new TransactionContext(string.Empty, string.Empty, false);
+    }
+
     /// <summary>
     /// No-Op.
     /// </summary>

src/Sentry/Extensibility/HubAdapter.cs

@@ -106,6 +106,24 @@ public void BindException(Exception exception, ISpan span) =>
     public SentryTraceHeader? GetTraceHeader()
         => SentrySdk.GetTraceHeader();
 
+    /// <summary>
+    /// Forwards the call to <see cref="SentrySdk"/>.
+    /// </summary>
+    [DebuggerStepThrough]
+    public BaggageHeader? GetBaggage()
+        => SentrySdk.GetBaggage();
+
+    /// <summary>
+    /// Forwards the call to <see cref="SentrySdk"/>.
+    /// </summary>
+    [DebuggerStepThrough]
+    public TransactionContext ContinueTrace(
+        SentryTraceHeader? traceHeader,
+        BaggageHeader? baggageHeader,
+        string? name = null,
+        string? operation = null)
+        => SentrySdk.ContinueTrace(traceHeader, baggageHeader, name, operation);
+
     /// <summary>
     /// Forwards the call to <see cref="SentrySdk"/>.
     /// </summary>

src/Sentry/IHub.cs

@@ -40,10 +40,27 @@ ITransaction StartTransaction(
     ISpan? GetSpan();
 
     /// <summary>
-    /// Gets the Sentry trace header for the last active span.
+    /// Gets the Sentry trace header that allows tracing across services
     /// </summary>
     SentryTraceHeader? GetTraceHeader();
 
+    /// <summary>
+    /// Gets the Sentry baggage header that allows tracing across services
+    /// </summary>
+    BaggageHeader? GetBaggage();
+
+    /// <summary>
+    /// Continues a trace based on HTTP header values.
+    /// </summary>
+    /// <remarks>
+    /// If no "sentry-trace" header is provided a random trace ID and span ID is created.
+    /// </remarks>
+    TransactionContext ContinueTrace(
+        SentryTraceHeader? traceHeader,
+        BaggageHeader? baggageHeader,
+        string? name = null,
+        string? operation = null);
+
     /// <summary>
     /// Starts a new session.
     /// </summary>