Make TracerSettings properly immutable and remove ImmutableTracerSettings (#6415)

Merge `TracerSettings` with `ImmutableTracerSettings`

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

- Make the properties in `TracerSettings` get-only.
- Make the collections in `TracerSettings` readonly.
- Move logic that used to be in the constructor of
`ImmutableTracerSettings` into `TracerSettings`
- e.g. Service/Version/Env were being changed based on DD_TAGS values.
Moved that to TracerSettings and (importantly) added missing telemetry
recording of these values.
  - Added missing recording of _effective_ `DisabledInstegrations`
- Moving this logic caused some _tests_ to be broken (checking default
values). Updated the expected values of those tests in a single
- Replace all usages of `ImmutableTracerSettings` with `TracerSettings`
- Move `ITracer` to Datadog.Trace.Manual
- It's only used there, and references the manual-version of
`ImmutableTracerSettings` which we _want_ to keep.
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization in tests

All covered by existing tests (I hope) 🤞

There's still a _lot_ of scope to improve this

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397
- #6399
- #6400
- #6405
- #6408
- #6415 👈 This PR

Author: andrewlock

tracer/src/Datadog.Trace.Manual/Datadog.Trace.Manual.csproj

@@ -35,7 +35,6 @@
     <Compile Include="..\Datadog.Trace\IScope.cs" />
     <Compile Include="..\Datadog.Trace\ISpan.cs" />
     <Compile Include="..\Datadog.Trace\ISpanContext.cs" />
-    <Compile Include="..\Datadog.Trace\ITracer.cs" />
     <Compile Include="..\Datadog.Trace\SamplingPriority.cs" />
     <Compile Include="..\Datadog.Trace\SamplingPriorityValues.cs" />
     <Compile Include="..\Datadog.Trace\SpanCreationSettings.cs" />

tracer/src/Datadog.Trace/ITracer.cs tracer/src/Datadog.Trace.Manual/ITracer.cs

@@ -406,8 +406,7 @@ public static string GetEnvironmentVariable(string key, string defaultValue = nu
             configurationSource.Add(new NameValueConfigurationSource(env, ConfigurationOrigins.EnvVars));
             configurationSource.Add(GlobalConfigurationSource.Instance);
 
-            var tracerSettings = new TracerSettings(configurationSource, new ConfigurationTelemetry(), new OverrideErrorLog());
-            var settings = new ImmutableTracerSettings(tracerSettings, unusedParamNotToUsePublicApi: true);
+            var settings = new TracerSettings(configurationSource, new ConfigurationTelemetry(), new OverrideErrorLog());
 
             Log.Debug("Creating DiscoveryService for: {AgentUri}", settings.Exporter.AgentUri);
             var discoveryService = DiscoveryService.Create(
@@ -425,7 +424,7 @@ public static string GetEnvironmentVariable(string key, string defaultValue = nu
             using (cts.Token.Register(
                        () =>
                        {
-                           WriteError($"Error connecting to the Datadog Agent at {tracerSettings.Exporter.AgentUri}.");
+                           WriteError($"Error connecting to the Datadog Agent at {settings.Exporter.AgentUri}.");
                            tcs.TrySetResult(null);
                        }))
             {

tracer/src/Datadog.Trace.Tools.Runner/Utils.cs

@@ -46,7 +46,7 @@ internal class StatsAggregator : IStatsAggregator
 
         private int _currentBuffer;
 
-        internal StatsAggregator(IApi api, ImmutableTracerSettings settings, IDiscoveryService discoveryService)
+        internal StatsAggregator(IApi api, TracerSettings settings, IDiscoveryService discoveryService)
         {
             _api = api;
             _processExit = new TaskCompletionSource<bool>();
@@ -91,7 +91,7 @@ internal StatsAggregator(IApi api, ImmutableTracerSettings settings, IDiscoveryS
 
         public bool? CanComputeStats { get; private set; } = null;
 
-        public static IStatsAggregator Create(IApi api, ImmutableTracerSettings settings, IDiscoveryService discoveryService)
+        public static IStatsAggregator Create(IApi api, TracerSettings settings, IDiscoveryService discoveryService)
         {
             return settings.StatsComputationEnabled ? new StatsAggregator(api, settings, discoveryService) : new NullStatsAggregator();
         }

tracer/src/Datadog.Trace/Agent/StatsAggregator.cs

@@ -18,7 +18,7 @@ internal class RareSampler : ITraceChunkSampler
         private readonly HashSet<StatsAggregationKey> _keys = new();
         private readonly Queue<StatsAggregationKey> _cache = new();
 
-        public RareSampler(ImmutableTracerSettings settings)
+        public RareSampler(TracerSettings settings)
         {
             IsEnabled = settings.IsRareSamplerEnabled;
         }

tracer/src/Datadog.Trace/Agent/TraceSamplers/RareSampler.cs

@@ -25,7 +25,7 @@ internal class ApmAgentWriter : IEventWriter
     private static Span[]? _spanArray;
     private readonly AgentWriter _agentWriter;
 
-    public ApmAgentWriter(ImmutableTracerSettings settings, Action<Dictionary<string, float>> updateSampleRates, IDiscoveryService discoveryService, int maxBufferSize = DefaultMaxBufferSize)
+    public ApmAgentWriter(TracerSettings settings, Action<Dictionary<string, float>> updateSampleRates, IDiscoveryService discoveryService, int maxBufferSize = DefaultMaxBufferSize)
     {
         var partialFlushEnabled = settings.Exporter.PartialFlushEnabled;
         var apiRequestFactory = TracesTransportStrategy.Get(settings.Exporter);

tracer/src/Datadog.Trace/Ci/Agent/ApmAgentWriter.cs

@@ -29,7 +29,7 @@ internal class CITracerManager : TracerManager
         private static readonly IDatadogLogger Log = DatadogLogging.GetLoggerFor<CITracerManager>();
 
         public CITracerManager(
-            ImmutableTracerSettings settings,
+            TracerSettings settings,
             IAgentWriter agentWriter,
             IScopeManager scopeManager,
             IDogStatsd statsd,
@@ -145,7 +145,7 @@ public void WriteEvent(IEvent @event)
         internal class LockedManager : CITracerManager, ILockedTracer
         {
             public LockedManager(
-                ImmutableTracerSettings settings,
+                TracerSettings settings,
                 IAgentWriter agentWriter,
                 IScopeManager scopeManager,
                 IDogStatsd statsd,

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

@@ -39,7 +39,7 @@ public CITracerManagerFactory(CIVisibilitySettings settings, IDiscoveryService d
         }
 
         protected override TracerManager CreateTracerManagerFrom(
-            ImmutableTracerSettings settings,
+            TracerSettings settings,
             IAgentWriter agentWriter,
             IScopeManager scopeManager,
             IDogStatsd statsd,
@@ -64,24 +64,24 @@ protected override TracerManager CreateTracerManagerFrom(
             return new CITracerManager(settings, agentWriter, scopeManager, statsd, runtimeMetrics, logSubmissionManager, telemetry, discoveryService, dataStreamsManager, defaultServiceName, gitMetadataTagsProvider, traceSampler, spanSampler, remoteConfigurationManager, dynamicConfigurationManager, tracerFlareManager);
         }
 
-        protected override ITelemetryController CreateTelemetryController(ImmutableTracerSettings settings, IDiscoveryService discoveryService)
+        protected override ITelemetryController CreateTelemetryController(TracerSettings settings, IDiscoveryService discoveryService)
         {
             return TelemetryFactory.Instance.CreateCiVisibilityTelemetryController(settings, discoveryService, isAgentAvailable: !_settings.Agentless);
         }
 
-        protected override IGitMetadataTagsProvider GetGitMetadataTagsProvider(ImmutableTracerSettings settings, IScopeManager scopeManager, ITelemetryController telemetry)
+        protected override IGitMetadataTagsProvider GetGitMetadataTagsProvider(TracerSettings settings, IScopeManager scopeManager, ITelemetryController telemetry)
         {
             return new CIGitMetadataTagsProvider(telemetry);
         }
 
-        protected override ITraceSampler GetSampler(ImmutableTracerSettings settings)
+        protected override ITraceSampler GetSampler(TracerSettings settings)
         {
             return new CISampler();
         }
 
-        protected override bool ShouldEnableRemoteConfiguration(ImmutableTracerSettings settings) => false;
+        protected override bool ShouldEnableRemoteConfiguration(TracerSettings settings) => false;
 
-        protected override IAgentWriter GetAgentWriter(ImmutableTracerSettings settings, IDogStatsd statsd, Action<Dictionary<string, float>> updateSampleRates, IDiscoveryService discoveryService)
+        protected override IAgentWriter GetAgentWriter(TracerSettings settings, IDogStatsd statsd, Action<Dictionary<string, float>> updateSampleRates, IDiscoveryService discoveryService)
         {
             // Check for agentless scenario
             if (_settings.Agentless)
@@ -107,7 +107,7 @@ protected override IAgentWriter GetAgentWriter(ImmutableTracerSettings settings,
             return new ApmAgentWriter(settings, updateSampleRates, discoveryService, traceBufferSize);
         }
 
-        protected override IDiscoveryService GetDiscoveryService(ImmutableTracerSettings settings)
+        protected override IDiscoveryService GetDiscoveryService(TracerSettings settings)
             => _discoveryService;
     }
 }

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

@@ -133,7 +133,7 @@ public static void Initialize()
 
             // Initialize Tracer
             Log.Information("Initialize Test Tracer instance");
-            TracerManager.ReplaceGlobalManager(new ImmutableTracerSettings(tracerSettings, true), new CITracerManagerFactory(settings, discoveryService, eventPlatformProxyEnabled, UseLockedTracerManager));
+            TracerManager.ReplaceGlobalManager(tracerSettings, new CITracerManagerFactory(settings, discoveryService, eventPlatformProxyEnabled, UseLockedTracerManager));
             _ = Tracer.Instance;
 
             // Initialize FrameworkDescription
@@ -192,7 +192,7 @@ internal static void InitializeFromRunner(CIVisibilitySettings settings, IDiscov
 
             // Initialize Tracer
             Log.Information("Initialize Test Tracer instance");
-            TracerManager.ReplaceGlobalManager(new ImmutableTracerSettings(tracerSettings, true), new CITracerManagerFactory(settings, discoveryService, eventPlatformProxyEnabled, UseLockedTracerManager));
+            TracerManager.ReplaceGlobalManager(tracerSettings, new CITracerManagerFactory(settings, discoveryService, eventPlatformProxyEnabled, UseLockedTracerManager));
             _ = Tracer.Instance;
 
             // Initialize FrameworkDescription
@@ -402,12 +402,12 @@ internal static string GetServiceNameFromRepository(string? repository)
             return string.Empty;
         }
 
-        internal static IApiRequestFactory GetRequestFactory(ImmutableTracerSettings settings)
+        internal static IApiRequestFactory GetRequestFactory(TracerSettings settings)
         {
             return GetRequestFactory(settings, TimeSpan.FromSeconds(15));
         }
 
-        internal static IApiRequestFactory GetRequestFactory(ImmutableTracerSettings tracerSettings, TimeSpan timeout)
+        internal static IApiRequestFactory GetRequestFactory(TracerSettings tracerSettings, TimeSpan timeout)
         {
             IApiRequestFactory? factory = null;
             var exporterSettings = tracerSettings.Exporter;

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

@@ -87,7 +87,7 @@ public IntelligentTestRunnerClient(string? workingDirectory, CIVisibilitySetting
         _getRepositoryUrlTask = GetRepositoryUrlAsync();
         _getBranchNameTask = GetBranchNameAsync();
         _getShaTask = GetCommitShaAsync();
-        _apiRequestFactory = CIVisibility.GetRequestFactory(new ImmutableTracerSettings(_settings.TracerSettings, true), TimeSpan.FromSeconds(45));
+        _apiRequestFactory = CIVisibility.GetRequestFactory(_settings.TracerSettings, TimeSpan.FromSeconds(45));
 
         const string settingsUrlPath = "api/v2/libraries/tests/services/setting";
         const string searchCommitsUrlPath = "api/v2/git/repository/search_commits";
@@ -166,7 +166,7 @@ public IntelligentTestRunnerClient(string? workingDirectory, CIVisibilitySetting
         }
     }
 
-    internal static Dictionary<string, string>? GetCustomTestsConfigurations(IDictionary<string, string> globalTags)
+    internal static Dictionary<string, string>? GetCustomTestsConfigurations(IReadOnlyDictionary<string, string> globalTags)
     {
         Dictionary<string, string>? customConfiguration = null;
         if (globalTags is not null)

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

@@ -51,6 +51,6 @@ internal static void ConfigureSettingsWithManualOverrides(Dictionary<string, obj
         var settings = new TracerSettings(source, new ConfigurationTelemetry(), new OverrideErrorLog());
 
         // Update the global instance
-        Trace.Tracer.ConfigureInternal(new ImmutableTracerSettings(settings, true));
+        Trace.Tracer.ConfigureInternal(settings);
     }
 }

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/ManualInstrumentation/Tracer/ConfigureIntegration.cs

@@ -42,7 +42,7 @@ internal static CallTargetState OnMethodBegin<TTarget>(TTarget instance, object?
         return CallTargetState.GetDefault();
     }
 
-    internal static void PopulateSettings(Dictionary<string, object?> values, ImmutableTracerSettings settings)
+    internal static void PopulateSettings(Dictionary<string, object?> values, TracerSettings settings)
     {
         // record all the settings in the dictionary
         // This key is used to detect if the settings have been populated _at all_, so should always be sent

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/ManualInstrumentation/Tracer/CtorIntegration.cs

@@ -16,7 +16,7 @@ internal static class ServerlessMiniAgent
 {
     private static readonly IDatadogLogger Log = DatadogLogging.GetLoggerFor(typeof(ServerlessMiniAgent));
 
-    internal static string GetMiniAgentPath(PlatformID os, ImmutableTracerSettings settings)
+    internal static string GetMiniAgentPath(PlatformID os, TracerSettings settings)
     {
         if (!settings.IsRunningInGCPFunctions && !settings.IsRunningMiniAgentInAzureFunctions)
         {
@@ -52,7 +52,7 @@ internal static string GetMiniAgentPath(PlatformID os, ImmutableTracerSettings s
         return Path.Combine(rustBinaryPathRoot, rustBinaryPathOsFolder, rustBinaryName);
     }
 
-    internal static void StartServerlessMiniAgent(ImmutableTracerSettings settings)
+    internal static void StartServerlessMiniAgent(TracerSettings settings)
     {
         var serverlessMiniAgentPath = ServerlessMiniAgent.GetMiniAgentPath(Environment.OSVersion.Platform, settings);
         if (string.IsNullOrEmpty(serverlessMiniAgentPath))

tracer/src/Datadog.Trace/ClrProfiler/ServerlessInstrumentation/ServerlessMiniAgent.cs

@@ -83,7 +83,7 @@ private static void OnConfigurationChanged(ConfigurationBuilder settings)
                 GlobalSamplingRate = settings.WithKeys(ConfigurationKeys.GlobalSamplingRate).AsDouble(),
                 // SpanSamplingRules = settings.WithKeys(ConfigurationKeys.SpanSamplingRules).AsString(),
                 LogsInjectionEnabled = settings.WithKeys(ConfigurationKeys.LogsInjectionEnabled).AsBool(),
-                HeaderTags = headerTags == null ? null : new ReadOnlyDictionary<string, string>(headerTags),
+                HeaderTags = headerTags,
                 // ServiceNameMappings = serviceNameMappings == null ? null : new ReadOnlyDictionary<string, string>(serviceNameMappings)
                 GlobalTags = globalTags == null ? null : new ReadOnlyDictionary<string, string>(globalTags)
             };

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

@@ -20,12 +20,12 @@ namespace Datadog.Trace.Configuration;
 internal class GitMetadataTagsProvider : IGitMetadataTagsProvider
 {
     private readonly ITelemetryController _telemetry;
-    private readonly ImmutableTracerSettings _immutableTracerSettings;
+    private readonly TracerSettings _immutableTracerSettings;
     private readonly IScopeManager _scopeManager;
     private GitMetadata? _cachedGitTags = null;
     private int _tryCount = 0;
 
-    public GitMetadataTagsProvider(ImmutableTracerSettings immutableTracerSettings, IScopeManager scopeManager, ITelemetryController telemetry)
+    public GitMetadataTagsProvider(TracerSettings immutableTracerSettings, IScopeManager scopeManager, ITelemetryController telemetry)
     {
         _immutableTracerSettings = immutableTracerSettings;
         _scopeManager = scopeManager;