From 3919e9149fa6cd5153b162e6138bf08a24eaec9a Mon Sep 17 00:00:00 2001
From: James Crosswell <jamescrosswell@users.noreply.github.com>
Date: Mon, 2 Oct 2023 12:16:55 +1300
Subject: [PATCH] Use Lazy<T> for measurments in immutable Spans/Transactions

---
 src/Sentry/Span.cs        | 14 +++++++-------
 src/Sentry/Transaction.cs | 14 +++++++-------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/Sentry/Span.cs b/src/Sentry/Span.cs
index 5abed5d210..57873ad742 100644
--- a/src/Sentry/Span.cs
+++ b/src/Sentry/Span.cs
@@ -30,15 +30,14 @@ public class Span : ISpanData, IJsonSerializable
     public bool IsFinished => EndTimestamp is not null;
 
     // Not readonly because of deserialization
-    private Dictionary<string, Measurement>? _measurements;
-    private Dictionary<string, Measurement> LazyMeasurements => _measurements ??= new();
+    private Lazy<Dictionary<string, Measurement>> _measurements;
 
     /// <inheritdoc />
-    public IReadOnlyDictionary<string, Measurement> Measurements => LazyMeasurements;
+    public IReadOnlyDictionary<string, Measurement> Measurements => _measurements.Value;
 
     /// <inheritdoc />
     public void SetMeasurement(string name, Measurement measurement) =>
-        LazyMeasurements[name] = measurement;
+        _measurements.Value[name] = measurement;
 
     /// <inheritdoc />
     public string Operation { get; set; }
@@ -84,6 +83,7 @@ public Span(SpanId? parentSpanId, string operation)
         ParentSpanId = parentSpanId;
         TraceId = SentryId.Create();
         Operation = operation;
+        _measurements = new Lazy<Dictionary<string, Measurement>>();
     }
 
     /// <summary>
@@ -100,7 +100,7 @@ public Span(ISpan tracer)
         Status = tracer.Status;
         IsSampled = tracer.IsSampled;
         _extra = tracer.Extra.ToDictionary();
-        _measurements = tracer.Measurements.ToDictionary();
+        _measurements = new Lazy<Dictionary<string, Measurement>>(() => tracer.Measurements.ToDictionary());
         _tags = tracer is SpanTracer s ? s.InternalTags?.ToDictionary() : tracer.Tags.ToDictionary();
     }
 
@@ -125,7 +125,7 @@ public void WriteTo(Utf8JsonWriter writer, IDiagnosticLogger? logger)
         writer.WriteStringIfNotNull("timestamp", EndTimestamp);
         writer.WriteStringDictionaryIfNotEmpty("tags", _tags!);
         writer.WriteDictionaryIfNotEmpty("data", _extra!, logger);
-        writer.WriteDictionaryIfNotEmpty("measurements", _measurements, logger);
+        writer.WriteDictionaryIfNotEmpty("measurements", Measurements, logger);
 
         writer.WriteEndObject();
     }
@@ -160,7 +160,7 @@ public static Span FromJson(JsonElement json)
             IsSampled = isSampled,
             _tags = tags!,
             _extra = data!,
-            _measurements = measurements
+            _measurements = new Lazy<Dictionary<string, Measurement>>(() =>  measurements),
         };
     }
 
diff --git a/src/Sentry/Transaction.cs b/src/Sentry/Transaction.cs
index 588ba13d30..36f86690b5 100644
--- a/src/Sentry/Transaction.cs
+++ b/src/Sentry/Transaction.cs
@@ -69,15 +69,14 @@ public SentryId TraceId
     public DateTimeOffset? EndTimestamp { get; internal set; } // internal for testing
 
     // Not readonly because of deserialization
-    private Dictionary<string, Measurement>? _measurements;
-    private Dictionary<string, Measurement> LazyMeasurements => _measurements ??= new();
+    private Lazy<Dictionary<string, Measurement>> _measurements;
 
     /// <inheritdoc />
-    public IReadOnlyDictionary<string, Measurement> Measurements => LazyMeasurements;
+    public IReadOnlyDictionary<string, Measurement> Measurements => _measurements.Value;
 
     /// <inheritdoc />
     public void SetMeasurement(string name, Measurement measurement) =>
-        LazyMeasurements[name] = measurement;
+        _measurements.Value[name] = measurement;
 
     /// <inheritdoc />
     public string Operation
@@ -210,6 +209,7 @@ private Transaction(string name, TransactionNameSource nameSource)
         EventId = SentryId.Create();
         Name = name;
         NameSource = nameSource;
+        _measurements = new Lazy<Dictionary<string, Measurement>>();
     }
 
     /// <summary>
@@ -267,6 +267,7 @@ public Transaction(ITransaction tracer)
         _spans = tracer.Spans
             .Where(s => s is not SpanTracer { IsSentryRequest: true }) // Filter sentry requests created by Sentry.OpenTelemetry.SentrySpanProcessor
             .Select(s => new Span(s)).ToArray();
+        _measurements = new Lazy<Dictionary<string, Measurement>>(() => tracer.Measurements.ToDictionary());
 
         // Some items are not on the interface, but we only ever pass in a TransactionTracer anyway.
         if (tracer is TransactionTracer transactionTracer)
@@ -274,7 +275,6 @@ public Transaction(ITransaction tracer)
             SampleRate = transactionTracer.SampleRate;
             DynamicSamplingContext = transactionTracer.DynamicSamplingContext;
             TransactionProfiler = transactionTracer.TransactionProfiler;
-            _measurements = transactionTracer.Measurements.ToDictionary();
         }
     }
 
@@ -348,7 +348,7 @@ public void WriteTo(Utf8JsonWriter writer, IDiagnosticLogger? logger)
         writer.WriteDictionaryIfNotEmpty("extra", _extra, logger);
         writer.WriteStringDictionaryIfNotEmpty("tags", _tags!);
         writer.WriteArrayIfNotEmpty("spans", _spans, logger);
-        writer.WriteDictionaryIfNotEmpty("measurements", _measurements, logger);
+        writer.WriteDictionaryIfNotEmpty("measurements", Measurements, logger);
 
         writer.WriteEndObject();
     }
@@ -404,7 +404,7 @@ public static Transaction FromJson(JsonElement json)
             _breadcrumbs = breadcrumbs,
             _extra = extra,
             _tags = tags,
-            _measurements = measurements,
+            _measurements = new Lazy<Dictionary<string, Measurement>>(() =>  measurements),
             _spans = spans
         };
     }