Metrics: Avoid defensive copies of MetricPoint struct (#3065)

open-telemetry · Mar 18, 2022 · bdcf942 · bdcf942
1 parent 45964ca
commit bdcf942
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Showing 2 changed files with 16 additions and 12 deletions.
diff --git a/src/OpenTelemetry/CHANGELOG.md b/src/OpenTelemetry/CHANGELOG.md
@@ -20,6 +20,10 @@
   to `-1`.
   ([#3038](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3038))
 
+* Marked members of the `MetricPoint` `struct` which do not mutate state as
+  `readonly`
+  ([#3065](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3065))
+
 ## 1.2.0-rc3
 
 Released 2022-Mar-04

diff --git a/src/OpenTelemetry/Metrics/MetricPoint.cs b/src/OpenTelemetry/Metrics/MetricPoint.cs
@@ -74,7 +74,7 @@ internal MetricPoint(
         /// <summary>
         /// Gets the tags associated with the metric point.
         /// </summary>
-        public ReadOnlyTagCollection Tags
+        public readonly ReadOnlyTagCollection Tags
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             get;
@@ -86,7 +86,7 @@ public ReadOnlyTagCollection Tags
         public DateTimeOffset StartTime
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get;
+            readonly get;
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             internal set;
@@ -98,7 +98,7 @@ public DateTimeOffset StartTime
         public DateTimeOffset EndTime
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get;
+            readonly get;
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             internal set;
@@ -107,7 +107,7 @@ public DateTimeOffset EndTime
         internal MetricPointStatus MetricPointStatus
         {
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get;
+            readonly get;
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             private set;
@@ -121,7 +121,7 @@ internal MetricPointStatus MetricPointStatus
         /// </remarks>
         /// <returns>Long sum value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public long GetSumLong()
+        public readonly long GetSumLong()
         {
             if (this.aggType != AggregationType.LongSumIncomingDelta && this.aggType != AggregationType.LongSumIncomingCumulative)
             {
@@ -139,7 +139,7 @@ public long GetSumLong()
         /// </remarks>
         /// <returns>Double sum value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public double GetSumDouble()
+        public readonly double GetSumDouble()
         {
             if (this.aggType != AggregationType.DoubleSumIncomingDelta && this.aggType != AggregationType.DoubleSumIncomingCumulative)
             {
@@ -157,7 +157,7 @@ public double GetSumDouble()
         /// </remarks>
         /// <returns>Long gauge value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public long GetGaugeLastValueLong()
+        public readonly long GetGaugeLastValueLong()
         {
             if (this.aggType != AggregationType.LongGauge)
             {
@@ -175,7 +175,7 @@ public long GetGaugeLastValueLong()
         /// </remarks>
         /// <returns>Double gauge value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public double GetGaugeLastValueDouble()
+        public readonly double GetGaugeLastValueDouble()
         {
             if (this.aggType != AggregationType.DoubleGauge)
             {
@@ -193,7 +193,7 @@ public double GetGaugeLastValueDouble()
         /// </remarks>
         /// <returns>Count value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public long GetHistogramCount()
+        public readonly long GetHistogramCount()
         {
             if (this.aggType != AggregationType.Histogram && this.aggType != AggregationType.HistogramSumCount)
             {
@@ -211,7 +211,7 @@ public long GetHistogramCount()
         /// </remarks>
         /// <returns>Sum value.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public double GetHistogramSum()
+        public readonly double GetHistogramSum()
         {
             if (this.aggType != AggregationType.Histogram && this.aggType != AggregationType.HistogramSumCount)
             {
@@ -229,7 +229,7 @@ public double GetHistogramSum()
         /// </remarks>
         /// <returns><see cref="HistogramBuckets"/>.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public HistogramBuckets GetHistogramBuckets()
+        public readonly HistogramBuckets GetHistogramBuckets()
         {
             if (this.aggType != AggregationType.Histogram && this.aggType != AggregationType.HistogramSumCount)
             {
@@ -542,7 +542,7 @@ internal void TakeSnapshot(bool outputDelta)
         }
 
         [MethodImpl(MethodImplOptions.NoInlining)]
-        private void ThrowNotSupportedMetricTypeException(string methodName)
+        private readonly void ThrowNotSupportedMetricTypeException(string methodName)
         {
             throw new NotSupportedException($"{methodName} is not supported for this metric type.");
         }