Allow strong-typed metrics with 30+ tags

docs/list-of-diagnostics.md

@@ -117,7 +117,6 @@ You may continue using obsolete APIs in your application, but we advise explorin
 | `METGEN010` | Metric methods must be static |
 | `METGEN011` | A strong type object contains duplicate tag names |
 | `METGEN012` | A metric class contains an invalid tag name type |
-| `METGEN013` | A metric class contains too many tag names |
 | `METGEN014` | A metering attribute type argument is invalid |
 | `METGEN015` | Metric methods mustn't use any external type as the return type |
 | `METGEN016` | Metric methods mustn't use any generic type as the return type |

src/Generators/Microsoft.Gen.Metrics/DiagDescriptors.cs

@@ -89,12 +89,6 @@ internal sealed class DiagDescriptors : DiagDescriptorsBase
         messageFormat: Resources.ErrorInvalidTagTypeMessage,
         category: Category);
 
-    public static DiagnosticDescriptor ErrorTooManyTagNames { get; } = Make(
-        id: DiagnosticIds.Metrics.METGEN013,
-        title: Resources.ErrorTooManyTagNamesTitle,
-        messageFormat: Resources.ErrorTooManyTagNamesMessage,
-        category: Category);
-
     public static DiagnosticDescriptor ErrorInvalidAttributeGenericType { get; } = Make(
         id: DiagnosticIds.Metrics.METGEN014,
         title: Resources.ErrorInvalidAttributeGenericTypeTitle,

src/Generators/Microsoft.Gen.Metrics/Parser.cs

@@ -20,8 +20,6 @@ namespace Microsoft.Gen.Metrics;
 
 internal sealed class Parser
 {
-    private const int MaxTagNames = 30;
-
     private static readonly Regex _regex = new("^[A-Z]+[A-za-z0-9]*$", RegexOptions.Compiled);
     private static readonly Regex _regexTagNames = new("^[A-Za-z_]+[A-Za-z0-9_.:-]*$", RegexOptions.Compiled);
     private static readonly SymbolDisplayFormat _typeSymbolFormat =
@@ -667,11 +665,6 @@ private StrongTypeAttributeParameters ExtractStrongTypeAttributeParameters(
                 ex.NamedType.ToDisplayString());
         }
 
-        if (strongTypeAttributeParameters.TagHashSet.Count > MaxTagNames)
-        {
-            Diag(DiagDescriptors.ErrorTooManyTagNames, strongTypeSymbol.Locations[0]);
-        }
-
         strongTypeAttributeParameters.StrongTypeObjectName = constructorArg.Value.ToString();
         return strongTypeAttributeParameters;
     }

src/Generators/Microsoft.Gen.Metrics/Resources.resx

@@ -213,12 +213,6 @@
   <data name="ErrorNotStaticMethodTitle" xml:space="preserve">
     <value>Metric methods must be static</value>
   </data>
-  <data name="ErrorTooManyTagNamesMessage" xml:space="preserve">
-    <value>The type {0} has too many tag names</value>
-  </data>
-  <data name="ErrorTooManyTagNamesTitle" xml:space="preserve">
-    <value>A metric class contains too many tag names</value>
-  </data>
   <data name="ErrorXmlNotLoadedCorrectlyTitle" xml:space="preserve">
     <value>Xml comment was not parsed correctly</value>
   </data>

test/Generators/Microsoft.Gen.Metrics/Generated/MetricTests.cs

@@ -608,4 +608,24 @@ public void ValidateCounterStrongType()
             },
             measurement.Tags.Select(x => (x.Key, x.Value)));
     }
+
+    [Fact]
+    public void ValidateStrongTypeWithMoreThanThirtyTags()
+    {
+        var tags = new ManyTagsDimensions();
+        for (int i = 1; i <= 33; i++)
+        {
+            typeof(ManyTagsDimensions).GetProperty($"D{i}")!.SetValue(tags, $"v{i}");
+        }
+
+        using var collector = new MetricCollector<long>(_meter, nameof(ManyTagsCounter));
+        ManyTagsCounter counter = ManyTagsTestExtensions.CreateManyTagsCounter(_meter);
+        counter.Add(1L, tags);
+
+        var measurement = Assert.Single(collector.GetMeasurementSnapshot());
+        Assert.Equal(1L, measurement.Value);
+        Assert.Equal(
+            Enumerable.Range(1, 33).Select(i => ($"D{i}", (object?)$"v{i}")),
+            measurement.Tags.Select(x => (x.Key, x.Value)));
+    }
 }

test/Generators/Microsoft.Gen.Metrics/TestClasses/ManyTagsTestExtensions.cs

@@ -0,0 +1,53 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.Metrics;
+using Microsoft.Extensions.Diagnostics.Metrics;
+
+namespace TestClasses
+{
+#pragma warning disable SA1402 // File may only contain a single type
+    internal static partial class ManyTagsTestExtensions
+    {
+        [Counter(typeof(ManyTagsDimensions))]
+        public static partial ManyTagsCounter CreateManyTagsCounter(Meter meter);
+    }
+
+    public class ManyTagsDimensions
+    {
+        public string D1 { get; set; } = string.Empty;
+        public string D2 { get; set; } = string.Empty;
+        public string D3 { get; set; } = string.Empty;
+        public string D4 { get; set; } = string.Empty;
+        public string D5 { get; set; } = string.Empty;
+        public string D6 { get; set; } = string.Empty;
+        public string D7 { get; set; } = string.Empty;
+        public string D8 { get; set; } = string.Empty;
+        public string D9 { get; set; } = string.Empty;
+        public string D10 { get; set; } = string.Empty;
+        public string D11 { get; set; } = string.Empty;
+        public string D12 { get; set; } = string.Empty;
+        public string D13 { get; set; } = string.Empty;
+        public string D14 { get; set; } = string.Empty;
+        public string D15 { get; set; } = string.Empty;
+        public string D16 { get; set; } = string.Empty;
+        public string D17 { get; set; } = string.Empty;
+        public string D18 { get; set; } = string.Empty;
+        public string D19 { get; set; } = string.Empty;
+        public string D20 { get; set; } = string.Empty;
+        public string D21 { get; set; } = string.Empty;
+        public string D22 { get; set; } = string.Empty;
+        public string D23 { get; set; } = string.Empty;
+        public string D24 { get; set; } = string.Empty;
+        public string D25 { get; set; } = string.Empty;
+        public string D26 { get; set; } = string.Empty;
+        public string D27 { get; set; } = string.Empty;
+        public string D28 { get; set; } = string.Empty;
+        public string D29 { get; set; } = string.Empty;
+        public string D30 { get; set; } = string.Empty;
+        public string D31 { get; set; } = string.Empty;
+        public string D32 { get; set; } = string.Empty;
+        public string D33 { get; set; } = string.Empty;
+    }
+#pragma warning restore SA1402
+}

test/Generators/Microsoft.Gen.Metrics/Unit/ParserTests.Diagnostics.cs

@@ -357,32 +357,6 @@ public static partial class MetricClass
         Assert.Equal(DiagDescriptors.ErrorInvalidTagNameType.Id, d[0].Id);
     }
 
-    [Fact]
-    public async Task TooManyDimensions()
-    {
-        StringBuilder sb = new StringBuilder();
-
-        int i = 0;
-
-        for (; i < 30; i++)
-        {
-            sb.AppendLine($"public class C{i} : C{i + 1} {{ public string dim{i} {{get;set;}}}}");
-        }
-
-        sb.AppendLine($"public class C{i} {{ public string dim{i} {{get;set;}}}}");
-
-        sb.AppendLine(@"        public static partial class MetricClass
-        {
-            [Histogram(typeof(C0), Name=""TotalCountTest"")]
-            public static partial TotalCount CreateTotalCountCounter(Meter meter);
-        }");
-
-        var d = await RunGenerator(sb.ToString());
-
-        _ = Assert.Single(d);
-        Assert.Equal(DiagDescriptors.ErrorTooManyTagNames.Id, d[0].Id);
-    }
-
     [Theory]
     [InlineData("ulong")]
     [InlineData("uint")]
@@ -540,29 +514,27 @@ partial class C
     }
 
     [Fact]
-    public async Task Gauge_StrongType_TooManyTags()
+    public async Task Gauge_StrongType_MoreThanThirtyTags()
     {
         var sb = new StringBuilder();
 
-        // Create 31 nested classes (max is 30)
-        for (int i = 0; i < 31; i++)
+        for (int i = 0; i < 33; i++)
         {
             sb.AppendLine($"public class C{i} : C{i + 1} {{ public string Tag{i} {{ get; set; }} }}");
         }
 
-        sb.AppendLine("public class C31 { public string Tag31 { get; set; } }");
+        sb.AppendLine("public class C33 { public string Tag33 { get; set; } }");
 
         sb.AppendLine(@"
         partial class C
         {
-            [Gauge(typeof(C0), Name=""TooManyTags"")]
-            static partial TooManyTags CreateGauge(Meter meter);
+            [Gauge(typeof(C0), Name=""ManyTags"")]
+            static partial ManyTags CreateGauge(Meter meter);
         }");
 
         var d = await RunGenerator(sb.ToString());
 
-        var diag = Assert.Single(d);
-        Assert.Equal(DiagDescriptors.ErrorTooManyTagNames.Id, diag.Id);
+        Assert.Empty(d);
     }
 
     [Fact]

test/Generators/Microsoft.Gen.Metrics/Unit/ParserTests.StrongTypes.cs

@@ -593,19 +593,20 @@ public static partial class MetricClass
     }
 
     [Fact]
-    public async Task MaxDimensions()
+    public async Task MoreThanThirtyDimensions()
     {
         StringBuilder sb = new StringBuilder();
-        int i = 1;
-        for (; i < 30; i++)
+        sb.AppendLine("public class ManyTags");
+        sb.AppendLine("{");
+        for (int i = 1; i <= 33; i++)
         {
-            sb.AppendLine($"public class C{i} : C{i + 1} {{ public string dim{i} {{get;set;}}}}");
+            sb.AppendLine($"    public string D{i} {{ get; set; }} = string.Empty;");
         }
 
-        sb.AppendLine($"public class C{i} {{ public string dim{i} {{get;set;}}}}");
+        sb.AppendLine("}");
         sb.AppendLine(@"        public static partial class MetricClass
         {
-            [Histogram(typeof(C1), Name=""TotalCountTest"")]
+            [Histogram(typeof(ManyTags), Name=""TotalCountTest"")]
             public static partial TotalCount CreateTotalCountCounter(Meter meter);
         }");
         var d = await RunGenerator(sb.ToString());