Feature Request: Add ability to automatically hide metric columns if value is not set

src/BenchmarkDotNet/Attributes/ExceptionDiagnoserAttribute.cs

@@ -9,6 +9,10 @@ public class ExceptionDiagnoserAttribute : Attribute, IConfigSource
     {
         public IConfig Config { get; }
 
-        public ExceptionDiagnoserAttribute() => Config = ManualConfig.CreateEmpty().AddDiagnoser(ExceptionDiagnoser.Default);
+        /// <param name="displayExceptionsIfZeroValue">Display Exceptions column. True by default.</param>
+        public ExceptionDiagnoserAttribute(bool displayExceptionsIfZeroValue = true)
+        {
+            Config = ManualConfig.CreateEmpty().AddDiagnoser(new ExceptionDiagnoser(new ExceptionDiagnoserConfig(displayExceptionsIfZeroValue)));
+        }
     }
 }

src/BenchmarkDotNet/Attributes/ExceptionDiagnoserConfig.cs

@@ -0,0 +1,20 @@
+using JetBrains.Annotations;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BenchmarkDotNet.Attributes
+{
+    public class ExceptionDiagnoserConfig
+    {
+        /// <param name="displayExceptionsIfZeroValue">Determines whether the Exceptions column is displayed when its value is not calculated. True by default.</param>
+
+        [PublicAPI]
+        public ExceptionDiagnoserConfig(bool displayExceptionsIfZeroValue = true)
+        {
+            DisplayExceptionsIfZeroValue = displayExceptionsIfZeroValue;
+        }
+
+        public bool DisplayExceptionsIfZeroValue { get; }
+    }
+}

src/BenchmarkDotNet/Attributes/ThreadingDiagnoserAttribute.cs

@@ -1,6 +1,7 @@
 using System;
 using BenchmarkDotNet.Configs;
 using BenchmarkDotNet.Diagnosers;
+using JetBrains.Annotations;
 
 namespace BenchmarkDotNet.Attributes
 {
@@ -9,6 +10,15 @@ public class ThreadingDiagnoserAttribute : Attribute, IConfigSource
     {
         public IConfig Config { get; }
 
-        public ThreadingDiagnoserAttribute() => Config = ManualConfig.CreateEmpty().AddDiagnoser(ThreadingDiagnoser.Default);
+        //public ThreadingDiagnoserAttribute() => Config = ManualConfig.CreateEmpty().AddDiagnoser(ThreadingDiagnoser.Default);
+
+        /// <param name="displayLockContentionWhenZero">Display configuration for 'LockContentionCount' when it is empty. True (displayed) by default.</param>
+        /// <param name="displayCompletedWorkItemCountWhenZero">Display configuration for 'CompletedWorkItemCount' when it is empty. True (displayed) by default.</param>
+
+        [PublicAPI]
+        public ThreadingDiagnoserAttribute(bool displayLockContentionWhenZero = true, bool displayCompletedWorkItemCountWhenZero = true)
+        {
+            Config = ManualConfig.CreateEmpty().AddDiagnoser(new ThreadingDiagnoser(new ThreadingDiagnoserConfig(displayLockContentionWhenZero, displayCompletedWorkItemCountWhenZero)));
+        }
     }
 }

src/BenchmarkDotNet/Diagnosers/ExceptionDiagnoser.cs

@@ -1,4 +1,5 @@
 using BenchmarkDotNet.Analysers;
+using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Columns;
 using BenchmarkDotNet.Engines;
 using BenchmarkDotNet.Exporters;
@@ -14,9 +15,11 @@ namespace BenchmarkDotNet.Diagnosers
 {
     public class ExceptionDiagnoser : IDiagnoser
     {
-        public static readonly ExceptionDiagnoser Default = new ExceptionDiagnoser();
+        public static readonly ExceptionDiagnoser Default = new ExceptionDiagnoser(new ExceptionDiagnoserConfig(displayExceptionsIfZeroValue: true));
 
-        private ExceptionDiagnoser() { }
+        public ExceptionDiagnoser(ExceptionDiagnoserConfig config) => Config = config;
+
+        public ExceptionDiagnoserConfig Config { get; }
 
         public IEnumerable<string> Ids => new[] { nameof(ExceptionDiagnoser) };
 
@@ -32,14 +35,18 @@ public void Handle(HostSignal signal, DiagnoserActionParameters parameters) { }
 
         public IEnumerable<Metric> ProcessResults(DiagnoserResults results)
         {
-            yield return new Metric(ExceptionsFrequencyMetricDescriptor.Instance, results.ExceptionFrequency);
+            yield return new Metric(new ExceptionsFrequencyMetricDescriptor(Config), results.ExceptionFrequency);
         }
 
         public IEnumerable<ValidationError> Validate(ValidationParameters validationParameters) => Enumerable.Empty<ValidationError>();
 
-        private class ExceptionsFrequencyMetricDescriptor : IMetricDescriptor
+        internal class ExceptionsFrequencyMetricDescriptor : IMetricDescriptor
         {
-            internal static readonly IMetricDescriptor Instance = new ExceptionsFrequencyMetricDescriptor();
+            public ExceptionDiagnoserConfig Config { get; }
+            public ExceptionsFrequencyMetricDescriptor(ExceptionDiagnoserConfig config = null)
+            {
+                Config = config;
+            }
 
             public string Id => "ExceptionFrequency";
             public string DisplayName => Column.Exceptions;
@@ -49,7 +56,13 @@ private class ExceptionsFrequencyMetricDescriptor : IMetricDescriptor
             public string Unit => "Count";
             public bool TheGreaterTheBetter => false;
             public int PriorityInCategory => 0;
-            public bool GetIsAvailable(Metric metric) => true;
+            public bool GetIsAvailable(Metric metric)
+            {
+                if (Config == null)
+                    return metric.Value > 0;
+                else
+                    return Config.DisplayExceptionsIfZeroValue || metric.Value > 0;
+            }
         }
     }
-}
+}

src/BenchmarkDotNet/Diagnosers/ThreadingDiagnoser.cs

@@ -15,9 +15,10 @@ namespace BenchmarkDotNet.Diagnosers
 {
     public class ThreadingDiagnoser : IDiagnoser
     {
-        public static readonly ThreadingDiagnoser Default = new ThreadingDiagnoser();
+        public static readonly ThreadingDiagnoser Default = new ThreadingDiagnoser(new ThreadingDiagnoserConfig(displayCompletedWorkItemCountWhenZero: true, displayLockContentionWhenZero: true));
 
-        private ThreadingDiagnoser() { }
+        public ThreadingDiagnoser(ThreadingDiagnoserConfig config) => Config = config;
+        public ThreadingDiagnoserConfig Config { get; }
 
         public IEnumerable<string> Ids => new[] { nameof(ThreadingDiagnoser) };
 
@@ -33,8 +34,9 @@ public void Handle(HostSignal signal, DiagnoserActionParameters parameters) { }
 
         public IEnumerable<Metric> ProcessResults(DiagnoserResults results)
         {
-            yield return new Metric(CompletedWorkItemCountMetricDescriptor.Instance, results.ThreadingStats.CompletedWorkItemCount / (double)results.ThreadingStats.TotalOperations);
-            yield return new Metric(LockContentionCountMetricDescriptor.Instance, results.ThreadingStats.LockContentionCount / (double)results.ThreadingStats.TotalOperations);
+
+            yield return new Metric(new CompletedWorkItemCountMetricDescriptor(Config), results.ThreadingStats.CompletedWorkItemCount / (double)results.ThreadingStats.TotalOperations);
+            yield return new Metric(new LockContentionCountMetricDescriptor(Config), results.ThreadingStats.LockContentionCount / (double)results.ThreadingStats.TotalOperations);
         }
 
         public IEnumerable<ValidationError> Validate(ValidationParameters validationParameters)
@@ -50,10 +52,15 @@ public IEnumerable<ValidationError> Validate(ValidationParameters validationPara
             }
         }
 
-        private class CompletedWorkItemCountMetricDescriptor : IMetricDescriptor
+        internal class CompletedWorkItemCountMetricDescriptor : IMetricDescriptor
         {
             internal static readonly IMetricDescriptor Instance = new CompletedWorkItemCountMetricDescriptor();
 
+            private ThreadingDiagnoserConfig Config { get; }
+            public CompletedWorkItemCountMetricDescriptor(ThreadingDiagnoserConfig config = null)
+            {
+                Config = config;
+            }
             public string Id => "CompletedWorkItemCount";
             public string DisplayName => Column.CompletedWorkItems;
             public string Legend => "The number of work items that have been processed in ThreadPool (per single operation)";
@@ -62,13 +69,26 @@ private class CompletedWorkItemCountMetricDescriptor : IMetricDescriptor
             public string Unit => "Count";
             public bool TheGreaterTheBetter => false;
             public int PriorityInCategory => 0;
-            public bool GetIsAvailable(Metric metric) => true;
+            public bool GetIsAvailable(Metric metric)
+            {
+                if (Config == null)
+                    return metric.Value > 0;
+                else
+                    return Config.DisplayCompletedWorkItemCountWhenZero || metric.Value > 0;
+            }
         }
 
-        private class LockContentionCountMetricDescriptor : IMetricDescriptor
+        internal class LockContentionCountMetricDescriptor : IMetricDescriptor
         {
             internal static readonly IMetricDescriptor Instance = new LockContentionCountMetricDescriptor();
 
+            private ThreadingDiagnoserConfig Config { get; }
+
+            public LockContentionCountMetricDescriptor(ThreadingDiagnoserConfig config = null)
+            {
+                Config = config;
+            }
+
             public string Id => "LockContentionCount";
             public string DisplayName => Column.LockContentions;
             public string Legend => "The number of times there was contention upon trying to take a Monitor's lock (per single operation)";
@@ -77,7 +97,13 @@ private class LockContentionCountMetricDescriptor : IMetricDescriptor
             public string Unit => "Count";
             public bool TheGreaterTheBetter => false;
             public int PriorityInCategory => 0;
-            public bool GetIsAvailable(Metric metric) => true;
+            public bool GetIsAvailable(Metric metric)
+            {
+                if (Config == null)
+                    return metric.Value > 0;
+                else
+                    return Config.DisplayLockContentionWhenZero || metric.Value > 0;
+            }
         }
     }
 }

src/BenchmarkDotNet/Diagnosers/ThreadingDiagnoserConfig.cs

@@ -0,0 +1,23 @@
+using JetBrains.Annotations;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BenchmarkDotNet.Diagnosers
+{
+    public class ThreadingDiagnoserConfig
+    {
+        /// <param name="displayLockContentionWhenZero">Display configuration for 'LockContentionCount' when it is empty. True (displayed) by default.</param>
+        /// <param name="displayCompletedWorkItemCountWhenZero">Display configuration for 'CompletedWorkItemCount' when it is empty. True (displayed) by default.</param>
+
+        [PublicAPI]
+        public ThreadingDiagnoserConfig(bool displayLockContentionWhenZero = true, bool displayCompletedWorkItemCountWhenZero = true)
+        {
+            DisplayLockContentionWhenZero = displayLockContentionWhenZero;
+            DisplayCompletedWorkItemCountWhenZero = displayCompletedWorkItemCountWhenZero;
+        }
+
+        public bool DisplayLockContentionWhenZero { get; }
+        public bool DisplayCompletedWorkItemCountWhenZero { get; }
+    }
+}