Was added the GC Mode, Total Exceptions and Reason of Exceptions (#37)

* Was added the GC Mode, Total Exceptions and Reason of Exceptions

* Removed the redundant metric, created a unit test for exception statistics and metric name adjustment according to prometheus convention.

* Decreasing the waiting time

* Label changed to error class namespace and unit test improvement

examples/AspNetCoreExample/Controllers/ValuesController.cs

@@ -28,7 +28,14 @@ public async Task<ActionResult<IEnumerable<string>>> Get()
 
             var val = this.r.Next();
             CompileMe(() => val);
-
+
+            try
+            {
+                var divide = 0;
+                var result = 1 / divide;
+            }
+            catch { }
+
             return new string[] {"value1" + this.r.Next(), "value2"+ this.r.Next()};
         }
 

examples/AspNetCoreExample/Program.cs

@@ -26,6 +26,7 @@ public static void Main(string[] args)
                     .WithGcStats()
                     .WithJitStats()
                     .WithThreadPoolStats()
+                    .WithExceptionStats()
                     .WithErrorHandler(ex => Console.WriteLine("ERROR: " + ex.ToString()))
                     //.WithDebuggingMetrics(true);
                     .StartCollecting();

src/prometheus-net.DotNetRuntime.Tests/StatsCollectors/IntegrationTests/ExceptionStatsCollectorTests.cs

@@ -0,0 +1,52 @@
+using NUnit.Framework;
+using Prometheus.DotNetRuntime.StatsCollectors;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Prometheus.DotNetRuntime.Tests.StatsCollectors.IntegrationTests
+{
+    [TestFixture]
+    internal class ExceptionStatsCollectorTests : StatsCollectorIntegrationTestBase<ExceptionStatsCollector>
+    {
+        protected override ExceptionStatsCollector CreateStatsCollector()
+        {
+            return new ExceptionStatsCollector();
+        }
+
+        [Test]
+        public void Will_measure_when_occurring_an_exception()
+        {
+            // arrange
+            int divider = 0;
+            string exceptionMessage = string.Empty;
+
+            // act
+            try
+            {
+                var result = 1 / divider;
+            }
+            catch (Exception ex)
+            {
+                exceptionMessage = ex.GetType().FullName;
+            }
+
+            // assert
+            Assert.That(() => StatsCollector.ExceptionReasons.Labels(exceptionMessage).Value, Is.EqualTo(1).After(100, 1000));
+        }
+
+        [Test]
+        public void Will_measure_when_not_occurring_an_exception()
+        {
+            // arrange
+            int divider = 1;
+            string exceptionMessage = string.Empty;
+
+            // act
+            var result = 1 / divider;
+
+            // assert
+            Assert.That(() => StatsCollector.ExceptionReasons.Labels(exceptionMessage).Value, Is.EqualTo(0).After(100, 1000));
+        }
+    }
+}

src/prometheus-net.DotNetRuntime/DotNetRuntimeStatsBuilder.cs

@@ -28,7 +28,8 @@ public static Builder Default()
                 .WithJitStats()
                 .WithThreadPoolSchedulingStats()
                 .WithThreadPoolStats()
-                .WithGcStats();
+                .WithGcStats()
+                .WithExceptionStats();
         }
 
         /// <summary>
@@ -149,6 +150,15 @@ public Builder WithGcStats(double[] histogramBuckets = null)
                 return this;
             }
 
+            /// <summary>
+            /// Includes quantitative and qualitative metrics of exceptions thrown
+            /// </summary>
+            public Builder WithExceptionStats()
+            {
+                StatsCollectors.AddOrReplace(new ExceptionStatsCollector());
+                return this;
+            }
+
             public Builder WithCustomCollector(IEventSourceStatsCollector statsCollector)
             {
                 StatsCollectors.AddOrReplace(statsCollector);

src/prometheus-net.DotNetRuntime/DotNetRuntimeStatsCollector.cs

@@ -3,6 +3,7 @@
 using System.Collections.Immutable;
 using System.Linq;
 using System.Reflection;
+using System.Runtime;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 #if PROMV2
@@ -114,15 +115,17 @@ private void SetupConstantMetrics(MetricFactory metrics)
                     "target_framework",
                     "runtime_version",
                     "os_version",
-                    "process_architecture"
+                    "process_architecture",
+                    "gc_mode"
                 );
 
                 buildInfo.Labels(
                         this.GetType().Assembly.GetName().Version.ToString(),
                         Assembly.GetEntryAssembly().GetCustomAttribute<TargetFrameworkAttribute>().FrameworkName,
                         RuntimeInformation.FrameworkDescription,
                         RuntimeInformation.OSDescription,
-                        RuntimeInformation.ProcessArchitecture.ToString()
+                        RuntimeInformation.ProcessArchitecture.ToString(),
+                        GCSettings.IsServerGC ? "Server" : "Workstation"
                     )
                     .Set(1);
             }

src/prometheus-net.DotNetRuntime/StatsCollectors/ExceptionStatsCollector.cs

@@ -0,0 +1,46 @@
+using Prometheus.DotNetRuntime.EventSources;
+using System;
+using System.Diagnostics.Tracing;
+#if PROMV2
+using Prometheus.Advanced;
+#endif
+
+
+namespace Prometheus.DotNetRuntime.StatsCollectors
+{
+    public class ExceptionStatsCollector : IEventSourceStatsCollector
+    {
+        private const int EventIdExceptionThrown = 80;
+        private const string LabelReason = "exception";
+
+        internal Counter ExceptionReasons { get; private set; }
+
+        public Guid EventSourceGuid => DotNetRuntimeEventSource.Id;
+
+        public EventKeywords Keywords => (EventKeywords)DotNetRuntimeEventSource.Keywords.Exception;
+        public EventLevel Level => EventLevel.Informational;
+
+        public void RegisterMetrics(MetricFactory metrics)
+        {
+            ExceptionReasons = metrics.CreateCounter(
+                "dotnet_exception_reasons_total",
+                "Reasons that led to an exception",
+                LabelReason
+            );
+        }
+
+        public void UpdateMetrics()
+        {
+
+        }
+
+        public void ProcessEvent(EventWrittenEventArgs e)
+        {
+            if (e.EventId == EventIdExceptionThrown)
+            {
+                ExceptionReasons.Labels((string)e.Payload[0]).Inc();
+            }
+        }
+    }
+
+}