Restructure solution layout by module

src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Diagnostics/EntryTraceMetrics.cs

@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using System.Diagnostics.Metrics;
+
+namespace StellaOps.Scanner.EntryTrace.Diagnostics;
+
+public static class EntryTraceInstrumentation
+{
+    public static readonly Meter Meter = new("stellaops.scanner.entrytrace", "1.0.0");
+}
+
+public sealed class EntryTraceMetrics
+{
+    private readonly Counter<long> _resolutions;
+    private readonly Counter<long> _unresolved;
+
+    public EntryTraceMetrics()
+    {
+        _resolutions = EntryTraceInstrumentation.Meter.CreateCounter<long>(
+            "entrytrace_resolutions_total",
+            description: "Number of entry trace attempts by outcome.");
+        _unresolved = EntryTraceInstrumentation.Meter.CreateCounter<long>(
+            "entrytrace_unresolved_total",
+            description: "Number of unresolved entry trace hops by reason.");
+    }
+
+    public void RecordOutcome(string imageDigest, string scanId, EntryTraceOutcome outcome)
+    {
+        _resolutions.Add(1, CreateTags(imageDigest, scanId, ("outcome", outcome.ToString().ToLowerInvariant())));
+    }
+
+    public void RecordUnknown(string imageDigest, string scanId, EntryTraceUnknownReason reason)
+    {
+        _unresolved.Add(1, CreateTags(imageDigest, scanId, ("reason", reason.ToString().ToLowerInvariant())));
+    }
+
+    private static KeyValuePair<string, object?>[] CreateTags(string imageDigest, string scanId, params (string Key, object? Value)[] extras)
+    {
+        var tags = new List<KeyValuePair<string, object?>>(2 + extras.Length)
+        {
+            new("image", imageDigest),
+            new("scan.id", scanId)
+        };
+
+        foreach (var extra in extras)
+        {
+            tags.Add(new KeyValuePair<string, object?>(extra.Key, extra.Value));
+        }
+
+        return tags.ToArray();
+    }
+}