Implement EventId to LogEventProperty cache.

Author: andrii-babanin-sym

src/Serilog.Extensions.Logging/Extensions/Logging/EventIdPropertyCache.cs

@@ -0,0 +1,72 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Serilog.Extensions.Logging
+{
+    using Microsoft.Extensions.Logging;
+    using Serilog.Events;
+
+    internal sealed class EventIdPropertyCache
+    {
+        private readonly object _createLock = new();
+        private readonly int _maxCapacity;
+        private readonly Dictionary<int, LogEventProperty> _propertyCache;
+
+        private int count;
+
+        public EventIdPropertyCache(int maxCapacity)
+        {
+            this._maxCapacity = maxCapacity;
+            this._propertyCache = new Dictionary<int, LogEventProperty>(capacity: maxCapacity);
+        }
+
+        public LogEventProperty GetOrCreateProperty(in EventId eventId)
+        {
+            if (_propertyCache.TryGetValue(eventId.Id, out var cachedProperty))
+            {
+                return cachedProperty;
+            }
+
+            lock (_createLock)
+            {
+                return GetOrCreateSynchronized(in eventId);
+            }
+        }
+
+        private static LogEventProperty CreateCore(in EventId eventId)
+        {
+            var properties = new List<LogEventProperty>(2);
+
+            if (eventId.Id != 0)
+            {
+                properties.Add(new LogEventProperty("Id", new ScalarValue(eventId.Id)));
+            }
+
+            if (eventId.Name != null)
+            {
+                properties.Add(new LogEventProperty("Name", new ScalarValue(eventId.Name)));
+            }
+
+            return new LogEventProperty("EventId", new StructureValue(properties));
+        }
+
+        private LogEventProperty GetOrCreateSynchronized(in EventId eventId)
+        {
+            // Double check under lock
+            if (_propertyCache.TryGetValue(eventId.Id, out var cachedProperty))
+            {
+                return cachedProperty;
+            }
+
+            cachedProperty = CreateCore(in eventId);
+
+            if (count < _maxCapacity)
+            {
+                _propertyCache[eventId.Id] = cachedProperty;
+                count++;
+            }
+            
+            return cachedProperty;
+        }
+    }
+}