Removed boxing and string allocations in DateTimeOffset/DateTime seri…

…alization for legacy (but still frequently used) MessageTemplateTextFormatter
serilog · Aug 20, 2024 · 64fccfa · 64fccfa
1 parent 8c82a50
commit 64fccfa
Showing 1 changed file with 37 additions and 0 deletions.
diff --git a/src/Serilog/Events/ScalarValue.cs b/src/Serilog/Events/ScalarValue.cs
@@ -95,6 +95,43 @@ internal static void Render(object? value, TextWriter output, string? format = n
         }
     }
 
+#if FEATURE_SPAN
+    internal static void Render<T>(T value, TextWriter output, string? format = null, IFormatProvider? formatProvider = null) where T : struct, IFormattable, ISpanFormattable
+    {
+        Guard.AgainstNull(output);
+
+        var custom = (ICustomFormatter?)formatProvider?.GetFormat(typeof(ICustomFormatter));
+        if (custom != null)
+        {
+            WriteWithCustomFormatter(value, output, format, formatProvider, custom);
+            return;
+        }
+
+        formatProvider ??= CultureInfo.InvariantCulture;
+        if (TryWriteSpanFormattable(value, output, format, formatProvider))
+            return;
+
+        output.Write(value.ToString(format, formatProvider));
+    }
+
+    static void WriteWithCustomFormatter<T>(T value, TextWriter output, string? format, IFormatProvider? formatProvider, ICustomFormatter custom) where T : struct, IFormattable
+    {
+        output.Write(custom.Format(format, value, formatProvider));
+    }
+
+    static bool TryWriteSpanFormattable<T>(T value, TextWriter output, string? format, IFormatProvider formatProvider) where T : struct, ISpanFormattable
+    {
+        Span<char> buffer = stackalloc char[36]; // large enough to fit ISO 8601 timestamp (DateTimeOffset.ToString("O"))
+        if (value.TryFormat(buffer, out var charsWritten, format, formatProvider))
+        {
+            output.Write(buffer[..charsWritten]);
+            return true;
+        }
+
+        return false;
+    }
+#endif
+
     /// <summary>
     /// Determine if this instance is equal to <paramref name="obj"/>.
     /// </summary>