ASP.NET Core Performant logging

One of the hidden features of ASP.NET Core is the support for LoggerMessage.

From the documentation:

LoggerMessage features create cacheable delegates that require fewer object allocations and reduced computational overhead compared to logger extension methods, such as LogInformation, LogDebug, and LogError. For high-performance logging scenarios, use the LoggerMessage pattern.

LoggerMessage provides the following performance advantages over Logger extension methods:

• Logger extension methods require "boxing" (converting) value types, such as int, into object. The LoggerMessage pattern avoids boxing by using static Action fields and extension methods with strongly-typed parameters.
• Logger extension methods must parse the message template (named format string) every time a log message is written. LoggerMessage only requires parsing a template once when the message is defined.

The best way to use it is through some extension methods on the ILogger interface:

• Create a static LoggerExtensions class

	public static class LoggerExtensions
	{
	}

view raw ILoggerExtensions.cs hosted with ❤ by GitHub
• Add a static constructor and use the Define(LogLevel, EventId, String) method to create an Action delegate for logging a message. For the Action, specify:
• The log level.
• A unique event identifier (EventId) with the name of the static extension method.
• The message template (named format string).

	static LoggerExtensions()
	{
	_indexPageRequested = LoggerMessage.Define(
	LogLevel.Information,
	new EventId(1, nameof(IndexPageRequested)),
	"GET request for Index page");
	}

view raw ILoggerExtensionsConstructor.cs hosted with ❤ by GitHub
• Store the created Action delegate in a private static field

private static readonly Action<ILogger, Exception> _indexPageRequested;

view raw ILoggerExtensionsField.cs hosted with ❤ by GitHub
• Create an extension method that invokes the delegate

	public static void IndexPageRequested(this ILogger logger)
	{
	_indexPageRequested(logger, null);
	}

view raw ILoggerExtensionsMethod.cs hosted with ❤ by GitHub