CA1848Performance Enabled by default: No

Use the LoggerMessage delegates

Description

For high-performance logging scenarios, use the LoggerMessage pattern instead of Microsoft.Extensions.Logging.Logger`1 extension methods.

Cause

Use of logger extension methods, such as Microsoft.Extensions.Logging.LoggerExtensions.LogInformation and Microsoft.Extensions.Logging.LoggerExtensions.LogDebug.

How to fix violations

Use Microsoft.Extensions.Logging.LoggerMessageAttribute to fix violations of this rule. (Or, if you're using .NET 5 or earlier, use the Microsoft.Extensions.Logging.LoggerMessage class.)

The following code fixes the violation.

Microsoft.Extensions.Logging.LoggerMessage provides the following performance advantages over Microsoft.Extensions.Logging.Logger`1 extension methods:

Logger extension methods require "boxing" (converting) value types, such as int, into object. The Microsoft.Extensions.Logging.LoggerMessage pattern avoids boxing by using static System.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. Microsoft.Extensions.Logging.LoggerMessage only requires parsing a template once when the message is defined.

Example

public class SomethingDoer
{
   private readonly ILogger _logger;
   public SomethingDoer(ILogger<SomethingDoer> logger)
   {
       _logger = logger;
   }

   public void DoSomething()
   {
       // This call violates CA1848.
       _logger.LogInformation("Did something!");
   }
}

When to suppress

Do not suppress a warning from this rule.

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