Uploaded image for project: 'SLF4J'
  1. SLF4J
  2. SLF4J-371

Support the lambda expression in the Logger

    XMLWordPrintable

Details

    • Icon: Improvement Improvement
    • Resolution: Fixed
    • Icon: Major Major
    • 2.0.0-alpha1
    • 1.7.22
    • Core API
    • None

    Description

      In some cases, we don't want to calculate the expression for logging eagerly cause the performance reason. Then, we would write the code like the following:

      if (LOGGER.isWarnEnabled())
      {
       LOGGER.warn("some message: {}", Json.serialize(obj));
      }

      Before JDK8, there is no way to encapsulate the above code, because the expression is always calculated before passed as an argument. So, many "if"s appear in the code and smell badly.

      Now, the lambda expression is supported by JDK8, the above could be simplified like following:

      LOGGER.warn(formatter -> formatter.format("some message: {}", Json.serialize(obj)));

      With the default method definition in the org.slf4j.Logger:

      public interface Logger
      {
       default void warn(Function<MessageFormatter, String> messageSupplier)
       {
        if (this.isWarnEnabled())
        {
         /* Calculate the expression only if the WARN level logging is enabled. */
         this.warn(messageSupplier.apply(this.getFormatter()));
        }
       }
      }

      Attachments

        There are no Sub-Tasks for this issue.

        Activity

          People

            ceki Ceki Gülcü
            JasonMing MiNG
            Votes:
            65 Vote for this issue
            Watchers:
            55 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved: