Uploaded image for project: 'Log4j 2'
  1. Log4j 2
  2. LOG4J2-1447

Garbage-free data structure for LogEvent's context map data

VotersWatch issueWatchersLinkCloneUpdate Comment AuthorReplace String in CommentUpdate Comment VisibilityDelete Comments


    • Improvement
    • Status: Closed
    • Major
    • Resolution: Fixed
    • 2.6.1
    • 2.7
    • Core
    • None


      With each logging call, context map data is copied from the ThreadContext map into the LogEvent.

      The LogEvent interface exposes this data via the getContextMap() : Map<String, String> method, and this is implementated by storing the data in a Map<String, String>. The JDK Map is not an easy data structure to make garbage-free. It would also be nice to have the ability in LogEvent to carry data of any type.

      One idea is to introduce a small interface that is general enough to be map-like but can be implemented in a garbage-free manner.

      LogEvent implementations would have an instance of this interface instead of the current java.util.Map<String, String> contextMap attribute.

      The interface could look something like this:

      interface ContextData<String, V> {
          /** Called to implement {@link LogEvent#getContextMap()}. */
          Map<String, String> asMap();
          /** Put key-value pair into the table.
              Remove key if value is null. */
          void put(String key, V value);
          /** Returns the value for the specified key. */
          V getValue(String key);
          /** Number of key-value pairs. */
          int size();
          /** Removes all key-value pairs. */
          void clear();
      // Instead of Iterators, client code provides the consumer.
           * Performs the given action for each key-value pair in this data structure
           * until all entries have been processed or the action throws an exception.
          void forEach(BiConsumer<String, ? super V> action);
       * An operation that accepts two input arguments and returns no result.
      interface BiConsumer<T,U> {
          /** Performs the operation given the specified arguments. */
          void accept(T t, U u);

      The LogEvent interface would have an additional method getContextData() : ContextData<K, V> that gives downstream components direct access to the new data structure.

      Existing downstream components would still be able to call logEvent.getContextMap() to get a Map<String, String> view of the context map data and this would work as expected.


        Issue Links


          This comment will be Viewable by All Users Viewable by All Users


            rpopma Remko Popma
            rpopma Remko Popma
            0 Vote for this issue
            4 Start watching this issue




                Issue deployment