package org.lsst.ccs.utilities.logging;
   
   import java.util.LinkedHashMap;
   import java.util.Map;
   import java.util.logging.LogRecord;
   
   /**
    * A utility to plug into Handlers that want to detect duplicate logs.
    * it keeps a list of the 32 last logs and return false to the <TT>isLoggable</TT> method
   * if a <TT>LogRecord</TT> with the same sequence number has been processed.
   * @author bamade
   */
  // Date: 29/05/13
  
  public class IsLoggableDelegate {
      private static final int MAX_ENTRIES = 32;
      private LinkedHashMap<Long, String> mapRecords =
              // the size of the Map is the nearest prime number more than MAX_ENTRIES
              new LinkedHashMap<Long, String>(37){
                  @Override
                  protected boolean removeEldestEntry(Map.Entry eldest) {
                      return size() > MAX_ENTRIES;
                  }
              } ;
      // if the logRecord is already in the map the put does not return null
      public boolean isLoggable(LogRecord logRecord) {
          String logger = logRecord.getLoggerName();
          long seqNumber = logRecord.getSequenceNumber() ;
          return null == mapRecords.put(seqNumber,logger) ;
      }
  }