package org.webslinger.io;

 import java.io.IOException;

 import java.io.Writer;

 import org.webslinger.util.RolloverLogic;

 public abstract class RollingWriter {

     protected final RolloverLogic logic;

     protected Writer writer;

     protected RollingWriter(RolloverLogic logic) {

         this.logic = logic;

     }

     // private, so it can only be called while synchronized

     public Writer getWriter() throws IOException {

         synchronized (this) {

             if (writer != null) {

                 if (!logic.checkRollover()) return writer;

                 writer.flush();

                 writer.close();

                 writer = makeWriter(true);

             } else {

                 writer = makeWriter(false);

             }

             return writer;

         }

     }

     protected abstract Writer makeWriter(boolean rollover) throws IOException;

 }