package org.apache.maven.scm.util;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  * http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 import java.lang.ref.SoftReference;

 import java.text.DateFormat;

 import java.text.FieldPosition;

 import java.text.ParsePosition;

 import java.text.SimpleDateFormat;

 import java.util.Date;

 /**

  * Thread-safe version of java.text.DateFormat.

  * You can declare it as a static final variable:

  * @author Olivier Lamy

  * <code>

  * private static final ThreadSafeDateFormat DATE_FORMAT = new ThreadSafeDateFormat( DATE_PATTERN );

  * </code>

  */

 public class ThreadSafeDateFormat

     extends DateFormat

 {

     private static final long serialVersionUID = 3786090697869963812L;

     private final String m_sDateFormat;

     public ThreadSafeDateFormat( String sDateFormat )

     {

         m_sDateFormat = sDateFormat;

     }

     private final ThreadLocal<SoftReference<SimpleDateFormat>> m_formatCache = new ThreadLocal<SoftReference<SimpleDateFormat>>()

     {

         public SoftReference<SimpleDateFormat> get()

         {

             SoftReference<SimpleDateFormat> softRef = super.get();

             if ( softRef == null || softRef.get() == null )

             {

                 softRef = new SoftReference<SimpleDateFormat>( new SimpleDateFormat( m_sDateFormat ) );

                 super.set( softRef );

             }

             return softRef;

         }

     };

     private DateFormat getDateFormat()

     {

         return m_formatCache.get().get();

     }

     public StringBuffer format( Date date, StringBuffer toAppendTo, FieldPosition fieldPosition )

     {

         return getDateFormat().format( date, toAppendTo, fieldPosition );

     }

     public Date parse( String source, ParsePosition pos )

     {

         return getDateFormat().parse( source, pos );

     }

 }