--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/eclipse/jetty/util/DateCache.java	Wed Sep 07 21:15:48 2016 -0600
@@ -0,0 +1,311 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.util;
+
+import java.text.DateFormatSymbols;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+/* ------------------------------------------------------------ */
+/**  Date Format Cache.
+ * Computes String representations of Dates and caches
+ * the results so that subsequent requests within the same minute
+ * will be fast.
+ *
+ * Only format strings that contain either "ss" or "ss.SSS" are
+ * handled.
+ *
+ * The timezone of the date may be included as an ID with the "zzz"
+ * format string or as an offset with the "ZZZ" format string.
+ *
+ * If consecutive calls are frequently very different, then this
+ * may be a little slower than a normal DateFormat.
+ *
+ * 
+ * 
+ */
+
+public class DateCache  
+{
+    public static String DEFAULT_FORMAT="EEE MMM dd HH:mm:ss zzz yyyy";
+    private static long __hitWindow=60*60;
+    
+    private String _formatString;
+    private String _tzFormatString;
+    private SimpleDateFormat _tzFormat;
+    
+    private String _minFormatString;
+    private SimpleDateFormat _minFormat;
+
+    private String _secFormatString;
+    private String _secFormatString0;
+    private String _secFormatString1;
+
+    private long _lastMinutes = -1;
+    private long _lastSeconds = -1;
+    private int _lastMs = -1;
+    private String _lastResult = null;
+
+    private Locale _locale	= null;
+    private DateFormatSymbols	_dfs	= null;
+
+    /* ------------------------------------------------------------ */
+    /** Constructor.
+     * Make a DateCache that will use a default format. The default format
+     * generates the same results as Date.toString().
+     */
+    public DateCache()
+    {
+        this(DEFAULT_FORMAT);
+        getFormat().setTimeZone(TimeZone.getDefault());
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Constructor.
+     * Make a DateCache that will use the given format
+     */
+    public DateCache(String format)
+    {
+        _formatString=format;
+        setTimeZone(TimeZone.getDefault());
+        
+    }
+    
+    /* ------------------------------------------------------------ */
+    public DateCache(String format,Locale l)
+    {
+        _formatString=format;
+        _locale = l;
+        setTimeZone(TimeZone.getDefault());       
+    }
+    
+    /* ------------------------------------------------------------ */
+    public DateCache(String format,DateFormatSymbols s)
+    {
+        _formatString=format;
+        _dfs = s;
+        setTimeZone(TimeZone.getDefault());
+    }
+
+    /* ------------------------------------------------------------ */
+    /** Set the timezone.
+     * @param tz TimeZone
+     */
+    public synchronized void setTimeZone(TimeZone tz)
+    {
+        setTzFormatString(tz);        
+        if( _locale != null ) 
+        {
+            _tzFormat=new SimpleDateFormat(_tzFormatString,_locale);
+            _minFormat=new SimpleDateFormat(_minFormatString,_locale);
+        }
+        else if( _dfs != null ) 
+        {
+            _tzFormat=new SimpleDateFormat(_tzFormatString,_dfs);
+            _minFormat=new SimpleDateFormat(_minFormatString,_dfs);
+        }
+        else 
+        {
+            _tzFormat=new SimpleDateFormat(_tzFormatString);
+            _minFormat=new SimpleDateFormat(_minFormatString);
+        }
+        _tzFormat.setTimeZone(tz);
+        _minFormat.setTimeZone(tz);
+        _lastSeconds=-1;
+        _lastMinutes=-1;        
+    }
+
+    /* ------------------------------------------------------------ */
+    public TimeZone getTimeZone()
+    {
+        return _tzFormat.getTimeZone();
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Set the timezone.
+     * @param timeZoneId TimeZoneId the ID of the zone as used by
+     * TimeZone.getTimeZone(id)
+     */
+    public void setTimeZoneID(String timeZoneId)
+    {
+        setTimeZone(TimeZone.getTimeZone(timeZoneId));
+    }
+    
+    /* ------------------------------------------------------------ */
+    private synchronized void setTzFormatString(final  TimeZone tz )
+    {
+        int zIndex = _formatString.indexOf( "ZZZ" );
+        if( zIndex >= 0 )
+        {
+            String ss1 = _formatString.substring( 0, zIndex );
+            String ss2 = _formatString.substring( zIndex+3 );
+            int tzOffset = tz.getRawOffset();
+            
+            StringBuilder sb = new StringBuilder(_formatString.length()+10);
+            sb.append(ss1);
+            sb.append("'");
+            if( tzOffset >= 0 )
+                sb.append( '+' );
+            else
+            {
+                tzOffset = -tzOffset;
+                sb.append( '-' );
+            }
+            
+            int raw = tzOffset / (1000*60);		// Convert to seconds
+            int hr = raw / 60;
+            int min = raw % 60;
+            
+            if( hr < 10 )
+                sb.append( '0' );
+            sb.append( hr );
+            if( min < 10 )
+                sb.append( '0' );
+            sb.append( min );
+            sb.append( '\'' );
+            
+            sb.append(ss2);
+            _tzFormatString=sb.toString();            
+        }
+        else
+            _tzFormatString=_formatString;
+        setMinFormatString();
+    }
+
+    
+    /* ------------------------------------------------------------ */
+    private void setMinFormatString()
+    {
+        int i = _tzFormatString.indexOf("ss.SSS");
+        int l = 6;
+        if (i>=0)
+            throw new IllegalStateException("ms not supported");
+        i = _tzFormatString.indexOf("ss");
+        l=2;
+        
+        // Build a formatter that formats a second format string
+        String ss1=_tzFormatString.substring(0,i);
+        String ss2=_tzFormatString.substring(i+l);
+        _minFormatString =ss1+"'ss'"+ss2;
+    }
+
+    /* ------------------------------------------------------------ */
+    /** Format a date according to our stored formatter.
+     * @param inDate 
+     * @return Formatted date
+     */
+    public synchronized String format(Date inDate)
+    {
+        return format(inDate.getTime());
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Format a date according to our stored formatter.
+     * @param inDate 
+     * @return Formatted date
+     */
+    public synchronized String format(long inDate)
+    {
+        long seconds = inDate / 1000;
+
+        // Is it not suitable to cache?
+        if (seconds<_lastSeconds ||
+            _lastSeconds>0 && seconds>_lastSeconds+__hitWindow)
+        {
+            // It's a cache miss
+            Date d = new Date(inDate);
+            return _tzFormat.format(d);
+            
+        }
+                                          
+        // Check if we are in the same second
+        // and don't care about millis
+        if (_lastSeconds==seconds )
+            return _lastResult;
+
+        Date d = new Date(inDate);
+        
+        // Check if we need a new format string
+        long minutes = seconds/60;
+        if (_lastMinutes != minutes)
+        {
+            _lastMinutes = minutes;
+            _secFormatString=_minFormat.format(d);
+
+            int i=_secFormatString.indexOf("ss");
+            int l=2;
+            _secFormatString0=_secFormatString.substring(0,i);
+            _secFormatString1=_secFormatString.substring(i+l);
+        }
+
+        // Always format if we get here
+        _lastSeconds = seconds;
+        StringBuilder sb=new StringBuilder(_secFormatString.length());
+        sb.append(_secFormatString0);
+        int s=(int)(seconds%60);
+        if (s<10)
+            sb.append('0');
+        sb.append(s);
+        sb.append(_secFormatString1);
+        _lastResult=sb.toString();
+
+                
+        return _lastResult;
+    }
+
+    /* ------------------------------------------------------------ */
+    /** Format to string buffer. 
+     * @param inDate Date the format
+     * @param buffer StringBuilder
+     */
+    public void format(long inDate, StringBuilder buffer)
+    {
+        buffer.append(format(inDate));
+    }
+    
+    /* ------------------------------------------------------------ */
+    /** Get the format.
+     */
+    public SimpleDateFormat getFormat()
+    {
+        return _minFormat;
+    }
+
+    /* ------------------------------------------------------------ */
+    public String getFormatString()
+    {
+        return _formatString;
+    }    
+
+    /* ------------------------------------------------------------ */
+    public String now()
+    {
+        long now=System.currentTimeMillis();
+        _lastMs=(int)(now%1000);
+        return format(now);
+    }
+
+    /* ------------------------------------------------------------ */
+    public int lastMs()
+    {
+        return _lastMs;
+    }
+}