package org.apache.commons.net.ntp;
/*
* 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.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
/***
* TimeStamp class represents the Network Time Protocol (NTP) timestamp
* as defined in RFC-1305 and SNTP (RFC-2030). It is represented as a
* 64-bit unsigned fixed-point number in seconds relative to 0-hour on 1-January-1900.
* The 32-bit low-order bits are the fractional seconds whose precision is
* about 200 picoseconds. Assumes overflow date when date passes MAX_LONG
* and reverts back to 0 is 2036 and not 1900. Test for most significant
* bit: if MSB=0 then 2036 basis is used otherwise 1900 if MSB=1.
* <p>
* Methods exist to convert NTP timestamps to and from the equivalent Java date
* representation, which is the number of milliseconds since the standard base
* time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.
* </p>
*
* @author Jason Mathews, MITRE Corp
* @version $Revision: 658518 $ $Date: 2008-05-21 02:04:30 +0100 (Wed, 21 May 2008) $
* @see java.util.Date
*/
public class TimeStamp implements java.io.Serializable, Comparable // TODO add comparable type?
{
/**
* baseline NTP time if bit-0=0 -> 7-Feb-2036 @ 06:28:16 UTC
*/
protected static final long msb0baseTime = 2085978496000L;
/**
* baseline NTP time if bit-0=1 -> 1-Jan-1900 @ 01:00:00 UTC
*/
protected static final long msb1baseTime = -2208988800000L;
/**
* Default NTP date string format. E.g. Fri, Sep 12 2003 21:06:23.860.
* See <code>java.text.SimpleDateFormat</code> for code descriptions.
*/
public final static String NTP_DATE_FORMAT = "EEE, MMM dd yyyy HH:mm:ss.SSS";
/*
* Caches for the DateFormatters used by various toString methods.
*/
private static SoftReference<DateFormat> simpleFormatter = null;
private static SoftReference<DateFormat> utcFormatter = null;
/**
* NTP timestamp value: 64-bit unsigned fixed-point number as defined in RFC-1305
* with high-order 32 bits the seconds field and the low-order 32-bits the
* fractional field.
*/
private long ntpTime;
private static final long serialVersionUID = 8139806907588338737L;
// initialization of static time bases
/*
static {
TimeZone utcZone = TimeZone.getTimeZone("UTC");
Calendar calendar = Calendar.getInstance(utcZone);
calendar.set(1900, Calendar.JANUARY, 1, 0, 0, 0);
calendar.set(Calendar.MILLISECOND, 0);
msb1baseTime = calendar.getTime().getTime();
calendar.set(2036, Calendar.FEBRUARY, 7, 6, 28, 16);
calendar.set(Calendar.MILLISECOND, 0);
msb0baseTime = calendar.getTime().getTime();
}
*/
/***
* Constructs a newly allocated NTP timestamp object
* that represents the native 64-bit long argument.
*/
public TimeStamp(long ntpTime)
{
this.ntpTime = ntpTime;
}
/***
* Constructs a newly allocated NTP timestamp object
* that represents the value represented by the string
* in hexdecimal form (e.g. "c1a089bd.fc904f6d").
*
* @throws NumberFormatException - if the string does not contain a parsable timestamp.
*/
public TimeStamp(String s) throws NumberFormatException
{
ntpTime = decodeNtpHexString(s);
}
/***
* Constructs a newly allocated NTP timestamp object
* that represents the Java Date argument.
*
* @param d - the Date to be represented by the Timestamp object.
*/
public TimeStamp(Date d)
{
ntpTime = (d == null) ? 0 : toNtpTime(d.getTime());
}
/***
* Returns the value of this Timestamp as a long value.
*
* @return the 64-bit long value represented by this object.
*/
public long ntpValue()
{
return ntpTime;
}
/***
* Returns high-order 32-bits representing the seconds of this NTP timestamp.
*
* @return seconds represented by this NTP timestamp.
*/
public long getSeconds()
{
return (ntpTime >>> 32) & 0xffffffffL;
}
/***
* Returns low-order 32-bits representing the fractional seconds.
*
* @return fractional seconds represented by this NTP timestamp.
*/
public long getFraction()
{
return ntpTime & 0xffffffffL;
}
/***
* Convert NTP timestamp to Java standard time.
*
* @return NTP Timestamp in Java time
*/
public long getTime()
{
return getTime(ntpTime);
}
/***
* Convert NTP timestamp to Java Date object.
*
* @return NTP Timestamp in Java Date
*/
public Date getDate()
{
long time = getTime(ntpTime);
return new Date(time);
}
/***
* Convert 64-bit NTP timestamp to Java standard time.
*
* Note that java time (milliseconds) by definition has less precision
* then NTP time (picoseconds) so converting NTP timestamp to java time and back
* to NTP timestamp loses precision. For example, Tue, Dec 17 2002 09:07:24.810 EST
* is represented by a single Java-based time value of f22cd1fc8a, but its
* NTP equivalent are all values ranging from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.
*
* @param ntpTimeValue
* @return the number of milliseconds since January 1, 1970, 00:00:00 GMT
* represented by this NTP timestamp value.
*/
public static long getTime(long ntpTimeValue)
{
long seconds = (ntpTimeValue >>> 32) & 0xffffffffL; // high-order 32-bits
long fraction = ntpTimeValue & 0xffffffffL; // low-order 32-bits
// Use round-off on fractional part to preserve going to lower precision
fraction = Math.round(1000D * fraction / 0x100000000L);
/*
* If the most significant bit (MSB) on the seconds field is set we use
* a different time base. The following text is a quote from RFC-2030 (SNTP v4):
*
* If bit 0 is set, the UTC time is in the range 1968-2036 and UTC time
* is reckoned from 0h 0m 0s UTC on 1 January 1900. If bit 0 is not set,
* the time is in the range 2036-2104 and UTC time is reckoned from
* 6h 28m 16s UTC on 7 February 2036.
*/
long msb = seconds & 0x80000000L;
if (msb == 0) {
// use base: 7-Feb-2036 @ 06:28:16 UTC
return msb0baseTime + (seconds * 1000) + fraction;
} else {
// use base: 1-Jan-1900 @ 01:00:00 UTC
return msb1baseTime + (seconds * 1000) + fraction;
}
}
/***
* Helper method to convert Java time to NTP timestamp object.
* Note that Java time (milliseconds) by definition has less precision
* then NTP time (picoseconds) so converting Ntptime to Javatime and back
* to Ntptime loses precision. For example, Tue, Dec 17 2002 09:07:24.810
* is represented by a single Java-based time value of f22cd1fc8a, but its
* NTP equivalent are all values from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.
* @param date the milliseconds since January 1, 1970, 00:00:00 GMT.
* @return NTP timestamp object at the specified date.
*/
public static TimeStamp getNtpTime(long date)
{
return new TimeStamp(toNtpTime(date));
}
/***
* Constructs a NTP timestamp object and initializes it so that
* it represents the time at which it was allocated, measured to the
* nearest millisecond.
* @return NTP timestamp object set to the current time.
* @see java.lang.System#currentTimeMillis()
*/
public static TimeStamp getCurrentTime()
{
return getNtpTime(System.currentTimeMillis());
}
/***
* Convert NTP timestamp hexstring (e.g. "c1a089bd.fc904f6d") to the NTP
* 64-bit unsigned fixed-point number.
*
* @return NTP 64-bit timestamp value.
* @throws NumberFormatException - if the string does not contain a parsable timestamp.
*/
protected static long decodeNtpHexString(String s)
throws NumberFormatException
{
if (s == null) {
throw new NumberFormatException("null");
}
int ind = s.indexOf('.');
if (ind == -1) {
if (s.length() == 0) return 0;
return Long.parseLong(s, 16) << 32; // no decimal
}
return Long.parseLong(s.substring(0, ind), 16) << 32 |
Long.parseLong(s.substring(ind + 1), 16);
}
/***
* Parses the string argument as a NTP hexidecimal timestamp representation string
* (e.g. "c1a089bd.fc904f6d").
*
* @param s - hexstring.
* @return the Timestamp represented by the argument in hexidecimal.
* @throws NumberFormatException - if the string does not contain a parsable timestamp.
*/
public static TimeStamp parseNtpString(String s)
throws NumberFormatException
{
return new TimeStamp(decodeNtpHexString(s));
}
/***
* Converts Java time to 64-bit NTP time representation.
*
* @param t Java time
* @return NTP timestamp representation of Java time value.
*/
protected static long toNtpTime(long t)
{
boolean useBase1 = t < msb0baseTime; // time < Feb-2036
long baseTime;
if (useBase1) {
baseTime = t - msb1baseTime; // dates <= Feb-2036
} else {
// if base0 needed for dates >= Feb-2036
baseTime = t - msb0baseTime;
}
long seconds = baseTime / 1000;
long fraction = ((baseTime % 1000) * 0x100000000L) / 1000;
if (useBase1) {
seconds |= 0x80000000L; // set high-order bit if msb1baseTime 1900 used
}
long time = seconds << 32 | fraction;
return time;
}
/***
* Computes a hashcode for this Timestamp. The result is the exclusive
* OR of the two halves of the primitive <code>long</code> value
* represented by this <code>TimeStamp</code> object. That is, the hashcode
* is the value of the expression:
* <blockquote><pre>
* (int)(this.ntpValue()^(this.ntpValue() >>> 32))
* </pre></blockquote>
*
* @return a hash code value for this object.
*/
@Override
public int hashCode()
{
return (int) (ntpTime ^ (ntpTime >>> 32));
}
/***
* Compares this object against the specified object.
* The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is a <code>Long</code> object that
* contains the same <code>long</code> value as this object.
*
* @param obj the object to compare with.
* @return <code>true</code> if the objects are the same;
* <code>false</code> otherwise.
*/
@Override
public boolean equals(Object obj)
{
if (obj instanceof TimeStamp) {
return ntpTime == ((TimeStamp) obj).ntpValue();
}
return false;
}
/***
* Converts this <code>TimeStamp</code> object to a <code>String</code>.
* The NTP timestamp 64-bit long value is represented as hex string with
* seconds separated by fractional seconds by a decimal point;
* e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986
*
* @return NTP timestamp 64-bit long value as hex string with seconds
* separated by fractional seconds.
*/
@Override
public String toString()
{
return toString(ntpTime);
}
/***
* Left-pad 8-character hex string with 0's
*
* @param buf - StringBuffer which is appended with leading 0's.
* @param l - a long.
*/
private static void appendHexString(StringBuffer buf, long l)
{
String s = Long.toHexString(l);
for (int i = s.length(); i < 8; i++)
buf.append('0');
buf.append(s);
}
/***
* Converts 64-bit NTP timestamp value to a <code>String</code>.
* The NTP timestamp value is represented as hex string with
* seconds separated by fractional seconds by a decimal point;
* e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986
*
* @return NTP timestamp 64-bit long value as hex string with seconds
* separated by fractional seconds.
*/
public static String toString(long ntpTime)
{
StringBuffer buf = new StringBuffer();
// high-order second bits (32..63) as hexstring
appendHexString(buf, (ntpTime >>> 32) & 0xffffffffL);
// low-order fractional seconds bits (0..31) as hexstring
buf.append('.');
appendHexString(buf, ntpTime & 0xffffffffL);
return buf.toString();
}
/***
* Converts this <code>TimeStamp</code> object to a <code>String</code>
* of the form:
* <blockquote><pre>
* EEE, MMM dd yyyy HH:mm:ss.SSS</pre></blockquote>
* See java.text.SimpleDataFormat for code descriptions.
*
* @return a string representation of this date.
*/
public String toDateString()
{
DateFormat formatter = null;
if (simpleFormatter != null) {
formatter = simpleFormatter.get();
}
if (formatter == null) {
// No cache yet, or cached formatter GC'd
formatter = new SimpleDateFormat(NTP_DATE_FORMAT, Locale.US);
formatter.setTimeZone(TimeZone.getDefault());
simpleFormatter = new SoftReference<DateFormat>(formatter);
}
Date ntpDate = getDate();
synchronized (formatter) {
return formatter.format(ntpDate);
}
}
/***
* Converts this <code>TimeStamp</code> object to a <code>String</code>
* of the form:
* <blockquote><pre>
* EEE, MMM dd yyyy HH:mm:ss.SSS UTC</pre></blockquote>
* See java.text.SimpleDataFormat for code descriptions.
*
* @return a string representation of this date in UTC.
*/
public String toUTCString()
{
DateFormat formatter = null;
if (utcFormatter != null)
formatter = utcFormatter.get();
if (formatter == null) {
// No cache yet, or cached formatter GC'd
formatter = new SimpleDateFormat(NTP_DATE_FORMAT + " 'UTC'",
Locale.US);
formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
utcFormatter = new SoftReference<DateFormat>(formatter);
}
Date ntpDate = getDate();
synchronized (formatter) {
return formatter.format(ntpDate);
}
}
/***
* Compares two Timestamps numerically.
*
* @param anotherTimeStamp - the <code>TimeStamp</code> to be compared.
* @return the value <code>0</code> if the argument TimeStamp is equal to
* this TimeStamp; a value less than <code>0</code> if this TimeStamp
* is numerically less than the TimeStamp argument; and a
* value greater than <code>0</code> if this TimeStamp is
* numerically greater than the TimeStamp argument
* (signed comparison).
*/
public int compareTo(TimeStamp anotherTimeStamp)
{
long thisVal = this.ntpTime;
long anotherVal = anotherTimeStamp.ntpTime;
return (thisVal < anotherVal ? -1 : (thisVal == anotherVal ? 0 : 1));
}
/***
* Compares this TimeStamp to another Object. If the Object is a TimeStamp,
* this function behaves like <code>compareTo(TimeStamp)</code>. Otherwise,
* it throws a <code>ClassCastException</code> (as TimeStamps are comparable
* only to other TimeStamps).
*
* @param o the <code>Object</code> to be compared.
* @return the value <code>0</code> if the argument is a TimeStamp
* numerically equal to this TimeStamp; a value less than
* <code>0</code> if the argument is a TimeStamp numerically
* greater than this TimeStamp; and a value greater than
* <code>0</code> if the argument is a TimeStamp numerically
* less than this TimeStamp.
* @exception ClassCastException if the argument is not a
* <code>TimeStamp</code>.
* @see java.lang.Comparable
*/
public int compareTo(Object o)
{
return compareTo((TimeStamp) o);
}
}