Source for java.rmi.server.UID

   1: /* UID.java --
   2:    Copyright (c) 1996, 1997, 1998, 1999, 2004 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10:  
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.rmi.server;
  40: 
  41: import java.io.DataInput;
  42: import java.io.DataOutput;
  43: import java.io.IOException;
  44: import java.io.Serializable;
  45: 
  46: public final class UID implements Serializable
  47: {
  48: private static final long serialVersionUID = 1086053664494604050L;
  49: 
  50: private static final Object lock = UID.class;
  51: private static long baseTime = System.currentTimeMillis();
  52: private static short nextCount = Short.MIN_VALUE;
  53: // This is sun's algorithm - don't ask me why ...
  54: private static final int uniqueNr = (new Object()).hashCode();
  55: 
  56: private int unique;
  57: private long time;
  58: private short count;
  59: 
  60: /**
  61:  * This is sun's algorithm - don't ask me why ...
  62:  */
  63: public UID() {
  64:     synchronized (lock) {
  65:         if (nextCount == Short.MAX_VALUE) {
  66:             long newtime;
  67:             for (;;) {
  68:                 newtime = System.currentTimeMillis();
  69:                 if (newtime - baseTime > 1000) {
  70:                     break;
  71:                 }
  72:                 try {
  73:                     Thread.sleep(1000);
  74:                 }
  75:                 catch (InterruptedException _) {
  76:                 }
  77:             }
  78:             baseTime = newtime;
  79:             nextCount = Short.MIN_VALUE;
  80:         }
  81:         count = nextCount++;
  82:         unique = uniqueNr;
  83:         time = baseTime;
  84:     }
  85: }
  86: 
  87: public UID(short num) {
  88:     unique = (int)num;
  89:     time = 0;
  90:     count = 0;
  91: }
  92: 
  93: public int hashCode() {
  94:     return (unique);
  95: }
  96: 
  97: public boolean equals(Object obj) {
  98:     if (obj instanceof UID) {
  99:         UID uid = (UID)obj;
 100:         if (this.unique == uid.unique &&
 101:             this.time == uid.time &&
 102:             this.count == uid.count) {
 103:             return (true);
 104:         }
 105:     }
 106:     return (false);
 107: }
 108: 
 109: public String toString() {
 110:     return ("[UID: " + unique + "," + time + "," + count + "]");
 111: }
 112: 
 113: public void write(DataOutput out) throws IOException {
 114:     out.writeInt(unique);
 115:     out.writeLong(time);
 116:     out.writeShort(count);
 117: }
 118: 
 119: public static UID read(DataInput in) throws IOException {
 120:     UID id = new UID();
 121:     id.unique = in.readInt();
 122:     id.time = in.readLong();
 123:     id.count = in.readShort();
 124:     return (id);
 125: }
 126: 
 127: }