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comparison src/org/dancres/blitz/oid/UIDImpl.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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-1:000000000000 0:3dc0c5604566
1 package org.dancres.blitz.oid;
2
3 import java.io.Serializable;
4
5 import org.dancres.util.BytePacker;
6
7 /**
8 A unique identifier which can be generated by an Allocator.
9 */
10 final class UIDImpl implements OID {
11 static final int KEY_SIZE = 12;
12
13 private transient byte[] theKey;
14
15 private long theId;
16 private int theZoneId;
17
18 UIDImpl(byte[] aKey) {
19 theKey = aKey;
20
21 BytePacker myPacker = BytePacker.getMSBPacker(theKey);
22 theZoneId = myPacker.getInt(0);
23 theId = myPacker.getLong(4);
24 }
25
26 UIDImpl(int aZoneId, long anId) {
27 theId = anId;
28 theZoneId = aZoneId;
29 }
30
31 public int getZoneId() {
32 return theZoneId;
33 }
34
35 public long getId() {
36 return theId;
37 }
38
39 synchronized byte[] getKey() {
40 if (theKey == null) {
41 theKey = keyFor(theZoneId, theId);
42 }
43
44 return theKey;
45 }
46
47 public String toString() {
48 return " " + theZoneId + "->" + theId;
49 }
50
51 public int hashCode() {
52 /*
53 We include theZoneId to allow for the fact that all allocators for
54 a given Entry type will be allocating id's close to each other
55 because of the random allocator selection used when an id is
56 generated. Because the id's are allocated evenly, there's a high
57 chance of two UID's allocated close together in time colliding unless
58 we also factor in theZoneId.
59 */
60 return theZoneId ^ ((int) (theId ^ (theId >>> 32)));
61 }
62
63 public int compareTo(Object anObject) {
64 UIDImpl myOther = (UIDImpl) anObject;
65
66 if (theZoneId < myOther.theZoneId)
67 return -1;
68 else if (theZoneId > myOther.theZoneId)
69 return 1;
70
71 if (theId < myOther.theId)
72 return -1;
73 else if (theId > myOther.theId)
74 return 1;
75 else
76 return 0;
77 }
78
79 public boolean equals(Object anObject) {
80 if (anObject instanceof UIDImpl) {
81 UIDImpl myOther = (UIDImpl) anObject;
82
83 return ((theZoneId == myOther.theZoneId) &&
84 (theId == myOther.theId));
85 }
86
87 return false;
88 }
89
90 private byte[] keyFor(int aZoneId, long anId) {
91 byte[] myKey = new byte[12];
92
93 BytePacker myPacker = BytePacker.getMSBPacker(myKey);
94 myPacker.putInt(aZoneId, 0);
95 myPacker.putLong(anId, 4);
96
97 return myKey;
98 }
99 }