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comparison src/org/dancres/blitz/entry/ExpiredLocatorImpl.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 package org.dancres.blitz.entry;
2
3 import java.io.IOException;
4
5 import java.util.logging.Level;
6
7 import com.sleepycat.je.Cursor;
8 import com.sleepycat.je.DatabaseEntry;
9 import com.sleepycat.je.DatabaseException;
10 import com.sleepycat.je.OperationStatus;
11
12 import org.dancres.blitz.oid.OID;
13 import org.dancres.blitz.oid.OIDFactory;
14
15 /**
16 TupleLocator implementation to be used on Lease tables. See LeaseTrackerImpl
17 for information on the database format.
18 */
19 class ExpiredLocatorImpl implements TupleLocator {
20 private Cursor theCursor;
21 private boolean isFirst = true;
22
23 private DatabaseEntry theLeaseRecord;
24 private DatabaseEntry theLeaseBucket;
25
26 private long theScanTime;
27
28 /**
29 @param aCursor the cursor to use for iteration
30 */
31 ExpiredLocatorImpl(Cursor aCursor) {
32 theCursor = aCursor;
33 theScanTime = System.currentTimeMillis();
34 theLeaseBucket = new DatabaseEntry();
35 }
36
37 /**
38 Invoke this to load the next matching Tuple.
39
40 @return <code>true</code> if there was a tuple, <code>false</code>
41 otherwise
42 */
43 public boolean fetchNext() throws IOException {
44 /*
45 The cursor will have been initialised whilst we decided which
46 field was best to search on which means it will already be pointed
47 at the first record so we must handle this case specially.
48 */
49 if (isFirst) {
50 isFirst = false;
51
52 return loadNext();
53 } else {
54 return loadNextMove();
55 }
56 }
57
58 private boolean loadNextMove() throws IOException {
59 return loadNext(true);
60 }
61
62 private boolean loadNext() throws IOException {
63 return loadNext(false);
64 }
65
66 private boolean loadNext(boolean advance) throws IOException {
67 OperationStatus myResult;
68
69 try {
70 theLeaseRecord = new DatabaseEntry();
71
72 if (advance)
73 myResult = theCursor.getNextDup(theLeaseBucket, theLeaseRecord,
74 null);
75 else
76 myResult = theCursor.getFirst(theLeaseBucket, theLeaseRecord,
77 null);
78 } catch (DatabaseException aDbe) {
79 EntryStorage.theLogger.log(Level.SEVERE, "Got Dbe", aDbe);
80 throw new IOException("Dbe");
81 }
82
83 if ((myResult.equals(OperationStatus.NOTFOUND)) ||
84 (theScanTime <
85 LeaseRecordUtils.unpackExpiry(theLeaseRecord.getData()))) {
86
87 if (myResult != OperationStatus.NOTFOUND)
88 // System.err.println("Exceeding Expiry: " +
89 // LeaseRecordUtils.unpackExpiry(theLeaseRecord.getData()));
90
91 // Try for the next non-dupe
92 theLeaseRecord = new DatabaseEntry();
93
94 try {
95 // System.err.println("Skipping to next bucket");
96
97 myResult =
98 theCursor.getNextNoDup(theLeaseBucket, theLeaseRecord, null);
99
100 if (myResult.equals(OperationStatus.SUCCESS))
101 return true;
102 } catch (DatabaseException aDbe) {
103 EntryStorage.theLogger.log(Level.SEVERE, "Got Dbe", aDbe);
104 throw new IOException("Dbe");
105 }
106
107 return false;
108 } else {
109 // System.err.println("Maybe expiring one: " +
110 // LeaseRecordUtils.unpackExpiry(theLeaseRecord.getData()));
111 return true;
112 }
113 }
114
115 /**
116 @return the OID of the tuple just fetched with
117 <code>fetchNext</code>
118 */
119 public OID getOID() {
120 OID myResult =
121 OIDFactory.newOID(
122 LeaseRecordUtils.unpackId(theLeaseRecord.getData()));
123
124 // System.err.println("Time is up for: " + myResult);
125
126 return myResult;
127 }
128
129 /**
130 When you've finished with the TupleLocator instance, call release.
131 */
132 public void release() throws IOException {
133 try {
134 theCursor.close();
135 } catch (DatabaseException aDbe) {
136 EntryStorage.theLogger.log(Level.SEVERE, "Got Dbe", aDbe);
137 throw new IOException("Dbe");
138 }
139 }
140 }