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comparison src/org/dancres/blitz/txnlock/LockMgr.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.txnlock;
2
3 import org.dancres.blitz.oid.OID;
4
5 /**
6 A lock mgr instance is responsible for tracking all transaction locks
7 for a particular Entry type.
8 */
9 public class LockMgr {
10 /**
11 For as long as any transaction has a reference to the lock, it will
12 be maintained by the LockMgr. Obviously, if there are no pending
13 transactions there's no need to hold the lock or it's state because
14 the lock should be clear. If it's not clear, we have a bug!!!! :)
15 */
16 // private SoftHashMap theLocks = new SoftHashMap();
17 private LockCache theLocks = new LockCache();
18
19 public TxnLock getLock(OID aOID) {
20 return theLocks.getOrInsert(aOID);
21 }
22
23 public TxnLock newLock(OID aOID) {
24 TxnLock myLock = new TxnLock();
25
26 theLocks.put(aOID, myLock);
27
28 return myLock;
29 }
30
31 /**
32 Test to see if the specified OID has an active lock associated
33 with it. This is only truly useful in situations where the associated
34 Entry is in an unchanging state perhaps because it has been DELETED
35 or it's lease has expired.
36 */
37 public boolean hasActiveLock(OID aOID) {
38 TxnLock myLock = (TxnLock) theLocks.get(aOID);
39
40 if (myLock != null) {
41 synchronized(myLock) {
42 return myLock.isActive();
43 }
44 }
45
46 return false;
47 }
48
49 }