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comparison src/org/dancres/blitz/txn/PersistentReboot.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.txn;
2
3 import java.util.logging.Level;
4
5 import org.dancres.blitz.meta.Registry;
6 import org.dancres.blitz.meta.RegistryFactory;
7
8 import org.dancres.blitz.config.PersistentBase;
9
10 import org.dancres.blitz.BootContext;
11
12 import org.dancres.blitz.disk.DiskTxn;
13
14 /**
15 Certain steps need to be carried out as part of a reboot of a persistent
16 (normal or time-barrier) instance of Blitz. Those steps are the
17 responsibility of this class.
18 */
19 class PersistentReboot {
20 private static final String BOOT_STATE = "BootState";
21
22 private static final byte[] MAX_LOGS_KEY = {0x00, 0x00, 0x00, 0x01};
23
24 private PersistentBase theBaseStorageModel;
25
26 PersistentReboot(PersistentBase aBaseModel) {
27 theBaseStorageModel = aBaseModel;
28 }
29
30 public void execute() throws Exception {
31 int myCurrentMaxLogsBeforeSync =
32 theBaseStorageModel.getMaxLogsBeforeSync();
33
34 Registry myRegistry = RegistryFactory.get(BOOT_STATE, null);
35
36 UnsyncdOps myBarrier = null;
37
38 // Recover the old barrier information and use that for BootContext
39 //
40 DiskTxn myTxn = DiskTxn.newTxn();
41
42 try {
43 myBarrier = (UnsyncdOps)
44 myRegistry.getAccessor().load(MAX_LOGS_KEY);
45
46 if (myBarrier != null) {
47 TxnManager.theLogger.log(Level.INFO,
48 "Restoring UnsyncdOps state: " +
49 myBarrier.getOpsSinceLastCheckpoint());
50
51 BootContext.add(myBarrier);
52 }
53 } finally {
54 myTxn.commit();
55 }
56
57 // Update recovery barrier - this can only ever increase, we can't
58 // decrease it due to recovery constraints
59 //
60 if ((myBarrier == null) ||
61 (myCurrentMaxLogsBeforeSync >
62 myBarrier.getOpsSinceLastCheckpoint())) {
63
64 // System.err.println("Updating UnsyncdOps to: " +
65 // myCurrentMaxLogsBeforeSync);
66
67 myTxn = DiskTxn.newTxn();
68
69 try {
70 myRegistry.getAccessor().save(MAX_LOGS_KEY,
71 new UnsyncdOps(myCurrentMaxLogsBeforeSync));
72 } finally {
73 myTxn.commit();
74 }
75 }
76
77 myRegistry.close();
78 }
79 }