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comparison src/org/prevayler/implementation/SnapshotterImpl.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.prevayler.implementation;
2
3 import java.io.File;
4 import java.io.FileOutputStream;
5 import java.io.ByteArrayOutputStream;
6 import java.io.ObjectOutputStream;
7 import java.io.IOException;
8
9 import org.prevayler.PrevalentSystem;
10
11 /**
12 Represents a snapshot waiting to be persisted to disk. Invoke save() to
13 place the snapshot on disk - should only be called once all dirty state
14 (if any) has been flushed to disk.
15
16 @see org.dancres.blitz.txn.TxnManager
17 */
18 class SnapshotterImpl implements Snapshotter {
19 private File theTemp;
20 private File theReal;
21 private byte[] theCachedCopy;
22
23 private NumberFileCreator theFileCreator;
24
25 private boolean shouldClean;
26
27 SnapshotterImpl(NumberFileCreator aCreator, boolean doClean)
28 throws IOException {
29
30 theTemp = aCreator.newTempSnapshot();
31 theReal = aCreator.newSnapshot();
32
33 theFileCreator = aCreator;
34 shouldClean = doClean;
35 }
36
37 void cacheSnapshot(PrevalentSystem aSystem) throws IOException {
38 ByteArrayOutputStream myCache = new ByteArrayOutputStream();
39 ObjectOutputStream mySnapper = new ObjectOutputStream(myCache);
40
41 mySnapper.writeObject(aSystem);
42 mySnapper.close();
43
44 theCachedCopy = myCache.toByteArray();
45 }
46
47 public void save() throws IOException {
48 FileOutputStream myOutput = new FileOutputStream(theTemp);
49 myOutput.write(theCachedCopy);
50 myOutput.close();
51
52 if (!theTemp.renameTo(theReal))
53 throw new IOException("Unable to rename " + theTemp +
54 " to " + theReal);
55
56 if (shouldClean)
57 theFileCreator.newCleaner().clean();
58 }
59 }