Mercurial > hg > blitz_stable

annotate src/org/prevayler/implementation/SnapshotterImpl.java @ 27:511648fa4d64 Version 2.1

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Version to 2.1
author Dan Creswell <dan.creswell@gmail.com>
date Mon, 04 Jan 2010 13:00:40 +0000
parents 3dc0c5604566
children
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1 package org.prevayler.implementation;
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2
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3 import java.io.File;
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4 import java.io.FileOutputStream;
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5 import java.io.ByteArrayOutputStream;
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6 import java.io.ObjectOutputStream;
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7 import java.io.IOException;
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8
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9 import org.prevayler.PrevalentSystem;
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10
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11 /**
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12 Represents a snapshot waiting to be persisted to disk. Invoke save() to
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13 place the snapshot on disk - should only be called once all dirty state
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14 (if any) has been flushed to disk.
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15
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16 @see org.dancres.blitz.txn.TxnManager
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17 */
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18 class SnapshotterImpl implements Snapshotter {
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19 private File theTemp;
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20 private File theReal;
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21 private byte[] theCachedCopy;
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22
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23 private NumberFileCreator theFileCreator;
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24
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25 private boolean shouldClean;
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26
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27 SnapshotterImpl(NumberFileCreator aCreator, boolean doClean)
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28 throws IOException {
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29
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30 theTemp = aCreator.newTempSnapshot();
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31 theReal = aCreator.newSnapshot();
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32
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33 theFileCreator = aCreator;
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34 shouldClean = doClean;
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35 }
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36
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37 void cacheSnapshot(PrevalentSystem aSystem) throws IOException {
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38 ByteArrayOutputStream myCache = new ByteArrayOutputStream();
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39 ObjectOutputStream mySnapper = new ObjectOutputStream(myCache);
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40
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41 mySnapper.writeObject(aSystem);
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42 mySnapper.close();
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43
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44 theCachedCopy = myCache.toByteArray();
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45 }
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46
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47 public void save() throws IOException {
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48 FileOutputStream myOutput = new FileOutputStream(theTemp);
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49 myOutput.write(theCachedCopy);
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50 myOutput.close();
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51
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52 if (!theTemp.renameTo(theReal))
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53 throw new IOException("Unable to rename " + theTemp +
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54 " to " + theReal);
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55
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56 if (shouldClean)
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57 theFileCreator.newCleaner().clean();
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58 }
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59 }