mirror of https://github.com/sipwise/jitsi.git
- Now use this utility in MclStorageManagercusax-fix
Benoit Pradelle
19 years ago
parent
a723f66398
commit
7c550c0c7b
@ -0,0 +1,199 @@
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/*
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* SIP Communicator, the OpenSource Java VoIP and Instant Messaging client.
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*
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* Distributable under LGPL license.
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* See terms of license at gnu.org.
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*/
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package net.java.sip.communicator.util;
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import java.io.*;
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/**
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* A failsafe transaction utility class. By failsafe we mean here that the file
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* concerned always stays in a coherent state. This class use the transactional
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* model.
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*
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* @author Benoit Pradelle
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*/
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public class FailSafeTransaction
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{
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/**
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* Original file used by the transaction
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*/
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private File file;
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/**
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* Backup file used by the transaction
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*/
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private File backup;
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/**
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* Extension of a partial file
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*/
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private static final String PART_EXT = ".part";
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/**
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* Extension of a backup copy
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*/
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private static final String BAK_EXT = ".bak";
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/**
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* Creates a new transaction.
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*
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* @param file The file associated with this transaction
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*
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* @throws NullPointerException if the file is null
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*/
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public FailSafeTransaction(File file)
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throws NullPointerException
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{
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if (file == null) {
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throw new NullPointerException("null file provided");
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}
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this.file = file;
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this.backup = null;
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}
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/**
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* Ensure that the file accessed is in a coherent state. This function is
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* useful to do a failsafe read without starting a transaction.
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*
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* @throws IllegalStateException if the file doesn't exists anymore
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* @throws IOException if an IOException occurs during the file restoration
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*/
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public void restoreFile()
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throws IllegalStateException, IOException
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{
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File back = new File(this.file.getAbsolutePath() + BAK_EXT);
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// if a backup copy is still present, simply restore it
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if (back.exists()) {
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failsafeCopy(back.getAbsolutePath(),
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this.file.getAbsolutePath());
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back.delete();
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}
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}
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/**
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* Begins a new transaction. If a transaction is already active, commits the
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* changes and begin a new transaction.
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* A transaction can be closed by a commit or rollback operation.
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* When the transaction begins, the file is restored to a coherent state if
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* needed.
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*
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* @return The fail-safe file in which every modification must be done.
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*
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* @throws IllegalStateException if the file doesn't exists anymore
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* @throws IOException if an IOException occurs during the transaction
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* creation
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*/
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public void beginTransaction()
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throws IllegalStateException, IOException
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{
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// if the last transaction hasn't been closed, commit it
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if (this.backup != null) {
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this.commit();
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}
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// if needed, restore the file in its previous state
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restoreFile();
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this.backup = new File(this.file.getAbsolutePath() + BAK_EXT);
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// else backup the current file
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failsafeCopy(this.file.getAbsolutePath(),
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this.backup.getAbsolutePath());
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}
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/**
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* Closes the transaction and commit the changes. Everything written in the
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* file during the transaction is saved.
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*
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* @throws IllegalStateException if the file doesn't exists anymore
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* @throws IOException if an IOException occurs during the operation
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*/
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public void commit()
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throws IllegalStateException, IOException
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{
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if (this.backup == null) {
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return;
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}
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// simply delete the backup file
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this.backup.delete();
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this.backup = null;
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}
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/**
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* Closes the transation and cancel the changes. Everything written in the
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* file during the transaction is NOT saved.
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* @throws IllegalStateException if the file doesn't exists anymore
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* @throws IOException if an IOException occurs during the operation
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*/
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public void rollback()
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throws IllegalStateException, IOException
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{
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if (this.backup == null) {
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return;
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}
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// restore the backup and delete it
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failsafeCopy(this.backup.getAbsolutePath(),
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this.file.getAbsolutePath());
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this.backup.delete();
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this.backup = null;
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}
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/**
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* Copy a file in a fail-safe way. The destination is created in an atomic
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* way.
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*
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* @param from The file to copy
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* @param to The copy to create
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*
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* @throws IllegalStateException if the file doesn't exists anymore
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* @throws IOException if an IOException occurs during the operation
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*/
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private void failsafeCopy(String from, String to)
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throws IllegalStateException, IOException
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{
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FileInputStream in = null;
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FileOutputStream out = null;
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// to ensure a perfect copy, delete the destination if it exists
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File toF = new File(to);
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if (toF.exists()) {
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toF.delete();
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}
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File ptoF = new File(to + PART_EXT);
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if (ptoF.exists()) {
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ptoF.delete();
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}
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try {
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in = new FileInputStream(from);
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out = new FileOutputStream(to + PART_EXT);
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} catch (FileNotFoundException e) {
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throw new IllegalStateException(e.getMessage());
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}
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// actually copy the file
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byte[] buf = new byte[1024];
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int len;
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while ((len = in.read(buf)) > 0)
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{
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out.write(buf, 0, len);
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}
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in.close();
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out.close();
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// once done, rename the partial file to the final copy
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ptoF.renameTo(toF);
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}
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}
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@ -0,0 +1,229 @@
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/*
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* SIP Communicator, the OpenSource Java VoIP and Instant Messaging client.
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*
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* Distributable under LGPL license.
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* See terms of license at gnu.org.
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*/
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package net.java.sip.communicator.slick.slickless.util;
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import java.io.*;
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import net.java.sip.communicator.util.*;
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import junit.framework.*;
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/**
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* Tests for the fail safe transactions
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*
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* @author Benoit Pradelle
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*/
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public class TestFailSafeTransaction
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extends TestCase
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{
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/**
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* Test data to write in the original file
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*/
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private static final String origData = "this is a test for the fail safe "
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+ "transaction ability in SIP Communicator";
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/**
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* Test data to add to the file
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*/
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private static final String addedData = " which is the greatest IM client "
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+ "in the world !";
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/**
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* Test data to never write in the file
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*/
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private static final String wrongData = "all the file is damaged now !";
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/**
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* The base for the name of the temp file
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*/
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private static String tempName = "wzsxedcrfv" + System.currentTimeMillis();
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/**
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* Tests the commit operation
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*/
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public void testCommit() {
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try {
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// setup a temp file
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File temp = File.createTempFile(tempName + "a", null);
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FileOutputStream out = new FileOutputStream(temp);
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out.write(origData.getBytes());
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// write a modification during a transaction
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FailSafeTransaction trans = new FailSafeTransaction(temp);
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trans.beginTransaction();
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out.write(addedData.getBytes());
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trans.commit();
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out.close();
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// test if the two writes are ok
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// file length
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assertEquals("the file hasn't the right size after a commit",
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temp.length(),
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origData.length() + addedData.length());
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FileInputStream in = new FileInputStream(temp);
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byte[] buffer = new byte[in.available()];
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in.read(buffer);
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in.close();
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String content = new String(buffer);
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// file content
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assertEquals("the file content isn't correct",
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origData + addedData,
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content);
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temp.delete();
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} catch (Exception e) {
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Assert.fail(e.getMessage());
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}
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}
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/**
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* Tests the rollback operation
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*/
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public void testRollback() {
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try {
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// setup a temp file
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File temp = File.createTempFile(tempName + "b", null);
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FileOutputStream out = new FileOutputStream(temp);
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out.write(origData.getBytes());
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// write a modification during a transaction
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FailSafeTransaction trans = new FailSafeTransaction(temp);
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trans.beginTransaction();
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out.write(wrongData.getBytes());
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trans.rollback();
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out.close();
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// test if the two writes are ok
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// file length
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assertEquals("the file hasn't the right size after a commit",
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temp.length(),
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origData.length());
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FileInputStream in = new FileInputStream(temp);
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byte[] buffer = new byte[in.available()];
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in.read(buffer);
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in.close();
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String content = new String(buffer);
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// file content
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assertEquals("the file content isn't correct",
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origData,
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content);
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temp.delete();
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} catch (Exception e) {
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Assert.fail(e.getMessage());
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}
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}
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/**
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* Tests if the file is commited when we start a new transaction
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*/
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public void testCommitOnReOpen() {
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try {
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// setup a temp file
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File temp = File.createTempFile(tempName + "c", null);
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FileOutputStream out = new FileOutputStream(temp);
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out.write(origData.getBytes());
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// write a modification during a transaction
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FailSafeTransaction trans = new FailSafeTransaction(temp);
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trans.beginTransaction();
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out.write(addedData.getBytes());
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// this transaction isn't closed, it should commit the changes
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trans.beginTransaction();
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// just to be sure to clean everything
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// the rollback must rollback nothing
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trans.rollback();
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out.close();
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// test if the two writes are ok
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// file length
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assertEquals("the file hasn't the right size after a commit",
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temp.length(),
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origData.length() + addedData.length());
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FileInputStream in = new FileInputStream(temp);
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byte[] buffer = new byte[in.available()];
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in.read(buffer);
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in.close();
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String content = new String(buffer);
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// file content
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assertEquals("the file content isn't correct",
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origData + addedData,
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content);
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temp.delete();
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} catch (Exception e) {
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Assert.fail(e.getMessage());
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}
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}
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/**
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* Tests if the file is rollback-ed if the transaction is never closed
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*/
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public void testRollbackOnFailure() {
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try {
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// setup a temp file
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File temp = File.createTempFile(tempName + "d", null);
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FileOutputStream out = new FileOutputStream(temp);
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out.write(origData.getBytes());
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// write a modification during a transaction
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FailSafeTransaction trans = new FailSafeTransaction(temp);
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FailSafeTransaction trans2 = new FailSafeTransaction(temp);
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trans.beginTransaction();
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out.write(wrongData.getBytes());
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// we suppose here that SC crashed without closing properly the
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// transaction. When it restarts, the modification must have been
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// rollback-ed
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trans2.restoreFile();
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out.close();
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// test if the two writes are ok
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// file length
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assertEquals("the file hasn't the right size after a commit",
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temp.length(),
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origData.length());
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FileInputStream in = new FileInputStream(temp);
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byte[] buffer = new byte[in.available()];
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in.read(buffer);
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in.close();
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String content = new String(buffer);
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// file content
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assertEquals("the file content isn't correct",
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origData,
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content);
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temp.delete();
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} catch (Exception e) {
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Assert.fail(e.getMessage());
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}
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}
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}
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