Package org.xwiki.store

Class FileDeleteTransactionRunnable

java.lang.Object

org.xwiki.store.TransactionRunnable<R>

org.xwiki.store.ProvidingTransactionRunnable<T,T>

org.xwiki.store.StartableTransactionRunnable<TransactionRunnable>

org.xwiki.store.FileDeleteTransactionRunnable

public class FileDeleteTransactionRunnable
extends StartableTransactionRunnable<TransactionRunnable>

A TransactionRunnable for deleting a file safely. The operation can be rolled back even after the onCommit() function is called. It is only final when the onComplete function is called.

Since:

3.0M2

Version:

$Id: e57fe7e5a1eee5d6734ee4ede2c2070407b0e98a $

Constructor Summary

Constructors

Constructor	Description
FileDeleteTransactionRunnable(File toDelete, File backupFile, ReadWriteLock lock)	The Constructor.

Method Summary

Modifier and Type	Method	Description
protected void	onComplete()
protected void	onPreRun()
protected void	onRollback()
protected void	onRun()

Methods inherited from class org.xwiki.store.StartableTransactionRunnable

start

Methods inherited from class org.xwiki.store.ProvidingTransactionRunnable

asProvider, getProvidedContext

Methods inherited from class org.xwiki.store.TransactionRunnable

commit, complete, getContext, onCommit, preRun, rollback, run, runIn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileDeleteTransactionRunnable

public FileDeleteTransactionRunnable(File toDelete,
                                     File backupFile,
                                     ReadWriteLock lock)

The Constructor.

Parameters:

toDelete - the file to delete.

backupFile - a temporary file, this should not contain anything important as it will be deleted and must not be altered while the operation is running. This will contain whatever was in the toDelete file prior, just in case onRollback must be called.

lock - a ReadWriteLock whose writeLock will be locked as the beginning of the process and unlocked when complete.

Method Detail

onPreRun

protected void onPreRun()
                 throws IOException

Obtain the lock and make sure the temporary and backup files are deleted.

Overrides:

onPreRun in class TransactionRunnable<TransactionRunnable>

Throws:

IOException

See Also:

TransactionRunnable.onPreRun()

onRun

protected void onRun()
              throws IOException

Overrides:

onRun in class TransactionRunnable<TransactionRunnable>

Throws:

IOException

onRollback

protected void onRollback()

There are a few possibilities. If preRun() has not completed then there may be an old backup from a previous delete, anyway if preRun() has not completed then we know there is nothing to rollback. Otherwise:

1. There is a backup file but no main file, it has been renamed, rename it back to the main location.
2. There is a main file and no backup. Nothing has probably happened, do nothing to rollback.
3. There are neither backup nor main files, this means we tried to delete a file which didn't exist to begin with.
4. There are both main and backup files. AAAAAaaa what do we do?! Throw an exception which will be reported.

Overrides:

onRollback in class TransactionRunnable<TransactionRunnable>

See Also:

TransactionRunnable.onRollback()

onComplete

protected void onComplete()
                   throws IOException

Once this is called, there is no going back. Remove backup file and unlock the lock.

Overrides:

onComplete in class TransactionRunnable<TransactionRunnable>

Throws:

IOException

See Also:

TransactionRunnable.onComplete()