atg.vfs.journal

Class JournalingFileSystem

java.lang.Object

atg.vfs.VirtualFileSystemImpl

atg.vfs.journal.JournalingFileSystem

All Implemented Interfaces:

atg.vfs.DeployableVirtualFileSystem, atg.vfs.owner.OwnerCacheFileSystem, VirtualFileSystem

public class JournalingFileSystem
extends atg.vfs.VirtualFileSystemImpl
implements VirtualFileSystem

A virtual file system which wraps an underlying virtual file system and keeps a journal of changes made to the underlying file system. The changes can later be examined, replayed, or undone.

The journal can be used for various applications. One straightforward use of the journal is a VFS recovery feature. An application can journal VFS operations and then later undo the operations. For a large VFS with many files this would be more efficient than simple saving a copy of the entire virtual file system. Another example is VFS mirroring. A journaling file system could be used to track changes to one master virtual file systems and then later replay those changes against one or more slave virtual file systems.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	CLASS_VERSION Class version string

Fields inherited from class atg.vfs.VirtualFileSystemImpl

CONFIG_PROPERTIES_PATH, DISPLAY_NAME_PROPERTY, mDescriptor, READ_ONLY_PROPERTY

Constructor Summary

Constructors

Constructor and Description
JournalingFileSystem(VirtualFileSystem pUnderlyingFileSystem, java.io.File pJournalDirectory) Construct a journaling file system for the underlying VFS using the specified directory to store the journal.

Method Summary

Modifier and Type	Method and Description
void	close() Close the journal used by this file system.
protected void	finalize() Close journal when we are GCed
VirtualFileSystemDescriptor	getDescriptor() Get the descriptor for this file system.
VirtualFile	getFile(java.lang.String pPath) Get the specified virtual file
VirtualFile	getFile(atg.vfs.VirtualPath pPath) Get the specified virtual file
Journal	getJournal() Get property journal.
java.io.File	getJournalDirectory() Get property journalDirectory.
boolean	getJournalFileContent() Get property journalFileContent.
atg.vfs.owner.OwnerCache	getOwnerCache() OwnerCache
VirtualFileSystem	getUnderlyingFileSystem() Get property underlyingFileSystem.
java.lang.String	getVFSName() Get property VFSName.
void	open() Open or create the journal used by this file system.
java.lang.String	separator() Get the directory separator for this filesystem
void	setJournalFileContent(boolean pJournalFileContent) Set property journalFileContent.
void	setOwnerCache(atg.vfs.owner.OwnerCache pOwnerCache)
void	setVFSName(java.lang.String pVFSName) Set property VFSName.
java.lang.String	toString() Get a string representation of this object

Methods inherited from class atg.vfs.VirtualFileSystemImpl

addUpdateListener, createDescriptor, deleteAllBeforeDate, deleteAllBeforeDate, deleteAllFiles, deleteOldEmptyFolders, getChecksumCache, getDefaultName, getLogger, getUpdateListeners, handleUpdate, removeUpdateListener, setChecksumCache, setDescriptor, setLogger, setUpdateListeners

Methods inherited from class java.lang.Object

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

Methods inherited from interface atg.vfs.VirtualFileSystem

handleUpdate

Field Detail

CLASS_VERSION

public static java.lang.String CLASS_VERSION

Class version string

Constructor Detail

JournalingFileSystem

public JournalingFileSystem(VirtualFileSystem pUnderlyingFileSystem,
                            java.io.File pJournalDirectory)
                     throws JournalException

Construct a journaling file system for the underlying VFS using the specified directory to store the journal.

Parameters:

pUnderlyingFileSystem - VFS to wrap and journal

pJournalDirectory - directory to use to hold journal. This must be non null and refer to a directory that is readable and writable. Any data that already exists in the directory will be deleted.

Throws:

JournalException - if there is a problem creating the file system

Method Detail

setVFSName

public void setVFSName(java.lang.String pVFSName)

Set property VFSName. This is the name of this file system

Overrides:

setVFSName in class atg.vfs.VirtualFileSystemImpl

Parameters:

pVFSName - new value to set

getVFSName

public java.lang.String getVFSName()

Get property VFSName. This is the name of this file system

Specified by:

getVFSName in interface VirtualFileSystem

Overrides:

getVFSName in class atg.vfs.VirtualFileSystemImpl

Returns:

VFSName

getUnderlyingFileSystem

public VirtualFileSystem getUnderlyingFileSystem()

Get property underlyingFileSystem. This is the underlying VFS to which all operations are relayed.

Returns:

UnderlyingFileSystem

getJournalDirectory

public java.io.File getJournalDirectory()

Get property journalDirectory. This is the directory to hold the journal of changes made to the underlying VFS.

Returns:

journalDirectory

getJournal

public Journal getJournal()

Get property journal. This is the journal of modifications.

Returns:

journal

setJournalFileContent

public void setJournalFileContent(boolean pJournalFileContent)

Set property journalFileContent. This is a flag which, if true indicates that the contents of journaled files should also be journaled. If this property is false then file operations are still logged in the journal, but the contents of files modified is not journaled. The false setting reduces the overhead of journaling for callers who do not need to journal content. The default value is false.

Parameters:

pJournalFileContent - new value to set

getJournalFileContent

public boolean getJournalFileContent()

Get property journalFileContent. This is a flag which, if true indicates that the contents of journaled files should also be journaled. If this property is false then file operations are still logged in the journal, but the contents of files modified is not journaled. The false setting reduces the overhead of journaling for callers who do not need to journal content. The default value is false.

Returns:

journalFileContent

getDescriptor

public VirtualFileSystemDescriptor getDescriptor()

Get the descriptor for this file system.

Specified by:

getDescriptor in interface VirtualFileSystem

Overrides:

getDescriptor in class atg.vfs.VirtualFileSystemImpl

Returns:

the descriptor

getFile

public VirtualFile getFile(java.lang.String pPath)

Get the specified virtual file

Specified by:

getFile in interface VirtualFileSystem

Overrides:

getFile in class atg.vfs.VirtualFileSystemImpl

Parameters:

pPath - path of virtual file

Returns:

the file

getFile

public VirtualFile getFile(atg.vfs.VirtualPath pPath)

Get the specified virtual file

Specified by:

getFile in interface VirtualFileSystem

Parameters:

pPath - path of virtual file

Returns:

the file

separator

public java.lang.String separator()

Get the directory separator for this filesystem

Specified by:

separator in interface VirtualFileSystem

Returns:

the separator

open

public void open()
          throws JournalException

Open or create the journal used by this file system. The caller must guarantee that close() is called later to free resources.

Throws:

JournalException - if there is a journaling problem

close

public void close()
           throws JournalException

Close the journal used by this file system. After close() is called the file system cannot be used until open() is called. guarantee that close() is called later to free resources.

Throws:

JournalException - if there is a journaling problem

setOwnerCache

public void setOwnerCache(atg.vfs.owner.OwnerCache pOwnerCache)

Specified by:

setOwnerCache in interface atg.vfs.owner.OwnerCacheFileSystem

Overrides:

setOwnerCache in class atg.vfs.VirtualFileSystemImpl

getOwnerCache

public atg.vfs.owner.OwnerCache getOwnerCache()

OwnerCache

Specified by:

getOwnerCache in interface atg.vfs.owner.OwnerCacheFileSystem

Overrides:

getOwnerCache in class atg.vfs.VirtualFileSystemImpl

finalize

protected void finalize()
                 throws java.lang.Throwable

Close journal when we are GCed

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable

toString

public java.lang.String toString()

Get a string representation of this object

Overrides:

toString in class java.lang.Object

Returns:

the string