com.persistit

Class Volume

java.lang.Object

com.persistit.Volume

public class Volume
extends Object

Represent the identity and optionally the service classes that manage a volume. A newly constructed Volume is "hollow" in the sense that it has no ability to perform I/O on a backing file or allocate pages. In this state it represents the identity, but not the content, of the volume.

To enable the Volume to act on data, you must supply a VolumeSpecification object, either through the constructor or with setSpecification(com.persistit.VolumeSpecification), and then call the open(Persistit) method.

Method Summary

Modifier and Type	Method and Description
void	close() Release all resources for this Volume and invalidate all its buffers in the BufferPool.
void	close(long timeout) Release all resources for this Volume and invalidate all its buffers in the BufferPool.
boolean	delete() Delete the file backing this Volume.
boolean	equals(Object o)
File	getAbsoluteFile() Returns the absolute file by which this volume was opened.
Object	getAppCache()
long	getExtendedPageCount()
int	getHandle()
long	getId()
String	getName()
long	getNextAvailablePage()
int	getPageSize()
String	getPath() Returns the path name by which this volume was opened.
Tree	getTree(String name, boolean createIfNecessary) Looks up by name and returns a NewTree within this Volume.
String[]	getTreeNames() Returns an array of all currently defined Tree names.
int	hashCode()
boolean	isClosed() Indicate whether this Volume has been closed.
boolean	isOpened() Indicate whether this Volume has been opened or created, i.e., whether a backing volume file has been created or opened.
boolean	isReadOnly() Indicate whether this Volume prohibits updates.
static boolean	isValidPageSize(int pageSize)
void	setAppCache(Object appCache) Store an Object with this Volume for the convenience of an application.
String	toString()
void	truncate() Remove all data from this volume.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

isValidPageSize

public static boolean isValidPageSize(int pageSize)

close

public void close()
           throws PersistitException

Release all resources for this Volume and invalidate all its buffers in the BufferPool. Exchanges based on this Volume may no longer be used after this call. Waits up to 60000L milliseconds for other threads to relinquish access to the volume.

Throws:

PersistitException

close

public void close(long timeout)
           throws PersistitException

Release all resources for this Volume and invalidate all its buffers in the BufferPool. Exchanges based on this Volume may no longer be used after this call.

Parameters:

timeout - Maximum time in milliseconds to wait for other threads to relinquish access to the volume.

Throws:

PersistitException

truncate

public void truncate()
              throws PersistitException

Remove all data from this volume. This is equivalent to deleting and then recreating the Volume except that it does not actually delete and close the file. Instead, this method truncates the file, rewrites the head page, and invalidates all buffers belonging to this Volume in the BufferPool.

Throws:

PersistitException

delete

public boolean delete()
               throws PersistitException

Delete the file backing this Volume.

Returns:

true if the file existed and was successfully deleted.

Throws:

PersistitException

getPath

public String getPath()

Returns the path name by which this volume was opened.

Returns:

The path name

getAbsoluteFile

public File getAbsoluteFile()

Returns the absolute file by which this volume was opened.

Returns:

The file

getNextAvailablePage

public long getNextAvailablePage()

Returns:

page address of the first unused page in this Volume

getExtendedPageCount

public long getExtendedPageCount()

Returns:

number of pages allocated to this Volume. Note that this method reflects the current length of the volume file, but on sparse file systems the disk space needed to store new pages may not yet have been allocated.

getPageSize

public int getPageSize()

Returns:

The size in bytes of one page in this Volume.

getTree

public Tree getTree(String name,
                    boolean createIfNecessary)
             throws PersistitException

Looks up by name and returns a NewTree within this Volume. If no such tree exists, this method either creates a new tree or returns null depending on whether the createIfNecessary parameter is true.

Parameters:

name - The tree name

createIfNecessary - Determines whether this method will create a new tree if there is no tree having the specified name.

Returns:

The NewTree, or null if createIfNecessary is false and there is no such tree in this Volume.

Throws:

PersistitException

getTreeNames

public String[] getTreeNames()
                      throws PersistitException

Returns an array of all currently defined Tree names.

Returns:

The array

Throws:

PersistitException

isOpened

public boolean isOpened()

Indicate whether this Volume has been opened or created, i.e., whether a backing volume file has been created or opened.

Returns:

true if there is a backing volume file.

isClosed

public boolean isClosed()

Indicate whether this Volume has been closed.

Returns:

true if this Volume is closed.

isReadOnly

public boolean isReadOnly()

Indicate whether this Volume prohibits updates.

Returns:

true if this Volume prohibits updates.

getName

public String getName()

getId

public long getId()

setAppCache

public void setAppCache(Object appCache)

Store an Object with this Volume for the convenience of an application.

Parameters:

appCache - the object to be cached for application convenience.

getAppCache

public Object getAppCache()

Returns:

the object cached for application convenience

getHandle

public int getHandle()

Returns:

The handle value used to identify this Tree in the journal

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object