Package org.apache.derby.impl.io

Class BaseStorageFactory

java.lang.Object

org.apache.derby.impl.io.BaseStorageFactory

All Implemented Interfaces:

StorageFactory

Direct Known Subclasses:

CPStorageFactory, DirStorageFactory, JarStorageFactory, URLStorageFactory

abstract class BaseStorageFactory
extends java.lang.Object
implements StorageFactory

This class provides a base for implementations of the StorageFactory interface. It is used by the database engine to access persistent data and transaction logs under the directory (default) subsubprotocol.

Field Summary

Fields

Modifier and Type	Field	Description
protected java.lang.String	canonicalName
protected java.lang.String	dataDirectory
(package private) java.lang.String	home
protected java.lang.String	separatedDataDirectory
private static java.lang.String	TEMP_DIR_PREFIX
protected StorageFile	tempDir
protected java.lang.String	tempDirPath
protected java.lang.String	uniqueName

Fields inherited from interface org.apache.derby.io.StorageFactory

VERSION_NUMBER

Constructor Summary

Constructors

Constructor	Description
BaseStorageFactory()	Most of the initialization is done in the init method.

Method Summary

Modifier and Type	Method	Description
(package private) void	createTempDir()
StorageFile	createTemporaryFile(java.lang.String prefix, java.lang.String suffix)	Create and returns a temporary file in temporary file system of database.
(package private) abstract void	doInit()
java.lang.String	getCanonicalName()	Get the canonical name of the database.
char	getSeparator()	Get the pathname separator character used by the StorageFile implementation.
int	getStorageFactoryVersion()
StorageFile	getTempDir()	Get the abstract name of the directory that holds temporary files.
void	init(java.lang.String home, java.lang.String databaseName, java.lang.String tempDirName, java.lang.String uniqueName)	Classes implementing the StorageFactory interface must have a null constructor.
boolean	isFast()	This method is used to determine whether the storage is fast (RAM based) or slow (disk based).
boolean	isReadOnlyDatabase()	Determine whether the database is read only.
(package private) abstract StorageFile	newPersistentFile(java.lang.String path)	Construct a persistent StorageFile from a path name.
(package private) abstract StorageFile	newPersistentFile(java.lang.String directoryName, java.lang.String fileName)	Construct a persistent StorageFile from a directory and path name.
(package private) abstract StorageFile	newPersistentFile(StorageFile directoryName, java.lang.String fileName)	Construct a persistent StorageFile from a directory and path name.
StorageFile	newStorageFile(java.lang.String path)	Construct a StorageFile from a path name.
StorageFile	newStorageFile(java.lang.String directoryName, java.lang.String fileName)	Construct a StorageFile from a directory and file name.
StorageFile	newStorageFile(StorageFile directoryName, java.lang.String fileName)	Construct a StorageFile from a directory and file name.
private java.lang.String	readOnlyTempRoot()
void	setCanonicalName(java.lang.String name)	Set the canonicalName.
void	shutdown()	The shutdown method is called during the normal shutdown of the database.
boolean	supportsRandomAccess()	Determine whether the storage supports random access.

Methods inherited from class java.lang.Object

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

Field Detail

home

java.lang.String home

tempDir

protected StorageFile tempDir

tempDirPath

protected java.lang.String tempDirPath

dataDirectory

protected java.lang.String dataDirectory

separatedDataDirectory

protected java.lang.String separatedDataDirectory

uniqueName

protected java.lang.String uniqueName

canonicalName

protected java.lang.String canonicalName

TEMP_DIR_PREFIX

private static final java.lang.String TEMP_DIR_PREFIX

See Also:

Constant Field Values

Constructor Detail

BaseStorageFactory

BaseStorageFactory()

Most of the initialization is done in the init method.

Method Detail

init

public void init(java.lang.String home,
                 java.lang.String databaseName,
                 java.lang.String tempDirName,
                 java.lang.String uniqueName)
          throws java.io.IOException

Classes implementing the StorageFactory interface must have a null constructor. This method is called when the database is booted up to initialize the class. It should perform all actions necessary to start the basic storage, such as creating a temporary file directory. The init method will be called once, before any other method is called, and will not be called again.

Specified by:

init in interface StorageFactory

Parameters:

home - The name of the directory containing the database. It comes from the system.home system property. It may be null. A storage factory may decide to ignore this parameter. (For instance the classpath storage factory ignores it.

databaseName - The name of the database (directory). All relative pathnames are relative to this directory. If null then the storage factory will only be used to deal with the directory containing the databases.

tempDirName - The name of the temporary file directory set in properties. If null then a default directory should be used. Each database should get a separate temporary file directory within this one to avoid collisions.

uniqueName - A unique name that can be used to create the temporary file directory for this database.

Throws:

java.io.IOException - on an error (unexpected).

doInit

abstract void doInit()
              throws java.io.IOException

Throws:

java.io.IOException

shutdown

public void shutdown()

Description copied from interface: StorageFactory

The shutdown method is called during the normal shutdown of the database. However, the database engine cannot guarantee that shutdown will be called. If the JVM terminates abnormally then it will not be called.

Specified by:

shutdown in interface StorageFactory

getCanonicalName

public java.lang.String getCanonicalName()
                                  throws java.io.IOException

Get the canonical name of the database. This is a name that uniquely identifies it. It is system dependent. The normal, disk based implementation uses method java.io.File.getCanonicalPath on the directory holding the database to construct the canonical name.

Specified by:

getCanonicalName in interface StorageFactory

Returns:

the canonical name

Throws:

java.io.IOException - if an IO error occurred during the construction of the name.

setCanonicalName

public void setCanonicalName(java.lang.String name)

Set the canonicalName. May need adjustment due to DERBY-5096

Specified by:

setCanonicalName in interface StorageFactory

Parameters:

name - uniquely identifiable name for this database

newStorageFile

public StorageFile newStorageFile(java.lang.String path)

Construct a StorageFile from a path name.

Specified by:

newStorageFile in interface StorageFactory

Parameters:

path - The path name of the file

Returns:

A corresponding StorageFile object

newStorageFile

public StorageFile newStorageFile(java.lang.String directoryName,
                                  java.lang.String fileName)

Construct a StorageFile from a directory and file name.

Specified by:

newStorageFile in interface StorageFactory

Parameters:

directoryName - The directory part of the path name.

fileName - The name of the file within the directory.

Returns:

A corresponding StorageFile object

newStorageFile

public StorageFile newStorageFile(StorageFile directoryName,
                                  java.lang.String fileName)

Construct a StorageFile from a directory and file name.

Specified by:

newStorageFile in interface StorageFactory

Parameters:

directoryName - The directory part of the path name.

fileName - The name of the file within the directory.

Returns:

A corresponding StorageFile object

newPersistentFile

abstract StorageFile newPersistentFile(java.lang.String path)

Construct a persistent StorageFile from a path name.

Parameters:

path - The path name of the file. Guaranteed not to be in the temporary file directory. If null then the database directory should be returned.

Returns:

A corresponding StorageFile object

newPersistentFile

abstract StorageFile newPersistentFile(java.lang.String directoryName,
                                       java.lang.String fileName)

Construct a persistent StorageFile from a directory and path name.

Parameters:

directoryName - The path name of the directory. Guaranteed not to be in the temporary file directory. Guaranteed not to be null

fileName - The name of the file within the directory. Guaranteed not to be null.

Returns:

A corresponding StorageFile object

newPersistentFile

abstract StorageFile newPersistentFile(StorageFile directoryName,
                                       java.lang.String fileName)

Construct a persistent StorageFile from a directory and path name.

Parameters:

directoryName - The path name of the directory. Guaranteed not to be to be null. Guaranteed to be created by a call to one of the newPersistentFile methods.

fileName - The name of the file within the directory. Guaranteed not to be null.

Returns:

A corresponding StorageFile object

getSeparator

public char getSeparator()

Get the pathname separator character used by the StorageFile implementation.

Specified by:

getSeparator in interface StorageFactory

Returns:

the pathname separator character. (Normally '/' or '\').

getTempDir

public StorageFile getTempDir()

Get the abstract name of the directory that holds temporary files.

Specified by:

getTempDir in interface StorageFactory

Returns:

a directory name

isFast

public boolean isFast()

This method is used to determine whether the storage is fast (RAM based) or slow (disk based). It may be used by the database engine to determine the default size of the page cache.

Specified by:

isFast in interface StorageFactory

Returns:

true if the storage is fast, false if it is slow.

isReadOnlyDatabase

public boolean isReadOnlyDatabase()

Description copied from interface: StorageFactory

Determine whether the database is read only. The database engine supports read-only databases, even in file systems that are writable.

Specified by:

isReadOnlyDatabase in interface StorageFactory

Returns:

true if the storage is read only, false if it is writable.

supportsRandomAccess

public boolean supportsRandomAccess()

Determine whether the storage supports random access. If random access is not supported then it will only be accessed using InputStreams and OutputStreams (if the database is writable).

Specified by:

supportsRandomAccess in interface StorageFactory

Returns:

true if the storage supports random access, false if it is writable.

createTempDir

void createTempDir()
            throws java.io.IOException

Throws:

java.io.IOException

readOnlyTempRoot

private java.lang.String readOnlyTempRoot()
                                   throws java.io.IOException

Throws:

java.io.IOException

getStorageFactoryVersion

public int getStorageFactoryVersion()

Specified by:

getStorageFactoryVersion in interface StorageFactory

Returns:

the StorageFactory version supported by this implementation

createTemporaryFile

public StorageFile createTemporaryFile(java.lang.String prefix,
                                       java.lang.String suffix)
                                throws java.io.IOException

Create and returns a temporary file in temporary file system of database.

Specified by:

createTemporaryFile in interface StorageFactory

Parameters:

prefix - String to prefix the random name generator.

suffix - String to suffix the random name generator.

Returns:

StorageFile

Throws:

java.io.IOException