org.apache.derby.impl.io

Class DirStorageFactory

java.lang.Object

org.apache.derby.impl.io.DirStorageFactory

All Implemented Interfaces:

StorageFactory, WritableStorageFactory

public class DirStorageFactory
extends java.lang.Object
implements WritableStorageFactory

This class provides a disk based implementation 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 inherited from interface org.apache.derby.io.StorageFactory

VERSION_NUMBER

Constructor Summary

Constructors

Constructor and Description
DirStorageFactory()

Method Summary

Modifier and Type	Method and Description
StorageFile	createTemporaryFile(java.lang.String prefix, java.lang.String suffix) Create and returns a temporary file in temporary file system of database.
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.
StorageFile	newStorageFile(StorageFile directoryName, java.lang.String fileName) Construct a StorageFile from a directory and file 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.
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.
boolean	supportsWriteSync() This method tests whether the "rws" and "rwd" modes are implemented.
void	sync(java.io.OutputStream stream, boolean metaData) Force the data of an output stream out to the underlying storage.

Methods inherited from class java.lang.Object

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

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

createTemporaryFile, getCanonicalName, getSeparator, getStorageFactoryVersion, getTempDir, init, isFast, setCanonicalName, shutdown

Constructor Detail

DirStorageFactory

public DirStorageFactory()

Method Detail

newStorageFile

public final 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 final 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 final 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

sync

public void sync(java.io.OutputStream stream,
                 boolean metaData)
          throws java.io.IOException,
                 java.io.SyncFailedException

Force the data of an output stream out to the underlying storage. That is, ensure that it has been made persistent. If the database is to be transient, that is, if the database does not survive a restart, then the sync method implementation need not do anything.

Specified by:

sync in interface WritableStorageFactory

Parameters:

stream - The stream to be synchronized.

metaData - If true then this method must force both changes to the file's contents and metadata to be written to storage; if false, it need only force file content changes to be written. The implementation is allowed to ignore this parameter and always force out metadata changes.

Throws:

java.io.IOException - if an I/O error occurs.

java.io.SyncFailedException - Thrown when the buffers cannot be flushed, or because the system cannot guarantee that all the buffers have been synchronized with physical media.

supportsWriteSync

public boolean supportsWriteSync()

This method tests whether the "rws" and "rwd" modes are implemented. If the "rws" and "rwd" modes are supported then the database engine will conclude that the write methods of "rws"/"rwd" mode StorageRandomAccessFiles are slow but the sync method is fast and optimize accordingly.

Specified by:

supportsWriteSync in interface WritableStorageFactory

Returns:

true if an StIRandomAccess file opened with "rws" or "rwd" modes immediately writes data to the underlying storage, false if not.

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.

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).

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

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.

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