org.crosswire.jsword.book.sword.state

Class OpenFileStateManager

java.lang.Object

org.crosswire.jsword.book.sword.state.OpenFileStateManager

public final class OpenFileStateManager
extends Object

Manages the creation and re-distribution of open file states. This increases performance as more often than not, the same file state may be used. For example we may be carrying out a contains() operation followed by a read to disk for a particular key Each BookMetaData has a corresponding a file state which is different to another. Furthermore, concurrent accesses cannot share this file state as the OpenFileState records where in the file it is, for reading several verses together for example. As a result, we want to key a lookup by BookMetaData, which then gives us a pool of available file states... We create some more if none are available. In order to prevent memory leaks (OpenFileStates might be quite heavy as they do some internal caching of file data.. In order to avoid many file references piling up in memory, we implement a background cleaning thread which will clean up redundant keys every so often.

Author:

DM Smith, Chris Burrell

See Also:

The GNU Lesser General Public License for details.

Field Summary

Fields

Modifier and Type	Field and Description
private static org.slf4j.Logger	LOGGER
private static OpenFileStateManager	manager
private Map<BookMetaData,Queue<OpenFileState>>	metaToStates
private ScheduledFuture<?>	monitoringThread
private boolean	shuttingDown

Constructor Summary

Constructors

Modifier	Constructor and Description
private	OpenFileStateManager(int cleanupIntervalSeconds, int maxExpiry) prevent instantiation

Method Summary

Methods

Modifier and Type	Method and Description
private void	ensureNotShuttingDown()
GenBookBackendState	getGenBookBackendState(BookMetaData metadata)
private <T extends OpenFileState> T	getInstance(BookMetaData metadata)
private Queue<OpenFileState>	getQueueForMeta(BookMetaData metadata)
RawBackendState	getRawBackendState(BookMetaData metadata)
RawFileBackendState	getRawFileBackendState(BookMetaData metadata)
RawLDBackendState	getRawLDBackendState(BookMetaData metadata)
ZLDBackendState	getZLDBackendState(BookMetaData metadata)
ZVerseBackendState	getZVerseBackendState(BookMetaData metadata, BlockType blockType)
static void	init(int cleanupIntervalSeconds, int maxExpiry) Allow the caller to initialize with their own settings.
static OpenFileStateManager	instance() Singleton instance method to return the one and only Open File State Manager
void	release(OpenFileState fileState)
void	shutDown() Shuts down all open files

Methods inherited from class java.lang.Object

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

Field Detail

monitoringThread

private final ScheduledFuture<?> monitoringThread

metaToStates

private final Map<BookMetaData,Queue<OpenFileState>> metaToStates

shuttingDown

private volatile boolean shuttingDown

manager

private static volatile OpenFileStateManager manager

LOGGER

private static final org.slf4j.Logger LOGGER

Constructor Detail

OpenFileStateManager

private OpenFileStateManager(int cleanupIntervalSeconds,
                    int maxExpiry)

prevent instantiation

Method Detail

init

public static void init(int cleanupIntervalSeconds,
        int maxExpiry)

Allow the caller to initialize with their own settings. Should the OpenFileStateManager already be initialized a no-op will occur. No need for double-checked locking here

Parameters:

cleanupIntervalSeconds - seconds before cleanup

maxExpiry -

instance

public static OpenFileStateManager instance()

Singleton instance method to return the one and only Open File State Manager

Returns:

the singleton

getRawBackendState

public RawBackendState getRawBackendState(BookMetaData metadata)
                                   throws BookException

Throws:

BookException

getRawFileBackendState

public RawFileBackendState getRawFileBackendState(BookMetaData metadata)
                                           throws BookException

Throws:

BookException

getGenBookBackendState

public GenBookBackendState getGenBookBackendState(BookMetaData metadata)
                                           throws BookException

Throws:

BookException

getRawLDBackendState

public RawLDBackendState getRawLDBackendState(BookMetaData metadata)
                                       throws BookException

Throws:

BookException

getZLDBackendState

public ZLDBackendState getZLDBackendState(BookMetaData metadata)
                                   throws BookException

Throws:

BookException

getZVerseBackendState

public ZVerseBackendState getZVerseBackendState(BookMetaData metadata,
                                       BlockType blockType)
                                         throws BookException

Throws:

BookException

getInstance

private <T extends OpenFileState> T getInstance(BookMetaData metadata)

getQueueForMeta

private Queue<OpenFileState> getQueueForMeta(BookMetaData metadata)

release

public void release(OpenFileState fileState)

shutDown

public void shutDown()

Shuts down all open files

ensureNotShuttingDown

private void ensureNotShuttingDown()
                            throws BookException

Throws:

BookException