org.rrd4j.core

Class RrdNioBackendFactory

java.lang.Object

org.rrd4j.core.RrdBackendFactory

org.rrd4j.core.RrdFileBackendFactory

org.rrd4j.core.RrdNioBackendFactory

public class RrdNioBackendFactory
extends RrdFileBackendFactory

Factory class which creates actual RrdNioBackend objects. This is the default factory since 1.4.0 version.

Managing the thread pool

Each RrdNioBackendFactory is backed by a RrdSyncThreadPool, which it uses to sync the memory-mapped files to disk. In order to avoid having these threads live longer than they should, it is recommended that clients create and destroy thread pools at the appropriate time in their application's life time. Failure to manage thread pools appropriately may lead to the thread pool hanging around longer than necessary, which in turn may cause memory leaks.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_SYNC_CORE_POOL_SIZE The core pool size for the sync executor.
static int	DEFAULT_SYNC_PERIOD Period in seconds between consecutive synchronizations when sync-mode is set to SYNC_BACKGROUND.

Constructor Summary

Constructors

Constructor and Description
RrdNioBackendFactory() Creates a new RrdNioBackendFactory.

Method Summary

Methods

Modifier and Type	Method and Description
String	getName() getName.
static int	getSyncPeriod() Returns time between two consecutive background synchronizations.
static int	getSyncPoolSize() Returns the number of synchronizing threads.
protected RrdBackend	open(String path, boolean readOnly) Creates RrdBackend object for the given storage path.
static void	setSyncPeriod(int syncPeriod) Sets time between consecutive background synchronizations.
static void	setSyncPoolSize(int syncPoolSize) Sets the number of synchronizing threads.
void	setSyncThreadPool(RrdSyncThreadPool syncThreadPool) Setter for the field syncThreadPool.
void	setSyncThreadPool(ScheduledExecutorService syncThreadPool) Setter for the field syncThreadPool.

Methods inherited from class org.rrd4j.core.RrdFileBackendFactory

exists, shouldValidateHeader

Methods inherited from class org.rrd4j.core.RrdBackendFactory

getDefaultFactory, getFactory, registerAndSetAsDefaultFactory, registerFactory, setDefaultFactory

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_SYNC_PERIOD

public static final int DEFAULT_SYNC_PERIOD

Period in seconds between consecutive synchronizations when sync-mode is set to SYNC_BACKGROUND. By default in-memory cache will be transferred to the disc every 300 seconds (5 minutes). Default value can be changed via setSyncPeriod(int) method.

See Also:

Constant Field Values

DEFAULT_SYNC_CORE_POOL_SIZE

public static final int DEFAULT_SYNC_CORE_POOL_SIZE

The core pool size for the sync executor. Defaults to 6.

See Also:

Constant Field Values

Constructor Detail

RrdNioBackendFactory

public RrdNioBackendFactory()

Creates a new RrdNioBackendFactory. One should call setSyncThreadPool(RrdSyncThreadPool syncThreadPool) or setSyncThreadPool(RrdSyncThreadPool syncThreadPool) before the first call to open(String path, boolean readOnly). Failure to do so will lead to memory leaks in anything but the simplest applications because the underlying thread pool will not be shut down cleanly. Read the Javadoc for this class to understand why using this constructor is discouraged.

Method Detail

getSyncPeriod

public static int getSyncPeriod()

Returns time between two consecutive background synchronizations. If not changed via setSyncPeriod(int) method call, defaults to DEFAULT_SYNC_PERIOD. See setSyncPeriod(int) for more information.

Returns:

Time in seconds between consecutive background synchronizations.

setSyncPeriod

public static void setSyncPeriod(int syncPeriod)

Sets time between consecutive background synchronizations.

Parameters:

syncPeriod - Time in seconds between consecutive background synchronizations.

getSyncPoolSize

public static int getSyncPoolSize()

Returns the number of synchronizing threads. If not changed via setSyncPoolSize(int) method call, defaults to DEFAULT_SYNC_CORE_POOL_SIZE. See setSyncPoolSize(int) for more information.

Returns:

Number of synchronizing threads.

setSyncPoolSize

public static void setSyncPoolSize(int syncPoolSize)

Sets the number of synchronizing threads. It must be set before the first use of this factory. It will not have any effect afterward.

Parameters:

syncPoolSize - Number of synchronizing threads.

setSyncThreadPool

public void setSyncThreadPool(RrdSyncThreadPool syncThreadPool)

Setter for the field syncThreadPool.

Parameters:

syncThreadPool - the RrdSyncThreadPool to use to sync the memory-mapped files.

setSyncThreadPool

public void setSyncThreadPool(ScheduledExecutorService syncThreadPool)

Setter for the field syncThreadPool.

Parameters:

syncThreadPool - the ScheduledExecutorService that will back the RrdSyncThreadPool used to sync the memory-mapped files.

open

protected RrdBackend open(String path,
              boolean readOnly)
                   throws IOException

Creates RrdBackend object for the given storage path. Creates RrdNioBackend object for the given file path.

Specified by:

open in class RrdBackendFactory

Parameters:

path - Storage path

readOnly - True, if the storage should be accessed in read/only mode. False otherwise.

Returns:

Backend object which handles all I/O operations for the given storage path

Throws:

IOException - Thrown in case of I/O error.

getName

public String getName()

getName.

Specified by:

getName in class RrdBackendFactory

Returns:

The String "NIO".