RrdNioBackendFactory

org.rrd4j.core.RrdNioBackendFactory

All Implemented Interfaces:: Closeable, AutoCloseable

@RrdBackendAnnotation(name="NIO", shouldValidateHeader=true) public class RrdNioBackendFactoryextends 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 optionally 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.

if sync period is negative, no sync thread will be launched

Nested Class Summary
Nested Classes
Modifier and Type
Class
Description
private static class
RrdNioBackendFactory.DefaultSyncThreadPool
The shared pool that flushes writes to disk.
Field Summary
Modifier and Type
Field
Description
private static ThreadFactory
_threadFactory
Factory naming the sync pool's threads.
static final int
DEFAULT_SYNC_CORE_POOL_SIZE
The core pool size for the sync executor.
static final int
DEFAULT_SYNC_PERIOD
Period in seconds between consecutive synchronizations when sync-mode is set to SYNC_BACKGROUND.
private static int
defaultSyncPeriod
Writes between forced syncs, for factories that name none.
private static int
defaultSyncPoolSize
Threads in the shared sync pool.
private final int
syncPeriod
Writes between forced syncs for this factory's backends.
private RrdSyncThreadPool
syncThreadPool
The thread pool to pass to newly-created RrdNioBackend instances.
Fields inherited from class RrdBackendFactory
cachingAllowed, DEFAULTFACTORY, name, scheme, validateHeader
Modifier and Type
Field
Description
protected final boolean
cachingAllowed
Whether this factory's backends may cache data in memory.
static final String
DEFAULTFACTORY
Default backend factory name.
protected final String
name
Storage name this factory reports to RrdDb.
protected final String
scheme
URI scheme this factory's storage URIs start with.
protected final boolean
validateHeader
Whether opened files must carry the RRD header.
Constructor Summary
Constructors
Constructor
Description
RrdNioBackendFactory()
Creates a new RrdNioBackendFactory with default settings.
RrdNioBackendFactory(int syncPeriod)
Creates a new RrdNioBackendFactory, using a default RrdSyncThreadPool.
RrdNioBackendFactory(int syncPeriod, int syncPoolSize)
Creates a new RrdNioBackendFactory.
RrdNioBackendFactory(int syncPeriod, ScheduledExecutorService syncThreadPool)
Creates a new RrdNioBackendFactory.
RrdNioBackendFactory(int syncPeriod, RrdSyncThreadPool syncThreadPool)
Creates a new RrdNioBackendFactory.
Method Summary
Modifier and Type
Method
Description
void
close()
A generic close handle, default implementation does nothing.
static int
getSyncPeriod()
Returns time between two consecutive background synchronizations.
static int
getSyncPoolSize()
Returns the number of synchronizing threads.
RrdSyncThreadPool
getSyncThreadPool()
Return the pool that periodically flushes dirty buffers to disk.
protected RrdBackend
open(String path, boolean readOnly)
/** /** Opens the backend serving a storage path.
static void
setSyncPeriod(int syncPeriod)
Sets time between consecutive background synchronizations.
static void
setSyncPoolSize(int syncPoolSize)
Sets the number of synchronizing threads.
static void
setThreadFactory(ThreadFactory factory)
Set a custom thread factory for the default sync pool.
Methods inherited from class RrdFileBackendFactory
canStore, exists, getCanonicalUri, getPath, getUri
Modifier and Type
Method
Description
boolean
canStore(URI uri)
Tests whether this factory recognises a storage URI.
protected boolean
exists(String path)
Determines if a storage with the given path already exists.
URI
getCanonicalUri(URI uri)
Ensure that an URI is returned in a non-ambiguous way.
String
getPath(URI uri)
Extract the local path from an URI.
URI
getUri(String path)
Transform an path in a valid URI for this backend.
Methods inherited from class RrdBackendFactory
addActiveFactories, buildGenericUri, checkClosing, exists, findFactory, getActiveFactories, getBackend, getBackend, getDefaultFactory, getName, getRootUri, getScheme, resolve, setActiveFactories, shouldValidateHeader, shouldValidateHeader
Modifier and Type
Method
Description
static void
addActiveFactories(RrdBackendFactory... newFactories)
Add factories to the list of active factories, i.e.
static URI
buildGenericUri(String rrdpath)
Try to detect an URI from a path.
void
checkClosing()
Check that all phantom reference are indeed safely closed.
protected boolean
exists(URI uri)
Determines if a storage with the given URI already exists.
static RrdBackendFactory
findFactory(URI uri)
For a given URI, try to find a factory that can manage it in the list of active factories.
static java.util.stream.Stream<RrdBackendFactory>
getActiveFactories()
Return the current active factories as a stream.
(package private) RrdBackend
getBackend(RrdDb rrdDb, String path, boolean readOnly)
Creates RrdBackend object for the given storage path.
(package private) RrdBackend
getBackend(RrdDb rrdDb, URI uri, boolean readOnly)
Creates RrdBackend object for the given storage path.
static RrdBackendFactory
getDefaultFactory()
Returns the default backend factory.
String
getName()
Returns the name (primary ID) for the factory.
protected URI
getRootUri()
Builds the root URI for this factory's scheme.
String
getScheme()
The URI scheme that selects this backend, used to build every RRD URI the factory hands out.
protected URI
resolve(URI rootUri, URI uri, boolean relative)
Try to match an URI against a root URI using a few rules: scheme must match if they are given.
static void
setActiveFactories(RrdBackendFactory... newFactories)
Set the list of active factories, i.e.
protected boolean
shouldValidateHeader(String path)
Determines if the header should be validated.
protected boolean
shouldValidateHeader(URI uri)
Determines if the header should be validated.
Methods inherited from class Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details
- 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
- defaultSyncPeriod
  private static int defaultSyncPeriod
  Writes between forced syncs, for factories that name none.
- 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
- defaultSyncPoolSize
  private static int defaultSyncPoolSize
  Threads in the shared sync pool.
- _threadFactory
  private static volatile ThreadFactory _threadFactory
  Factory naming the sync pool's threads.
- syncPeriod
  private final int syncPeriod
  Writes between forced syncs for this factory's backends.
- syncThreadPool
  private RrdSyncThreadPool syncThreadPool
  The thread pool to pass to newly-created RrdNioBackend instances.
Constructor Details
- RrdNioBackendFactory
  public RrdNioBackendFactory()
  Creates a new RrdNioBackendFactory with default settings.
- RrdNioBackendFactory
  public RrdNioBackendFactory(int syncPeriod)
  Creates a new RrdNioBackendFactory, using a default RrdSyncThreadPool.
  Parameters:
  syncPeriod - the sync period, in seconds. If negative or 0, sync threads are disabled.
- RrdNioBackendFactory
  public RrdNioBackendFactory(int syncPeriod, int syncPoolSize)
  Creates a new RrdNioBackendFactory.
  Parameters:
  syncPeriod - the sync period, in seconds.
  syncPoolSize - The number of threads to use to sync the mapped file to disk, if negative or 0, sync threads are disabled.
- RrdNioBackendFactory
  public RrdNioBackendFactory(int syncPeriod, ScheduledExecutorService syncThreadPool)
  Creates a new RrdNioBackendFactory.
  Parameters:
  syncPeriod - the sync period, in seconds.
  syncThreadPool - If null, disable background sync threads
- RrdNioBackendFactory
  public RrdNioBackendFactory(int syncPeriod, RrdSyncThreadPool syncThreadPool)
  Creates a new RrdNioBackendFactory.
  Parameters:
  syncPeriod - the sync period, in seconds.
  syncThreadPool - If null, disable background sync threads
Method Details
- 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. If negative, it will disabling syncing for all NIO backend factory.
  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.
- open
  protected RrdBackend open(String path, boolean readOnly) throws IOException
  /** /** Opens the backend serving a storage path.
  Creates RrdNioBackend object for the given file path.
  Specified by:
  open in class RrdBackendFactory
  Parameters:
  path - the storage path, relative to this factory's root URI
  readOnly - true to open the storage for reading only, false to allow writes
  Returns:
  the backend that performs all I/O for the given storage path
  Throws:
  IOException - if the storage cannot be opened
- getSyncThreadPool
  public RrdSyncThreadPool getSyncThreadPool()
  Return the pool that periodically flushes dirty buffers to disk.
  Returns:
  The RrdSyncThreadPool or null if syncing is disabled
- close
  public void close()
  Description copied from class: RrdBackendFactory
  A generic close handle, default implementation does nothing.
  Specified by:
  close in interface AutoCloseable
  Specified by:
  close in interface Closeable
  Overrides:
  close in class RrdBackendFactory
- setThreadFactory
  public static void setThreadFactory(ThreadFactory factory)
  Set a custom thread factory for the default sync pool. Must be called before the first use of the factory, otherwise the default thread naming is used.
  Parameters:
  factory - may be null to reset to default

Managing the thread pool

Nested Class Summary

Field Summary

Fields inherited from class RrdBackendFactory

Constructor Summary

Method Summary

Methods inherited from class RrdFileBackendFactory

Methods inherited from class RrdBackendFactory

Methods inherited from class Object

Field Details

DEFAULT_SYNC_PERIOD

defaultSyncPeriod

DEFAULT_SYNC_CORE_POOL_SIZE

defaultSyncPoolSize

_threadFactory

syncPeriod

syncThreadPool

Constructor Details