org.rrd4j.core.RrdBackendFactory

All Implemented Interfaces:: Closeable, AutoCloseable

Direct Known Subclasses:: RrdFileBackendFactory, RrdMemoryBackendFactory

public abstract class RrdBackendFactory
extends Object
implements Closeable

Base (abstract) backend factory class which holds references to all concrete backend factories and defines abstract methods which must be implemented in all concrete factory implementations.

Factory classes are used to create concrete RrdBackend implementations. Each factory creates unlimited number of specific backend objects. Rrd4j supports six different backend types (backend factories) out of the box:

RrdRandomAccessFileBackend: objects of this class are created from the RrdRandomAccessFileBackendFactory class. This was the default backend used in all Rrd4j releases before 1.4.0 release. It uses java.io.* package and RandomAccessFile class to store RRD data in files on the disk.
RrdSafeFileBackend: objects of this class are created from the RrdSafeFileBackendFactory class. It uses java.io.* package and RandomAccessFile class to store RRD data in files on the disk. This backend is SAFE: it locks the underlying RRD file during update/fetch operations, and caches only static parts of a RRD file in memory. Therefore, this backend is safe to be used when RRD files should be shared between several JVMs at the same time. However, this backend is *slow* since it does not use fast java.nio.* package (it's still based on the RandomAccessFile class).
RrdNioBackend: objects of this class are created from the RrdNioBackendFactory class. The backend uses java.io.* and java.nio.* classes (mapped ByteBuffer) to store RRD data in files on the disk. This is the default backend since 1.4.0 release.
RrdMemoryBackend: objects of this class are created from the RrdMemoryBackendFactory class. This backend stores all data in memory. Once JVM exits, all data gets lost. The backend is extremely fast and memory hungry.

Each backend factory used to be identified by its name. Constructors are provided in the RrdDb class to create RrdDb objects (RRD databases) backed with a specific backend.

A more generic management was added in version 3.2 that allows multiple instances of a backend to be used. Each backend can manage custom URL. They are tried in the declared order by the setActiveFactories(RrdBackendFactory...) or addFactories(RrdBackendFactory...) and the method canStore(URI) return true when it can manage the given URI. Using setActiveFactories(RrdBackendFactory...) with new created instance is the preferred way to manage factories, as it provides a much precise control of creation and end of life of factories.

Since 3.4, using only setActiveFactories(RrdBackendFactory...) and addActiveFactories(RrdBackendFactory...) will not register any named backend at all. getDefaultFactory() will return the first active factory. All methods using named backend and the registry of factory were deprecated.

For default implementation, the path is separated in a root URI prefix and the path components. The root URI can be used to identify different name spaces or just be `/`.

See javadoc for RrdBackend to find out how to create your custom backends.

Field Summary

Fields
Modifier and Type	Field	Description
`protected boolean`	`cachingAllowed`
`static String`	`DEFAULTFACTORY`	The default factory type.
`protected String`	`name`
`protected String`	`scheme`
`protected boolean`	`validateHeader`

Constructor Summary

Constructors

Modifier Constructor Description

protected RrdBackendFactory()

Method Summary

Modifier and Type	Method	Description
`static void`	`addActiveFactories(RrdBackendFactory... newFactories)`	Add factories to the list of active factories, i.e.
`static void`	`addFactories(RrdBackendFactory... newFactories)`	Deprecated. Uses `addActiveFactories(RrdBackendFactory...)` instead.
`static URI`	`buildGenericUri(String rrdpath)`	Try to detect an URI from a path.
`boolean`	`canStore(URI uri)`
`void`	`checkClosing()`	Check that all phantom reference are indeed safely closed.
`void`	`close()`	A generic close handle, default implementation does nothing.
`protected abstract boolean`	`exists(String path)`	Determines if a storage with the given path already exists.
`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.
`URI`	`getCanonicalUri(URI uri)`	Ensure that an URI is returned in a non-ambiguous way.
`static RrdBackendFactory`	`getDefaultFactory()`	Returns the default backend factory.
`static RrdBackendFactory`	`getFactory(String name)`	Deprecated. Uses active factory instead
`String`	`getName()`	Returns the name (primary ID) for the factory.
`String`	`getPath(URI uri)`	Extract the local path from an URI.
`protected URI`	`getRootUri()`
`String`	`getScheme()`
`URI`	`getUri(String path)`	Transform an path in a valid URI for this backend.
`protected abstract RrdBackend`	`open(String path, boolean readOnly)`
`static void`	`registerAndSetAsDefaultFactory(RrdBackendFactory factory)`	Deprecated. Uses `setActiveFactories(RrdBackendFactory...)` instead.
`static void`	`registerFactory(RrdBackendFactory factory)`	Deprecated. Uses active factory instead
`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.
`static void`	`setDefaultFactory(String factoryName)`	Deprecated. Uses active factory instead
`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 java.lang.Object

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

Field Details
- DEFAULTFACTORY
  
  public static final String DEFAULTFACTORY
  
  The default factory type. It will also put in the active factories list.
  
  See Also:
  
  Constant Field Values
- name
  
  protected final String name
- cachingAllowed
  
  protected final boolean cachingAllowed
- scheme
  
  protected final String scheme
- validateHeader
  
  protected final boolean validateHeader
Constructor Details
- RrdBackendFactory
  
  protected RrdBackendFactory()
Method Details
- getFactory
  
  @Deprecated public static RrdBackendFactory getFactory(String name)
  
  Deprecated.
  Uses active factory instead
  
  Returns backend factory for the given backend factory name.
  Parameters:
  
  name - Backend factory name. Initially supported names are:
  
  FILE: Default factory which creates backends based on the java.io.* package. RRD data is stored in files on the disk
  SAFE: Default factory which creates backends based on the java.io.* package. RRD data is stored in files on the disk. This backend is "safe". Being safe means that RRD files can be safely shared between several JVM's.
  NIO: Factory which creates backends based on the java.nio.* package. RRD data is stored in files on the disk
  MEMORY: Factory which creates memory-oriented backends. RRD data is stored in memory, it gets lost as soon as JVM exits.
  BERKELEY: a memory-oriented backend that ensure persistent in a Berkeley Db storage.
  MONGODB: a memory-oriented backend that ensure persistent in a MongoDB storage.
  
  Returns:
  
  Backend factory for the given factory name
- registerFactory
  
  @Deprecated public static void registerFactory(RrdBackendFactory factory)
  
  Deprecated.
  Uses active factory instead
  
  Registers new (custom) backend factory within the Rrd4j framework.
  
  Parameters:
  
  factory - Factory to be registered
- registerAndSetAsDefaultFactory
  
  @Deprecated public static void registerAndSetAsDefaultFactory(RrdBackendFactory factory)
  
  Deprecated.
  Uses setActiveFactories(RrdBackendFactory...) instead.
  
  Registers new (custom) backend factory within the Rrd4j framework and sets this factory as the default.
  
  Parameters:
  
  factory - Factory to be registered and set as default
- getDefaultFactory
  
  public static RrdBackendFactory getDefaultFactory()
  
  Returns the default backend factory. This factory is used to construct RrdDb objects if no factory is specified in the RrdDb constructor.
  
  Returns:
  
  Default backend factory.
- setDefaultFactory
  
  @Deprecated public static void setDefaultFactory(String factoryName)
  
  Deprecated.
  Uses active factory instead
  
  Replaces the default backend factory with a new one. This method must be called before the first RRD gets created.
  It also clear the list of actives factories and set it to the default factory.
  
  Parameters:
  
  factoryName - Name of the default factory..
- setActiveFactories
  
  public static void setActiveFactories(RrdBackendFactory... newFactories)
  
  Set the list of active factories, i.e. the factory used to resolve URI.
  
  Parameters:
  
  newFactories - the new active factories.
- getActiveFactories
  
  public static java.util.stream.Stream<RrdBackendFactory> getActiveFactories()
  
  Return the current active factories as a stream.
  
  Returns:
  
  Since:
  
  3.7
- addFactories
  
  @Deprecated public static void addFactories(RrdBackendFactory... newFactories)
  
  Deprecated.
  Uses addActiveFactories(RrdBackendFactory...) instead.
  
  Add factories to the list of active factories, i.e. the factory used to resolve URI.
  
  Parameters:
  
  newFactories - active factories to add.
- addActiveFactories
  
  public static void addActiveFactories(RrdBackendFactory... newFactories)
  
  Add factories to the list of active factories, i.e. the factory used to resolve URI.
  
  Parameters:
  
  newFactories - active factories to add.
- findFactory
  
  public static RrdBackendFactory findFactory(URI uri)
  
  For a given URI, try to find a factory that can manage it in the list of active factories.
  
  Parameters:
  
  uri - URI to try.
  
  Returns:
  
  a RrdBackendFactory that can manage that URI.
  
  Throws:
  
  IllegalArgumentException - when no matching factory is found.
- buildGenericUri
  
  public static URI buildGenericUri(String rrdpath)
  
  Try to detect an URI from a path. It's needed because of Microsoft Windows path that look's like an URI and to URL-encode the path.
  
  Parameters:
  
  rrdpath - a file URI that can be a Windows path
  
  Returns:
  
  an URI
- checkClosing
  
  public void checkClosing()
  
  Check that all phantom reference are indeed safely closed.
- getScheme
  
  public String getScheme()
  
  Returns:
  
  the scheme name for URI, default to getName().toLowerCase()
- getRootUri
  
  protected URI getRootUri()
- canStore
  
  public boolean canStore(URI uri)
- resolve
  
  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.
  authority must match if they are given.
  if uri is opaque (scheme:nonabsolute), the scheme specific part is resolve as a relative path.
  query and fragment is kept as is.
  Parameters:
  
  rootUri - the URI to match against
  
  uri - an URI that the current backend can handle.
  
  relative - if true, return an URI relative to the rootUri
  
  Returns:
  
  a calculate normalized absolute URI or null if the tried URL don't match against the root.
- getCanonicalUri
  
  public URI getCanonicalUri(URI uri)
  
  Ensure that an URI is returned in a non-ambiguous way.
  
  Parameters:
  
  uri - a valid URI for this backend.
  
  Returns:
  
  the canonized URI.
- getUri
  
  public URI getUri(String path)
  
  Transform an path in a valid URI for this backend.
  
  Parameters:
  
  path - a path local to the current backend.
  
  Returns:
  
  an URI that the current backend can handle.
- getPath
  
  public String getPath(URI uri)
  
  Extract the local path from an URI.
  
  Parameters:
  
  uri - The URI to parse.
  
  Returns:
  
  the local path from the URI.
- open
  
  protected abstract RrdBackend open(String path, boolean readOnly) throws IOException
  
  Throws:
  
  IOException
- getBackend
  
  RrdBackend getBackend(RrdDb rrdDb, String path, boolean readOnly) throws IOException
  
  Creates RrdBackend object for the given storage path.
  
  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.
- getBackend
  
  RrdBackend getBackend(RrdDb rrdDb, URI uri, boolean readOnly) throws IOException
  
  Creates RrdBackend object for the given storage path.
  
  Parameters:
  
  rrdDb -
  
  uri - Storage uri
  
  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.
- exists
  
  protected abstract boolean exists(String path) throws IOException
  
  Determines if a storage with the given path already exists.
  
  Parameters:
  
  path - Storage path
  
  Returns:
  
  a boolean.
  
  Throws:
  
  IOException - in case of I/O error.
- exists
  
  protected boolean exists(URI uri) throws IOException
  
  Determines if a storage with the given URI already exists.
  
  Parameters:
  
  uri - Storage URI.
  
  Returns:
  
  a boolean.
  
  Throws:
  
  IOException - in case of I/O error.
- shouldValidateHeader
  
  protected boolean shouldValidateHeader(String path) throws IOException
  
  Determines if the header should be validated.
  
  Parameters:
  
  path - Storage path
  
  Returns:
  
  a boolean.
  
  Throws:
  
  IOException - if header validation fails
- shouldValidateHeader
  
  protected boolean shouldValidateHeader(URI uri) throws IOException
  
  Determines if the header should be validated.
  
  Parameters:
  
  uri - Storage URI
  
  Returns:
  
  a boolean.
  
  Throws:
  
  IOException - if header validation fails
- getName
  
  public String getName()
  
  Returns the name (primary ID) for the factory.
  
  Returns:
  
  Name of the factory.
- close
  
  public void close() throws IOException
  
  A generic close handle, default implementation does nothing.
  
  Specified by:
  
  close in interface AutoCloseable
  
  Specified by:
  
  close in interface Closeable
  
  Throws:
  
  IOException - if the close fails
  
  Since:
  
  3.4

Class RrdBackendFactory

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Details

Constructor Details

Method Details