RrdMemoryBackendFactory

java.lang.Object

org.rrd4j.core.RrdBackendFactory

org.rrd4j.core.RrdMemoryBackendFactory

All Implemented Interfaces:: Closeable, AutoCloseable

@RrdBackendAnnotation(name="MEMORY", shouldValidateHeader=false) public class RrdMemoryBackendFactoryextends RrdBackendFactory

Factory class which creates actual RrdMemoryBackend objects. Rrd4j's support for in-memory RRDs is still experimental. You should know that all active RrdMemoryBackend objects are held in memory, each backend object stores RRD data in one big byte array. This implementation is therefore quite basic and memory hungry but runs very fast.

Calling close() on RrdDb objects does not release any memory at all (RRD data must be available for the next new RrdDb(path) call. To release allocated memory, you'll have to call delete(path) method of this class.

Field Summary
Fields
Modifier and Type
Field
Description
protected final Map<String, AtomicReference<ByteBuffer>>
backends
Open RRD buffers by RRD ID, held until delete() removes them.
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
RrdMemoryBackendFactory()
A factory holding no open backends; the map starts empty and is filled by open(String, boolean) as RRDs are opened and released by delete(String).
Method Summary
All Methods
Modifier and Type
Method
Description
boolean
canStore(URI uri)
Accepts only URIs whose scheme matches this backend's memory scheme.
boolean
delete(String id)
Removes the storage with the given ID from the memory.
protected boolean
exists(String id)
Determines if a storage with the given path already exists.
protected RrdBackend
open(String id, boolean readOnly)
Opens the backend serving a storage path.
Methods inherited from class RrdBackendFactory
addActiveFactories, buildGenericUri, checkClosing, close, exists, findFactory, getActiveFactories, getBackend, getBackend, getCanonicalUri, getDefaultFactory, getName, getPath, getRootUri, getScheme, getUri, 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.
void
close()
A generic close handle, default implementation does nothing.
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.
String
getName()
Returns the name (primary ID) for the factory.
String
getPath(URI uri)
Extract the local path from an URI.
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.
URI
getUri(String path)
Transform an path in a valid URI for this backend.
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
- backends
  protected final Map<String, AtomicReference<ByteBuffer>> backends
  Open RRD buffers by RRD ID, held until delete() removes them.
Constructor Details
- RrdMemoryBackendFactory
  public RrdMemoryBackendFactory()
  A factory holding no open backends; the map starts empty and is filled by open(String, boolean) as RRDs are opened and released by delete(String).
Method Details
- open
  protected RrdBackend open(String id, boolean readOnly)
  Opens the backend serving a storage path.
  Creates RrdMemoryBackend object.
  Specified by:
  open in class RrdBackendFactory
  Parameters:
  id - 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
- canStore
  public boolean canStore(URI uri)
  Accepts only URIs whose scheme matches this backend's memory scheme.
  Overrides:
  canStore in class RrdBackendFactory
  Parameters:
  uri - the candidate storage URI to test against this factory
  Returns:
  false unless a subclass overrides this to recognise its own URIs
- exists
  protected boolean exists(String id)
  Determines if a storage with the given path already exists.
  Method to determine if a memory storage with the given ID already exists.
  Specified by:
  exists in class RrdBackendFactory
  Parameters:
  id - File system path to probe for.
  Returns:
  true if a storage already exists at the given path
- delete
  public boolean delete(String id)
  Removes the storage with the given ID from the memory.
  Parameters:
  id - Storage ID, the key this factory registered the storage under
  Returns:
  true if a storage was removed, false if the ID was unknown

Field Summary

Fields inherited from class RrdBackendFactory

Constructor Summary

Method Summary

Methods inherited from class RrdBackendFactory

Methods inherited from class Object

Field Details

backends

Constructor Details

Method Details

open

canStore

exists

delete