RrdSafeFileBackendFactory

org.rrd4j.core.RrdSafeFileBackendFactory

All Implemented Interfaces:: Closeable, AutoCloseable

@RrdBackendAnnotation(name="SAFE", shouldValidateHeader=true, cachingAllowed=false) public class RrdSafeFileBackendFactoryextends RrdRandomAccessFileBackendFactory

Factory class which creates actual RrdSafeFileBackend objects.

Because of locking, each RrdDb can be open only once even from within the JVM. So usage of the RrdDbPool is mandatory with this backend.

Field Summary
Modifier and Type
Field
Description
private static long
defaultLockRetryPeriod
Pause between lock attempts, in ms.
private static long
defaultLockWaitTime
How long a lock is retried, in ms.
static final long
LOCK_RETRY_PERIOD
Default time between two consecutive file locking attempts.
static final long
LOCK_WAIT_TIME
Default time (in milliseconds) this backend will wait for a file lock.
private final long
lockRetryPeriod
Retry period this factory hands to its backends.
private final long
lockWaitTime
Wait time this factory hands to its backends.
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
RrdSafeFileBackendFactory()
Generate a factory using the default system wide lock settings
RrdSafeFileBackendFactory(long lockWaitTime, long lockRetryPeriod)
Generate a factory with custom lock settings
Method Summary
Modifier and Type
Method
Description
static long
getLockRetryPeriod()
Returns time between two consecutive file locking attempts.
static long
getLockWaitTime()
Returns time this backend will wait for a file lock.
protected RrdBackend
open(String path, boolean readOnly)
Opens the backend serving a storage path.
static void
setLockRetryPeriod(long lockRetryPeriod)
Sets time between two consecutive file locking attempts.
static void
setLockWaitTime(long lockWaitTime)
Sets time this backend will wait for a file lock.
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, close, 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.
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.
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
- LOCK_WAIT_TIME
  public static final long LOCK_WAIT_TIME
  Default time (in milliseconds) this backend will wait for a file lock.
  See Also:
  Constant Field Values
- defaultLockWaitTime
  private static long defaultLockWaitTime
  How long a lock is retried, in ms.
- LOCK_RETRY_PERIOD
  public static final long LOCK_RETRY_PERIOD
  Default time between two consecutive file locking attempts.
  See Also:
  Constant Field Values
- defaultLockRetryPeriod
  private static long defaultLockRetryPeriod
  Pause between lock attempts, in ms.
- lockWaitTime
  private final long lockWaitTime
  Wait time this factory hands to its backends.
- lockRetryPeriod
  private final long lockRetryPeriod
  Retry period this factory hands to its backends.
Constructor Details
- RrdSafeFileBackendFactory
  public RrdSafeFileBackendFactory()
  Generate a factory using the default system wide lock settings
- RrdSafeFileBackendFactory
  public RrdSafeFileBackendFactory(long lockWaitTime, long lockRetryPeriod)
  Generate a factory with custom lock settings
  Parameters:
  lockWaitTime - wait time in ms
  lockRetryPeriod - retry period in ms
Method Details
- open
  protected RrdBackend open(String path, boolean readOnly) throws IOException
  Opens the backend serving a storage path.
  Creates RrdFileBackend object for the given file path.
  Creates RrdSafeFileBackend object for the given file path.
  Overrides:
  open in class RrdRandomAccessFileBackendFactory
  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
- getLockWaitTime
  public static long getLockWaitTime()
  Returns time this backend will wait for a file lock.
  Returns:
  Time (in milliseconds) this backend will wait for a file lock.
- setLockWaitTime
  public static void setLockWaitTime(long lockWaitTime)
  Sets time this backend will wait for a file lock.
  Parameters:
  lockWaitTime - Maximum lock wait time (in milliseconds)
- getLockRetryPeriod
  public static long getLockRetryPeriod()
  Returns time between two consecutive file locking attempts.
  Returns:
  Time (im milliseconds) between two consecutive file locking attempts.
- setLockRetryPeriod
  public static void setLockRetryPeriod(long lockRetryPeriod)
  Sets time between two consecutive file locking attempts.
  Parameters:
  lockRetryPeriod - time (in milliseconds) between two consecutive file locking attempts.

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

LOCK_WAIT_TIME

defaultLockWaitTime

LOCK_RETRY_PERIOD

defaultLockRetryPeriod

lockWaitTime

lockRetryPeriod

Constructor Details

RrdSafeFileBackendFactory

Method Details

open

getLockWaitTime

setLockWaitTime

getLockRetryPeriod

setLockRetryPeriod