org.rrd4j.core

Class RrdSafeFileBackend

java.lang.Object

org.rrd4j.core.RrdBackend

org.rrd4j.core.RrdFileBackend

org.rrd4j.core.RrdRandomAccessFileBackend

org.rrd4j.core.RrdSafeFileBackend

public class RrdSafeFileBackend
extends RrdRandomAccessFileBackend

Backend which is used to store RRD data to ordinary files on the disk, using locking. 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 a little bit slow since it does not use fast java.nio.* package (it's still based on the RandomAccessFile class).

Field Summary

Fields inherited from class org.rrd4j.core.RrdRandomAccessFileBackend

rafile

Fields inherited from class org.rrd4j.core.RrdFileBackend

file, readOnly

Constructor Summary

Constructors

Constructor and Description
RrdSafeFileBackend(String path, long lockWaitTime, long lockRetryPeriod) Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() close.
static String	getLockInfo() getLockInfo.
protected boolean	isCachingAllowed() Defines the caching policy for this backend.

Methods inherited from class org.rrd4j.core.RrdRandomAccessFileBackend

read, setLength, write

Methods inherited from class org.rrd4j.core.RrdFileBackend

getCanonicalPath, getCanonicalPath, getLength

Methods inherited from class org.rrd4j.core.RrdBackend

getPath, readAll

Methods inherited from class java.lang.Object

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

Constructor Detail

RrdSafeFileBackend

public RrdSafeFileBackend(String path,
                  long lockWaitTime,
                  long lockRetryPeriod)
                   throws IOException

Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Parameters:

path - Path to a file

lockWaitTime - a long.

lockRetryPeriod - a long.

Throws:

IOException - Thrown in case of I/O error

Method Detail

close

public void close()
           throws IOException

close.

Overrides:

close in class RrdRandomAccessFileBackend

Throws:

IOException - if any.

isCachingAllowed

protected boolean isCachingAllowed()

Defines the caching policy for this backend.

Overrides:

isCachingAllowed in class RrdBackend

Returns:

false

getLockInfo

public static String getLockInfo()

getLockInfo.

Returns:

a String object.