public class

RrdDb

extends Object
java.lang.Object
   ↳ org.rrd4j.core.RrdDb

Class Overview

Main class used to create and manipulate round robin databases (RRDs). Use this class to perform update and fetch operations on exisiting RRDs, to create new RRD from the definition (object of class RrdDef) or from XML file (dumped content of RRDTool's or Rrd4j's RRD file).

Each RRD is backed with some kind of storage. For example, RRDTool supports only one kind of storage (disk file). On the contrary, Rrd4j gives you freedom to use other storage (backend) types even to create your own backend types for some special purposes. Rrd4j by default stores RRD data in files (as RRDTool), but you might choose to store RRD data in memory (this is supported in Rrd4j), to use java.nio.* instead of java.io.* package for file manipulation (also supported) or to store whole RRDs in the SQL database (you'll have to extend some classes to do this).

Note that Rrd4j uses binary format different from RRDTool's format. You cannot use this class to manipulate RRD files created with RRDTool. However, if you perform the same sequence of create, update and fetch operations, you will get exactly the same results from Rrd4j and RRDTool.

You will not be able to use Rrd4j API if you are not familiar with basic RRDTool concepts. Good place to start is the official RRD tutorial and relevant RRDTool man pages: rrdcreate, rrdupdate, rrdfetch and rrdgraph. For RRDTool's advanced graphing capabilities (RPN extensions), also supported in Rrd4j, there is an excellent CDEF tutorial.

Summary

Constants
String PREFIX_RRDTool Prefix to identify external RRDTool file source used in various RrdDb constructors.
String PREFIX_XML Prefix to identify external XML file source used in various RrdDb constructors.
Public Constructors
RrdDb(RrdDef rrdDef)

Constructor used to create new RRD object from the definition.

RrdDb(RrdDef rrdDef, RrdBackendFactory factory)
Constructor used to create new RRD object from the definition object but with a storage (backend) different from default.
RrdDb(String path, boolean readOnly)
Constructor used to open already existing RRD.
RrdDb(String path, boolean readOnly, RrdBackendFactory factory)
Constructor used to open already existing RRD backed with a storage (backend) different from default.
RrdDb(String path)

Constructor used to open already existing RRD in R/W mode, with a default storage (backend) type (file on the disk).

RrdDb(String path, RrdBackendFactory factory)

Constructor used to open already existing RRD in R/W mode with a storage (backend) type different from default.

RrdDb(String rrdPath, String externalPath)

Constructor used to create RRD files from external file sources.

RrdDb(String rrdPath, String externalPath, RrdBackendFactory factory)

Constructor used to create RRD files from external file sources with a backend type different from default.

Public Methods
synchronized void close()
Closes RRD.
boolean containsDs(String dsName)
Checks presence of a specific datasource.
synchronized void copyStateTo(RrdUpdater other)
Copies object's internal state to another RrdDb object.
FetchRequest createFetchRequest(ConsolFun consolFun, long fetchStart, long fetchEnd, long resolution)

Prepares fetch request to be executed on this RRD.

FetchRequest createFetchRequest(ConsolFun consolFun, long fetchStart, long fetchEnd)

Prepares fetch request to be executed on this RRD.

Sample createSample(long time)

Creates new sample with the given timestamp and all datasource values set to 'unknown'.

Sample createSample()

Creates new sample with the current timestamp and all data source values set to 'unknown'.

synchronized String dump()

Returns string representing complete internal RRD state.

synchronized void dumpXml(String filename)
Dumps internal RRD state to XML file.
synchronized void dumpXml(OutputStream destination)

Writes the RRD content to OutputStream using XML format.

synchronized String exportXml()
This method is just an alias for getXml method.
synchronized void exportXml(OutputStream destination)
This method is just an alias for dumpXml method.
synchronized void exportXml(String filename)
This method is just an alias for dumpXml(String) method.
Archive findMatchingArchive(FetchRequest request)
Archive findStartMatchArchive(String consolFun, long startTime, long resolution)
Finds the archive that best matches to the start time (time period being start-time until now) and requested resolution.
int getArcCount()
Returns the number of RRA archives defined in the file
int getArcIndex(ConsolFun consolFun, int steps)
Returns index of Archive object with the given consolidation function and the number of steps.
Archive getArchive(int arcIndex)
Returns Archive object for the given archive index.
Archive getArchive(ConsolFun consolFun, int steps)
Returns Archive object with the given consolidation function and the number of steps.
synchronized byte[] getBytes()
Returns an array of bytes representing the whole RRD.
String getCanonicalPath()
Returns canonical path to the underlying RRD file.
Datasource getDatasource(String dsName)
Returns Datasource object corresponding to the given datasource name.
Datasource getDatasource(int dsIndex)
Returns Datasource object for the given datasource index.
int getDsCount()
Returns the number of datasources defined in the file
int getDsIndex(String dsName)
Returns internal index number for the given datasource name.
String[] getDsNames()

Returns an array of datasource names defined in RRD.

Header getHeader()
Returns RRD header.
synchronized String getInfo()
long getLastArchiveUpdateTime()
Returns the last time when some of the archives in this RRD was updated.
synchronized double getLastDatasourceValue(String dsName)
Returns the last stored value for the given datasource.
synchronized double[] getLastDatasourceValues()
Returns an array of last datasource values.
synchronized long getLastUpdateTime()
Returns time of last update operation as timestamp (in seconds).
String getPath()
Returns path to this RRD.
RrdAllocator getRrdAllocator()
Required to implement RrdUpdater interface.
RrdBackend getRrdBackend()
Returns backend object for this RRD which performs actual I/O operations.
synchronized RrdDef getRrdDef()

Returns RRD definition object which can be used to create new RRD with the same creation parameters but with no data in it.

synchronized String getXml()

Returns string representing internal RRD state in XML format.

boolean isClosed()
Returns true if the RRD is closed.
static void main(String[] args)
static void setDefaultFactory(String factoryName)
Sets default backend factory to be used.
synchronized void setInfo(String info)
Protected Methods
void finalize()
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final String PREFIX_RRDTool

Prefix to identify external RRDTool file source used in various RrdDb constructors.

Constant Value: "rrdtool:/"

public static final String PREFIX_XML

Prefix to identify external XML file source used in various RrdDb constructors.

Constant Value: "xml:/"

Public Constructors

public RrdDb (RrdDef rrdDef)

Constructor used to create new RRD object from the definition. This RRD object will be backed with a storage (backend) of the default type. Initially, storage type defaults to "NIO" (RRD bytes will be put in a file on the disk). Default storage type can be changed with a static setDefaultFactory(String) method call.

New RRD file structure is specified with an object of class RrdDef. The underlying RRD storage is created as soon as the constructor returns.

Typical scenario:

 // create new RRD definition
 RrdDef def = new RrdDef("test.rrd", 300);
 def.addDatasource("input", DsType.DT_COUNTER, 600, 0, Double.NaN);
 def.addDatasource("output", DsType.DT_COUNTER, 600, 0, Double.NaN);
 def.addArchive(ConsolFun.CF_AVERAGE, 0.5, 1, 600);
 def.addArchive(ConsolFun.CF_AVERAGE, 0.5, 6, 700);
 def.addArchive(ConsolFun.CF_AVERAGE, 0.5, 24, 797);
 def.addArchive(ConsolFun.CF_AVERAGE, 0.5, 288, 775);
 def.addArchive(ConsolFun.CF_MAX, 0.5, 1, 600);
 def.addArchive(ConsolFun.CF_MAX, 0.5, 6, 700);
 def.addArchive(ConsolFun.CF_MAX, 0.5, 24, 797);
 def.addArchive(ConsolFun.CF_MAX, 0.5, 288, 775);
 

// RRD definition is now completed, create the database! RrdDb rrd = new RrdDb(def); // new RRD file has been created on your disk

Parameters
rrdDef Object describing the structure of the new RRD file.
Throws
IOException Thrown in case of I/O error.

public RrdDb (RrdDef rrdDef, RrdBackendFactory factory)

Constructor used to create new RRD object from the definition object but with a storage (backend) different from default.

Rrd4j uses factories to create RRD backend objecs. There are three different backend factories supplied with Rrd4j, and each factory has its unique name:

  • FILE: backends created from this factory will store RRD data to files by using java.io.* classes and methods
  • NIO: backends created from this factory will store RRD data to files by using java.nio.* classes and methods
  • MEMORY: backends created from this factory will store RRD data in memory. This might be useful in runtime environments which prohibit disk utilization, or for storing temporary, non-critical data (it gets lost as soon as JVM exits).

For example, to create RRD in memory, use the following code

 RrdBackendFactory factory = RrdBackendFactory.getFactory("MEMORY");
 RrdDb rrdDb = new RrdDb(rrdDef, factory);
 rrdDb.close();
 

New RRD file structure is specified with an object of class RrdDef. The underlying RRD storage is created as soon as the constructor returns.

Parameters
rrdDef RRD definition object
factory The factory which will be used to create storage for this RRD
Throws
IOException Thrown in case of I/O error

public RrdDb (String path, boolean readOnly)

Constructor used to open already existing RRD. This RRD object will be backed with a storage (backend) of the default type (file on the disk). Constructor obtains read or read/write access to this RRD.

Parameters
path Path to existing RRD.
readOnly Should be set to false if you want to update the underlying RRD. If you want just to fetch data from the RRD file (read-only access), specify true. If you try to update RRD file open in read-only mode (readOnly set to true), IOException will be thrown.
Throws
IOException Thrown in case of I/O error.

public RrdDb (String path, boolean readOnly, RrdBackendFactory factory)

Constructor used to open already existing RRD backed with a storage (backend) different from default. Constructor obtains read or read/write access to this RRD.

Parameters
path Path to existing RRD.
readOnly Should be set to false if you want to update the underlying RRD. If you want just to fetch data from the RRD file (read-only access), specify true. If you try to update RRD file open in read-only mode (readOnly set to true), IOException will be thrown.
factory Backend factory which will be used for this RRD.
Throws
FileNotFoundException Thrown if the requested file does not exist.
IOException Thrown in case of general I/O error (bad RRD file, for example).

public RrdDb (String path)

Constructor used to open already existing RRD in R/W mode, with a default storage (backend) type (file on the disk).

Parameters
path Path to existing RRD.
Throws
IOException Thrown in case of I/O error.

public RrdDb (String path, RrdBackendFactory factory)

Constructor used to open already existing RRD in R/W mode with a storage (backend) type different from default.

Parameters
path Path to existing RRD.
factory Backend factory used to create this RRD.
Throws
IOException Thrown in case of I/O error.

public RrdDb (String rrdPath, String externalPath)

Constructor used to create RRD files from external file sources. Supported external file sources are:

  • RRDTool/Rrd4j XML file dumps (i.e files created with rrdtool dump command).
  • RRDTool binary files.

Newly created RRD will be backed with a default storage (backend) type (file on the disk).

Rrd4j and RRDTool use the same format for XML dump and this constructor should be used to (re)create Rrd4j RRD files from XML dumps. First, dump the content of a RRDTool RRD file (use command line):

 rrdtool dump original.rrd > original.xml
 

Than, use the file original.xml to create Rrd4j RRD file named copy.rrd:

 RrdDb rrd = new RrdDb("copy.rrd", "original.xml");
 

or:

 RrdDb rrd = new RrdDb("copy.rrd", "xml:/original.xml");
 

See documentation for dumpXml() method to see how to convert Rrd4j files to RRDTool's format.

To read RRDTool files directly, specify rrdtool:/ prefix in the externalPath argument. For example, to create Rrd4j compatible file named copy.rrd from the file original.rrd created with RRDTool, use the following code:

 RrdDb rrd = new RrdDb("copy.rrd", "rrdtool:/original.rrd");
 

Note that the prefix xml:/ or rrdtool:/ is necessary to distinguish between XML and RRDTool's binary sources. If no prefix is supplied, XML format is assumed

Parameters
rrdPath Path to a RRD file which will be created
externalPath Path to an external file which should be imported, with an optional xml:/ or rrdtool:/ prefix.
Throws
IOException Thrown in case of I/O error

public RrdDb (String rrdPath, String externalPath, RrdBackendFactory factory)

Constructor used to create RRD files from external file sources with a backend type different from default. Supported external file sources are:

  • RRDTool/Rrd4j XML file dumps (i.e files created with rrdtool dump command).
  • RRDTool binary files.

Rrd4j and RRDTool use the same format for XML dump and this constructor should be used to (re)create Rrd4j RRD files from XML dumps. First, dump the content of a RRDTool RRD file (use command line):

 rrdtool dump original.rrd > original.xml
 

Than, use the file original.xml to create Rrd4j RRD file named copy.rrd:

 RrdDb rrd = new RrdDb("copy.rrd", "original.xml");
 

or:

 RrdDb rrd = new RrdDb("copy.rrd", "xml:/original.xml");
 

See documentation for dumpXml() method to see how to convert Rrd4j files to RRDTool's format.

To read RRDTool files directly, specify rrdtool:/ prefix in the externalPath argument. For example, to create Rrd4j compatible file named copy.rrd from the file original.rrd created with RRDTool, use the following code:

 RrdDb rrd = new RrdDb("copy.rrd", "rrdtool:/original.rrd");
 

Note that the prefix xml:/ or rrdtool:/ is necessary to distinguish between XML and RRDTool's binary sources. If no prefix is supplied, XML format is assumed

Parameters
rrdPath Path to RRD which will be created
externalPath Path to an external file which should be imported, with an optional xml:/ or rrdtool:/ prefix.
factory Backend factory which will be used to create storage (backend) for this RRD.
Throws
IOException Thrown in case of I/O error

Public Methods

public synchronized void close ()

Closes RRD. No further operations are allowed on this RrdDb object.

Throws
IOException Thrown in case of I/O related error.

public boolean containsDs (String dsName)

Checks presence of a specific datasource.

Parameters
dsName Datasource name to check
Returns
  • true if datasource is present in this RRD, false otherwise
Throws
IOException Thrown in case of I/O error.

public synchronized void copyStateTo (RrdUpdater other)

Copies object's internal state to another RrdDb object.

Parameters
other New RrdDb object to copy state to
Throws
IOException Thrown in case of I/O error

public FetchRequest createFetchRequest (ConsolFun consolFun, long fetchStart, long fetchEnd, long resolution)

Prepares fetch request to be executed on this RRD. Use returned FetchRequest object and its fetchData() method to actually fetch data from the RRD file.

Parameters
consolFun Consolidation function to be used in fetch request. Allowed values are "AVERAGE", "MIN", "MAX" and "LAST" (these constants are conveniently defined in the ConsolFun class).
fetchStart Starting timestamp for fetch request.
fetchEnd Ending timestamp for fetch request.
resolution Fetch resolution (see RRDTool's rrdfetch man page for an explanation of this parameter.
Returns
  • Request object that should be used to actually fetch data from RRD

public FetchRequest createFetchRequest (ConsolFun consolFun, long fetchStart, long fetchEnd)

Prepares fetch request to be executed on this RRD. Use returned FetchRequest object and its fetchData() method to actually fetch data from this RRD. Data will be fetched with the smallest possible resolution (see RRDTool's rrdfetch man page for the explanation of the resolution parameter).

Parameters
consolFun Consolidation function to be used in fetch request. Allowed values are AVERAGE, MIN, MAX and LAST (see ConsolFun enum).
fetchStart Starting timestamp for fetch request.
fetchEnd Ending timestamp for fetch request.
Returns
  • Request object that should be used to actually fetch data from RRD.

public Sample createSample (long time)

Creates new sample with the given timestamp and all datasource values set to 'unknown'. Use returned Sample object to specify datasource values for the given timestamp. See documentation for Sample for an explanation how to do this.

Once populated with data source values, call Sample's update() method to actually store sample in the RRD associated with it.

Parameters
time Sample timestamp rounded to the nearest second (without milliseconds).
Returns
  • Fresh sample with the given timestamp and all data source values set to 'unknown'.
Throws
IOException Thrown in case of I/O error.

public Sample createSample ()

Creates new sample with the current timestamp and all data source values set to 'unknown'. Use returned Sample object to specify datasource values for the current timestamp. See documentation for Sample for an explanation how to do this.

Once populated with data source values, call Sample's update() method to actually store sample in the RRD associated with it.

Returns
  • Fresh sample with the current timestamp and all data source values set to 'unknown'.
Throws
IOException Thrown in case of I/O error.

public synchronized String dump ()

Returns string representing complete internal RRD state. The returned string can be printed to stdout and/or used for debugging purposes.

Returns
  • String representing internal RRD state.
Throws
IOException Thrown in case of I/O related error.

public synchronized void dumpXml (String filename)

Dumps internal RRD state to XML file. Use this XML file to convert your Rrd4j RRD to RRDTool format.

Suppose that you have a Rrd4j RRD file original.rrd and you want to convert it to RRDTool format. First, execute the following java code:

RrdDb rrd = new RrdDb("original.rrd"); rrd.dumpXml("original.xml");

Use original.xml file to create the corresponding RRDTool file (from your command line): rrdtool restore copy.rrd original.xml

Parameters
filename Path to XML file which will be created.
Throws
IOException Thrown in case of I/O related error.

public synchronized void dumpXml (OutputStream destination)

Writes the RRD content to OutputStream using XML format. This format is fully compatible with RRDTool's XML dump format and can be used for conversion purposes or debugging.

Parameters
destination Output stream to receive XML data
Throws
IOException Thrown in case of I/O related error

public synchronized String exportXml ()

This method is just an alias for getXml method.

Returns
  • Internal RRD state in XML format.
Throws
IOException Thrown in case of I/O related error

public synchronized void exportXml (OutputStream destination)

This method is just an alias for dumpXml method.

Throws
IOException Thrown in case of I/O related error

public synchronized void exportXml (String filename)

This method is just an alias for dumpXml(String) method.

Throws
IOException Thrown in case of I/O related error

public Archive findMatchingArchive (FetchRequest request)

Throws
IOException

public Archive findStartMatchArchive (String consolFun, long startTime, long resolution)

Finds the archive that best matches to the start time (time period being start-time until now) and requested resolution.

Parameters
consolFun Consolidation function of the datasource.
startTime Start time of the time period in seconds.
resolution Requested fetch resolution.
Returns
  • Reference to the best matching archive.
Throws
IOException Thrown in case of I/O related error.

public int getArcCount ()

Returns the number of RRA archives defined in the file

Returns
  • The number of RRA archives defined in the file

public int getArcIndex (ConsolFun consolFun, int steps)

Returns index of Archive object with the given consolidation function and the number of steps. Exception is thrown if such archive could not be found.

Parameters
consolFun Consolidation function
steps Number of archive steps
Returns
  • Requested Archive object
Throws
IOException Thrown in case of I/O error

public Archive getArchive (int arcIndex)

Returns Archive object for the given archive index.

Parameters
arcIndex Archive index (zero based)
Returns
  • Archive object

public Archive getArchive (ConsolFun consolFun, int steps)

Returns Archive object with the given consolidation function and the number of steps.

Parameters
consolFun Consolidation function
steps Number of archive steps
Returns
  • Requested Archive object or null if no such archive could be found
Throws
IOException Thrown in case of I/O error

public synchronized byte[] getBytes ()

Returns an array of bytes representing the whole RRD.

Returns
  • All RRD bytes
Throws
IOException Thrown in case of I/O related error.

public String getCanonicalPath ()

Returns canonical path to the underlying RRD file. Note that this method makes sense just for ordinary RRD files created on the disk - an exception will be thrown for RRD objects created in memory or with custom backends.

Returns
  • Canonical path to RRD file;
Throws
IOException Thrown in case of I/O error or if the underlying backend is not derived from RrdFileBackend.

public Datasource getDatasource (String dsName)

Returns Datasource object corresponding to the given datasource name.

Parameters
dsName Datasource name
Returns
  • Datasource object corresponding to the give datasource name or null if not found.
Throws
IOException Thrown in case of I/O error

public Datasource getDatasource (int dsIndex)

Returns Datasource object for the given datasource index.

Parameters
dsIndex Datasource index (zero based)
Returns
  • Datasource object

public int getDsCount ()

Returns the number of datasources defined in the file

Returns
  • The number of datasources defined in the file

public int getDsIndex (String dsName)

Returns internal index number for the given datasource name.

Parameters
dsName Data source name.
Returns
  • Internal index of the given data source name in this RRD.
Throws
IOException Thrown in case of I/O error.

public String[] getDsNames ()

Returns an array of datasource names defined in RRD.

Returns
  • Array of datasource names.
Throws
IOException Thrown in case of I/O error.

public Header getHeader ()

Returns RRD header.

Returns
  • Header object

public synchronized String getInfo ()

Throws
IOException

public long getLastArchiveUpdateTime ()

Returns the last time when some of the archives in this RRD was updated. This time is not the same as the getLastUpdateTime() since RRD file can be updated without updating any of the archives.

Returns
  • last time when some of the archives in this RRD was updated
Throws
IOException Thrown in case of I/O error

public synchronized double getLastDatasourceValue (String dsName)

Returns the last stored value for the given datasource.

Parameters
dsName Datasource name
Returns
  • Last stored value for the given datasource
Throws
IOException Thrown in case of I/O error
IllegalArgumentException Thrown if no datasource in this RrdDb matches the given datasource name

public synchronized double[] getLastDatasourceValues ()

Returns an array of last datasource values. The first value in the array corresponds to the first datasource defined in the RrdDb and so on.

Returns
  • Array of last datasource values
Throws
IOException Thrown in case of I/O error

public synchronized long getLastUpdateTime ()

Returns time of last update operation as timestamp (in seconds).

Returns
  • Last update time (in seconds).
Throws
IOException

public String getPath ()

Returns path to this RRD.

Returns
  • Path to this RRD.

public RrdAllocator getRrdAllocator ()

Required to implement RrdUpdater interface. You should never call this method directly.

Returns
  • Allocator object

public RrdBackend getRrdBackend ()

Returns backend object for this RRD which performs actual I/O operations.

Returns
  • RRD backend for this RRD.

public synchronized RrdDef getRrdDef ()

Returns RRD definition object which can be used to create new RRD with the same creation parameters but with no data in it.

Example:

 RrdDb rrd1 = new RrdDb("original.rrd");
 RrdDef def = rrd1.getRrdDef();
 // fix path
 def.setPath("empty_copy.rrd");
 // create new RRD file
 RrdDb rrd2 = new RrdDb(def);
 

Returns
  • RRD definition.
Throws
IOException

public synchronized String getXml ()

Returns string representing internal RRD state in XML format. This format is fully compatible with RRDTool's XML dump format and can be used for conversion purposes or debugging.

Returns
  • Internal RRD state in XML format.
Throws
IOException Thrown in case of I/O related error

public boolean isClosed ()

Returns true if the RRD is closed.

Returns
  • true if closed, false otherwise

public static void main (String[] args)

public static void setDefaultFactory (String factoryName)

Sets default backend factory to be used. This method is just an alias for setDefaultFactory(String).

Parameters
factoryName Name of the backend factory to be set as default.
Throws
IllegalArgumentException Thrown if invalid factory name is supplied, or not called before the first backend object (before the first RrdDb object) is created.

public synchronized void setInfo (String info)

Throws
IOException

Protected Methods

protected void finalize ()

Throws
Throwable