org.jrobin.core
Class RrdDb

java.lang.Object
  extended by org.jrobin.core.RrdDb

public class RrdDb
extends Object

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 JRobin'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, JRobin gives you freedom to use other storage (backend) types even to create your own backend types for some special purposes. JRobin by default stores RRD data in files (as RRDTool), but you might choose to store RRD data in memory (this is supported in JRobin), 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 JRobin 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 JRobin and RRDTool.

You will not be able to use JRobin 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 JRobin, there is an excellent CDEF tutorial.

See Also:
RrdBackend, RrdBackendFactory

Field Summary
static String PREFIX_RRDTool
          prefix to identify external RRDTool file source used in various RrdDb constructors
static String PREFIX_XML
          prefix to identify external XML file source used in various RrdDb constructors
 
Constructor Summary
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)
          Constructor used to open already existing RRD in R/W mode, with a default storage (backend) type (file on the disk).
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, 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.
 
Method Summary
 void close()
          Closes RRD.
 boolean containsDs(String dsName)
          Checks presence of a specific datasource.
 void copyStateTo(org.jrobin.core.RrdUpdater other)
          Copies object's internal state to another RrdDb object.
 FetchRequest createFetchRequest(String consolFun, long fetchStart, long fetchEnd)
          Prepares fetch request to be executed on this RRD.
 FetchRequest createFetchRequest(String consolFun, long fetchStart, long fetchEnd, long resolution)
          Prepares fetch request to be executed on this RRD.
 Sample createSample()
          Creates new sample with the current timestamp and all data source values set to 'unknown'.
 Sample createSample(long time)
          Creates new sample with the given timestamp and all datasource values set to 'unknown'.
 String dump()
          Returns string representing complete internal RRD state.
 void dumpXml(OutputStream destination)
          Writes the RRD content to OutputStream using XML format.
 void dumpXml(String filename)
          Dumps internal RRD state to XML file.
 String exportXml()
          This method is just an alias for getXml method.
 void exportXml(OutputStream destination)
          This method is just an alias for dumpXml method.
 void exportXml(String filename)
          This method is just an alias for dumpXml(String) method.
protected  void finalize()
           
 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 arcihves defined in the file
 Archive getArchive(int arcIndex)
          Returns Archive object for the given archive index.
 Archive getArchive(String consolFun, int steps)
          Returns Archive object with the given consolidation function and the number of steps.
 int getArcIndex(String consolFun, int steps)
          Returns index of Archive object with the given consolidation function and the number of steps.
 byte[] getBytes()
          Returns an array of bytes representing the whole RRD.
 String getCanonicalPath()
          Returns canonical path to the underlying RRD file.
 Datasource getDatasource(int dsIndex)
          Returns Datasource object for the given datasource index.
 Datasource getDatasource(String dsName)
          Returns Datasource object corresponding to the given datasource name.
 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.
 String getInfo()
           
 long getLastArchiveUpdateTime()
          Returns the last time when some of the archives in this RRD was updated.
 double getLastDatasourceValue(String dsName)
          Returns the last stored value for the given datasource.
 double[] getLastDatasourceValues()
          Returns an array of last datasource values.
 long getLastUpdateTime()
          Returns time of last update operation as timestamp (in seconds).
 String getPath()
          Returns path to this RRD.
 org.jrobin.core.RrdAllocator getRrdAllocator()
          Required to implement RrdUpdater interface.
 RrdBackend getRrdBackend()
          Returns backend object for this RRD which performs actual I/O operations.
 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.
 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.
 void setInfo(String info)
           
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

PREFIX_XML

public static final String PREFIX_XML
prefix to identify external XML file source used in various RrdDb constructors

See Also:
Constant Field Values

PREFIX_RRDTool

public static final String PREFIX_RRDTool
prefix to identify external RRDTool file source used in various RrdDb constructors

See Also:
Constant Field Values
Constructor Detail

RrdDb

public RrdDb(RrdDef rrdDef)
      throws RrdException,
             IOException

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 RrdBackendFactory.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", DsTypes.DT_COUNTER, 600, 0, Double.NaN);
 def.addDatasource("output", DsTypes.DT_COUNTER, 600, 0, Double.NaN);
 def.addArchive(ConsolFuns.CF_AVERAGE, 0.5, 1, 600);
 def.addArchive(ConsolFuns.CF_AVERAGE, 0.5, 6, 700);
 def.addArchive(ConsolFuns.CF_AVERAGE, 0.5, 24, 797);
 def.addArchive(ConsolFuns.CF_AVERAGE, 0.5, 288, 775);
 def.addArchive(ConsolFuns.CF_MAX, 0.5, 1, 600);
 def.addArchive(ConsolFuns.CF_MAX, 0.5, 6, 700);
 def.addArchive(ConsolFuns.CF_MAX, 0.5, 24, 797);
 def.addArchive(ConsolFuns.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.
RrdException - Thrown if invalid RrdDef object is supplied.

RrdDb

public RrdDb(RrdDef rrdDef,
             RrdBackendFactory factory)
      throws RrdException,
             IOException

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

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

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:
RrdException - Thrown if invalid factory or definition is supplied
IOException - Thrown in case of I/O error
See Also:
RrdBackendFactory

RrdDb

public RrdDb(String path,
             boolean readOnly)
      throws IOException,
             RrdException

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.
RrdException - Thrown in case of JRobin specific error.

RrdDb

public RrdDb(String path,
             boolean readOnly,
             RrdBackendFactory factory)
      throws FileNotFoundException,
             IOException,
             RrdException

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).
RrdException - Thrown in case of JRobin specific error.
See Also:
RrdBackendFactory

RrdDb

public RrdDb(String path)
      throws IOException,
             RrdException

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.
RrdException - Thrown in case of JRobin specific error.

RrdDb

public RrdDb(String path,
             RrdBackendFactory factory)
      throws IOException,
             RrdException

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.
RrdException - Thrown in case of JRobin specific error.
See Also:
RrdBackendFactory

RrdDb

public RrdDb(String rrdPath,
             String externalPath)
      throws IOException,
             RrdException

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

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

JRobin and RRDTool use the same format for XML dump and this constructor should be used to (re)create JRobin 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 JRobin 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 JRobin files to RRDTool's format.

To read RRDTool files directly, specify rrdtool:/ prefix in the externalPath argument. For example, to create JRobin 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
RrdException - Thrown in case of JRobin specific error

RrdDb

public RrdDb(String rrdPath,
             String externalPath,
             RrdBackendFactory factory)
      throws IOException,
             RrdException

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

JRobin and RRDTool use the same format for XML dump and this constructor should be used to (re)create JRobin 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 JRobin 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 JRobin files to RRDTool's format.

To read RRDTool files directly, specify rrdtool:/ prefix in the externalPath argument. For example, to create JRobin 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
RrdException - Thrown in case of JRobin specific error
See Also:
RrdBackendFactory
Method Detail

close

public void close()
           throws IOException
Closes RRD. No further operations are allowed on this RrdDb object.

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

isClosed

public boolean isClosed()
Returns true if the RRD is closed.

Returns:
true if closed, false otherwise

getHeader

public Header getHeader()
Returns RRD header.

Returns:
Header object

getDatasource

public Datasource getDatasource(int dsIndex)
Returns Datasource object for the given datasource index.

Parameters:
dsIndex - Datasource index (zero based)
Returns:
Datasource object

getArchive

public Archive getArchive(int arcIndex)
Returns Archive object for the given archive index.

Parameters:
arcIndex - Archive index (zero based)
Returns:
Archive object

getDsNames

public String[] getDsNames()
                    throws IOException

Returns an array of datasource names defined in RRD.

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

createSample

public Sample createSample(long time)
                    throws IOException

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.

createSample

public Sample createSample()
                    throws IOException

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.

createFetchRequest

public FetchRequest createFetchRequest(String consolFun,
                                       long fetchStart,
                                       long fetchEnd,
                                       long resolution)
                                throws RrdException

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 ConsolFuns 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.
Throws:
RrdException - In case of JRobin related error (invalid consolidation function or invalid time span).

createFetchRequest

public FetchRequest createFetchRequest(String consolFun,
                                       long fetchStart,
                                       long fetchEnd)
                                throws RrdException

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" (these constants are conveniently defined in the ConsolFuns class).
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.
Throws:
RrdException - In case of JRobin related error (invalid consolidation function or invalid time span).

findMatchingArchive

public Archive findMatchingArchive(FetchRequest request)
                            throws RrdException,
                                   IOException
Throws:
RrdException
IOException

findStartMatchArchive

public Archive findStartMatchArchive(String consolFun,
                                     long startTime,
                                     long resolution)
                              throws IOException
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.

dump

public String dump()
            throws IOException

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.

getDsIndex

public int getDsIndex(String dsName)
               throws RrdException,
                      IOException

Returns internal index number for the given datasource name. This index is heavily used by jrobin.graph package and has no value outside of it.

Parameters:
dsName - Data source name.
Returns:
Internal index of the given data source name in this RRD.
Throws:
RrdException - Thrown in case of JRobin related error (invalid data source name, for example)
IOException - Thrown in case of I/O error.

containsDs

public boolean containsDs(String dsName)
                   throws IOException
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.

dumpXml

public void dumpXml(OutputStream destination)
             throws IOException

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

exportXml

public void exportXml(OutputStream destination)
               throws IOException
This method is just an alias for dumpXml method.

Throws:
IOException - Thrown in case of I/O related error

getXml

public String getXml()
              throws IOException,
                     RrdException

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
RrdException - Thrown in case of JRobin specific error

exportXml

public String exportXml()
                 throws IOException,
                        RrdException
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
RrdException - Thrown in case of JRobin specific error

dumpXml

public void dumpXml(String filename)
             throws IOException,
                    RrdException

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

Suppose that you have a JRobin 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.
RrdException - Thrown in case of JRobin related error.

exportXml

public void exportXml(String filename)
               throws IOException,
                      RrdException
This method is just an alias for dumpXml(String) method.

Throws:
IOException - Thrown in case of I/O related error
RrdException - Thrown in case of JRobin specific error

getLastUpdateTime

public long getLastUpdateTime()
                       throws IOException
Returns time of last update operation as timestamp (in seconds).

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

getRrdDef

public RrdDef getRrdDef()
                 throws RrdException,
                        IOException

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:
RrdException - Thrown in case of JRobin specific error.
IOException

finalize

protected void finalize()
                 throws Throwable
Overrides:
finalize in class Object
Throws:
Throwable

copyStateTo

public void copyStateTo(org.jrobin.core.RrdUpdater other)
                 throws IOException,
                        RrdException
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
RrdException - Thrown if supplied argument is not a compatible RrdDb object

getDatasource

public Datasource getDatasource(String dsName)
                         throws IOException
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

getArcIndex

public int getArcIndex(String consolFun,
                       int steps)
                throws RrdException,
                       IOException
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
RrdException - Thrown if no such archive could be found

getArchive

public Archive getArchive(String consolFun,
                          int steps)
                   throws IOException
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

getCanonicalPath

public String getCanonicalPath()
                        throws IOException
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.

getPath

public String getPath()
Returns path to this RRD.

Returns:
Path to this RRD.

getRrdBackend

public RrdBackend getRrdBackend()
Returns backend object for this RRD which performs actual I/O operations.

Returns:
RRD backend for this RRD.

getRrdAllocator

public org.jrobin.core.RrdAllocator getRrdAllocator()
Required to implement RrdUpdater interface. You should never call this method directly.

Returns:
Allocator object

getBytes

public byte[] getBytes()
                throws IOException
Returns an array of bytes representing the whole RRD.

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

setDefaultFactory

public static void setDefaultFactory(String factoryName)
                              throws RrdException
Sets default backend factory to be used. This method is just an alias for RrdBackendFactory.setDefaultFactory(java.lang.String).

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

getLastDatasourceValues

public double[] getLastDatasourceValues()
                                 throws IOException
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

getLastDatasourceValue

public double getLastDatasourceValue(String dsName)
                              throws IOException,
                                     RrdException
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
RrdException - Thrown if no datasource in this RrdDb matches the given datasource name

getDsCount

public int getDsCount()
Returns the number of datasources defined in the file

Returns:
The number of datasources defined in the file

getArcCount

public int getArcCount()
Returns the number of RRA arcihves defined in the file

Returns:
The number of RRA arcihves defined in the file

getLastArchiveUpdateTime

public long getLastArchiveUpdateTime()
                              throws IOException
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

getInfo

public String getInfo()
               throws IOException
Throws:
IOException

setInfo

public void setInfo(String info)
             throws IOException
Throws:
IOException

main

public static void main(String[] args)


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