java.lang.Object | |
↳ | org.rrd4j.core.RrdDb |
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.
Constants | |||||||||||
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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 | |||||||||||
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Constructor used to create new RRD object from the definition. | |||||||||||
Constructor used to create new RRD object from the definition object but with a storage
(backend) different from default.
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Constructor used to open already existing RRD.
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Constructor used to open already existing RRD backed
with a storage (backend) different from default.
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Constructor used to open already existing RRD in R/W mode, with a default storage (backend) type (file on the disk). | |||||||||||
Constructor used to open already existing RRD in R/W mode with a storage (backend) type different from default. | |||||||||||
Constructor used to create RRD files from external file sources. | |||||||||||
Constructor used to create RRD files from external file sources with a backend type different from default. |
Public Methods | |||||||||||
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Closes RRD.
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Checks presence of a specific datasource.
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Copies object's internal state to another RrdDb object.
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Prepares fetch request to be executed on this RRD. | |||||||||||
Prepares fetch request to be executed on this RRD. | |||||||||||
Creates new sample with the given timestamp and all datasource values set to 'unknown'. | |||||||||||
Creates new sample with the current timestamp and all data source values set to 'unknown'. | |||||||||||
Returns string representing complete internal RRD state. | |||||||||||
Dumps internal RRD state to XML file.
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Writes the RRD content to OutputStream using XML format. | |||||||||||
This method is just an alias for
getXml method. | |||||||||||
This method is just an alias for
dumpXml method. | |||||||||||
This method is just an alias for
dumpXml(String) method. | |||||||||||
Finds the archive that best matches to the start time (time period being start-time until now)
and requested resolution.
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Returns the number of RRA archives defined in the file
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Returns index of Archive object with the given consolidation function and the number
of steps.
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Returns Archive object for the given archive index.
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Returns Archive object with the given consolidation function and the number
of steps.
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Returns an array of bytes representing the whole RRD.
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Returns canonical path to the underlying RRD file.
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Returns Datasource object corresponding to the given datasource name.
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Returns Datasource object for the given datasource index.
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Returns the number of datasources defined in the file
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Returns internal index number for the given datasource name.
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Returns an array of datasource names defined in RRD. | |||||||||||
Returns RRD header.
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Returns the last time when some of the archives in this RRD was updated.
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Returns the last stored value for the given datasource.
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Returns an array of last datasource values.
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Returns time of last update operation as timestamp (in seconds).
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Returns path to this RRD.
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Required to implement RrdUpdater interface.
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Returns backend object for this RRD which performs actual I/O operations.
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Returns RRD definition object which can be used to create new RRD with the same creation parameters but with no data in it. | |||||||||||
Returns string representing internal RRD state in XML format. | |||||||||||
Returns true if the RRD is closed.
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Sets default backend factory to be used.
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Protected Methods | |||||||||||
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[Expand]
Inherited Methods | |||||||||||
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Prefix to identify external RRDTool file source used in various RrdDb constructors.
Prefix to identify external XML file source used in various RrdDb constructors.
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
rrdDef | Object describing the structure of the new RRD file. |
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IOException | Thrown in case of I/O error. |
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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:
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.
rrdDef | RRD definition object |
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factory | The factory which will be used to create storage for this RRD |
IOException | Thrown in case of I/O error |
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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.
path | Path to existing RRD. |
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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. |
IOException | Thrown in case of I/O error. |
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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.
path | Path to existing RRD. |
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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. |
FileNotFoundException | Thrown if the requested file does not exist. |
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IOException | Thrown in case of general I/O error (bad RRD file, for example). |
Constructor used to open already existing RRD in R/W mode, with a default storage (backend) type (file on the disk).
path | Path to existing RRD. |
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IOException | Thrown in case of I/O error. |
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Constructor used to open already existing RRD in R/W mode with a storage (backend) type different from default.
path | Path to existing RRD. |
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factory | Backend factory used to create this RRD. |
IOException | Thrown in case of I/O error. |
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Constructor used to create RRD files from external file sources. Supported external file sources are:
rrdtool dump
command).
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
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. |
IOException | Thrown in case of I/O error |
---|
Constructor used to create RRD files from external file sources with a backend type different from default. Supported external file sources are:
rrdtool dump
command).
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
rrdPath | Path to RRD which will be created |
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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. |
IOException | Thrown in case of I/O error |
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Closes RRD. No further operations are allowed on this RrdDb object.
IOException | Thrown in case of I/O related error. |
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Checks presence of a specific datasource.
dsName | Datasource name to check |
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true
if datasource is present in this RRD, false
otherwiseIOException | Thrown in case of I/O error. |
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Copies object's internal state to another RrdDb object.
other | New RrdDb object to copy state to |
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IOException | Thrown in case of I/O error |
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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.
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). |
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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. |
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).
consolFun | Consolidation function to be used in fetch request. Allowed values are
AVERAGE, MIN, MAX and LAST (see ConsolFun enum). |
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fetchStart | Starting timestamp for fetch request. |
fetchEnd | Ending timestamp for fetch request. |
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.
time | Sample timestamp rounded to the nearest second (without milliseconds). |
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IOException | Thrown in case of I/O error. |
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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.
IOException | Thrown in case of I/O error. |
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Returns string representing complete internal RRD state. The returned
string can be printed to stdout
and/or used for debugging purposes.
IOException | Thrown in case of I/O related error. |
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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
filename | Path to XML file which will be created. |
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IOException | Thrown in case of I/O related error. |
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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.
destination | Output stream to receive XML data |
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IOException | Thrown in case of I/O related error |
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This method is just an alias for getXml
method.
IOException | Thrown in case of I/O related error |
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This method is just an alias for dumpXml
method.
IOException | Thrown in case of I/O related error |
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This method is just an alias for dumpXml(String)
method.
IOException | Thrown in case of I/O related error |
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Finds the archive that best matches to the start time (time period being start-time until now) and requested resolution.
consolFun | Consolidation function of the datasource. |
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startTime | Start time of the time period in seconds. |
resolution | Requested fetch resolution. |
IOException | Thrown in case of I/O related error. |
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Returns the number of RRA archives defined in the file
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.
consolFun | Consolidation function |
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steps | Number of archive steps |
IOException | Thrown in case of I/O error |
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Returns Archive object for the given archive index.
arcIndex | Archive index (zero based) |
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Returns Archive object with the given consolidation function and the number of steps.
consolFun | Consolidation function |
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steps | Number of archive steps |
IOException | Thrown in case of I/O error |
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Returns an array of bytes representing the whole RRD.
IOException | Thrown in case of I/O related error. |
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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.
IOException | Thrown in case of I/O error or if the underlying backend is not derived from RrdFileBackend. |
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Returns Datasource object corresponding to the given datasource name.
dsName | Datasource name |
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IOException | Thrown in case of I/O error |
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Returns Datasource object for the given datasource index.
dsIndex | Datasource index (zero based) |
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Returns the number of datasources defined in the file
Returns internal index number for the given datasource name.
dsName | Data source name. |
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IOException | Thrown in case of I/O error. |
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Returns an array of datasource names defined in RRD.
IOException | Thrown in case of I/O error. |
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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.
IOException | Thrown in case of I/O error |
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Returns the last stored value for the given datasource.
dsName | Datasource name |
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IOException | Thrown in case of I/O error |
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IllegalArgumentException | Thrown if no datasource in this RrdDb matches the given datasource name |
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.
IOException | Thrown in case of I/O error |
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Returns time of last update operation as timestamp (in seconds).
IOException |
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Required to implement RrdUpdater interface. You should never call this method directly.
Returns backend object for this RRD which performs actual I/O operations.
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);
IOException |
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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.
IOException | Thrown in case of I/O related error |
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Returns true if the RRD is closed.
Sets default backend factory to be used. This method is just an alias for
setDefaultFactory(String)
.
factoryName | Name of the backend factory to be set as default. |
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IllegalArgumentException | Thrown if invalid factory name is supplied, or not called before the first backend object (before the first RrdDb object) is created. |
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