Package org.rrd4j.core

Class RrdDb

  • All Implemented Interfaces:
    Closeable, AutoCloseable, RrdUpdater<RrdDb>
    public class RrdDb
extends Object
implements RrdUpdater<RrdDb>, Closeable

    Main class used to create and manipulate round robin databases (RRDs). Use this class to perform update and fetch operations on existing 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.

    See Also:
    RrdBackend, RrdBackendFactory

    • 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

        @Deprecated
public RrdDb​(RrdDef rrdDef)
      throws IOException
        Deprecated.
        Use the builder instead.

        Constructor used to create new RRD object from the definition. If the rrdDef was constructed giving an URI, RrdBackendFactory.findFactory(URI) will be used to resolve the needed factory. If not, or a relative URI was given, 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", 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.

      • RrdDb

        @Deprecated
public RrdDb​(RrdDef rrdDef,
             RrdBackendFactory factory)
      throws IOException
        Deprecated.
        Use the builder instead.

        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 objects. 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
        See Also:
        RrdBackendFactory

      • RrdDb

        @Deprecated
public RrdDb​(String path,
             boolean readOnly)
      throws IOException
        Deprecated.
        Use the builder instead.

        Constructor used to open already existing RRD. The path will be parsed as an URI and checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        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.

      • RrdDb

        @Deprecated
public RrdDb​(URI uri,
             boolean readOnly)
      throws IOException
        Deprecated.
        Use the builder instead.

        Constructor used to open already existing RRD. The URI will checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        Constructor obtains read or read/write access to this RRD.

        Parameters:
        uri - URI 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.

      • RrdDb

        @Deprecated
public RrdDb​(String path,
             boolean readOnly,
             RrdBackendFactory factory)
      throws IOException
        Deprecated.
        Use the builder instead.

        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).
        See Also:
        RrdBackendFactory

      • RrdDb

        @Deprecated
public RrdDb​(String path)
      throws IOException
        Deprecated.
        Use the builder instead.

        Constructor used to open already existing RRD. The path will be parsed as an URI and checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        Constructor obtains read/write access to this RRD.

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

      • RrdDb

        @Deprecated
public RrdDb​(URI uri)
      throws IOException
        Deprecated.
        Use the builder instead.

        Constructor used to open already existing RRD. The URI will checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        Constructor obtains read/write access to this RRD.

        Parameters:
        uri - URI to existing RRD.
        Throws:
        IOException - Thrown in case of I/O error.

      • RrdDb

        @Deprecated
public RrdDb​(String path,
             RrdBackendFactory factory)
      throws IOException
        Deprecated.
        Use the builder instead.
        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.
        See Also:
        RrdBackendFactory

      • RrdDb

        @Deprecated
public RrdDb​(String rrdPath,
             String externalPath)
      throws IOException
        Deprecated.
        Use the builder instead.

        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.

        The path for the new rrd will be parsed as an URI and checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        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

      • RrdDb

        @Deprecated
public RrdDb​(URI uri,
             String externalPath)
      throws IOException
        Deprecated.
        Use the builder instead.

        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.

        The path for the new rrd will be parsed as an URI and checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        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:
        uri - 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

      • RrdDb

        @Deprecated
public RrdDb​(String rrdPath,
             String externalPath,
             RrdBackendFactory factory)
      throws IOException
        Deprecated.
        Use the builder instead.

        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
        See Also:
        RrdBackendFactory

    • Method Detail

      • of

        public static RrdDb of​(RrdDef rrdDef)
                throws IOException

        Returns a new RRD object from the definition. If the rrdDef was constructed giving an URI, RrdBackendFactory.findFactory(URI) will be used to resolve the needed factory. If not, or a relative URI was given, 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 method 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 = RrdDb.of(def);
 // new RRD file has been created on your disk
        Parameters:
        rrdDef - Object describing the structure of the new RRD file.
        Returns:
        a new Rrdb created from the definition.
        Throws:
        IOException - Thrown in case of I/O error.

      • of

        public static RrdDb of​(String path)
                throws IOException

        Opens an existing RRD with read/write access. The path will be parsed as an URI and checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        Parameters:
        path - Path to existing RRD.
        Returns:
        a {link RrdDb} opened with default settings
        Throws:
        IOException - Thrown in case of I/O error.

      • of

        public static RrdDb of​(URI uri)
                throws IOException

        Opens an existing RRD with read/write access. The URI will checked against the active factories. If it's a relative URI (no scheme given, or just a plain path), the default factory will be used.

        Parameters:
        uri - URI to existing RRD.
        Returns:
        a {link RrdDb} opened with default settings
        Throws:
        IOException - Thrown in case of I/O 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​(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.
        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

      • createFetchRequest

        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.
        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.

      • 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 IOException
        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.

      • 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.

      • getArchives

        Archive[] getArchives()

      • 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

      • getXml

        public String getXml()
              throws IOException
        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

      • exportXml

        public String exportXml()
                 throws IOException
        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

      • dumpXml

        public void dumpXml​(String filename)
             throws IOException
        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.

      • getLastUpdateTime

        public long getLastUpdateTime()
                       throws IOException
        Returns time of last update operation as timestamp (in seconds).
        Returns:
        Last update time (in seconds).
        Throws:
        IOException - if any.

      • getRrdDef

        public RrdDef getRrdDef()
                 throws 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:
        IOException - if any.

      • 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​(ConsolFun consolFun,
                       int steps)
                throws 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

      • getArchive

        public Archive getArchive​(ConsolFun 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 the path to this RRD.
        Returns:
        Path to this RRD.

      • getUri

        public URI getUri()
        Returns the URI to this RRD, as seen by the backend.
        Returns:
        URI to this RRD.

      • getCanonicalUri

        public URI getCanonicalUri()

      • getRrdBackend

        public RrdBackend getRrdBackend()
        Returns backend object for this RRD which performs actual I/O operations.
        Specified by:
        getRrdBackend in interface RrdUpdater<RrdDb>
        Returns:
        RRD backend for this RRD.

      • getRrdAllocator

        public RrdAllocator getRrdAllocator()
        Required to implement RrdUpdater interface. You should never call this method directly.
        Specified by:
        getRrdAllocator in interface RrdUpdater<RrdDb>
        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.

      • 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
        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

      • 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 archives defined in the file
        Returns:
        The number of RRA archives 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

      • main

        public static void main​(String[] args)
        main.
        Parameters:
        args - an array of String objects.