Package org.rrd4j.core

Class FetchData

  • public class FetchData
extends Object
    Class used to represent data fetched from the RRD. Object of this class is created when the method fetchData() is called on a FetchRequest object.

    Data returned from the RRD is, simply, just one big table filled with timestamps and corresponding datasource values. Use getRowCount() method to count the number of returned timestamps (table rows).

    The first table column is filled with timestamps. Time intervals between consecutive timestamps are guaranteed to be equal. Use getTimestamps() method to get an array of timestamps returned.

    Remaining columns are filled with datasource values for the whole timestamp range, on a column-per-datasource basis. Use getColumnCount() to find the number of datasources and getValues(i) method to obtain all values for the i-th datasource. Returned datasource values correspond to the values returned with getTimestamps() method.

    Author:
    Sasa Markovic

    • Method Detail

      • setTimestamps

        void setTimestamps​(long[] timestamps)

      • setValues

        void setValues​(double[][] values)

      • getRowCount

        public int getRowCount()
        Returns the number of rows fetched from the corresponding RRD. Each row represents datasource values for the specific timestamp.
        Returns:
        Number of rows.

      • getColumnCount

        public int getColumnCount()
        Returns the number of columns fetched from the corresponding RRD. This number is always equal to the number of datasources defined in the RRD. Each column represents values of a single datasource.
        Returns:
        Number of columns (datasources).

      • getTimestamps

        public long[] getTimestamps()
        Returns an array of timestamps covering the whole range specified in the FetchReguest object.
        Returns:
        Array of equidistant timestamps.

      • getStep

        public long getStep()
        Returns the step with which this data was fetched.
        Returns:
        Step as long.

      • getValues

        public double[] getValues​(int dsIndex)
        Returns all archived values for a single datasource. Returned values correspond to timestamps returned with getTimestamps() method.
        Parameters:
        dsIndex - Datasource index.
        Returns:
        Array of single datasource values.

      • getValues

        public double[][] getValues()
        Returns all archived values for all datasources. Returned values correspond to timestamps returned with getTimestamps() method.
        Returns:
        Two-dimensional aray of all datasource values.

      • getValues

        public double[] getValues​(String dsName)
        Returns all archived values for a single datasource. Returned values correspond to timestamps returned with getTimestamps() method.
        Parameters:
        dsName - Datasource name.
        Returns:
        Array of single datasource values.

      • getRpnValues

        public double[] getRpnValues​(String rpnExpression)
        Returns a set of values created by applying RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate values for (x+y)/2 use something like:

        getRpnValues("x,y,+,2,/");

        Parameters:
        rpnExpression - RRDTool-like RPN expression
        Returns:
        Calculated values
        Throws:
        IllegalArgumentException - Thrown if invalid RPN expression is supplied

      • getRequest

        public FetchRequest getRequest()
        Returns FetchRequest object used to create this FetchData object.
        Returns:
        Fetch request object.

      • getFirstTimestamp

        public long getFirstTimestamp()
        Returns the first timestamp in this FetchData object.
        Returns:
        The smallest timestamp.

      • getLastTimestamp

        public long getLastTimestamp()
        Returns the last timestamp in this FecthData object.
        Returns:
        The biggest timestamp.

      • getMatchingArchive

        public Archive getMatchingArchive()
        Returns Archive object which is determined to be the best match for the timestamps specified in the fetch request. All datasource values are obtained from round robin archives belonging to this archive.
        Returns:
        Matching archive.

      • getDsNames

        public String[] getDsNames()
        Returns array of datasource names found in the corresponding RRD. If the request was filtered (data was fetched only for selected datasources), only datasources selected for fetching are returned.
        Returns:
        Array of datasource names.

      • getDsIndex

        public int getDsIndex​(String dsName)
        Retrieve the table index number of a datasource by name. Names are case sensitive.
        Parameters:
        dsName - Name of the datasource for which to find the index.
        Returns:
        Index number of the datasources in the value table.

      • dump

        public String dump()
        Dumps the content of the whole FetchData object. Useful for debugging.
        Returns:
        a String containing the contents of this object, for debugging.

      • toString

        public String toString()
        Returns string representing fetched data in a RRDTool-like form.
        Overrides:
        toString in class Object
        Returns:
        Fetched data as a string in a rrdfetch-like output form.

      • getAggregate

        @Deprecated
public double getAggregate​(String dsName,
                           ConsolFun consolFun)
        Deprecated.
        This method is deprecated. Uses instance of Variable, used with DataProcessor.addDatasource(String, String, Variable)
        Returns single aggregated value from the fetched data for a single datasource.
        Parameters:
        dsName - Datasource name
        consolFun - Consolidation function to be applied to fetched datasource values. Valid consolidation functions are "MIN", "MAX", "LAST", "FIRST", "AVERAGE" and "TOTAL" (these string constants are conveniently defined in the ConsolFun class)
        Returns:
        a double.
        Throws:
        IllegalArgumentException - Thrown if the given datasource name cannot be found in fetched data.

      • getRpnAggregate

        @Deprecated
public double getRpnAggregate​(String rpnExpression,
                              ConsolFun consolFun)
        Deprecated.
        This method is deprecated. Uses instance of Variable, used with DataProcessor.addDatasource(String, String, Variable)
        Returns aggregated value for a set of values calculated by applying an RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate MAX value of (x+y)/2 use something like:

        getRpnAggregate("x,y,+,2,/", "MAX");

        Parameters:
        rpnExpression - RRDTool-like RPN expression
        consolFun - Consolidation function (MIN, MAX, LAST, FIRST, AVERAGE or TOTAL)
        Returns:
        Aggregated value
        Throws:
        IllegalArgumentException - Thrown if invalid RPN expression is supplied

      • getRpnAggregates

        @Deprecated
public Aggregates getRpnAggregates​(String rpnExpression)
                            throws IOException
        Deprecated.
        This method is deprecated. Uses instance of Variable, used with DataProcessor.addDatasource(String, String, Variable)
        Returns all aggregated values for a set of values calculated by applying an RPN expression to the fetched data. For example, if you have two datasources named x and y in this FetchData and you want to calculate MIN, MAX, LAST, FIRST, AVERAGE and TOTAL value of (x+y)/2 use something like:

        getRpnAggregates("x,y,+,2,/");

        Parameters:
        rpnExpression - RRDTool-like RPN expression
        Returns:
        Object containing all aggregated values
        Throws:
        IllegalArgumentException - Thrown if invalid RPN expression is supplied
        IOException - if any.

      • get95Percentile

        @Deprecated
public double get95Percentile​(String dsName)
        Deprecated.
        This method is deprecated. Uses instance of Variable.PERCENTILE, used with DataProcessor.addDatasource(String, String, Variable)
        Used by ISPs which charge for bandwidth utilization on a "95th percentile" basis.

        The 95th percentile is the highest source value left when the top 5% of a numerically sorted set of source data is discarded. It is used as a measure of the peak value used when one discounts a fair amount for transitory spikes. This makes it markedly different from the average.

        Read more about this topic at:

        Rednet or
        Bytemark.

        Parameters:
        dsName - Datasource name
        Returns:
        95th percentile of fetched source values
        Throws:
        IllegalArgumentException - Thrown if invalid source name is supplied

      • exportXml

        public void exportXml​(OutputStream outputStream)
               throws IOException
        Dumps fetch data to output stream in XML format. A flush is issued at the end of the xml generation.
        Parameters:
        outputStream - Output stream to dump fetch data to
        Throws:
        IOException - Thrown in case of I/O error

      • exportXml

        public void exportXml​(String filepath)
               throws IOException
        Dumps fetch data to file in XML format.
        Parameters:
        filepath - Path to destination file
        Throws:
        IOException - Thrown in case of I/O error

      • exportXml

        public String exportXml()
                 throws IOException
        Dumps fetch data in XML format.
        Returns:
        String containing XML formatted fetch data
        Throws:
        IOException - Thrown in case of I/O error

      • getArcStep

        public long getArcStep()
        Returns the step of the corresponding RRA archive
        Returns:
        Archive step in seconds

      • getArcEndTime

        public long getArcEndTime()
        Returns the timestamp of the last populated slot in the corresponding RRA archive
        Returns:
        Timestamp in seconds