Package org.eclipse.nebula.visualization.xygraph.dataprovider

Interface IDataProvider

All Known Implementing Classes:
AbstractDataProvider, CircularBufferDataProvider, ClippedCircularBufferDataProvider
public interface IDataProvider
Interface for the data provider of trace. This gives the possibilities to implement different data provider, which could have different data source or data storage structure. For example: the data source could be from user input, database, files, etc,. The storage structure could be array, queue, circular buffer, bucket buffer, etc,.

An API like public ISample[] getSamples() would be much easier to use by the XY Graph, but it forces the data provider to copy its samples into an array, which might be a performance and memory problem if considerable amounts of data are held in some other data structure that is more suitable to the application.

The API is therefore based on single-sample access, allowing the application to store the samples in arbitrary data structures.

Synchronization
Since the application data might change dynamically, the XY Graph synchronizes on the IDataProvider like this to assert that the sample count does not change while accessing individual samples: 

 IDataProvider data = ...;
 synchronized (data)
 {
     int count = data.getSize();
     ...
     ... getSample(i) ...
 }
Implementations of the IDataProvider should likewise synchronize on it whenever the data is changed, and other methods like getXDataMinMax should probably be synchronized implementations.

  • Method Details

    • getSize

      int getSize()
      Total number of samples.
      Returns:
      the size.
      See Also:
      getSample(int)

    • getSample

      ISample getSample​(int index)
      Get sample by index

      Synchronization: Since the data might change dynamically, synchronize on the IDataProvider around calls to getSize() and getSample().

      Parameters:
      index - Sample index, 0...getSize()-1
      Returns:
      the sample.

    • getXDataMinMax

      Range getXDataMinMax()
      Get the minimum and maximum xdata.
      Returns:
      a range includes the min and max as lower and upper. return null if there is no data.

    • getYDataMinMax

      Range getYDataMinMax()
      Get the minimum and maximum ydata.
      Returns:
      a range includes the min and max as lower and upper. return null if there is no data.

    • getXDataMinMax

      Range getXDataMinMax​(boolean positiveOnly)
      Get the minimum and maximum xdata.
      Parameters:
      positiveOnly - if true, return values greater than zero
      Returns:
      a range includes the min and max as lower and upper. return null if there is no data.

    • getYDataMinMax

      Range getYDataMinMax​(boolean positiveOnly)
      Get the minimum and maximum ydata.
      Parameters:
      positiveOnly - if true, return values greater than zero
      Returns:
      a range includes the min and max as lower and upper. return null if there is no data.

    • isChronological

      boolean isChronological()
      Returns:
      true if data is ascending sorted on X axis; false otherwise

    • addDataProviderListener

      void addDataProviderListener​(IDataProviderListener listener)
      Parameters:
      listener - New listener to notify when data changes

    • removeDataProviderListener

      boolean removeDataProviderListener​(IDataProviderListener listener)
      Parameters:
      listener - Listener to no longer notify when data changes
      Returns:
      true if listener was known and removed

    • hasErrors

      default boolean hasErrors()
      This method is optional to implement. It should return whether an ISample has errors or not.
      Returns:
      true if the ISample have error information.