Package org.apache.sis.internal.processing.image

Class TiledProcess.Task

java.lang.Object
org.apache.sis.internal.processing.image.TiledProcess.Task
All Implemented Interfaces:
Callable<R>
Direct Known Subclasses:
Parallelized.Tile
Enclosing class:
TiledProcess<R>
protected abstract class TiledProcess.Task extends Object implements Callable<R>
A task to be executed in TiledProcess for a sub-region of the image to process.

This class implements Callable for TiledProcess convenience. This implementation details should be ignored; it may change in any future version.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private final int
    index
    Index of this Task instance in the TiledProcess.tasks array.
    protected final PixelIterator
    iterator
    Iterator over the pixels in the sub-region explored by this task.
    private ReentrantLock
    merging
    Synchronization lock during the merge phase.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    Task()
    Creates a new sub-task to be executed in a sub-area of a two-dimensional plane.

  • Method Summary

    Modifier and Type
    Method
    Description
    final R
    call()
    Executes this sub-task, then tries to merge it with all neighbor sub-tasks that are completed.
    protected abstract void
    execute()
    Executes this sub-task.
    protected abstract void
    merge(TiledProcess<R>.Task neighbor)
    Merges the result of given sub-task into this one.
    protected abstract R
    result()
    Returns the computation result.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • index

      private final int index
      Index of this Task instance in the TiledProcess.tasks array.

    • iterator

      protected final PixelIterator iterator
      Iterator over the pixels in the sub-region explored by this task.

    • merging

      private ReentrantLock merging
      Synchronization lock during the merge phase. Created only before merge attempts. This reference shall be considered final after initialization.

  • Constructor Details

    • Task

      protected Task()
      Creates a new sub-task to be executed in a sub-area of a two-dimensional plane.

  • Method Details

    • execute

      protected abstract void execute() throws Exception
      Executes this sub-task. This method is invoked by TiledProcess.execute() in a background thread. Implementation should store the result in this Task instance for future merge.
      Throws:
      Exception - if an error occurred during sub-task execution.

    • merge

      protected abstract void merge(TiledProcess<R>.Task neighbor) throws Exception
      Merges the result of given sub-task into this one. The given Task will be a neighbor tile (located on top, left, right or bottom of this tile) on a best-effort basis (no guarantee). After this method call, all data should be in this and the neighbor sub-task will be discarded.
      Parameters:
      neighbor - the other sub-task to merge with this one.
      Throws:
      Exception - if an error occurred during merge operation.

    • result

      protected abstract R result() throws Exception
      Returns the computation result. This method is invoked by TiledProcess only once, on the last Task instance after all other instances have been merged on this.
      Returns:
      the computation result.
      Throws:
      Exception - if final result cannot be computed.

    • call

      public final R call() throws Exception
      Executes this sub-task, then tries to merge it with all neighbor sub-tasks that are completed. This method is public as an implementation side-effect and should not be invoked directly; it will typically be invoked by Executor instead.
      Specified by:
      call in interface Callable<R>
      Returns:
      value computed by this sub-task, or null if this is not the last task.
      Throws:
      Exception - if an error occurred during sub-task execution or merge operation.
      See Also: