# Class ParallelRunnable

java.lang.Object
org.apfloat.internal.ParallelRunnable

All Implemented Interfaces:
  `Runnable, StartableRunnable`

public abstract class ParallelRunnable extends Object implements StartableRunnable
Abstract class for a `Runnable` that can be run in parallel by multiple threads. Internally, the `ParallelRunnable` splits the work to many small batches, which are run one at a time, and can be run in parallel by multiple threads. The `ParallelRunnable` isn't completed until all batches are completed, i.e. the `run()` method only returns when all batches are completed.

Since:
  1.1
Version:
  1.16.0
Author:
  Mikko Tommila

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `ParallelRunnable(long length)`
  Subclass constructor.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected long`
  `getPreferredBatchSize()`
  Get the preferred batch size.
  `protected Runnable`
  `getRunnable(int startValue, int length)`
  Get the Runnable object for strides which fit in an `int`.
  `protected Runnable`
  `getRunnable(long startValue, long length)`
  Get the Runnable object for strides which fit only in a `long`.
  `boolean`
  `isWorkToBeCompleted()`
  Returns if there is some work that may be currently processed but not yet finished.
  `boolean`
  `isWorkToBeStarted()`
  Returns if there is still enough work left to start a new batch.
  `final void`
  `run()`
  Repeatedly get a batch of work and run it, until all batches are completed.
  `final boolean`
  `runBatch()`
  Run one batch if available.

  ### Methods inherited from class Object

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

  ### Methods inherited from interface StartableRunnable

  `submitted`

- ## Constructor Details

  - ### ParallelRunnable

    protected ParallelRunnable(long length)
    Subclass constructor.
    Parameters:
      `length` - The length of the work to be run.

- ## Method Details

  - ### run

    public final void run()
    Repeatedly get a batch of work and run it, until all batches are completed. This method can (and should) be called from multiple threads in parallel.
    Specified by:
      `run` in interface `Runnable`

  - ### runBatch

    public final boolean runBatch()
    Run one batch if available. Returns `true` if a batch was actually acquired and run, `false` if all batches were already started and none could be run. This method can be used by any thread to steal and complete a minimal amount of work.

    Note that if a batch could not be run, it does not mean that all of the batches are already completed - some could still be running.

    Returns:
      If a batch was actually run.

  - ### isWorkToBeStarted

    public boolean isWorkToBeStarted()
    Returns if there is still enough work left to start a new batch.
    Specified by:
      `isWorkToBeStarted` in interface `StartableRunnable`
    Returns:
      If a new batch could be started to still perform some work.
    Since:
      1.9.0

  - ### isWorkToBeCompleted

    public boolean isWorkToBeCompleted()
    Returns if there is some work that may be currently processed but not yet finished.
    Returns:
      If there is still some work left that is not completed yet.
    Since:
      1.9.0

  - ### getRunnable

    protected Runnable getRunnable(int startValue, int length)
    Get the Runnable object for strides which fit in an `int`.
    Parameters:
      `startValue` - The starting value for the stride.
      `length` - The length of the stride.
    Returns:
      The Runnable object for the specified stride.

  - ### getRunnable

    protected Runnable getRunnable(long startValue, long length)
    Get the Runnable object for strides which fit only in a `long`.
    Parameters:
      `startValue` - The starting value for the stride.
      `length` - The length of the stride.
    Returns:
      The Runnable object for the specified stride.

  - ### getPreferredBatchSize

    protected long getPreferredBatchSize()
    Get the preferred batch size.
    Returns:
      The preferred batch size.
    Since:
      1.7.0