Module org.cicirello.chips_n_salsa
Package org.cicirello.search.restarts

Class ConstantRestartSchedule

java.lang.Object
org.cicirello.search.restarts.ConstantRestartSchedule
All Implemented Interfaces:
Splittable<RestartSchedule>, RestartSchedule
public final class ConstantRestartSchedule extends Object implements RestartSchedule
This is the basic constant run length restart schedule, such that every restart of the multistart metaheuristic is the same in length.

  • Constructor Details

    • ConstantRestartSchedule

      public ConstantRestartSchedule(int runLength)
      Constructs the restart schedule.
      Parameters:
      runLength - The length of the run for all restarts. The runLength must be positive.
      Throws:
      IllegalArgumentException - if runLength < 1

  • Method Details

    • createRestartSchedules

      public static List<ConstantRestartSchedule> createRestartSchedules(int numThreads, int runLength)
      A convenience method for generating several ConstantRestartSchedule objects, such as when needed for a parallel search (e.g., if each instance needs its own restart schedule).
      Parameters:
      numThreads - The number of restart schedules to generate.
      runLength - The length of the run for all restarts. The runLength must be positive.
      Returns:
      a list of constant restart schedules
      Throws:
      IllegalArgumentException - if numThreads ≤ 0 or if runLength < 1

    • nextRunLength

      public int nextRunLength()
      Description copied from interface: RestartSchedule
      Gets the next run length in the restart schedule's sequence of run lengths.
      Specified by:
      nextRunLength in interface RestartSchedule
      Returns:
      the length for the next run of a multistart metaheuristic

    • reset

      public void reset()
      Description copied from interface: RestartSchedule
      Resets the restart schedule to its initial conditions, such that the next call to RestartSchedule.nextRunLength() will return the initial run length of the schedule.
      Specified by:
      reset in interface RestartSchedule

    • split

      public ConstantRestartSchedule split()
      Description copied from interface: Splittable
      Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms. The state of the object that is returned may or may not be identical to that of the original. Thus, this is a distinct concept from the functionality of the Copyable interface. Classes that implement this interface must ensure that the object returned performs the same functionality, and that it does not share any state data that would be either unsafe or inefficient for concurrent access by multiple threads. The split method is allowed to simply return the this reference, provided that it is both safe and efficient for multiple threads to share a single copy of the Splittable object. The intention is to provide a multithreaded search with the capability to provide spawned threads with their own distinct search operators. Such multithreaded algorithms can call the split method for each thread it spawns to generate a functionally identical copy of the operator, but with independent state.
      Specified by:
      split in interface Splittable<RestartSchedule>
      Returns:
      A functionally identical copy of the object, or a reference to this if it is both safe and efficient for multiple threads to share a single instance of this Splittable object.