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Chips-n-Salsa is a Java library of customizable, hybridizable, iterative, parallel, stochastic, and self-adaptive local search algorithms. The library includes implementations of several stochastic local search algorithms, including simulated annealing, hill climbers, as well as constructive search algorithms such as stochastic sampling. Chips-n-Salsa now also includes genetic algorithms as well as evolutionary algorithms more generally. The library very extensively supports simulated annealing. It includes several classes for representing solutions to a variety of optimization problems. For example, the library includes a BitVector class that implements vectors of bits, as well as classes for representing solutions to problems where we are searching for an optimal vector of integers or reals. For each of the built-in representations, the library provides the most common mutation operators for generating random neighbors of candidate solutions, as well as common crossover operators for use with evolutionary algorithms. Additionally, the library provides extensive support for permutation optimization problems, including implementations of many different mutation operators for permutations, and utilizing the efficiently implemented Permutation class of the JavaPermutationTools (JPT) library. Chips-n-Salsa is customizable, making extensive use of Java's generic types, enabling using the library to optimize other types of representations beyond what is provided in the library. It is hybridizable, providing support for integrating multiple forms of local search (e.g., using a hill climber on a solution generated by simulated annealing), creating hybrid mutation operators (e.g., local search using multiple mutation operators), as well as support for running more than one type of search for the same problem concurrently using multiple threads as a form of algorithm portfolio. Chips-n-Salsa is iterative, with support for multistart metaheuristics, including implementations of several restart schedules for varying the run lengths across the restarts. It also supports parallel execution of multiple instances of the same, or different, stochastic local search algorithms for an instance of a problem to accelerate the search process. The library supports self-adaptive search in a variety of ways, such as including implementations of adaptive annealing schedules for simulated annealing, such as the Modified Lam schedule, implementations of the simpler annealing schedules but which self-tune the initial temperature and other parameters, and restart schedules that adapt to run length.

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/*
 * Chips-n-Salsa: A library of parallel self-adaptive local search algorithms.
 * Copyright (C) 2002-2020  Vincent A. Cicirello
 *
 * This file is part of Chips-n-Salsa (https://chips-n-salsa.cicirello.org/).
 *
 * Chips-n-Salsa is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Chips-n-Salsa is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */

package org.cicirello.search;

import org.cicirello.search.concurrent.Splittable;
import org.cicirello.search.problems.Problem;
import org.cicirello.util.Copyable;

/**
 * This interface defines the required functionality of search algorithm implementations that
 * support tracking search progress across multiple runs, whether multiple sequential runs, or
 * multiple concurrent runs in the case of a parallel metaheuristic.
 *
 * @param  The type of object under optimization.
 * @author Vincent A. Cicirello, https://www.cicirello.org/
 * @version 6.15.2020
 */
public interface TrackableSearch> extends Splittable> {

  /**
   * Gets the {@link ProgressTracker} object that is in use for tracking search progress. The object
   * returned by this method contains the best solution found during the search (including across
   * multiple concurrent runs if the search is multithreaded, or across multiple restarts if the run
   * methods were called multiple times), as well as cost of that solution, among other information.
   * See the {@link ProgressTracker} documentation for more information about the search data
   * tracked by this object.
   *
   * @return the {@link ProgressTracker} in use by this metaheuristic.
   */
  ProgressTracker getProgressTracker();

  /**
   * Sets the {@link ProgressTracker} object that is in use for tracking search progress. Any
   * previously set ProgressTracker is replaced by this one.
   *
   * @param tracker The new ProgressTracker to set. The tracker must not be null. This method does
   *     nothing if tracker is null.
   */
  void setProgressTracker(ProgressTracker tracker);

  /**
   * Gets the total run length of the metaheuristic. This is the total run length across all calls
   * to the search. This may differ from what may be expected based on run lengths. For example, the
   * search terminates if it finds the theoretical best solution, and also immediately returns if a
   * prior call found the theoretical best. In such cases, the total run length may be less than the
   * requested run length.
   *
   * The meaning of run length may vary from one metaheuristic to another. Therefore,
   * implementing classes should provide fresh documentation rather than relying entirely on the
   * interface documentation.
   *
   * @return the total run length of the metaheuristic
   */
  long getTotalRunLength();

  /**
   * Gets a reference to the problem that this search is solving.
   *
   * @return a reference to the problem.
   */
  Problem getProblem();
}