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1   /*******************************************************************************
2    * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
3    *
4    * All rights reserved. This program and the accompanying materials
5    * are made available under the terms of the Eclipse Public License v1.0
6    * which accompanies this distribution, and is available at
7    *  http://www.eclipse.org/legal/epl-v10.html
8    *
9    * Alternatively, the contents of this file may be used under the terms of
10   * either the GNU Lesser General Public License Version 2.1 or later (the
11   * "LGPL"), in which case the provisions of the LGPL are applicable instead
12   * of those above. If you wish to allow use of your version of this file only
13   * under the terms of the LGPL, and not to allow others to use your version of
14   * this file under the terms of the EPL, indicate your decision by deleting
15   * the provisions above and replace them with the notice and other provisions
16   * required by the LGPL. If you do not delete the provisions above, a recipient
17   * may use your version of this file under the terms of the EPL or the LGPL.
18   *
19   * Based on the original MiniSat specification from:
20   *
21   * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
22   * Sixth International Conference on Theory and Applications of Satisfiability
23   * Testing, LNCS 2919, pp 502-518, 2003.
24   *
25   * See www.minisat.se for the original solver in C++.
26   *
27   * Contributors:
28   *   CRIL - initial API and implementation
29   *******************************************************************************/
30  package org.sat4j.minisat.core;
31  
32  import java.io.Serializable;
33  
34  /**
35   * Abstraction allowing to choose various restarts strategies.
36   * 
37   * @author leberre
38   * 
39   */
40  public interface RestartStrategy extends Serializable, ConflictTimer {
41  
42      /**
43       * Hook method called just before the search starts.
44       * 
45       * @param params
46       *            the user's search parameters.
47       * 
48       */
49      void init(SearchParams params);
50  
51      /**
52       * Ask for the next restart in number of conflicts. Deprecated since 2.3.2
53       * 
54       * @return the delay in conflicts before the next restart.
55       */
56      @Deprecated
57      long nextRestartNumberOfConflict();
58  
59      /**
60       * Ask the strategy if the solver should restart.
61       * 
62       * @return true if the solver should restart, else false.
63       */
64      boolean shouldRestart();
65  
66      /**
67       * Hook method called when a restart occurs (once the solver has backtracked
68       * to top decision level).
69       * 
70       */
71      void onRestart();
72  
73      /**
74       * Called when the solver backjumps to the root level.
75       * 
76       * @since 2.3.2
77       */
78      void onBackjumpToRootLevel();
79  
80      SearchParams getSearchParams();
81  
82      void newLearnedClause(Constr learned, int trailLevel);
83  }