Student Scheduling: Failed Neighbour Assignment

- backtrack and student swap now also listen for failed neibhours, putting the failed student/request back into the queue - improving success of each phase, especially when there are higher number of solver threads - also students are put at the beginning of the queue, ensuring that priority students are processed first
UniTime · Nov 15, 2020 · f555fa7 · f555fa7
1 parent 1639c6f
commit f555fa7
Show file tree

Hide file tree

Showing 4 changed files with 81 additions and 11 deletions.
diff --git a/src/org/cpsolver/studentsct/heuristics/StudentSctNeighbourSelection.java b/src/org/cpsolver/studentsct/heuristics/StudentSctNeighbourSelection.java
@@ -1,5 +1,7 @@
 package org.cpsolver.studentsct.heuristics;
 
+import java.util.Iterator;
+
 import org.cpsolver.ifs.assignment.Assignment;
 import org.cpsolver.ifs.heuristics.NeighbourSelection;
 import org.cpsolver.ifs.heuristics.RoundRobinNeighbourSelection;
@@ -112,6 +114,11 @@ public void init(Solver<Request, Enrollment> solver) {
         super.init(solver);
         setup(solver);
         solver.setUpdateProgress(false);
+        for (Iterator<SolverListener<Request, Enrollment>> i = solver.getSolverListeners().iterator(); i.hasNext(); ) {
+            SolverListener<Request, Enrollment> listener = i.next();
+            if (listener instanceof StudentSctNeighbourSelection)
+                i.remove();
+        }
         solver.addSolverListener(this);
     }
 
@@ -264,10 +271,11 @@ public boolean neighbourSelected(Assignment<Request, Enrollment> assignment, lon
         return true;
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public void neighbourFailed(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
         NeighbourSelection<Request, Enrollment> selection = getSelection();
-        if (neighbour instanceof BranchBoundSelection.BranchBoundNeighbour && selection instanceof BranchBoundSelection)
-            ((BranchBoundSelection)selection).addStudent(((BranchBoundSelection.BranchBoundNeighbour)neighbour).getStudent());
+        if (selection instanceof SolverListener)
+            ((SolverListener<Request, Enrollment>)selection).neighbourFailed(assignment, iteration, neighbour);
     }
 }
diff --git a/src/org/cpsolver/studentsct/heuristics/selection/BacktrackSelection.java b/src/org/cpsolver/studentsct/heuristics/selection/BacktrackSelection.java
@@ -7,14 +7,15 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.Queue;
 
 import org.cpsolver.ifs.assignment.Assignment;
+import org.cpsolver.ifs.heuristics.BacktrackNeighbourSelection;
 import org.cpsolver.ifs.heuristics.NeighbourSelection;
 import org.cpsolver.ifs.model.InfoProvider;
 import org.cpsolver.ifs.model.Neighbour;
 import org.cpsolver.ifs.solution.Solution;
 import org.cpsolver.ifs.solver.Solver;
+import org.cpsolver.ifs.solver.SolverListener;
 import org.cpsolver.ifs.util.DataProperties;
 import org.cpsolver.ifs.util.Progress;
 import org.cpsolver.studentsct.filter.StudentFilter;
@@ -52,10 +53,10 @@
  *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
  */
 
-public class BacktrackSelection implements NeighbourSelection<Request, Enrollment>, InfoProvider<Request, Enrollment> {
+public class BacktrackSelection implements NeighbourSelection<Request, Enrollment>, InfoProvider<Request, Enrollment>, SolverListener<Request, Enrollment> {
     private static DecimalFormat sDF = new DecimalFormat("0.00");
     protected RandomizedBacktrackNeighbourSelection iRBtNSel = null;
-    protected Queue<Request> iRequests = null;
+    protected LinkedList<Request> iRequests = null;
     protected boolean iIncludeAssignedRequests = false;
 
     protected long iNbrIterations = 0;
@@ -100,6 +101,10 @@ protected synchronized Request nextRequest() {
             if (iFilter == null || iFilter.accept(request.getStudent())) return request;
         }
     }
+
+    public synchronized void addRequest(Request request) {
+        if (iRequests != null && request != null && !request.getStudent().isDummy()) iRequests.addFirst(request);
+    }
 
     @Override
     public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) {
@@ -144,4 +149,22 @@ public void getInfo(Assignment<Request, Enrollment> assignment, Map<String, Stri
      * Only consider students meeting the given filter.
      */
     public BacktrackSelection withFilter(StudentFilter filter) { iFilter = filter; return this; }
+
+    @Override
+    public boolean variableSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable) {
+        return false;
+    }
+    @Override
+    public boolean valueSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable, Enrollment value) {
+        return false;
+    }
+    @Override
+    public boolean neighbourSelected(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        return false;
+    }
+    @Override
+    public void neighbourFailed(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        if (neighbour instanceof BacktrackNeighbourSelection.BackTrackNeighbour)
+            addRequest(((BacktrackNeighbourSelection<Request, Enrollment>.BackTrackNeighbour)neighbour).getAssignments().get(0).getRequest());
+    }
 }
diff --git a/src/org/cpsolver/studentsct/heuristics/selection/BranchBoundSelection.java b/src/org/cpsolver/studentsct/heuristics/selection/BranchBoundSelection.java
@@ -21,6 +21,7 @@
 import org.cpsolver.ifs.model.Neighbour;
 import org.cpsolver.ifs.solution.Solution;
 import org.cpsolver.ifs.solver.Solver;
+import org.cpsolver.ifs.solver.SolverListener;
 import org.cpsolver.ifs.util.DataProperties;
 import org.cpsolver.ifs.util.JProf;
 import org.cpsolver.ifs.util.Progress;
@@ -95,7 +96,7 @@
  *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
  */
 
-public class BranchBoundSelection implements NeighbourSelection<Request, Enrollment>, InfoProvider<Request, Enrollment> {
+public class BranchBoundSelection implements NeighbourSelection<Request, Enrollment>, InfoProvider<Request, Enrollment>, SolverListener<Request, Enrollment> {
     private static Logger sLog = Logger.getLogger(BranchBoundSelection.class);
     private static DecimalFormat sDF = new DecimalFormat("0.00");
     protected int iTimeout = 10000;
@@ -958,4 +959,22 @@ public void getInfo(Assignment<Request, Enrollment> assignment, Map<String, Stri
      * Only consider students meeting the given filter.
      */
     public BranchBoundSelection withFilter(StudentFilter filter) { iFilter = filter; return this; }
+
+    @Override
+    public boolean variableSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable) {
+        return false;
+    }
+    @Override
+    public boolean valueSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable, Enrollment value) {
+        return false;
+    }
+    @Override
+    public boolean neighbourSelected(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        return false;
+    }
+    @Override
+    public void neighbourFailed(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        if (neighbour instanceof BranchBoundNeighbour)
+            addStudent(((BranchBoundNeighbour)neighbour).getStudent());
+    }
 }
diff --git a/src/org/cpsolver/studentsct/heuristics/selection/SwapStudentSelection.java b/src/org/cpsolver/studentsct/heuristics/selection/SwapStudentSelection.java
@@ -9,7 +9,6 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.Queue;
 import java.util.Set;
 
 
@@ -20,6 +19,7 @@
 import org.cpsolver.ifs.model.Neighbour;
 import org.cpsolver.ifs.solution.Solution;
 import org.cpsolver.ifs.solver.Solver;
+import org.cpsolver.ifs.solver.SolverListener;
 import org.cpsolver.ifs.util.DataProperties;
 import org.cpsolver.ifs.util.JProf;
 import org.cpsolver.ifs.util.Progress;
@@ -92,10 +92,10 @@
  *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
  */
 
-public class SwapStudentSelection implements NeighbourSelection<Request, Enrollment>, ProblemStudentsProvider, InfoProvider<Request, Enrollment> {
+public class SwapStudentSelection implements NeighbourSelection<Request, Enrollment>, ProblemStudentsProvider, InfoProvider<Request, Enrollment>, SolverListener<Request, Enrollment> {
     private static Logger sLog = Logger.getLogger(SwapStudentSelection.class);
     private Set<Student> iProblemStudents = Collections.synchronizedSet(new HashSet<Student>());
-    private Queue<Student> iStudents = null;
+    private LinkedList<Student> iStudents = null;
     private static DecimalFormat sDF = new DecimalFormat("0.00");
     private int iTimeout = 5000;
     private int iMaxValues = 100;
@@ -146,8 +146,8 @@ protected synchronized Student nextStudent() {
         return iStudents.poll();
     }
 
-    protected synchronized void addStudent(Student student) {
-        if (iStudents != null && !student.isDummy()) iStudents.add(student);
+    public synchronized void addStudent(Student student) {
+        if (iStudents != null && !student.isDummy()) iStudents.addFirst(student);
     }
 
     /**
@@ -459,6 +459,8 @@ public SwapStudentNeighbour(double value, Enrollment enrollment, List<Enrollment
         public double value(Assignment<Request, Enrollment> assignment) {
             return iValue;
         }
+
+        public Student getStudent() { return iEnrollment.getStudent(); }
 
         /**
          * Perform the move. All the requeired swaps are identified and
@@ -513,4 +515,22 @@ public void getInfo(Assignment<Request, Enrollment> assignment, Map<String, Stri
     @Override
     public void getInfo(Assignment<Request, Enrollment> assignment, Map<String, String> info, Collection<Request> variables) {
     }
+
+    @Override
+    public boolean variableSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable) {
+        return false;
+    }
+    @Override
+    public boolean valueSelected(Assignment<Request, Enrollment> assignment, long iteration, Request variable, Enrollment value) {
+        return false;
+    }
+    @Override
+    public boolean neighbourSelected(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        return false;
+    }
+    @Override
+    public void neighbourFailed(Assignment<Request, Enrollment> assignment, long iteration, Neighbour<Request, Enrollment> neighbour) {
+        if (neighbour instanceof SwapStudentNeighbour)
+            addStudent(((SwapStudentNeighbour)neighbour).getStudent());
+    }
 }