@Override
public Iterator<Move> createRandomMoveIterator(
ScoreDirector scoreDirector, Random workingRandom) {
CheapTimeSolution cheapTimeSolution = (CheapTimeSolution) scoreDirector.getWorkingSolution();
Map<Machine, List<TaskAssignment>> positivePillarMap =
new LinkedHashMap<Machine, List<TaskAssignment>>(
cheapTimeSolution.getGlobalPeriodRangeTo());
Map<Machine, List<TaskAssignment>> negativePillarMap =
new LinkedHashMap<Machine, List<TaskAssignment>>(
cheapTimeSolution.getGlobalPeriodRangeTo());
List<TaskAssignment> taskAssignmentList = cheapTimeSolution.getTaskAssignmentList();
int pillarCapacity =
(taskAssignmentList.size() * 2 / cheapTimeSolution.getMachineList().size()) + 1;
for (TaskAssignment taskAssignment : taskAssignmentList) {
Machine machine = taskAssignment.getMachine();
Task task = taskAssignment.getTask();
Integer startPeriod = taskAssignment.getStartPeriod();
if (startPeriod != null) {
if (startPeriod < task.getStartPeriodRangeTo() - 1) {
List<TaskAssignment> pillar = positivePillarMap.get(machine);
if (pillar == null) {
pillar = new ArrayList<TaskAssignment>(pillarCapacity);
positivePillarMap.put(machine, pillar);
}
pillar.add(taskAssignment);
}
if (startPeriod > task.getStartPeriodRangeFrom()) {
List<TaskAssignment> pillar = negativePillarMap.get(machine);
if (pillar == null) {
pillar = new ArrayList<TaskAssignment>(pillarCapacity);
negativePillarMap.put(machine, pillar);
}
pillar.add(taskAssignment);
}
}
}
List<List<TaskAssignment>> positivePillarList =
new ArrayList<List<TaskAssignment>>(positivePillarMap.size());
for (List<TaskAssignment> pillar : positivePillarMap.values()) {
if (pillar.size() > 1) {
positivePillarList.add(pillar);
}
}
List<List<TaskAssignment>> negativePillarList =
new ArrayList<List<TaskAssignment>>(negativePillarMap.size());
for (List<TaskAssignment> pillar : negativePillarMap.values()) {
if (pillar.size() > 1) {
negativePillarList.add(pillar);
}
}
return new RandomCheapTimePillarSlideMoveIterator(
positivePillarList, negativePillarList, workingRandom);
}
public Move next() {
int listIndex = workingRandom.nextInt(totalSize);
boolean positive = listIndex < positivePillarList.size();
List<TaskAssignment> basePillar =
positive
? positivePillarList.get(listIndex)
: negativePillarList.get(listIndex - positivePillarList.size());
int basePillarSize = basePillar.size();
int subPillarSize = workingRandom.nextInt(basePillarSize);
// Random sampling: See http://eyalsch.wordpress.com/2010/04/01/random-sample/
// Used Swapping instead of Floyd because subPillarSize is large, to avoid hashCode() hit
TaskAssignment[] sandboxPillar =
basePillar.toArray(
new TaskAssignment[basePillar.size()]); // Clone to avoid changing basePillar
List<TaskAssignment> subPillar = new ArrayList<TaskAssignment>(subPillarSize);
int minimumAbsDiff = Integer.MAX_VALUE;
for (int i = 0; i < subPillarSize; i++) {
int index = i + workingRandom.nextInt(basePillarSize - i);
TaskAssignment taskAssignment = sandboxPillar[index];
Task task = taskAssignment.getTask();
int absDiff =
positive
? task.getStartPeriodRangeTo() - 1 - taskAssignment.getStartPeriod()
: taskAssignment.getStartPeriod() - task.getStartPeriodRangeFrom();
if (absDiff < minimumAbsDiff) {
minimumAbsDiff = absDiff;
}
subPillar.add(taskAssignment);
sandboxPillar[index] = sandboxPillar[i];
}
int startPeriodDiff = 1 + workingRandom.nextInt(minimumAbsDiff);
if (!positive) {
startPeriodDiff = -startPeriodDiff;
}
return new CheapTimePillarSlideMove(subPillar, startPeriodDiff);
}