/** This methods extracts and stores all open right branches for future exploration */
protected void extractOpenRightBranches(SearchLoop searchLoop) {
// update parameters for restarts
if (nodesRecompute > 0) {
double ratio = nodesRecompute * 1.d / searchLoop.mMeasures.getNodeCount();
if (ratio > b && Z <= N) {
Z *= 2;
} else if (ratio < a && Z >= 2) {
Z /= 2;
}
}
limit += Z;
// then start the extraction of open right branches
int i = compareSubpath(searchLoop);
if (i < _unkopen.size()) {
extractOB(searchLoop, i);
}
// finally, get the best ORB to keep up the search
Open next = opens.poll();
while (next != null && !isValid(next.currentBound())) {
next = opens.poll();
}
if (next != null) {
copen = next.toArray();
// the decision in 0 is the last taken, then the array us reversed
ArrayUtils.reverse(copen);
current = 0;
nodesRecompute = searchLoop.mMeasures.getNodeCount() + copen.length;
} else {
// to be sure not to use the previous path
current = copen.length;
}
// then do the restart
searchLoop.restart();
}
@Override
public boolean extend(SearchLoop searchLoop) {
boolean extend;
// as we observe the number of backtracks, no limit can be reached on extend()
if (current < copen.length) {
Decision tmp = searchLoop.decision;
searchLoop.decision = copen[current++];
assert searchLoop.decision != null;
searchLoop.decision.setPrevious(tmp);
searchLoop.mSolver.getEnvironment().worldPush();
extend = true;
} else /*cut will checker with propagation */ {
extend = super.extend(searchLoop);
}
return extend;
}
/**
* Extract the open right branches from the current path until it reaches the i^th decision of
* _unkopen
*
* @param searchLoop the search loop
* @param i the index of the decision, in _unkopen, that stops the loop
*/
private void extractOB(SearchLoop searchLoop, int i) {
Decision stopAt = _unkopen.get(i).getPrevious();
// then, goes up in the search tree, and detect open nodes
searchLoop.mSolver.getEnvironment().worldPop();
Decision decision = searchLoop.decision;
int bound;
while (decision != stopAt) {
bound =
isMinimization
? objectiveManager.getObjective().getLB()
: objectiveManager.getObjective().getUB();
if (decision.hasNext() && isValid(bound)) {
opens.add(new Open(decision, bound, isMinimization));
}
searchLoop.decision = searchLoop.decision.getPrevious();
decision.free();
decision = searchLoop.decision;
searchLoop.mSolver.getEnvironment().worldPop();
}
}
