@Override
public int compare(Schedulable s1, Schedulable s2) {
double minShareRatio1, minShareRatio2;
double tasksToWeightRatio1, tasksToWeightRatio2;
int minShare1 = Math.min(s1.getMinShare(), s1.getDemand());
int minShare2 = Math.min(s2.getMinShare(), s2.getDemand());
boolean s1Needy = s1.getRunningTasks() < minShare1;
boolean s2Needy = s2.getRunningTasks() < minShare2;
minShareRatio1 = s1.getRunningTasks() / Math.max(minShare1, 1.0);
minShareRatio2 = s2.getRunningTasks() / Math.max(minShare2, 1.0);
tasksToWeightRatio1 = s1.getRunningTasks() / s1.getWeight();
tasksToWeightRatio2 = s2.getRunningTasks() / s2.getWeight();
int res = 0;
if (s1Needy && !s2Needy) res = -1;
else if (s2Needy && !s1Needy) res = 1;
else if (s1Needy && s2Needy) res = (int) Math.signum(minShareRatio1 - minShareRatio2);
else // Neither schedulable is needy
res = (int) Math.signum(tasksToWeightRatio1 - tasksToWeightRatio2);
if (res == 0) {
// Jobs are tied in fairness ratio. Break the tie by submit time and job
// name to get a deterministic ordering, which is useful for unit tests.
res = (int) Math.signum(s1.getStartTime() - s2.getStartTime());
if (res == 0) res = s1.getName().compareTo(s2.getName());
}
return res;
}
/**
* Compute the number of slots assigned to a Schedulable given a particular weight-to-slot ratio
* w2sRatio, for use in computeFairShares as described in #{@link
* SchedulingAlgorithms#computeFairShares(Collection, double)}.
*/
private static double computeShare(Schedulable sched, double w2sRatio) {
double share = sched.getWeight() * w2sRatio;
share = Math.max(share, sched.getMinShare());
share = Math.min(share, sched.getDemand());
return share;
}
