No, if there were a way to reduce it down to one value, we would be using that instead of the vector!
To compare vector clocks you need to piece-wise compare the whole vector.
class VectorClock {
private long[] clocks;
...
/**
* This is before other iff both conditions are met:
* - each process's clock is less-than-or-equal-to its own clock in other; and
* - there is at least one process's clock which is strictly less-than its
* own clock in other
*/
public boolean isBefore(VectorClock other) {
boolean isBefore = false;
for (int i = 0; i < clocks.length; i++) {
int cmp = Long.compare(clocks[i], other.clocks[i]);
if (cmp > 0)
return false; // note, could return false even if isBefore is true
else if (cmp < 0)
isBefore = true;
}
return isBefore;
}
}
You can do a less-accurate pass using just the min and the max:
class VectorClockSummary {
private long min, max;
...
public tribool isBefore(VectorClockSummary other) {
if (max < other.min)
return true;
else if (min > other.max)
return false;
else
return maybe;
}
}