public static int GetNext() {
// Sequential search
ThreadLocalRandom tlr = ThreadLocalRandom.current();
long rank = tlr.nextLong(_obj_rank_min, _obj_rank_max + 1);
// Return the upper bound (, which is smaller than the lower bound)
if (_GETNEXT_METHOD == 'U') {
// A sequential search from the end. Won't be too bad. It might be better than the
// binary search since most of the random numbers will fall in the
// buckets toward the end.
int _ornrs_size = _ornrs.size();
double num_reqs = -1.0;
for (int i = _ornrs_size - 1; i >= 0; i --) {
if (_ornrs.get(i).obj_rank <= rank) {
if (i == _ornrs_size - 1) {
num_reqs = _ornrs.get(i).num_reqs;
} else {
num_reqs = _ornrs.get(i+1).num_reqs;
}
//Cons.P(String.format("%d %f %d", rank, num_reqs, Math.round(num_reqs)));
// Cast to float to call int round(float a);
return Math.round((float) num_reqs);
}
}
}
// Interpolate between lower and upper bound
else if (_GETNEXT_METHOD == 'I') {
int _ornrs_size = _ornrs.size();
double num_reqs = -1.0;
for (int i = _ornrs_size - 1; i >= 0; i --) {
if (_ornrs.get(i).obj_rank <= rank) {
if (i == _ornrs_size - 1) {
num_reqs = _ornrs.get(i).num_reqs;
} else {
// rank is always != _ornrs[i+1].obj_rank, since the same rank is
// filtered out when loading the file
num_reqs = (_ornrs.get(i+1).num_reqs - _ornrs.get(i).num_reqs)
* (rank - _ornrs.get(i).obj_rank) / (_ornrs.get(i+1).obj_rank - _ornrs.get(i).obj_rank)
+ _ornrs.get(i).num_reqs;
//Cons.P(String.format("rank=%d i=%d num_reqs=%f %d | %d %d %f %f"
// , rank, i, num_reqs, Math.round(num_reqs)
// , _ornrs.get(i).obj_rank, _ornrs.get(i+1).obj_rank
// , _ornrs.get(i).num_reqs, _ornrs.get(i+1).num_reqs));
}
return Math.round((float) num_reqs);
}
}
}
throw new RuntimeException(
String.format("Unexpected rank=%d _obj_rank_min=%d _obj_rank_max=%d",
rank, _obj_rank_min, _obj_rank_max));
}
/**
* Indicate that a non-root node is most recently used. Root node is not managed in usage list and
* cannot be evicted. Caller must hold any latch on node. Latch is never released by this method,
* even if an exception is thrown.
*/
void used(final Node node, final ThreadLocalRandom rnd) {
// Moving the node in the usage list is expensive for several reasons. First is the
// rapid rate at which shared memory is written to. This creates memory access
// contention between CPU cores. Second is the garbage collector. The G1 collector in
// particular appears to be very sensitive to old generation objects being shuffled
// around too much. Finally, latch acquisition itself can cause contention. If the node
// is popular, it will get more chances to be identified as most recently used. This
// strategy works well enough because cache eviction is always a best-guess approach.
if ((rnd.nextLong() & mUsedRate) == 0 && tryAcquireExclusive()) {
doUsed(node);
}
}
