in query/src/main/java/jetbrains/exodus/query/InMemoryTimSortIterable.java [116:207]
public void init() {
src = new ArrayList<>();
for (final Entity entity : getSrc()) {
src.add(entity);
}
int n = src.size();
if (n == 0) {
return;
}
int minRunLength = n;
int b = 0;
while (minRunLength >= InMemoryTimSortIterable.MIN_RUN_LENGTH) {
b |= minRunLength;
minRunLength >>= 1;
}
minRunLength += b & 1;
int maxRuns = 1 + (n + minRunLength - 1) / minRunLength;
from = new int[maxRuns * 2 - 1];
len = new int[maxRuns * 2 - 1];
left = new int[maxRuns * 2 - 1];
Arrays.fill(left, -1);
right = new int[maxRuns * 2 - 1];
ArrayList<Integer> stack = new ArrayList<>();
runCount = 0;
boolean growing = true;
for (int i = 1; i < n; i++) {
// on the run
if ((getComparator().compare(src.get(i - 1), src.get(i)) <= 0) == growing) {
continue;
}
// start of run
if (i == from[runCount] + 1) {
growing = !(growing);
continue;
}
// reverse if needed
if (!(growing)) {
reverse(i);
}
// insert several next elements into run to achieve run length minRunLength
for (; i < n && i - from[runCount] < minRunLength; i++) {
Entity t = src.get(i);
int j = i - 1;
for (; j >= from[runCount] && getComparator().compare(src.get(j), t) > 0; j--) {
src.set(j + 1, src.get(j));
}
src.set(j + 1, t);
}
len[runCount] = i - from[runCount];
from[++runCount] = i;
stack.add(runCount - 1);
// collapse
while (true) {
int s = stack.size();
if (s >= 3 && len[stack.get(s - 3)] <= len[stack.get(s - 2)] + len[stack.get(s - 1)]) {
if (len[stack.get(s - 3)] < len[stack.get(s - 1)]) {
unite(stack, s - 3, maxRuns);
} else {
unite(stack, s - 2, maxRuns);
}
} else if (s >= 2 && len[stack.get(s - 2)] <= len[stack.get(s - 1)]) {
unite(stack, s - 2, maxRuns);
} else {
break;
}
}
}
// last run
len[runCount] = n - from[runCount];
if (len[runCount] > 0) {
// reverse if needed
if (!(growing)) {
reverse(n);
}
stack.add(runCount);
runCount++;
}
// collapse remaining
for (int i = stack.size() - 2; i >= 0; i--) {
if (i > 0 && len[stack.get(i - 1)] < len[stack.get(i + 1)]) {
unite(stack, i - 1, maxRuns);
} else {
unite(stack, i, maxRuns);
}
}
// for inner nodes min value is unset
for (int i = 0; i < nodeCount; i++) {
from[i + maxRuns] = -1;
}
head = stack.get(0);
}