io.deephaven.engine.table.impl.util.ShiftInversionHelper Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of deephaven-engine-table Show documentation
Show all versions of deephaven-engine-table Show documentation
Engine Table: Implementation and closely-coupled utilities
/**
* Copyright (c) 2016-2022 Deephaven Data Labs and Patent Pending
*/
package io.deephaven.engine.table.impl.util;
import io.deephaven.base.verify.Assert;
import io.deephaven.engine.rowset.RowSetShiftData;
import java.util.function.LongUnaryOperator;
/**
* Helper utility for inverting row key shifts.
*/
public class ShiftInversionHelper {
private final RowSetShiftData shifted;
private final boolean reverseOrder;
private int destShiftIdx;
public ShiftInversionHelper(final RowSetShiftData shifted) {
// if not specified, assume forward viewport ordering
this(shifted, false);
}
public ShiftInversionHelper(final RowSetShiftData shifted, final boolean reverseOrder) {
this.shifted = shifted;
this.reverseOrder = reverseOrder;
this.destShiftIdx = reverseOrder ? shifted.size() : 0;
}
private void advanceDestShiftIdx(final long destKey) {
Assert.geq(destKey, "destKey", 0);
destShiftIdx = (int) binarySearch(
reverseOrder ? 0 : destShiftIdx,
reverseOrder ? destShiftIdx : shifted.size(),
innerShiftIdx -> {
long destEnd =
shifted.getEndRange((int) innerShiftIdx) + shifted.getShiftDelta((int) innerShiftIdx);
// due to destKey's expected range, we know this subtraction will not overflow
return destEnd - destKey;
});
}
/**
* Converts post-keyspace key to pre-keyspace key. It expects to be invoked in ascending key order.
*/
public long mapToPrevKeyspace(final long key, final boolean isEnd) {
if (shifted.empty()) {
return key;
}
advanceDestShiftIdx(key);
final long retval;
final int idx = destShiftIdx;
if (idx < shifted.size() && shifted.getBeginRange(idx) + shifted.getShiftDelta(idx) <= key) {
// inside of a destination shift; this is easy to map to prev
retval = key - shifted.getShiftDelta(idx);
} else if (idx < shifted.size() && shifted.getShiftDelta(idx) > 0 && shifted.getBeginRange(idx) <= key) {
// our key is left of the destination but to right of the shift start
retval = shifted.getBeginRange(idx) - (isEnd ? 1 : 0);
} else if (idx > 0 && shifted.getShiftDelta(idx - 1) < 0 && key <= shifted.getEndRange(idx - 1)) {
// our key is right of the destination but left of the shift start
retval = shifted.getEndRange(idx - 1) + (isEnd ? 0 : 1);
} else {
retval = key;
}
return retval;
}
private static long binarySearch(int low, int high, final LongUnaryOperator evaluate) {
while (low < high) {
final int mid = (low + high) / 2;
final long res = evaluate.applyAsLong(mid);
if (res < 0) {
low = mid + 1;
} else if (res > 0) {
high = mid;
} else {
return mid;
}
}
return low;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy