/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.operator.aggregation;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockBuilderStatus;
import com.facebook.presto.spi.type.Type;
import org.openjdk.jol.info.ClassLayout;
import static com.google.common.base.Preconditions.checkArgument;
import static io.airlift.slice.SizeOf.sizeOf;
public class TypedHeap
{
private static final int INSTANCE_SIZE = ClassLayout.parseClass(TypedHeap.class).instanceSize();
private static final int COMPACT_THRESHOLD_BYTES = 32768;
private static final int COMPACT_THRESHOLD_RATIO = 3; // when 2/3 of elements in heapBlockBuilder is unreferenced, do compact
private final BlockComparator comparator;
private final Type type;
private final int capacity;
private int positionCount;
private final int[] heapIndex;
private BlockBuilder heapBlockBuilder;
public TypedHeap(BlockComparator comparator, Type type, int capacity)
{
this.comparator = comparator;
this.type = type;
this.capacity = capacity;
this.heapIndex = new int[capacity];
this.heapBlockBuilder = type.createBlockBuilder(new BlockBuilderStatus(), capacity);
}
public int getCapacity()
{
return capacity;
}
public long getEstimatedSize()
{
return INSTANCE_SIZE + heapBlockBuilder.getRetainedSizeInBytes() + sizeOf(heapIndex);
}
public boolean isEmpty()
{
return positionCount == 0;
}
public void writeAll(BlockBuilder resultBlockBuilder)
{
for (int i = 0; i < positionCount; i++) {
type.appendTo(heapBlockBuilder, heapIndex[i], resultBlockBuilder);
}
}
public void popAll(BlockBuilder resultBlockBuilder)
{
while (positionCount > 0) {
pop(resultBlockBuilder);
}
}
public void pop(BlockBuilder resultBlockBuilder)
{
type.appendTo(heapBlockBuilder, heapIndex[0], resultBlockBuilder);
remove();
}
private void remove()
{
positionCount--;
heapIndex[0] = heapIndex[positionCount];
siftDown();
}
public void add(Block block, int position)
{
checkArgument(!block.isNull(position));
if (positionCount == capacity) {
if (comparator.compareTo(heapBlockBuilder, heapIndex[0], block, position) >= 0) {
return; // and new element is not larger than heap top: do not add
}
heapIndex[0] = heapBlockBuilder.getPositionCount();
type.appendTo(block, position, heapBlockBuilder);
siftDown();
}
else {
heapIndex[positionCount] = heapBlockBuilder.getPositionCount();
positionCount++;
type.appendTo(block, position, heapBlockBuilder);
siftUp();
}
compactIfNecessary();
}
public void addAll(TypedHeap other)
{
for (int i = 0; i < other.positionCount; i++) {
add(other.heapBlockBuilder, other.heapIndex[i]);
}
}
public void addAll(Block block)
{
for (int i = 0; i < block.getPositionCount(); i++) {
add(block, i);
}
}
private void siftDown()
{
int position = 0;
while (true) {
int leftPosition = position * 2 + 1;
if (leftPosition >= positionCount) {
break;
}
int rightPosition = leftPosition + 1;
int smallerChildPosition;
if (rightPosition >= positionCount) {
smallerChildPosition = leftPosition;
}
else {
smallerChildPosition = comparator.compareTo(heapBlockBuilder, heapIndex[leftPosition], heapBlockBuilder, heapIndex[rightPosition]) >= 0 ? rightPosition : leftPosition;
}
if (comparator.compareTo(heapBlockBuilder, heapIndex[smallerChildPosition], heapBlockBuilder, heapIndex[position]) >= 0) {
break; // child is larger or equal
}
int swapTemp = heapIndex[position];
heapIndex[position] = heapIndex[smallerChildPosition];
heapIndex[smallerChildPosition] = swapTemp;
position = smallerChildPosition;
}
}
private void siftUp()
{
int position = positionCount - 1;
while (position != 0) {
int parentPosition = (position - 1) / 2;
if (comparator.compareTo(heapBlockBuilder, heapIndex[position], heapBlockBuilder, heapIndex[parentPosition]) >= 0) {
break; // child is larger or equal
}
int swapTemp = heapIndex[position];
heapIndex[position] = heapIndex[parentPosition];
heapIndex[parentPosition] = swapTemp;
position = parentPosition;
}
}
private void compactIfNecessary()
{
// Byte size check is needed. Otherwise, if size * 3 is small, BlockBuilder can be reallocate too often.
// Position count is needed. Otherwise, for large elements, heap will be compacted every time.
// Size instead of retained size is needed because default allocation size can be huge for some block builders. And the first check will become useless in such case.
if (heapBlockBuilder.getSizeInBytes() < COMPACT_THRESHOLD_BYTES || heapBlockBuilder.getPositionCount() / positionCount < COMPACT_THRESHOLD_RATIO) {
return;
}
BlockBuilder newHeapBlockBuilder = type.createBlockBuilder(new BlockBuilderStatus(), heapBlockBuilder.getPositionCount());
for (int i = 0; i < positionCount; i++) {
type.appendTo(heapBlockBuilder, heapIndex[i], newHeapBlockBuilder);
heapIndex[i] = i;
}
heapBlockBuilder = newHeapBlockBuilder;
}
}