/*
* 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.array;
import io.airlift.slice.Slice;
import org.openjdk.jol.info.ClassLayout;
public final class SliceBigArray
{
private static final int SLICE_INSTANCE_SIZE = ClassLayout.parseClass(Slice.class).instanceSize();
private final ObjectBigArray<Slice> array;
private long sizeOfSlices;
public SliceBigArray()
{
array = new ObjectBigArray<>();
}
public SliceBigArray(Slice slice)
{
array = new ObjectBigArray<>(slice);
}
/**
* Returns the size of this big array in bytes.
*/
public long sizeOf()
{
return array.sizeOf() + sizeOfSlices;
}
/**
* Returns the element of this big array at specified index.
*
* @param index a position in this big array.
* @return the element of this big array at the specified position.
*/
public Slice get(long index)
{
return array.get(index);
}
/**
* Sets the element of this big array at specified index.
*
* @param index a position in this big array.
*/
public void set(long index, Slice value)
{
Slice currentValue = array.get(index);
if (currentValue != null) {
sizeOfSlices -= getSize(currentValue);
}
if (value != null) {
sizeOfSlices += getSize(value);
}
array.set(index, value);
}
// For now we approximate the retained size of a slice by object overhead plus length.
// In general this is more complicated than that as there may be multiple "view" slices
// pointing to the same backing memory of a slice.
private long getSize(Slice slice)
{
return slice.length() + SLICE_INSTANCE_SIZE;
}
/**
* Ensures this big array is at least the specified length. If the array is smaller, segments
* are added until the array is larger then the specified length.
*/
public void ensureCapacity(long length)
{
array.ensureCapacity(length);
}
}