package org.apache.lucene.util;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You 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.
*/
import java.util.Arrays;
import java.util.Comparator;
import org.apache.lucene.util.ArrayUtil;
import org.apache.lucene.util.ByteBlockPool;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.BytesRefIterator;
import org.apache.lucene.util.Counter;
import org.apache.lucene.util.IntroSorter;
import org.apache.lucene.util.RamUsageEstimator;
/**
* A simple append only random-access {@link BytesRef} array that stores full
* copies of the appended bytes in a {@link ByteBlockPool}.
*
*
* <b>Note: This class is not Thread-Safe!</b>
*
* @lucene.internal
* @lucene.experimental
*/
public final class BytesRefArray {
private final ByteBlockPool pool;
private int[] offsets = new int[1];
private int lastElement = 0;
private int currentOffset = 0;
private final Counter bytesUsed;
/**
* Creates a new {@link BytesRefArray} with a counter to track allocated bytes
*/
public BytesRefArray(Counter bytesUsed) {
this.pool = new ByteBlockPool(new ByteBlockPool.DirectTrackingAllocator(
bytesUsed));
pool.nextBuffer();
bytesUsed.addAndGet(RamUsageEstimator.NUM_BYTES_ARRAY_HEADER
+ RamUsageEstimator.NUM_BYTES_INT);
this.bytesUsed = bytesUsed;
}
/**
* Clears this {@link BytesRefArray}
*/
public void clear() {
lastElement = 0;
currentOffset = 0;
Arrays.fill(offsets, 0);
pool.reset(false, true); // no need to 0 fill the buffers we control the allocator
}
/**
* Appends a copy of the given {@link BytesRef} to this {@link BytesRefArray}.
* @param bytes the bytes to append
* @return the index of the appended bytes
*/
public int append(BytesRef bytes) {
if (lastElement >= offsets.length) {
int oldLen = offsets.length;
offsets = ArrayUtil.grow(offsets, offsets.length + 1);
bytesUsed.addAndGet((offsets.length - oldLen)
* RamUsageEstimator.NUM_BYTES_INT);
}
pool.append(bytes);
offsets[lastElement++] = currentOffset;
currentOffset += bytes.length;
return lastElement-1;
}
/**
* Returns the current size of this {@link BytesRefArray}
* @return the current size of this {@link BytesRefArray}
*/
public int size() {
return lastElement;
}
/**
* Returns the <i>n'th</i> element of this {@link BytesRefArray}
* @param spare a spare {@link BytesRef} instance
* @param index the elements index to retrieve
* @return the <i>n'th</i> element of this {@link BytesRefArray}
*/
public BytesRef get(BytesRef spare, int index) {
if (lastElement > index) {
int offset = offsets[index];
int length = index == lastElement - 1 ? currentOffset - offset
: offsets[index + 1] - offset;
assert spare.offset == 0;
spare.grow(length);
spare.length = length;
pool.readBytes(offset, spare.bytes, spare.offset, spare.length);
return spare;
}
throw new IndexOutOfBoundsException("index " + index
+ " must be less than the size: " + lastElement);
}
private int[] sort(final Comparator<BytesRef> comp) {
final int[] orderedEntries = new int[size()];
for (int i = 0; i < orderedEntries.length; i++) {
orderedEntries[i] = i;
}
new IntroSorter() {
@Override
protected void swap(int i, int j) {
final int o = orderedEntries[i];
orderedEntries[i] = orderedEntries[j];
orderedEntries[j] = o;
}
@Override
protected int compare(int i, int j) {
final int idx1 = orderedEntries[i], idx2 = orderedEntries[j];
return comp.compare(get(scratch1, idx1), get(scratch2, idx2));
}
@Override
protected void setPivot(int i) {
final int index = orderedEntries[i];
get(pivot, index);
}
@Override
protected int comparePivot(int j) {
final int index = orderedEntries[j];
return comp.compare(pivot, get(scratch2, index));
}
private final BytesRef pivot = new BytesRef(), scratch1 = new BytesRef(),
scratch2 = new BytesRef();
}.sort(0, size());
return orderedEntries;
}
/**
* sugar for {@link #iterator(Comparator)} with a <code>null</code> comparator
*/
public BytesRefIterator iterator() {
return iterator(null);
}
/**
* <p>
* Returns a {@link BytesRefIterator} with point in time semantics. The
* iterator provides access to all so far appended {@link BytesRef} instances.
* </p>
* <p>
* If a non <code>null</code> {@link Comparator} is provided the iterator will
* iterate the byte values in the order specified by the comparator. Otherwise
* the order is the same as the values were appended.
* </p>
* <p>
* This is a non-destructive operation.
* </p>
*/
public BytesRefIterator iterator(final Comparator<BytesRef> comp) {
final BytesRef spare = new BytesRef();
final int size = size();
final int[] indices = comp == null ? null : sort(comp);
return new BytesRefIterator() {
int pos = 0;
@Override
public BytesRef next() {
if (pos < size) {
return get(spare, indices == null ? pos++ : indices[pos++]);
}
return null;
}
@Override
public Comparator<BytesRef> getComparator() {
return comp;
}
};
}
}