/*
* 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.
*/
package org.apache.lucene.util;
import java.util.Arrays;
import java.util.Comparator;
/**
* 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 implements SortableBytesRefArray {
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 * Integer.BYTES);
this.bytesUsed = bytesUsed;
}
/**
* Clears this {@link BytesRefArray}
*/
@Override
public void clear() {
lastElement = 0;
currentOffset = 0;
// TODO: it's trappy that this does not return storage held by int[] offsets array!
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
*/
@Override
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) * Integer.BYTES);
}
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}
*/
@Override
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(BytesRefBuilder spare, int index) {
if (lastElement > index) {
int offset = offsets[index];
int length = index == lastElement - 1 ? currentOffset - offset
: offsets[index + 1] - offset;
spare.grow(length);
spare.setLength(length);
pool.readBytes(offset, spare.bytes(), 0, spare.length());
return spare.get();
}
throw new IndexOutOfBoundsException("index " + index
+ " must be less than the size: " + lastElement);
}
/** Used only by sort below, to set a {@link BytesRef} with the specified slice, avoiding copying bytes in the common case when the slice
* is contained in a single block in the byte block pool. */
private void setBytesRef(BytesRefBuilder spare, BytesRef result, int index) {
if (index < lastElement) {
int offset = offsets[index];
int length;
if (index == lastElement - 1) {
length = currentOffset - offset;
} else {
length = offsets[index + 1] - offset;
}
pool.setBytesRef(spare, result, offset, length);
} else {
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];
setBytesRef(scratch1, scratchBytes1, idx1);
setBytesRef(scratch2, scratchBytes2, idx2);
return comp.compare(scratchBytes1, scratchBytes2);
}
@Override
protected void setPivot(int i) {
final int index = orderedEntries[i];
setBytesRef(pivotBuilder, pivot, index);
}
@Override
protected int comparePivot(int j) {
final int index = orderedEntries[j];
setBytesRef(scratch2, scratchBytes2, index);
return comp.compare(pivot, scratchBytes2);
}
private final BytesRef pivot = new BytesRef();
private final BytesRef scratchBytes1 = new BytesRef();
private final BytesRef scratchBytes2 = new BytesRef();
private final BytesRefBuilder pivotBuilder = new BytesRefBuilder();
private final BytesRefBuilder scratch1 = new BytesRefBuilder();
private final BytesRefBuilder scratch2 = new BytesRefBuilder();
}.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>
*/
@Override
public BytesRefIterator iterator(final Comparator<BytesRef> comp) {
final BytesRefBuilder spare = new BytesRefBuilder();
final BytesRef result = 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) {
setBytesRef(spare, result, indices == null ? pos++ : indices[pos++]);
return result;
}
return null;
}
};
}
}