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/* * 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.packed; import static org.apache.lucene.util.packed.PackedInts.checkBlockSize; import org.apache.lucene.util.Accountable; import org.apache.lucene.util.ArrayUtil; import org.apache.lucene.util.LongValues; import org.apache.lucene.util.RamUsageEstimator; /** * Utility class to compress integers into a {@link LongValues} instance. */ public class PackedLongValues extends LongValues implements Accountable { private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(PackedLongValues.class); static final int DEFAULT_PAGE_SIZE = 1024; static final int MIN_PAGE_SIZE = 64; // More than 1M doesn't really makes sense with these appending buffers // since their goal is to try to have small numbers of bits per value static final int MAX_PAGE_SIZE = 1 << 20; /** Return a new {@link Builder} that will compress efficiently positive integers. */ public static PackedLongValues.Builder packedBuilder(int pageSize, float acceptableOverheadRatio) { return new PackedLongValues.Builder(pageSize, acceptableOverheadRatio); } /** @see #packedBuilder(int, float) */ public static PackedLongValues.Builder packedBuilder(float acceptableOverheadRatio) { return packedBuilder(DEFAULT_PAGE_SIZE, acceptableOverheadRatio); } /** Return a new {@link Builder} that will compress efficiently integers that * are close to each other. */ public static PackedLongValues.Builder deltaPackedBuilder(int pageSize, float acceptableOverheadRatio) { return new DeltaPackedLongValues.Builder(pageSize, acceptableOverheadRatio); } /** @see #deltaPackedBuilder(int, float) */ public static PackedLongValues.Builder deltaPackedBuilder(float acceptableOverheadRatio) { return deltaPackedBuilder(DEFAULT_PAGE_SIZE, acceptableOverheadRatio); } /** Return a new {@link Builder} that will compress efficiently integers that * would be a monotonic function of their index. */ public static PackedLongValues.Builder monotonicBuilder(int pageSize, float acceptableOverheadRatio) { return new MonotonicLongValues.Builder(pageSize, acceptableOverheadRatio); } /** @see #monotonicBuilder(int, float) */ public static PackedLongValues.Builder monotonicBuilder(float acceptableOverheadRatio) { return monotonicBuilder(DEFAULT_PAGE_SIZE, acceptableOverheadRatio); } final PackedInts.Reader[] values; final int pageShift, pageMask; private final long size; private final long ramBytesUsed; PackedLongValues(int pageShift, int pageMask, PackedInts.Reader[] values, long size, long ramBytesUsed) { this.pageShift = pageShift; this.pageMask = pageMask; this.values = values; this.size = size; this.ramBytesUsed = ramBytesUsed; } /** Get the number of values in this array. */ public final long size() { return size; } int decodeBlock(int block, long[] dest) { final PackedInts.Reader vals = values[block]; final int size = vals.size(); for (int k = 0; k < size;) { k += vals.get(k, dest, k, size - k); } return size; } long get(int block, int element) { return values[block].get(element); } @Override public final long get(long index) { assert index >= 0 && index < size(); final int block = (int) (index >> pageShift); final int element = (int) (index & pageMask); return get(block, element); } @Override public long ramBytesUsed() { return ramBytesUsed; } /** Return an iterator over the values of this array. */ public Iterator iterator() { return new Iterator(); } /** An iterator over long values. */ final public class Iterator { final long[] currentValues; int vOff, pOff; int currentCount; // number of entries of the current page Iterator() { currentValues = new long[pageMask + 1]; vOff = pOff = 0; fillBlock(); } private void fillBlock() { if (vOff == values.length) { currentCount = 0; } else { currentCount = decodeBlock(vOff, currentValues); assert currentCount > 0; } } /** Whether or not there are remaining values. */ public final boolean hasNext() { return pOff < currentCount; } /** Return the next long in the buffer. */ public final long next() { assert hasNext(); long result = currentValues[pOff++]; if (pOff == currentCount) { vOff += 1; pOff = 0; fillBlock(); } return result; } } /** A Builder for a {@link PackedLongValues} instance. */ public static class Builder implements Accountable { private static final int INITIAL_PAGE_COUNT = 16; private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(Builder.class); final int pageShift, pageMask; final float acceptableOverheadRatio; long[] pending; long size; PackedInts.Reader[] values; long ramBytesUsed; int valuesOff; int pendingOff; Builder(int pageSize, float acceptableOverheadRatio) { pageShift = checkBlockSize(pageSize, MIN_PAGE_SIZE, MAX_PAGE_SIZE); pageMask = pageSize - 1; this.acceptableOverheadRatio = acceptableOverheadRatio; values = new PackedInts.Reader[INITIAL_PAGE_COUNT]; pending = new long[pageSize]; valuesOff = 0; pendingOff = 0; size = 0; ramBytesUsed = baseRamBytesUsed() + RamUsageEstimator.sizeOf(pending) + RamUsageEstimator.shallowSizeOf(values); } /** Build a {@link PackedLongValues} instance that contains values that * have been added to this builder. This operation is destructive. */ public PackedLongValues build() { finish(); pending = null; final PackedInts.Reader[] values = ArrayUtil.copyOfSubArray(this.values, 0, valuesOff); final long ramBytesUsed = PackedLongValues.BASE_RAM_BYTES_USED + RamUsageEstimator.sizeOf(values); return new PackedLongValues(pageShift, pageMask, values, size, ramBytesUsed); } long baseRamBytesUsed() { return BASE_RAM_BYTES_USED; } @Override public final long ramBytesUsed() { return ramBytesUsed; } /** Return the number of elements that have been added to this builder. */ public final long size() { return size; } /** Add a new element to this builder. */ public Builder add(long l) { if (pending == null) { throw new IllegalStateException("Cannot be reused after build()"); } if (pendingOff == pending.length) { // check size if (values.length == valuesOff) { final int newLength = ArrayUtil.oversize(valuesOff + 1, 8); grow(newLength); } pack(); } pending[pendingOff++] = l; size += 1; return this; } final void finish() { if (pendingOff > 0) { if (values.length == valuesOff) { grow(valuesOff + 1); } pack(); } } private void pack() { pack(pending, pendingOff, valuesOff, acceptableOverheadRatio); ramBytesUsed += values[valuesOff].ramBytesUsed(); valuesOff += 1; // reset pending buffer pendingOff = 0; } void pack(long[] values, int numValues, int block, float acceptableOverheadRatio) { assert numValues > 0; // compute max delta long minValue = values[0]; long maxValue = values[0]; for (int i = 1; i < numValues; ++i) { minValue = Math.min(minValue, values[i]); maxValue = Math.max(maxValue, values[i]); } // build a new packed reader if (minValue == 0 && maxValue == 0) { this.values[block] = new PackedInts.NullReader(numValues); } else { final int bitsRequired = minValue < 0 ? 64 : PackedInts.bitsRequired(maxValue); final PackedInts.Mutable mutable = PackedInts.getMutable(numValues, bitsRequired, acceptableOverheadRatio); for (int i = 0; i < numValues;) { i += mutable.set(i, values, i, numValues - i); } this.values[block] = mutable; } } void grow(int newBlockCount) { ramBytesUsed -= RamUsageEstimator.shallowSizeOf(values); values = ArrayUtil.growExact(values, newBlockCount); ramBytesUsed += RamUsageEstimator.shallowSizeOf(values); } } }