| /* |
| * 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.solr.util; |
| |
| import java.util.Arrays; |
| |
| /** A native long priority queue. |
| * |
| * @lucene.internal |
| */ |
| public class LongPriorityQueue { |
| protected int size; // number of elements currently in the queue |
| protected int currentCapacity; // number of elements the queue can hold w/o expanding |
| protected int maxSize; // max number of elements allowed in the queue |
| protected long[] heap; |
| protected final long sentinel; // represents a null return value |
| |
| public LongPriorityQueue(int initialSize, int maxSize, long sentinel) { |
| this.maxSize = maxSize; |
| this.sentinel = sentinel; |
| initialize(initialSize); |
| } |
| |
| |
| protected void initialize(int sz) { |
| int heapSize; |
| if (0 == sz) |
| // We allocate 1 extra to avoid if statement in top() |
| heapSize = 2; |
| else { |
| // NOTE: we add +1 because all access to heap is |
| // 1-based not 0-based. heap[0] is unused. |
| heapSize = Math.max(sz, sz + 1); // handle overflow |
| } |
| heap = new long[heapSize]; |
| currentCapacity = sz; |
| } |
| |
| public int getCurrentCapacity() { |
| return currentCapacity; |
| } |
| |
| public void resize(int sz) { |
| int heapSize; |
| if (sz > maxSize) { |
| maxSize = sz; |
| } |
| if (0 == sz) |
| // We allocate 1 extra to avoid if statement in top() |
| heapSize = 2; |
| else { |
| heapSize = Math.max(sz, sz + 1); // handle overflow |
| } |
| heap = Arrays.copyOf(heap, heapSize); |
| currentCapacity = sz; |
| } |
| |
| /** |
| * Adds an object to a PriorityQueue in log(size) time. If one tries to add |
| * more objects than maxSize from initialize an |
| * {@link ArrayIndexOutOfBoundsException} is thrown. |
| * |
| * @return the new 'top' element in the queue. |
| */ |
| public long add(long element) { |
| if (size >= currentCapacity) { |
| int newSize = Math.min(currentCapacity <<1, maxSize); |
| if (newSize < currentCapacity) newSize = Integer.MAX_VALUE; // handle overflow |
| resize(newSize); |
| } |
| size++; |
| heap[size] = element; |
| upHeap(); |
| return heap[1]; |
| } |
| |
| /** |
| * Adds an object to a PriorityQueue in log(size) time. If one tries to add |
| * more objects than the current capacity, an |
| * {@link ArrayIndexOutOfBoundsException} is thrown. |
| */ |
| public void addNoCheck(long element) { |
| ++size; |
| heap[size] = element; |
| upHeap(); |
| } |
| |
| /** |
| * Adds an object to a PriorityQueue in log(size) time. |
| * It returns the smallest object (if any) that was |
| * dropped off the heap because it was full, or |
| * the sentinel value. |
| * |
| * This can be |
| * the given parameter (in case it is smaller than the |
| * full heap's minimum, and couldn't be added), or another |
| * object that was previously the smallest value in the |
| * heap and now has been replaced by a larger one, or null |
| * if the queue wasn't yet full with maxSize elements. |
| */ |
| public long insertWithOverflow(long element) { |
| if (size < maxSize) { |
| add(element); |
| return sentinel; |
| } else if (element > heap[1]) { |
| long ret = heap[1]; |
| heap[1] = element; |
| updateTop(); |
| return ret; |
| } else { |
| return element; |
| } |
| } |
| |
| /** inserts the element and returns true if this element caused another element |
| * to be dropped from the queue. */ |
| public boolean insert(long element) { |
| if (size < maxSize) { |
| add(element); |
| return false; |
| } else if (element > heap[1]) { |
| // long ret = heap[1]; |
| heap[1] = element; |
| updateTop(); |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| /** Returns the least element of the PriorityQueue in constant time. */ |
| public long top() { |
| return heap[1]; |
| } |
| |
| /** Removes and returns the least element of the PriorityQueue in log(size) |
| time. Only valid if size() > 0. |
| */ |
| public long pop() { |
| long result = heap[1]; // save first value |
| heap[1] = heap[size]; // move last to first |
| size--; |
| downHeap(); // adjust heap |
| return result; |
| } |
| |
| /** |
| * Should be called when the Object at top changes values. |
| * @return the new 'top' element. |
| */ |
| public long updateTop() { |
| downHeap(); |
| return heap[1]; |
| } |
| |
| /** Returns the number of elements currently stored in the PriorityQueue. */ |
| public int size() { |
| return size; |
| } |
| |
| /** Returns the array used to hold the heap, with the smallest item at array[1] |
| * and the last (but not necessarily largest) at array[size()]. This is *not* |
| * fully sorted. |
| */ |
| public long[] getInternalArray() { |
| return heap; |
| } |
| |
| /** Pops the smallest n items from the heap, placing them in the internal array at |
| * arr[size] through arr[size-(n-1)] with the smallest (first element popped) |
| * being at arr[size]. The internal array is returned. |
| */ |
| public long[] sort(int n) { |
| while (--n >= 0) { |
| long result = heap[1]; // save first value |
| heap[1] = heap[size]; // move last to first |
| heap[size] = result; // place it last |
| size--; |
| downHeap(); // adjust heap |
| } |
| return heap; |
| } |
| |
| /** Removes all entries from the PriorityQueue. */ |
| public void clear() { |
| size = 0; |
| } |
| |
| private void upHeap() { |
| int i = size; |
| long node = heap[i]; // save bottom node |
| int j = i >>> 1; |
| while (j > 0 && node < heap[j]) { |
| heap[i] = heap[j]; // shift parents down |
| i = j; |
| j = j >>> 1; |
| } |
| heap[i] = node; // install saved node |
| } |
| |
| private void downHeap() { |
| int i = 1; |
| long node = heap[i]; // save top node |
| int j = i << 1; // find smaller child |
| int k = j + 1; |
| if (k <= size && heap[k] < heap[j]) { |
| j = k; |
| } |
| while (j <= size && heap[j] < node) { |
| heap[i] = heap[j]; // shift up child |
| i = j; |
| j = i << 1; |
| k = j + 1; |
| if (k <= size && heap[k] < heap[j]) { |
| j = k; |
| } |
| } |
| heap[i] = node; // install saved node |
| } |
| } |