108 lines
2.8 KiB
Java
108 lines
2.8 KiB
Java
/*
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* Copyright 2021 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.buffer.api.pool;
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import java.util.Arrays;
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/**
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* Internal primitive priority queue, used by {@link PoolChunk}.
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* The implementation is based on the binary heap, as described in Algorithms by Sedgewick and Wayne.
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*/
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final class LongPriorityQueue {
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public static final int NO_VALUE = -1;
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private long[] array = new long[9];
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private int size;
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public void offer(long handle) {
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if (handle == NO_VALUE) {
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throw new IllegalArgumentException("The NO_VALUE (" + NO_VALUE + ") cannot be added to the queue.");
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}
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size++;
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if (size == array.length) {
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// Grow queue capacity.
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array = Arrays.copyOf(array, 1 + (array.length - 1) * 2);
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}
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array[size] = handle;
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lift(size);
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}
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public void remove(long value) {
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for (int i = 1; i <= size; i++) {
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if (array[i] == value) {
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array[i] = array[size--];
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lift(i);
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sink(i);
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return;
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}
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}
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}
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public long peek() {
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if (size == 0) {
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return NO_VALUE;
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}
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return array[1];
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}
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public long poll() {
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if (size == 0) {
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return NO_VALUE;
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}
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long val = array[1];
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array[1] = array[size];
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array[size] = 0;
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size--;
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sink(1);
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return val;
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}
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public boolean isEmpty() {
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return size == 0;
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}
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private void lift(int index) {
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int parentIndex;
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while (index > 1 && subord(parentIndex = index >> 1, index)) {
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swap(index, parentIndex);
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index = parentIndex;
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}
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}
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private void sink(int index) {
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int child;
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while ((child = index << 1) <= size) {
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if (child < size && subord(child, child + 1)) {
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child++;
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}
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if (!subord(index, child)) {
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break;
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}
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swap(index, child);
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index = child;
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}
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}
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private boolean subord(int a, int b) {
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return array[a] > array[b];
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}
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private void swap(int a, int b) {
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long value = array[a];
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array[a] = array[b];
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array[b] = value;
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}
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}
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