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fix: prevent blocking event loop thread by replacing ArrayDeque with …
…HashIndexedQueue (#2953) * fix: prevent long stall during reconnection/disconnection by providing LinkedHashSetQueue instead of ArrayDeque for CommandHandler#stack * Polishing * Missed out a file --------- Co-authored-by: Tihomir Mateev <[email protected]>
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src/main/java/io/lettuce/core/datastructure/queue/HashIndexedQueue.java
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * Copyright 2011-Present, Redis Ltd. and Contributors | ||
| * All rights reserved. | ||
| * | ||
| * Licensed under the MIT License. | ||
| */ | ||
| package io.lettuce.core.datastructure.queue; | ||
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| import java.util.AbstractQueue; | ||
| import java.util.ArrayList; | ||
| import java.util.Collection; | ||
| import java.util.HashMap; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.NoSuchElementException; | ||
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| import io.lettuce.core.internal.LettuceAssert; | ||
| import org.jetbrains.annotations.NotNull; | ||
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| /** | ||
| * A queue implementation that supports O(1) removal of elements. The queue is backed by a hash map and a doubly linked list. | ||
| * | ||
| * @author chenxiaofan | ||
| */ | ||
| @SuppressWarnings("unchecked") | ||
| public class HashIndexedQueue<E> extends AbstractQueue<E> { | ||
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| private final Map<E, Object> map; // Object can be Node<E> or List<Node<E>> | ||
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| private Node<E> head; | ||
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| private Node<E> tail; | ||
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| private int size; | ||
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| private static class Node<E> { | ||
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| E value; | ||
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| Node<E> next; | ||
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| Node<E> prev; | ||
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| Node(E value) { | ||
| this.value = value; | ||
| } | ||
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| } | ||
|
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| /** | ||
| * Create a new instance of the {@link HashIndexedQueue}. | ||
| */ | ||
| public HashIndexedQueue() { | ||
| map = new HashMap<>(); | ||
| size = 0; | ||
| } | ||
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| @Override | ||
| public boolean add(E e) { | ||
| return offer(e); | ||
| } | ||
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| @Override | ||
| public boolean offer(E e) { | ||
| final Node<E> newNode = new Node<>(e); | ||
| if (tail == null) { | ||
| head = tail = newNode; | ||
| } else { | ||
| tail.next = newNode; | ||
| newNode.prev = tail; | ||
| tail = newNode; | ||
| } | ||
|
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| if (!map.containsKey(e)) { | ||
| map.put(e, newNode); | ||
| } else { | ||
| Object current = map.get(e); | ||
| if (current instanceof Node) { | ||
| List<Node<E>> nodes = new ArrayList<>(); | ||
| nodes.add((Node<E>) current); | ||
| nodes.add(newNode); | ||
| map.put(e, nodes); | ||
| } else { | ||
| ((List<Node<E>>) current).add(newNode); | ||
| } | ||
| } | ||
| size++; | ||
| return true; | ||
| } | ||
|
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| @Override | ||
| public E poll() { | ||
| if (head == null) { | ||
| return null; | ||
| } | ||
| E value = head.value; | ||
| removeNodeFromMap(head); | ||
| head = head.next; | ||
| if (head == null) { | ||
| tail = null; | ||
| } else { | ||
| head.prev = null; | ||
| } | ||
| size--; | ||
| return value; | ||
| } | ||
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| @Override | ||
| public E peek() { | ||
| if (head == null) { | ||
| return null; | ||
| } | ||
| return head.value; | ||
| } | ||
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| @Override | ||
| public boolean remove(Object o) { | ||
| return removeFirstOccurrence(o); | ||
| } | ||
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| @Override | ||
| public int size() { | ||
| return size; | ||
| } | ||
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| @Override | ||
| public boolean contains(Object o) { | ||
| return map.containsKey(o); | ||
| } | ||
|
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| public class Iterator implements java.util.Iterator<E> { | ||
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| private Node<E> current; | ||
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| private Node<E> prev; | ||
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| private Iterator() { | ||
| current = HashIndexedQueue.this.head; | ||
| prev = null; | ||
| } | ||
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| @Override | ||
| public boolean hasNext() { | ||
| return current != null; | ||
| } | ||
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| @Override | ||
| public E next() { | ||
| if (!hasNext()) { | ||
| throw new NoSuchElementException(); | ||
| } | ||
| E value = current.value; | ||
| prev = current; | ||
| current = current.next; | ||
| return value; | ||
| } | ||
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| @Override | ||
| public void remove() { | ||
| if (prev != null) { | ||
| removeNodeFromMap(prev); | ||
| removeNode(prev); | ||
| size--; | ||
| // remove once | ||
| prev = null; | ||
| } | ||
| } | ||
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| } | ||
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| @NotNull | ||
| @Override | ||
| public Iterator iterator() { | ||
| return new Iterator(); | ||
| } | ||
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| @Override | ||
| public boolean removeAll(Collection<?> c) { | ||
| boolean modified = false; | ||
| for (Object e : c) { | ||
| if (removeAllOccurrences(e)) { | ||
| modified = true; | ||
| } | ||
| } | ||
| return modified; | ||
| } | ||
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| @Override | ||
| public void clear() { | ||
| head = null; | ||
| tail = null; | ||
| map.clear(); | ||
| size = 0; | ||
| } | ||
|
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| private boolean removeFirstOccurrence(Object element) { | ||
| Object current = map.get(element); | ||
| if (current == null) { | ||
| return false; | ||
| } | ||
| if (current instanceof Node) { | ||
| Node<E> node = (Node<E>) current; | ||
| removeNode(node); | ||
| map.remove(element); | ||
| } else { | ||
| List<Node<E>> nodes = (List<Node<E>>) current; | ||
| Node<E> node = nodes.remove(0); | ||
| if (nodes.isEmpty()) { | ||
| map.remove(element); | ||
| } | ||
| removeNode(node); | ||
| } | ||
| size--; | ||
| return true; | ||
| } | ||
|
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| private boolean removeAllOccurrences(Object element) { | ||
| Object current = map.get(element); | ||
| if (current == null) { | ||
| return false; | ||
| } | ||
| if (current instanceof Node) { | ||
| final Node<E> node = (Node<E>) current; | ||
| removeNode(node); | ||
| size--; | ||
| } else { | ||
| final List<Node<E>> nodes = (List<Node<E>>) current; | ||
| for (Node<E> node : nodes) { | ||
| removeNode(node); | ||
| size--; | ||
| } | ||
| } | ||
| map.remove(element); | ||
| return true; | ||
| } | ||
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| private void removeNode(Node<E> node) { | ||
| if (node.prev != null) { | ||
| node.prev.next = node.next; | ||
| } else { | ||
| head = node.next; | ||
| } | ||
| if (node.next != null) { | ||
| node.next.prev = node.prev; | ||
| } else { | ||
| tail = node.prev; | ||
| } | ||
| } | ||
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| private void removeNodeFromMap(Node<E> node) { | ||
| E value = node.value; | ||
| Object current = map.get(value); | ||
| if (current instanceof Node) { | ||
| LettuceAssert.assertState(current == node, "current != node"); | ||
| map.remove(value); | ||
| } else { | ||
| List<Node<E>> nodes = (List<Node<E>>) current; | ||
| final boolean removed = nodes.remove(node); | ||
| LettuceAssert.assertState(removed, "!nodes.remove(node)"); | ||
| if (nodes.isEmpty()) { | ||
| map.remove(value); | ||
| } | ||
| } | ||
| } | ||
|
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| } |
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