/*
* 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.ignite.internal.util;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Iterator;
/**
* Hash table and linked list implementation of the {@code Set} interface,
* with predictable iteration order. This implementation differs from
* {@code HashSet} in that it maintains a doubly-linked list running through
* all of its entries. This linked list defines the iteration ordering,
* which is the order in which elements were inserted into the set
* (<i>insertion-order</i>). Note that insertion order is <i>not</i> affected
* if an element is <i>re-inserted</i> into the set. (An element {@code e}
* is reinserted into a set {@code s} if {@code s.add(e)} is invoked when
* {@code s.contains(e)} would return {@code true} immediately prior to
* the invocation.)
* <p>
* HashSet is also has maximum capacity. When it is reached the
* newest elements supersede eldest ones.
*
* @param <E> Set element.
*
*/
public class GridBoundedLinkedHashSet<E> extends GridSerializableSet<E> implements Cloneable {
/** */
private static final long serialVersionUID = 0L;
/** */
private static final Object FAKE = Boolean.TRUE;
/** */
@SuppressWarnings({"TransientFieldNotInitialized", "CollectionDeclaredAsConcreteClass"})
private transient HashMap<E, Object> map;
/**
* Constructs a new, empty set; the backing {@code LinkedHashMap}
* instance has default initial capacity (16) and load factor (0.75).
*
* @param maxCap Maximum set capacity.
*/
public GridBoundedLinkedHashSet(int maxCap) {
assert maxCap > 0;
map = new GridBoundedLinkedHashMap<>(maxCap);
}
/**
* Constructs a new set containing the elements in the specified collection.
* The {@code LinkedHashMap} is created with default load factor (0.75)
* and an initial capacity sufficient to contain the elements in the specified
* collection.
*
* @param c The collection whose elements are to be placed into this set.
* @param maxCap Maximum set capacity.
*/
public GridBoundedLinkedHashSet(Collection<? extends E> c, int maxCap) {
assert maxCap > 0;
map = new GridBoundedLinkedHashMap<>(Math.max((int) (c.size() / 0.75f) + 1, 16), maxCap);
addAll(c);
}
/**
* Constructs a new, empty set; the backing {@code LinkedHashMap}
* instance has the specified initial capacity and the specified load factor.
*
* @param initCap The initial capacity of the hash map.
* @param maxCap Maximum set capacity.
* @param loadFactor the Load factor of the hash map.
*/
public GridBoundedLinkedHashSet(int initCap, int maxCap, float loadFactor) {
assert maxCap > 0;
map = new GridBoundedLinkedHashMap<>(initCap, maxCap, loadFactor);
}
/**
* Constructs a new, empty set; the backing {@code LinkedHashMap}
* instance has the specified initial capacity and the specified load factor.
*
* @param initCap The initial capacity of the hash map.
* @param maxCap Maximum set capacity.
* @param loadFactor the Load factor of the hash map.
* @param accessOrder {@code True} for access order, {@code false} for insertion order.
*/
public GridBoundedLinkedHashSet(int initCap, int maxCap, float loadFactor, boolean accessOrder) {
assert maxCap > 0;
map = new GridBoundedLinkedHashMap<>(initCap, maxCap, loadFactor, accessOrder);
}
/**
* Constructs a new, empty set; the backing {@code LinkedHashHashMap}
* instance has the specified initial capacity and default load factor, which
* is {@code 0.75}.
*
* @param initCap The initial capacity of the hash table.
* @param maxCap Maximum capacity.
*/
public GridBoundedLinkedHashSet(int initCap, int maxCap) {
assert maxCap > 0;
map = new GridBoundedLinkedHashMap<>(initCap, maxCap);
}
/**
* Returns an iterator over the elements in this set. The elements are
* returned in no particular order.
*
* @return An iterator over the elements in this set.
* @see ConcurrentModificationException
*/
@Override public Iterator<E> iterator() {
return map.keySet().iterator();
}
/**
* Returns the number of elements in this set (its cardinality).
*
* @return The number of elements in this set (its cardinality).
*/
@Override public int size() {
return map.size();
}
/**
* Returns {@code true} if this set contains no elements.
*
* @return {@code True} if this set contains no elements.
*/
@Override public boolean isEmpty() {
return map.isEmpty();
}
/**
* Returns {@code true} if this set contains the specified element.
*
* @param o Element whose presence in this set is to be tested.
* @return {@code true} if this set contains the specified element.
*/
@SuppressWarnings({"SuspiciousMethodCalls"})
@Override public boolean contains(Object o) {
return map.containsKey(o);
}
/**
* Adds the specified element to this set if it is not already present.
*
* @param o Element to be added to this set.
* @return {@code True} if the set did not already contain the specified
* element.
*/
@Override public boolean add(E o) {
return map.put(o, FAKE) == null;
}
/**
* Removes the specified element from this set if it is present.
*
* @param o Object to be removed from this set, if present.
* @return {@code True} if the set contained the specified element.
*/
@SuppressWarnings({"ObjectEquality"})
@Override public boolean remove(Object o) {
return map.remove(o) == FAKE;
}
/**
* Removes all of the elements from this set.
*/
@Override public void clear() {
map.clear();
}
/**
* Returns a shallow copy of this {@code GridBoundedLinkedHashSet}
* instance: the elements themselves are not cloned.
*
* @return a shallow copy of this set.
* @throws CloneNotSupportedException Thrown if cloning is not supported.
*/
@SuppressWarnings("unchecked")
@Override public Object clone() throws CloneNotSupportedException {
GridBoundedLinkedHashSet<E> newSet = (GridBoundedLinkedHashSet<E>)super.clone();
newSet.map = (HashMap<E, Object>)map.clone();
return newSet;
}
}