/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.util;
import org.elasticsearch.common.lease.Releasables;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* A hash table from native longs to objects. This implementation resolves collisions
* using open-addressing and does not support null values. This class is not thread-safe.
*/
public class LongObjectPagedHashMap<T> extends AbstractPagedHashMap implements Iterable<LongObjectPagedHashMap.Cursor<T>> {
private LongArray keys;
private ObjectArray<T> values;
public LongObjectPagedHashMap(BigArrays bigArrays) {
this(16, bigArrays);
}
public LongObjectPagedHashMap(long capacity, BigArrays bigArrays) {
this(capacity, DEFAULT_MAX_LOAD_FACTOR, bigArrays);
}
public LongObjectPagedHashMap(long capacity, float maxLoadFactor, BigArrays bigArrays) {
super(capacity, maxLoadFactor, bigArrays);
keys = bigArrays.newLongArray(capacity(), false);
values = bigArrays.newObjectArray(capacity());
}
/**
* Get the value that is associated with <code>key</code> or null if <code>key</code>
* was not present in the hash table.
*/
public T get(long key) {
for (long i = slot(hash(key), mask); ; i = nextSlot(i, mask)) {
final T value = values.get(i);
if (value == null) {
return null;
} else if (keys.get(i) == key) {
return value;
}
}
}
/**
* Put this new (key, value) pair into this hash table and return the value
* that was previously associated with <code>key</code> or null in case of
* an insertion.
*/
public T put(long key, T value) {
if (size >= maxSize) {
assert size == maxSize;
grow();
}
assert size < maxSize;
return set(key, value);
}
/**
* Remove the entry which has this key in the hash table and return the
* associated value or null if there was no entry associated with this key.
*/
public T remove(long key) {
for (long i = slot(hash(key), mask); ; i = nextSlot(i, mask)) {
final T previous = values.set(i, null);
if (previous == null) {
return null;
} else if (keys.get(i) == key) {
--size;
for (long j = nextSlot(i, mask); used(j); j = nextSlot(j, mask)) {
removeAndAdd(j);
}
return previous;
} else {
// repair and continue
values.set(i, previous);
}
}
}
private T set(long key, T value) {
if (value == null) {
throw new IllegalArgumentException("Null values are not supported");
}
for (long i = slot(hash(key), mask); ; i = nextSlot(i, mask)) {
final T previous = values.set(i, value);
if (previous == null) {
// slot was free
keys.set(i, key);
++size;
return null;
} else if (key == keys.get(i)) {
// we just updated the value
return previous;
} else {
// not the right key, repair and continue
values.set(i, previous);
}
}
}
@Override
public Iterator<Cursor<T>> iterator() {
return new Iterator<Cursor<T>>() {
boolean cached;
final Cursor<T> cursor;
{
cursor = new Cursor<>();
cursor.index = -1;
cached = false;
}
@Override
public boolean hasNext() {
if (!cached) {
while (true) {
++cursor.index;
if (cursor.index >= capacity()) {
break;
} else if (used(cursor.index)) {
cursor.key = keys.get(cursor.index);
cursor.value = values.get(cursor.index);
break;
}
}
cached = true;
}
return cursor.index < capacity();
}
@Override
public Cursor<T> next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
cached = false;
return cursor;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override
public void close() {
Releasables.close(keys, values);
}
@Override
protected void resize(long capacity) {
keys = bigArrays.resize(keys, capacity);
values = bigArrays.resize(values, capacity);
}
@Override
protected boolean used(long bucket) {
return values.get(bucket) != null;
}
@Override
protected void removeAndAdd(long index) {
final long key = keys.get(index);
final T value = values.set(index, null);
--size;
final T removed = set(key, value);
assert removed == null;
}
public static final class Cursor<T> {
public long index;
public long key;
public T value;
}
}