/*
* Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
package org.opendaylight.yangtools.util;
import com.google.common.annotations.Beta;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.base.Verify;
import com.google.common.collect.ImmutableMap;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import javax.annotation.Nonnull;
/**
* A mutable version of {@link ImmutableOffsetMap}. It inherits the set of mappings from the immutable version and
* allows updating/removing existing mappings. New mappings are stored in a dedicated {@link LinkedHashMap} to preserve
* insertion order. It also tracks the need to duplicate the backing array, so the sequence of
* <code>
* ImmutableOffsetMap<K, V> source;
* ImmutableOffsetMap<K, V> result = source.createMutableClone().immutableCopy();
* </code>
* results in source and result sharing the backing objects.
*
* <p>This map does not support null keys nor values.
*
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
*/
@Beta
public abstract class MutableOffsetMap<K, V> extends AbstractMap<K, V> implements Cloneable, ModifiableMapPhase<K, V> {
static final class Ordered<K, V> extends MutableOffsetMap<K, V> {
Ordered() {
super(new LinkedHashMap<>());
}
Ordered(final Map<K, V> source) {
super(OffsetMapCache.orderedOffsets(source.keySet()), source, new LinkedHashMap<>());
}
Ordered(final Map<K, Integer> offsets, final V[] objects) {
super(offsets, objects, new LinkedHashMap<>());
}
@Override
Object removedObject() {
return REMOVED;
}
@Override
UnmodifiableMapPhase<K, V> modifiedMap(final List<K> keys, final V[] objects) {
return new ImmutableOffsetMap.Ordered<>(OffsetMapCache.orderedOffsets(keys), objects);
}
@Override
UnmodifiableMapPhase<K, V> unmodifiedMap(final Map<K, Integer> offsets, final V[] objects) {
return new ImmutableOffsetMap.Ordered<>(offsets, objects);
}
@Override
SharedSingletonMap<K, V> singletonMap() {
return SharedSingletonMap.orderedCopyOf(this);
}
}
static final class Unordered<K, V> extends MutableOffsetMap<K, V> {
Unordered() {
super(new HashMap<>());
}
Unordered(final Map<K, V> source) {
super(OffsetMapCache.unorderedOffsets(source.keySet()), source, new HashMap<>());
}
Unordered(final Map<K, Integer> offsets, final V[] objects) {
super(offsets, objects, new HashMap<>());
}
@Override
Object removedObject() {
return null;
}
@Override
UnmodifiableMapPhase<K, V> modifiedMap(final List<K> keys, final V[] objects) {
final Map<K, Integer> offsets = OffsetMapCache.unorderedOffsets(keys);
return new ImmutableOffsetMap.Unordered<>(offsets, OffsetMapCache.adjustedArray(offsets, keys, objects));
}
@Override
UnmodifiableMapPhase<K, V> unmodifiedMap(final Map<K, Integer> offsets, final V[] objects) {
return new ImmutableOffsetMap.Unordered<>(offsets, objects);
}
@Override
SharedSingletonMap<K, V> singletonMap() {
return SharedSingletonMap.unorderedCopyOf(this);
}
}
private static final Object[] EMPTY_ARRAY = new Object[0];
private static final Object REMOVED = new Object();
private final Map<K, Integer> offsets;
private HashMap<K, V> newKeys;
private Object[] objects;
private int removed = 0;
private transient volatile int modCount;
private boolean needClone = true;
MutableOffsetMap(final Map<K, Integer> offsets, final V[] objects, final HashMap<K, V> newKeys) {
Verify.verify(newKeys.isEmpty());
this.offsets = Preconditions.checkNotNull(offsets);
this.objects = Preconditions.checkNotNull(objects);
this.newKeys = Preconditions.checkNotNull(newKeys);
}
@SuppressWarnings("unchecked")
MutableOffsetMap(final HashMap<K, V> newKeys) {
this(ImmutableMap.of(), (V[]) EMPTY_ARRAY, newKeys);
}
@SuppressWarnings("unchecked")
MutableOffsetMap(final Map<K, Integer> offsets, final Map<K, V> source, final HashMap<K, V> newKeys) {
this(offsets, (V[]) new Object[offsets.size()], newKeys);
for (Entry<K, V> e : source.entrySet()) {
objects[offsets.get(e.getKey())] = Preconditions.checkNotNull(e.getValue());
}
this.needClone = false;
}
public static <K, V> MutableOffsetMap<K, V> orderedCopyOf(final Map<K, V> m) {
if (m instanceof Ordered) {
return ((Ordered<K, V>) m).clone();
}
if (m instanceof ImmutableOffsetMap) {
final ImmutableOffsetMap<K, V> om = (ImmutableOffsetMap<K, V>) m;
return new Ordered<>(om.offsets(), om.objects());
}
return new Ordered<>(m);
}
public static <K, V> MutableOffsetMap<K, V> unorderedCopyOf(final Map<K, V> m) {
if (m instanceof Unordered) {
return ((Unordered<K, V>) m).clone();
}
if (m instanceof ImmutableOffsetMap) {
final ImmutableOffsetMap<K, V> om = (ImmutableOffsetMap<K, V>) m;
return new Unordered<>(om.offsets(), om.objects());
}
return new Unordered<>(m);
}
public static <K, V> MutableOffsetMap<K, V> ordered() {
return new MutableOffsetMap.Ordered<>();
}
public static <K, V> MutableOffsetMap<K, V> unordered() {
return new MutableOffsetMap.Unordered<>();
}
abstract Object removedObject();
abstract UnmodifiableMapPhase<K, V> modifiedMap(List<K> keys, V[] objects);
abstract UnmodifiableMapPhase<K, V> unmodifiedMap(Map<K, Integer> offsets, V[] objects);
abstract SharedSingletonMap<K, V> singletonMap();
@Override
public final int size() {
return offsets.size() + newKeys.size() - removed;
}
@Override
public final boolean isEmpty() {
return size() == 0;
}
@Override
public final boolean containsKey(final Object key) {
final Integer offset = offsets.get(key);
if (offset != null) {
final Object obj = objects[offset];
if (!REMOVED.equals(obj)) {
return obj != null;
}
}
return newKeys.containsKey(key);
}
@Override
public final V get(final Object key) {
final Integer offset = offsets.get(key);
if (offset != null) {
final Object obj = objects[offset];
/*
* This is a bit tricky: Ordered will put REMOVED to removed objects to retain strict insertion order.
* Unordered will add null, indicating that the slot may be reused in future. Hence if we see a REMOVED
* marker, we need to fall back to checking with new keys.
*/
if (!REMOVED.equals(obj)) {
@SuppressWarnings("unchecked")
final V ret = (V)obj;
return ret;
}
}
return newKeys.get(key);
}
private void cloneArray() {
if (needClone) {
needClone = false;
if (!EMPTY_ARRAY.equals(objects)) {
objects = objects.clone();
}
}
}
@Override
public final V put(final K key, final V value) {
Preconditions.checkNotNull(value);
final Integer offset = offsets.get(Preconditions.checkNotNull(key));
if (offset != null) {
final Object obj = objects[offset];
/*
* Put which can potentially replace something in objects. Replacing an object does not cause iterators
* to be invalidated and does follow insertion order (since it is not a fresh insert). If the object has
* been removed, we fall back to newKeys.
*/
if (!REMOVED.equals(obj)) {
@SuppressWarnings("unchecked")
final V ret = (V)obj;
cloneArray();
objects[offset] = value;
if (ret == null) {
modCount++;
removed--;
}
return ret;
}
}
final V ret = newKeys.put(key, value);
if (ret == null) {
modCount++;
}
return ret;
}
@Override
public final V remove(final Object key) {
final Integer offset = offsets.get(key);
if (offset != null) {
final Object obj = objects[offset];
/*
* A previous remove() may have indicated that the objects slot cannot be reused. In that case we need
* to fall back to checking with newKeys.
*/
if (!REMOVED.equals(obj)) {
cloneArray();
@SuppressWarnings("unchecked")
final V ret = (V)obj;
objects[offset] = removedObject();
if (ret != null) {
modCount++;
removed++;
}
return ret;
}
}
final V ret = newKeys.remove(key);
if (ret != null) {
modCount++;
}
return ret;
}
@Override
public final void clear() {
if (size() != 0) {
newKeys.clear();
cloneArray();
Arrays.fill(objects, removedObject());
removed = objects.length;
modCount++;
}
}
@Nonnull
@Override
public final Set<Entry<K, V>> entrySet() {
return new EntrySet();
}
@Nonnull
@Override
public Map<K, V> toUnmodifiableMap() {
if (removed == 0 && newKeys.isEmpty()) {
// Make sure next modification clones the array, as we leak it to the map we return.
needClone = true;
// We have ended up with no removed objects, hence this cast is safe
@SuppressWarnings("unchecked")
final V[] values = (V[])objects;
/*
* TODO: we could track the ImmutableOffsetMap from which this one was instantiated and if we do not
* perform any modifications, just return the original instance. The trade-off is increased complexity
* and an additional field in this class.
*/
return unmodifiedMap(offsets, values);
}
final int s = size();
if (s == 0) {
return ImmutableMap.of();
}
if (s == 1) {
return singletonMap();
}
// Construct the set of keys
final List<K> keyset = new ArrayList<>(s);
if (removed != 0) {
if (removed != offsets.size()) {
for (Entry<K, Integer> e : offsets.entrySet()) {
final Object o = objects[e.getValue()];
if (o != null && !REMOVED.equals(o)) {
keyset.add(e.getKey());
}
}
}
} else {
keyset.addAll(offsets.keySet());
}
keyset.addAll(newKeys.keySet());
// Construct the values
@SuppressWarnings("unchecked")
final V[] values = (V[])new Object[keyset.size()];
int i = 0;
if (removed != 0) {
if (removed != offsets.size()) {
for (Entry<K, Integer> e : offsets.entrySet()) {
final Object o = objects[e.getValue()];
if (o != null && !REMOVED.equals(o)) {
@SuppressWarnings("unchecked")
final V v = (V) o;
values[i++] = v;
}
}
}
} else {
System.arraycopy(objects, 0, values, 0, offsets.size());
i = offsets.size();
}
for (V v : newKeys.values()) {
values[i++] = v;
}
return modifiedMap(keyset, values);
}
@SuppressWarnings("unchecked")
@Override
public MutableOffsetMap<K, V> clone() {
final MutableOffsetMap<K, V> ret;
try {
ret = (MutableOffsetMap<K, V>) super.clone();
} catch (CloneNotSupportedException e) {
throw new IllegalStateException("Clone is expected to work", e);
}
ret.newKeys = (HashMap<K, V>) newKeys.clone();
ret.needClone = true;
return ret;
}
@Override
public final int hashCode() {
int result = 0;
for (Entry<K, Integer> e : offsets.entrySet()) {
final Object v = objects[e.getValue()];
if (v != null) {
result += e.getKey().hashCode() ^ v.hashCode();
}
}
return result + newKeys.hashCode();
}
@Override
public final boolean equals(final Object o) {
if (o == this) {
return true;
}
if (!(o instanceof Map)) {
return false;
}
if (o instanceof ImmutableOffsetMap) {
final ImmutableOffsetMap<?, ?> om = (ImmutableOffsetMap<?, ?>) o;
if (newKeys.isEmpty() && offsets.equals(om.offsets())) {
return Arrays.deepEquals(objects, om.objects());
}
} else if (o instanceof MutableOffsetMap) {
final MutableOffsetMap<?, ?> om = (MutableOffsetMap<?, ?>) o;
if (offsets.equals(om.offsets)) {
return Arrays.deepEquals(objects, om.objects) && newKeys.equals(om.newKeys);
}
}
// Fall back to brute map compare
final Map<?, ?> other = (Map<?, ?>)o;
// Size and key sets have to match
if (size() != other.size() || !keySet().equals(other.keySet())) {
return false;
}
try {
// Ensure all newKeys are present. Note newKeys is guaranteed to
// not contain null value.
for (Entry<K, V> e : newKeys.entrySet()) {
if (!e.getValue().equals(other.get(e.getKey()))) {
return false;
}
}
// Ensure all objects are present
for (Entry<K, Integer> e : offsets.entrySet()) {
final Object obj = objects[e.getValue()];
if (obj != null && !REMOVED.equals(obj) && !obj.equals(other.get(e.getKey()))) {
return false;
}
}
} catch (ClassCastException e) {
// Can be thrown by other.get() and indicate we have incompatible key types
return false;
}
return true;
}
@Nonnull
@Override
public final Set<K> keySet() {
return new KeySet();
}
@VisibleForTesting
final boolean needClone() {
return needClone;
}
@VisibleForTesting
final Object array() {
return objects;
}
@VisibleForTesting
final Object newKeys() {
return newKeys;
}
private final class EntrySet extends AbstractSet<Entry<K, V>> {
@Nonnull
@Override
public Iterator<Entry<K, V>> iterator() {
return new AbstractSetIterator<Entry<K, V>>() {
@Override
public Entry<K, V> next() {
final K key = nextKey();
return new SimpleEntry<>(key, get(key));
}
};
}
@Override
public int size() {
return MutableOffsetMap.this.size();
}
@Override
public boolean contains(final Object o) {
if (!(o instanceof Entry)) {
return false;
}
@SuppressWarnings("unchecked")
final Entry<K,V> e = (Entry<K,V>) o;
if (e.getValue() == null) {
return false;
}
return e.getValue().equals(MutableOffsetMap.this.get(e.getKey()));
}
@Override
public boolean add(final Entry<K, V> e) {
Preconditions.checkNotNull(e.getValue());
final V p = MutableOffsetMap.this.put(e.getKey(), e.getValue());
return !e.getValue().equals(p);
}
@Override
public boolean remove(final Object o) {
if (!(o instanceof Entry)) {
return false;
}
@SuppressWarnings("unchecked")
final Entry<K,V> e = (Entry<K,V>) o;
if (e.getValue() == null) {
return false;
}
final V v = MutableOffsetMap.this.get(e.getKey());
if (e.getValue().equals(v)) {
MutableOffsetMap.this.remove(e.getKey());
return true;
}
return false;
}
@Override
public void clear() {
MutableOffsetMap.this.clear();
}
}
private final class KeySet extends AbstractSet<K> {
@Nonnull
@Override
public Iterator<K> iterator() {
return new AbstractSetIterator<K>() {
@Override
public K next() {
return nextKey();
}
};
}
@Override
public int size() {
return MutableOffsetMap.this.size();
}
}
private abstract class AbstractSetIterator<E> implements Iterator<E> {
private final Iterator<Entry<K, Integer>> oldIterator = offsets.entrySet().iterator();
private final Iterator<K> newIterator = newKeys.keySet().iterator();
private int expectedModCount = modCount;
private K currentKey;
private K nextKey;
AbstractSetIterator() {
updateNextKey();
}
private void updateNextKey() {
while (oldIterator.hasNext()) {
final Entry<K, Integer> e = oldIterator.next();
final Object obj = objects[e.getValue()];
if (obj != null && !REMOVED.equals(obj)) {
nextKey = e.getKey();
return;
}
}
nextKey = newIterator.hasNext() ? newIterator.next() : null;
}
private void checkModCount() {
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
@Override
public final boolean hasNext() {
checkModCount();
return nextKey != null;
}
@Override
public final void remove() {
Preconditions.checkState(currentKey != null);
checkModCount();
final Integer offset = offsets.get(currentKey);
if (offset != null) {
cloneArray();
objects[offset] = removedObject();
removed++;
} else {
newIterator.remove();
}
expectedModCount = ++modCount;
currentKey = null;
}
protected final K nextKey() {
if (nextKey == null) {
throw new NoSuchElementException();
}
checkModCount();
currentKey = nextKey;
updateNextKey();
return currentKey;
}
}
}