2 * (C) Copyright 2016 Pantheon Technologies, s.r.o. and others.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 package org.opendaylight.yangtools.triemap;
18 import static com.google.common.base.Preconditions.checkNotNull;
19 import static org.opendaylight.yangtools.triemap.LookupResult.RESTART;
21 import com.google.common.annotations.Beta;
22 import java.io.ObjectStreamException;
23 import java.io.Serializable;
24 import java.util.AbstractMap;
25 import java.util.Iterator;
26 import java.util.Optional;
28 import java.util.concurrent.ConcurrentMap;
31 * This is a port of Scala's TrieMap class from the Scala Collections library. This implementation does not support
32 * null keys nor null values.
34 * @author Aleksandar Prokopec (original Scala implementation)
35 * @author Roman Levenstein (original Java 6 port)
36 * @author Robert Varga
38 * @param <K> the type of keys maintained by this map
39 * @param <V> the type of mapped values
42 public abstract class TrieMap<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K,V>, Serializable {
43 private static final long serialVersionUID = 1L;
48 private final EntrySet<K, V> entrySet = new EntrySet<>(this);
49 private final Equivalence<? super K> equiv;
51 TrieMap(final Equivalence<? super K> equiv) {
55 public static <K, V> TrieMap<K, V> create() {
56 return new MutableTrieMap<>(Equivalence.equals());
60 * Returns a snapshot of this TrieMap. This operation is lock-free and
63 * The snapshot is lazily updated - the first time some branch in the
64 * snapshot or this TrieMap are accessed, they are rewritten. This means
65 * that the work of rebuilding both the snapshot and this TrieMap is
66 * distributed across all the threads doing updates or accesses subsequent
67 * to the snapshot creation.
69 public abstract TrieMap<K, V> mutableSnapshot();
72 * Returns a read-only snapshot of this TrieMap. This operation is lock-free
75 * The snapshot is lazily updated - the first time some branch of this
76 * TrieMap are accessed, it is rewritten. The work of creating the snapshot
77 * is thus distributed across subsequent updates and accesses on this
78 * TrieMap by all threads. Note that the snapshot itself is never rewritten
79 * unlike when calling the `snapshot` method, but the obtained snapshot
82 * This method is used by other methods such as `size` and `iterator`.
84 public abstract ImmutableTrieMap<K, V> immutableSnapshot();
87 public final boolean containsKey(final Object key) {
88 return get(key) != null;
92 public final boolean containsValue(final Object value) {
93 return super.containsValue(checkNotNull(value));
97 public final Set<Entry<K, V>> entrySet() {
102 public final V get(final Object key) {
103 @SuppressWarnings("unchecked")
104 final K k = (K) checkNotNull(key);
105 return lookuphc(k, computeHash(k));
109 public abstract void clear();
112 public abstract V put(K key, V value);
115 public abstract V putIfAbsent(K key, V value);
118 public abstract V remove(Object key);
121 public abstract boolean remove(Object key, Object value);
124 public abstract boolean replace(K key, V oldValue, V newValue);
127 public abstract V replace(K key, V value);
130 public abstract int size();
132 /* internal methods implemented by subclasses */
134 abstract boolean isReadOnly();
136 abstract INode<K, V> RDCSS_READ_ROOT(boolean abort);
138 /* internal methods provided for subclasses */
140 @SuppressWarnings("null")
141 static <V> V toNullable(final Optional<V> opt) {
142 return opt.orElse(null);
145 final int computeHash(final K k) {
146 return equiv.hash(k);
149 final Object writeReplace() throws ObjectStreamException {
150 return new SerializationProxy(immutableSnapshot(), isReadOnly());
153 /* package-protected utility methods */
155 final Equivalence<? super K> equiv() {
159 final INode<K, V> readRoot() {
160 return RDCSS_READ_ROOT(false);
163 // FIXME: abort = false by default
164 final INode<K, V> readRoot(final boolean abort) {
165 return RDCSS_READ_ROOT(abort);
168 final INode<K, V> RDCSS_READ_ROOT() {
169 return RDCSS_READ_ROOT(false);
172 final boolean equal(final K k1, final K k2) {
173 return equiv.equivalent(k1, k2);
176 /* private implementation methods */
178 @SuppressWarnings("unchecked")
179 private V lookuphc(final K k, final int hc) {
182 // Keep looping as long as RESTART is being indicated
183 res = RDCSS_READ_ROOT().rec_lookup(k, hc, 0, null, this);
184 } while (res == RESTART);
190 * Return an iterator over a TrieMap.
192 * If this is a read-only snapshot, it would return a read-only iterator.
194 * If it is the original TrieMap or a non-readonly snapshot, it would return
195 * an iterator that would allow for updates.
199 final Iterator<Entry<K, V>> iterator() {
200 // FIXME: it would be nice to have a ReadWriteTrieMap with read-only iterator
201 return isReadOnly() ? new TrieMapReadOnlyIterator<>(0, this) : new TrieMapIterator<>(0, this);
205 * Return an iterator over a TrieMap.
206 * This is a read-only iterator.
210 final Iterator<Entry<K, V>> readOnlyIterator() {
211 return new TrieMapReadOnlyIterator<>(0, immutableSnapshot());