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;
45 private final Equivalence<? super K> equiv;
47 private AbstractEntrySet<K, V> entrySet;
49 TrieMap(final Equivalence<? super K> equiv) {
53 public static <K, V> TrieMap<K, V> create() {
54 return new MutableTrieMap<>(Equivalence.equals());
58 * Returns a snapshot of this TrieMap. This operation is lock-free and
61 * The snapshot is lazily updated - the first time some branch in the
62 * snapshot or this TrieMap are accessed, they are rewritten. This means
63 * that the work of rebuilding both the snapshot and this TrieMap is
64 * distributed across all the threads doing updates or accesses subsequent
65 * to the snapshot creation.
67 public abstract TrieMap<K, V> mutableSnapshot();
70 * Returns a read-only snapshot of this TrieMap. This operation is lock-free
73 * The snapshot is lazily updated - the first time some branch of this
74 * TrieMap are accessed, it is rewritten. The work of creating the snapshot
75 * is thus distributed across subsequent updates and accesses on this
76 * TrieMap by all threads. Note that the snapshot itself is never rewritten
77 * unlike when calling the `snapshot` method, but the obtained snapshot
80 * This method is used by other methods such as `size` and `iterator`.
82 public abstract ImmutableTrieMap<K, V> immutableSnapshot();
85 public final boolean containsKey(final Object key) {
86 return get(key) != null;
90 public final boolean containsValue(final Object value) {
91 return super.containsValue(checkNotNull(value));
95 public final Set<Entry<K, V>> entrySet() {
96 AbstractEntrySet<K, V> ret = entrySet;
98 entrySet = ret = createEntrySet();
104 public final V get(final Object key) {
105 @SuppressWarnings("unchecked")
106 final K k = (K) checkNotNull(key);
107 return lookuphc(k, computeHash(k));
111 public abstract void clear();
114 public abstract V put(K key, V value);
117 public abstract V putIfAbsent(K key, V value);
120 public abstract V remove(Object key);
123 public abstract boolean remove(Object key, Object value);
126 public abstract boolean replace(K key, V oldValue, V newValue);
129 public abstract V replace(K key, V value);
132 public abstract int size();
134 /* internal methods implemented by subclasses */
136 abstract AbstractEntrySet<K, V> createEntrySet();
138 abstract boolean isReadOnly();
140 abstract INode<K, V> RDCSS_READ_ROOT(boolean abort);
143 * Return an iterator over a TrieMap.
145 * If this is a read-only snapshot, it would return a read-only iterator.
147 * If it is the original TrieMap or a non-readonly snapshot, it would return
148 * an iterator that would allow for updates.
152 abstract Iterator<Entry<K, V>> iterator();
154 /* internal methods provided for subclasses */
157 * Return an iterator over a TrieMap.
158 * This is a read-only iterator.
162 final Iterator<Entry<K, V>> immutableIterator() {
163 return new TrieMapReadOnlyIterator<>(0, immutableSnapshot());
166 @SuppressWarnings("null")
167 static <V> V toNullable(final Optional<V> opt) {
168 return opt.orElse(null);
171 final int computeHash(final K k) {
172 return equiv.hash(k);
175 final Object writeReplace() throws ObjectStreamException {
176 return new SerializationProxy(immutableSnapshot(), isReadOnly());
179 /* package-protected utility methods */
181 final Equivalence<? super K> equiv() {
185 final INode<K, V> readRoot() {
186 return RDCSS_READ_ROOT(false);
189 // FIXME: abort = false by default
190 final INode<K, V> readRoot(final boolean abort) {
191 return RDCSS_READ_ROOT(abort);
194 final INode<K, V> RDCSS_READ_ROOT() {
195 return RDCSS_READ_ROOT(false);
198 final boolean equal(final K k1, final K k2) {
199 return equiv.equivalent(k1, k2);
202 /* private implementation methods */
204 @SuppressWarnings("unchecked")
205 private V lookuphc(final K k, final int hc) {
208 // Keep looping as long as RESTART is being indicated
209 res = RDCSS_READ_ROOT().rec_lookup(k, hc, 0, null, this);
210 } while (res == RESTART);