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 com.google.common.base.Preconditions.checkState;
20 import static org.opendaylight.yangtools.triemap.PresencePredicate.ABSENT;
21 import static org.opendaylight.yangtools.triemap.PresencePredicate.PRESENT;
23 import com.google.common.annotations.Beta;
24 import com.google.common.base.Verify;
25 import java.util.Optional;
26 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
31 * @author Robert Varga
33 * @param <K> the type of keys maintained by this map
34 * @param <V> the type of mapped values
37 final class MutableTrieMap<K, V> extends TrieMap<K, V> {
38 @SuppressWarnings("rawtypes")
39 private static final AtomicReferenceFieldUpdater<MutableTrieMap, Object> ROOT_UPDATER =
40 AtomicReferenceFieldUpdater.newUpdater(MutableTrieMap.class, Object.class, "root");
42 private volatile Object root;
44 MutableTrieMap(final Equivalence<? super K> equiv) {
45 this(equiv, newRootNode());
48 MutableTrieMap(final Equivalence<? super K> equiv, final INode<K, V> root) {
50 this.root = checkNotNull(root);
57 final INode<K, V> r = RDCSS_READ_ROOT();
58 success = RDCSS_ROOT(r, r.gcasRead(this), newRootNode());
63 public V put(final K key, final V value) {
64 final K k = checkNotNull(key);
65 return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), null));
69 public V putIfAbsent(final K key, final V value) {
70 final K k = checkNotNull(key);
71 return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), ABSENT));
75 public V remove(final Object key) {
76 @SuppressWarnings("unchecked")
77 final K k = (K) checkNotNull(key);
78 return toNullable(removehc(k, null, computeHash(k)));
82 public boolean remove(final Object key, final Object value) {
83 @SuppressWarnings("unchecked")
84 final K k = (K) checkNotNull(key);
85 return removehc(k, checkNotNull(value), computeHash(k)).isPresent();
89 public boolean replace(final K key, final V oldValue, final V newValue) {
90 final K k = checkNotNull(key);
91 return insertifhc(k, computeHash(k), checkNotNull(newValue), checkNotNull(oldValue)).isPresent();
95 public V replace(final K key, final V value) {
96 final K k = checkNotNull(key);
97 return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), PRESENT));
102 return immutableSnapshot().size();
106 public ImmutableTrieMap<K, V> immutableSnapshot() {
108 final INode<K, V> r = RDCSS_READ_ROOT();
109 final MainNode<K, V> expmain = r.gcasRead(this);
110 if (RDCSS_ROOT(r, expmain, r.copyToGen (new Gen(), this))) {
111 return new ImmutableTrieMap<>(r, equiv());
114 // Tail recursion: return readOnlySnapshot();
119 public MutableTrieMap<K, V> mutableSnapshot() {
121 final INode<K, V> r = RDCSS_READ_ROOT();
122 final MainNode<K, V> expmain = r.gcasRead(this);
123 if (RDCSS_ROOT(r, expmain, r.copyToGen(new Gen(), this))) {
124 return new MutableTrieMap<>(equiv(), r.copyToGen(new Gen(), this));
127 // Tail recursion: return snapshot();
132 boolean isReadOnly() {
137 INode<K, V> RDCSS_READ_ROOT(final boolean abort) {
138 final Object r = /* READ */ root;
139 if (r instanceof INode) {
140 return (INode<K, V>) r;
143 checkState(r instanceof RDCSS_Descriptor, "Unhandled root %s", r);
144 return RDCSS_Complete(abort);
147 void add(final K key, final V value) {
148 final K k = checkNotNull(key);
149 inserthc(k, computeHash(k), checkNotNull(value));
152 private static <K,V> INode<K, V> newRootNode() {
153 final Gen gen = new Gen();
154 return new INode<>(gen, new CNode<>(gen));
157 private void inserthc(final K k, final int hc, final V v) {
158 // TODO: this is called from serialization only, which means we should not be observing any races,
159 // hence we should not need to pass down the entire tree, just equality (I think).
160 final boolean success = RDCSS_READ_ROOT().rec_insert(k, v, hc, 0, null, this);
161 Verify.verify(success, "Concurrent modification during serialization of map %s", this);
164 private Optional<V> insertifhc(final K k, final int hc, final V v, final Object cond) {
167 // Keep looping as long as we do not get a reply
168 res = RDCSS_READ_ROOT().rec_insertif(k, v, hc, cond, 0, null, this);
169 } while (res == null);
174 private Optional<V> removehc(final K k, final Object cond, final int hc) {
177 // Keep looping as long as we do not get a reply
178 res = RDCSS_READ_ROOT().rec_remove(k, cond, hc, 0, null, this);
179 } while (res == null);
184 private boolean CAS_ROOT(final Object ov, final Object nv) {
185 return ROOT_UPDATER.compareAndSet(this, ov, nv);
188 private boolean RDCSS_ROOT(final INode<K, V> ov, final MainNode<K, V> expectedmain, final INode<K, V> nv) {
189 final RDCSS_Descriptor<K, V> desc = new RDCSS_Descriptor<> (ov, expectedmain, nv);
190 if (CAS_ROOT(ov, desc)) {
191 RDCSS_Complete(false);
192 return /* READ */desc.committed;
198 private INode<K, V> RDCSS_Complete(final boolean abort) {
200 final Object r = /* READ */ root;
201 if (r instanceof INode) {
202 return (INode<K, V>) r;
205 checkState(r instanceof RDCSS_Descriptor, "Unhandled root %s", r);
206 @SuppressWarnings("unchecked")
207 final RDCSS_Descriptor<K, V> desc = (RDCSS_Descriptor<K, V>) r;
208 final INode<K, V> ov = desc.old;
209 final MainNode<K, V> exp = desc.expectedmain;
210 final INode<K, V> nv = desc.nv;
213 if (CAS_ROOT(desc, ov)) {
217 // Tail recursion: return RDCSS_Complete(abort);
221 final MainNode<K, V> oldmain = ov.gcasRead(this);
222 if (oldmain == exp) {
223 if (CAS_ROOT(desc, nv)) {
224 desc.committed = true;
228 // Tail recursion: return RDCSS_Complete(abort);
232 if (CAS_ROOT(desc, ov)) {
236 // Tail recursion: return RDCSS_Complete(abort);
240 private static final class RDCSS_Descriptor<K, V> {
241 final INode<K, V> old;
242 final MainNode<K, V> expectedmain;
243 final INode<K, V> nv;
245 volatile boolean committed = false;
247 RDCSS_Descriptor (final INode<K, V> old, final MainNode<K, V> expectedmain, final INode<K, V> nv) {
249 this.expectedmain = expectedmain;