import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static org.opendaylight.yangtools.triemap.LookupResult.RESTART;
-import static org.opendaylight.yangtools.triemap.PresencePredicate.ABSENT;
-import static org.opendaylight.yangtools.triemap.PresencePredicate.PRESENT;
-import com.google.common.base.Verify;
-import com.google.common.collect.Iterators;
+import com.google.common.annotations.Beta;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
/***
* This is a port of Scala's TrieMap class from the Scala Collections library. This implementation does not support
* null keys nor null values.
*
- * @author Roman Levenstein <romixlev@gmail.com>
+ * @author Aleksandar Prokopec (original Scala implementation)
+ * @author Roman Levenstein (original Java 6 port)
+ * @author Robert Varga
*
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
*/
-public final class TrieMap<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K,V>, Serializable {
- @SuppressWarnings("rawtypes")
- private static final AtomicReferenceFieldUpdater<TrieMap, Object> ROOT_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(TrieMap.class, Object.class, "root");
+@Beta
+public abstract class TrieMap<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K,V>, Serializable {
private static final long serialVersionUID = 1L;
/**
*/
private final EntrySet entrySet = new EntrySet();
private final Equivalence<? super K> equiv;
- private final boolean readOnly;
-
- private volatile Object root;
-
- private TrieMap(final INode<K, V> r, final Equivalence<? super K> equiv, final boolean readOnly) {
- this.root = r;
- this.equiv = equiv;
- this.readOnly = readOnly;
- }
TrieMap(final Equivalence<? super K> equiv) {
- this(newRootNode(), equiv, false);
- }
-
- public TrieMap() {
- this(Equivalence.equals());
- }
-
- /* internal methods */
-
- final Equivalence<? super K> equiv() {
- return equiv;
- }
-
- private static <K,V> INode<K, V> newRootNode() {
- final Gen gen = new Gen();
- return new INode<>(gen, new CNode<>(gen));
- }
-
- private boolean CAS_ROOT(final Object ov, final Object nv) {
- checkState(!readOnly, "Attempted to modify a read-only snapshot");
- return ROOT_UPDATER.compareAndSet(this, ov, nv);
- }
-
- final INode<K, V> readRoot() {
- return RDCSS_READ_ROOT(false);
- }
-
- // FIXME: abort = false by default
- final INode<K, V> readRoot(final boolean abort) {
- return RDCSS_READ_ROOT(abort);
- }
-
- private final INode<K, V> RDCSS_READ_ROOT() {
- return RDCSS_READ_ROOT(false);
- }
-
- private final INode<K, V> RDCSS_READ_ROOT(final boolean abort) {
- final Object r = /* READ */ root;
- if (r instanceof INode) {
- return (INode<K, V>) r;
- }
-
- checkState(r instanceof RDCSS_Descriptor, "Unhandled root %s", r);
- return RDCSS_Complete(abort);
- }
-
- private INode<K, V> RDCSS_Complete(final boolean abort) {
- while (true) {
- final Object r = /* READ */ root;
- if (r instanceof INode) {
- return (INode<K, V>) r;
- }
-
- checkState(r instanceof RDCSS_Descriptor, "Unhandled root %s", r);
- @SuppressWarnings("unchecked")
- final RDCSS_Descriptor<K, V> desc = (RDCSS_Descriptor<K, V>) r;
- final INode<K, V> ov = desc.old;
- final MainNode<K, V> exp = desc.expectedmain;
- final INode<K, V> nv = desc.nv;
-
- if (abort) {
- if (CAS_ROOT(desc, ov)) {
- return ov;
- }
-
- // Tail recursion: return RDCSS_Complete(abort);
- continue;
- }
-
- final MainNode<K, V> oldmain = ov.gcasRead(this);
- if (oldmain == exp) {
- if (CAS_ROOT(desc, nv)) {
- desc.committed = true;
- return nv;
- }
-
- // Tail recursion: return RDCSS_Complete(abort);
- continue;
- }
-
- if (CAS_ROOT(desc, ov)) {
- return ov;
- }
-
- // Tail recursion: return RDCSS_Complete(abort);
- }
- }
-
- private boolean RDCSS_ROOT(final INode<K, V> ov, final MainNode<K, V> expectedmain, final INode<K, V> nv) {
- final RDCSS_Descriptor<K, V> desc = new RDCSS_Descriptor<> (ov, expectedmain, nv);
- if (CAS_ROOT(ov, desc)) {
- RDCSS_Complete(false);
- return /* READ */desc.committed;
- }
-
- return false;
- }
-
- private void inserthc(final K k, final int hc, final V v) {
- // TODO: this is called from serialization only, which means we should not be observing any races,
- // hence we should not need to pass down the entire tree, just equality (I think).
- final boolean success = RDCSS_READ_ROOT().rec_insert(k, v, hc, 0, null, this);
- Verify.verify(success, "Concurrent modification during serialization of map %s", this);
- }
-
- void add(final K key, final V value) {
- final K k = checkNotNull(key);
- inserthc(k, computeHash(k), checkNotNull(value));
- }
-
- private Optional<V> insertifhc(final K k, final int hc, final V v, final Object cond) {
- Optional<V> res;
- do {
- // Keep looping as long as we do not get a reply
- res = RDCSS_READ_ROOT().rec_insertif(k, v, hc, cond, 0, null, this);
- } while (res == null);
-
- return res;
- }
-
- @SuppressWarnings("unchecked")
- private V lookuphc(final K k, final int hc) {
- Object res;
- do {
- // Keep looping as long as RESTART is being indicated
- res = RDCSS_READ_ROOT().rec_lookup(k, hc, 0, null, this);
- } while (res == RESTART);
-
- return (V) res;
- }
-
- private Optional<V> removehc(final K k, final Object cond, final int hc) {
- Optional<V> res;
- do {
- // Keep looping as long as we do not get a reply
- res = RDCSS_READ_ROOT().rec_remove(k, cond, hc, 0, null, this);
- } while (res == null);
-
- return res;
- }
-
- /**
- * Ensure this instance is read-write, throw UnsupportedOperationException
- * otherwise. Used by Map-type methods for quick check.
- */
- private void ensureReadWrite() {
- if (readOnly) {
- throw new UnsupportedOperationException("Attempted to modify a read-only view");
- }
+ this.equiv = equiv;
}
- boolean isReadOnly() {
- return readOnly;
+ public static <K, V> TrieMap<K, V> create() {
+ return new MutableTrieMap<>(Equivalence.equals());
}
- /* public methods */
-
/**
* Returns a snapshot of this TrieMap. This operation is lock-free and
* linearizable.
* distributed across all the threads doing updates or accesses subsequent
* to the snapshot creation.
*/
- public TrieMap<K, V> snapshot() {
- while (true) {
- final INode<K, V> r = RDCSS_READ_ROOT();
- final MainNode<K, V> expmain = r.gcasRead(this);
- if (RDCSS_ROOT(r, expmain, r.copyToGen(new Gen(), this))) {
- return new TrieMap<> (r.copyToGen(new Gen(), this), equiv, readOnly);
- }
-
- // Tail recursion: return snapshot();
- }
- }
+ public abstract TrieMap<K, V> mutableSnapshot();
/**
* Returns a read-only snapshot of this TrieMap. This operation is lock-free
*
* This method is used by other methods such as `size` and `iterator`.
*/
- public TrieMap<K, V> readOnlySnapshot() {
- // Is it a snapshot of a read-only snapshot?
- if (readOnly) {
- return this;
- }
-
- while (true) {
- final INode<K, V> r = RDCSS_READ_ROOT();
- final MainNode<K, V> expmain = r.gcasRead(this);
- if (RDCSS_ROOT(r, expmain, r.copyToGen (new Gen(), this))) {
- return new TrieMap<>(r, equiv, true);
- }
-
- // Tail recursion: return readOnlySnapshot();
- }
- }
+ public abstract ImmutableTrieMap<K, V> immutableSnapshot();
@Override
- public void clear() {
- boolean success;
- do {
- final INode<K, V> r = RDCSS_READ_ROOT();
- success = RDCSS_ROOT(r, r.gcasRead(this), newRootNode());
- } while (!success);
+ public final boolean containsKey(final Object key) {
+ return get(key) != null;
}
- int computeHash(final K k) {
- return equiv.hash(k);
+ @Override
+ public final boolean containsValue(final Object value) {
+ return super.containsValue(checkNotNull(value));
}
- boolean equal(final K k1, final K k2) {
- return equiv.equivalent(k1, k2);
+ @Override
+ public final Set<Entry<K, V>> entrySet() {
+ return entrySet;
}
@Override
- public V get(final Object key) {
+ public final V get(final Object key) {
@SuppressWarnings("unchecked")
final K k = (K) checkNotNull(key);
return lookuphc(k, computeHash(k));
}
+ @Override
+ public abstract void clear();
+
+ @Override
+ public abstract V put(K key, V value);
+
+ @Override
+ public abstract V putIfAbsent(K key, V value);
+
+ @Override
+ public abstract V remove(Object key);
+
+ @Override
+ public abstract boolean remove(Object key, Object value);
+
+ @Override
+ public abstract boolean replace(K key, V oldValue, V newValue);
+
+ @Override
+ public abstract V replace(K key, V value);
+
+ @Override
+ public abstract int size();
+
+ /* internal methods implemented by subclasses */
+
+ abstract boolean isReadOnly();
+
+ abstract INode<K, V> RDCSS_READ_ROOT(boolean abort);
+
+ /* internal methods provided for subclasses */
+
@SuppressWarnings("null")
- private static <V> V toNullable(final Optional<V> opt) {
+ static <V> V toNullable(final Optional<V> opt) {
return opt.orElse(null);
}
- @Override
- public V put(final K key, final V value) {
- ensureReadWrite();
- final K k = checkNotNull(key);
- return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), null));
+ final int computeHash(final K k) {
+ return equiv.hash(k);
}
- @Override
- public V remove(final Object key) {
- ensureReadWrite();
- @SuppressWarnings("unchecked")
- final K k = (K) checkNotNull(key);
- return toNullable(removehc(k, null, computeHash(k)));
+ final Object writeReplace() throws ObjectStreamException {
+ return new SerializationProxy(immutableSnapshot(), isReadOnly());
}
- @Override
- public V putIfAbsent(final K key, final V value) {
- ensureReadWrite();
- final K k = checkNotNull(key);
- return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), ABSENT));
+ /* package-protected utility methods */
+
+ final Equivalence<? super K> equiv() {
+ return equiv;
}
- @Override
- public boolean remove(final Object key, final Object v) {
- ensureReadWrite();
- @SuppressWarnings("unchecked")
- final K k = (K) checkNotNull(key);
- return removehc(k, checkNotNull(v), computeHash(k)).isPresent();
+ final INode<K, V> readRoot() {
+ return RDCSS_READ_ROOT(false);
}
- @Override
- public boolean replace(final K key, final V oldValue, final V newValue) {
- ensureReadWrite();
- final K k = checkNotNull(key);
- return insertifhc(k, computeHash(k), checkNotNull(newValue), checkNotNull(oldValue)).isPresent();
+ // FIXME: abort = false by default
+ final INode<K, V> readRoot(final boolean abort) {
+ return RDCSS_READ_ROOT(abort);
}
- @Override
- public V replace(final K key, final V value) {
- ensureReadWrite();
- final K k = checkNotNull(key);
- return toNullable(insertifhc(k, computeHash(k), checkNotNull(value), PRESENT));
+ final INode<K, V> RDCSS_READ_ROOT() {
+ return RDCSS_READ_ROOT(false);
}
- /***
+ final boolean equal(final K k1, final K k2) {
+ return equiv.equivalent(k1, k2);
+ }
+
+ /* private implementation methods */
+
+ @SuppressWarnings("unchecked")
+ private V lookuphc(final K k, final int hc) {
+ Object res;
+ do {
+ // Keep looping as long as RESTART is being indicated
+ res = RDCSS_READ_ROOT().rec_lookup(k, hc, 0, null, this);
+ } while (res == RESTART);
+
+ return (V) res;
+ }
+
+ /**
* Return an iterator over a TrieMap.
*
* If this is a read-only snapshot, it would return a read-only iterator.
* @return
*/
Iterator<Entry<K, V>> iterator() {
- return readOnly ? new TrieMapReadOnlyIterator<>(0, this) : new TrieMapIterator<>(0, this);
+ // FIXME: it would be nice to have a ReadWriteTrieMap with read-only iterator
+ return isReadOnly() ? new TrieMapReadOnlyIterator<>(0, this) : new TrieMapIterator<>(0, this);
}
- /***
+ /**
* Return an iterator over a TrieMap.
* This is a read-only iterator.
*
* @return
*/
- Iterator<Entry<K, V>> readOnlyIterator() {
- return new TrieMapReadOnlyIterator<>(0, readOnly ? this : readOnlySnapshot());
- }
-
- private int cachedSize() {
- return RDCSS_READ_ROOT().cachedSize (this);
- }
-
- @Override
- public int size() {
- return readOnly ? cachedSize() : readOnlySnapshot().size();
- }
-
- @Override
- public boolean containsKey(final Object key) {
- return get(key) != null;
- }
-
- @Override
- public Set<Entry<K, V>> entrySet() {
- return entrySet;
+ final Iterator<Entry<K, V>> readOnlyIterator() {
+ return new TrieMapReadOnlyIterator<>(0, immutableSnapshot());
}
- private Object writeReplace() throws ObjectStreamException {
- return new ExternalForm(this);
- }
-
- private static final class RDCSS_Descriptor<K, V> {
- INode<K, V> old;
- MainNode<K, V> expectedmain;
- INode<K, V> nv;
- volatile boolean committed = false;
-
- RDCSS_Descriptor (final INode<K, V> old, final MainNode<K, V> expectedmain, final INode<K, V> nv) {
- this.old = old;
- this.expectedmain = expectedmain;
- this.nv = nv;
- }
- }
-
- /***
+ /**
* This iterator is a read-only one and does not allow for any update
* operations on the underlying data structure.
*
@Override
public final int size () {
- return Iterators.size(iterator());
+ return TrieMap.this.size();
}
@Override
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