/*
* (C) Copyright 2016 Pantheon Technologies, s.r.o. and others.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.opendaylight.yangtools.triemap;
import static org.opendaylight.yangtools.triemap.Constants.LEVEL_BITS;
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.VerifyException;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.util.Optional;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
final class INode<K, V> extends BasicNode {
@SuppressWarnings("rawtypes")
private static final AtomicReferenceFieldUpdater<INode, MainNode> MAINNODE_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(INode.class, MainNode.class, "mainnode");
private final Gen gen;
private volatile MainNode<K, V> mainnode;
INode(final Gen gen, final MainNode<K, V> mainnode) {
this.gen = gen;
this.mainnode = mainnode;
}
MainNode<K, V> gcasRead(final TrieMap<?, ?> ct) {
return GCAS_READ(ct);
}
private MainNode<K, V> GCAS_READ(final TrieMap<?, ?> ct) {
MainNode<K, V> m = /* READ */ mainnode;
MainNode<K, V> prevval = /* READ */ m.READ_PREV();
if (prevval == null) {
return m;
}
return GCAS_Complete(m, ct);
}
private MainNode<K, V> GCAS_Complete(final MainNode<K, V> oldmain, final TrieMap<?, ?> ct) {
MainNode<K, V> m = oldmain;
while (m != null) {
// complete the GCAS
final MainNode<K, V> prev = /* READ */ m.READ_PREV();
final INode<?, ?> ctr = ct.readRoot(true);
if (prev == null) {
return m;
}
if (prev instanceof FailedNode) {
// try to commit to previous value
FailedNode<K, V> fn = (FailedNode<K, V>) prev;
if (MAINNODE_UPDATER.compareAndSet(this, m, fn.READ_PREV())) {
return fn.READ_PREV();
}
// Tail recursion: return GCAS_Complete(/* READ */ mainnode, ct);
m = /* READ */ mainnode;
continue;
}
// Assume that you've read the root from the generation G.
// Assume that the snapshot algorithm is correct.
// ==> you can only reach nodes in generations <= G.
// ==> `gen` is <= G.
// We know that `ctr.gen` is >= G.
// ==> if `ctr.gen` = `gen` then they are both equal to G.
// ==> otherwise, we know that either `ctr.gen` > G, `gen` < G,
// or both
if (ctr.gen == gen && !ct.isReadOnly()) {
// try to commit
if (m.CAS_PREV(prev, null)) {
return m;
}
// Tail recursion: return GCAS_Complete(m, ct);
continue;
}
// try to abort
m.CAS_PREV(prev, new FailedNode<>(prev));
// Tail recursion: return GCAS_Complete(/* READ */ mainnode, ct);
m = /* READ */ mainnode;
}
return null;
}
private boolean GCAS(final MainNode<K, V> old, final MainNode<K, V> n, final TrieMap<?, ?> ct) {
n.WRITE_PREV(old);
if (MAINNODE_UPDATER.compareAndSet(this, old, n)) {
GCAS_Complete(n, ct);
return /* READ */ n.READ_PREV() == null;
}
return false;
}
private INode<K, V> inode(final MainNode<K, V> cn) {
return new INode<>(gen, cn);
}
INode<K, V> copyToGen(final Gen ngen, final TrieMap<?, ?> ct) {
return new INode<>(ngen, GCAS_READ(ct));
}
/**
* Inserts a key value pair, overwriting the old pair if the keys match.
*
* @return true if successful, false otherwise
*/
boolean rec_insert(final K key, final V value, final int hc, final int lev, final INode<K, V> parent,
final TrieMap<K, V> ct) {
return rec_insert(key, value, hc, lev, parent, gen, ct);
}
private boolean rec_insert(final K k, final V v, final int hc, final int lev, final INode<K, V> parent,
final Gen startgen, final TrieMap<K, V> ct) {
while (true) {
final MainNode<K, V> m = GCAS_READ(ct); // use -Yinline!
if (m instanceof CNode) {
// 1) a multiway node
final CNode<K, V> cn = (CNode<K, V>) m;
final int idx = (hc >>> lev) & 0x1f;
final int flag = 1 << idx;
final int bmp = cn.bitmap;
final int mask = flag - 1;
final int pos = Integer.bitCount(bmp & mask);
if ((bmp & flag) != 0) {
// 1a) insert below
final BasicNode cnAtPos = cn.array[pos];
if (cnAtPos instanceof INode) {
final INode<K, V> in = (INode<K, V>) cnAtPos;
if (startgen == in.gen) {
return in.rec_insert(k, v, hc, lev + LEVEL_BITS, this, startgen, ct);
}
if (GCAS(cn, cn.renewed(startgen, ct), ct)) {
// Tail recursion: return rec_insert(k, v, hc, lev, parent, startgen, ct);
continue;
}
return false;
} else if (cnAtPos instanceof SNode) {
final SNode<K, V> sn = (SNode<K, V>) cnAtPos;
if (sn.hc == hc && ct.equal(sn.k, k)) {
return GCAS(cn, cn.updatedAt(pos, new SNode<>(k, v, hc), gen), ct);
}
final CNode<K, V> rn = (cn.gen == gen) ? cn : cn.renewed(gen, ct);
final MainNode<K, V> nn = rn.updatedAt(pos, inode(
CNode.dual(sn, k, v, hc, lev + LEVEL_BITS, gen)), gen);
return GCAS(cn, nn, ct);
} else {
throw CNode.invalidElement(cnAtPos);
}
}
final CNode<K, V> rn = (cn.gen == gen) ? cn : cn.renewed(gen, ct);
final MainNode<K, V> ncnode = rn.insertedAt(pos, flag, new SNode<>(k, v, hc), gen);
return GCAS(cn, ncnode, ct);
} else if (m instanceof TNode) {
clean(parent, ct, lev - LEVEL_BITS);
return false;
} else if (m instanceof LNode) {
final LNode<K, V> ln = (LNode<K, V>) m;
final LNodeEntry<K, V> entry = ln.get(ct.equiv(), k);
return entry != null ? replaceln(ln, entry, v, ct) : insertln(ln, k, v, ct);
} else {
throw invalidElement(m);
}
}
}
private static VerifyException invalidElement(final BasicNode elem) {
throw new VerifyException("An INode can host only a CNode, a TNode or an LNode, not " + elem);
}
@SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
justification = "Returning null Optional indicates the need to restart.")
private Optional<V> insertDual(final TrieMap<K, V> ct, final CNode<K, V> cn, final int pos, final SNode<K, V> sn,
final K k, final V v, final int hc, final int lev) {
final CNode<K, V> rn = (cn.gen == gen) ? cn : cn.renewed(gen, ct);
final MainNode<K, V> nn = rn.updatedAt(pos, inode(CNode.dual(sn, k, v, hc, lev + LEVEL_BITS, gen)), gen);
return GCAS(cn, nn, ct) ? Optional.empty() : null;
}
/**
* Inserts a new key value pair, given that a specific condition is met.
*
* @param cond
* null - don't care if the key was there
* KEY_ABSENT - key wasn't there
* KEY_PRESENT - key was there
* other value `v` - key must be bound to `v`
* @return null if unsuccessful, Option[V] otherwise (indicating
* previous value bound to the key)
*/
Optional<V> rec_insertif(final K k, final V v, final int hc, final Object cond, final int lev,
final INode<K, V> parent, final TrieMap<K, V> ct) {
return rec_insertif(k, v, hc, cond, lev, parent, gen, ct);
}
@SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
justification = "Returning null Optional indicates the need to restart.")
private Optional<V> rec_insertif(final K k, final V v, final int hc, final Object cond, final int lev,
final INode<K, V> parent, final Gen startgen, final TrieMap<K, V> ct) {
while (true) {
final MainNode<K, V> m = GCAS_READ(ct); // use -Yinline!
if (m instanceof CNode) {
// 1) a multiway node
final CNode<K, V> cn = (CNode<K, V>) m;
final int idx = (hc >>> lev) & 0x1f;
final int flag = 1 << idx;
final int bmp = cn.bitmap;
final int mask = flag - 1;
final int pos = Integer.bitCount(bmp & mask);
if ((bmp & flag) != 0) {
// 1a) insert below
final BasicNode cnAtPos = cn.array[pos];
if (cnAtPos instanceof INode) {
final INode<K, V> in = (INode<K, V>) cnAtPos;
if (startgen == in.gen) {
return in.rec_insertif(k, v, hc, cond, lev + LEVEL_BITS, this, startgen, ct);
}
if (GCAS(cn, cn.renewed(startgen, ct), ct)) {
// Tail recursion: return rec_insertif(k, v, hc, cond, lev, parent, startgen, ct);
continue;
}
return null;
} else if (cnAtPos instanceof SNode) {
final SNode<K, V> sn = (SNode<K, V>) cnAtPos;
if (cond == null) {
if (sn.hc == hc && ct.equal(sn.k, k)) {
if (GCAS(cn, cn.updatedAt(pos, new SNode<>(k, v, hc), gen), ct)) {
return Optional.of(sn.v);
}
return null;
}
return insertDual(ct, cn, pos, sn, k, v, hc, lev);
} else if (cond == ABSENT) {
if (sn.hc == hc && ct.equal(sn.k, k)) {
return Optional.of(sn.v);
}
return insertDual(ct, cn, pos, sn, k, v, hc, lev);
} else if (cond == PRESENT) {
if (sn.hc == hc && ct.equal(sn.k, k)) {
if (GCAS(cn, cn.updatedAt(pos, new SNode<>(k, v, hc), gen), ct)) {
return Optional.of(sn.v);
}
return null;
}
return Optional.empty();
} else {
if (sn.hc == hc && ct.equal(sn.k, k) && cond.equals(sn.v)) {
if (GCAS(cn, cn.updatedAt(pos, new SNode<>(k, v, hc), gen), ct)) {
return Optional.of(sn.v);
}
return null;
}
return Optional.empty();
}
} else {
throw CNode.invalidElement(cnAtPos);
}
} else if (cond == null || cond == ABSENT) {
final CNode<K, V> rn = (cn.gen == gen) ? cn : cn.renewed(gen, ct);
final CNode<K, V> ncnode = rn.insertedAt(pos, flag, new SNode<>(k, v, hc), gen);
if (GCAS(cn, ncnode, ct)) {
return Optional.empty();
}
return null;
} else {
return Optional.empty();
}
} else if (m instanceof TNode) {
clean(parent, ct, lev - LEVEL_BITS);
return null;
} else if (m instanceof LNode) {
// 3) an l-node
final LNode<K, V> ln = (LNode<K, V>) m;
final LNodeEntry<K, V> entry = ln.get(ct.equiv(), k);
if (cond == null) {
if (entry != null) {
return replaceln(ln, entry, v, ct) ? Optional.of(entry.getValue()) : null;
}
return insertln(ln, k, v, ct) ? Optional.empty() : null;
} else if (cond == ABSENT) {
if (entry != null) {
return Optional.of(entry.getValue());
}
return insertln(ln, k, v, ct) ? Optional.empty() : null;
} else if (cond == PRESENT) {
if (entry == null) {
return Optional.empty();
}
return replaceln(ln, entry, v, ct) ? Optional.of(entry.getValue()) : null;
} else {
if (entry == null || !cond.equals(entry.getValue())) {
return Optional.empty();
}
return replaceln(ln, entry, v, ct) ? Optional.of(entry.getValue()) : null;
}
} else {
throw invalidElement(m);
}
}
}
private boolean insertln(final LNode<K, V> ln, final K k, final V v, final TrieMap<K, V> ct) {
return GCAS(ln, ln.insertChild(k, v), ct);
}
private boolean replaceln(final LNode<K, V> ln, final LNodeEntry<K, V> entry, final V v, final TrieMap<K, V> ct) {
return GCAS(ln, ln.replaceChild(entry, v), ct);
}
/**
* Looks up the value associated with the key.
*
* @return null if no value has been found, RESTART if the operation
* wasn't successful, or any other value otherwise
*/
Object rec_lookup(final K k, final int hc, final int lev, final INode<K, V> parent, final TrieMap<K, V> ct) {
return rec_lookup(k, hc, lev, parent, gen, ct);
}
private Object rec_lookup(final K k, final int hc, final int lev, final INode<K, V> parent, final Gen startgen,
final TrieMap<K, V> ct) {
while (true) {
final MainNode<K, V> m = GCAS_READ(ct); // use -Yinline!
if (m instanceof CNode) {
// 1) a multinode
final CNode<K, V> cn = (CNode<K, V>) m;
final int idx = (hc >>> lev) & 0x1f;
final int flag = 1 << idx;
final int bmp = cn.bitmap;
if ((bmp & flag) == 0) {
// 1a) bitmap shows no binding
return null;
}
// 1b) bitmap contains a value - descend
final int pos = (bmp == 0xffffffff) ? idx : Integer.bitCount(bmp & (flag - 1));
final BasicNode sub = cn.array[pos];
if (sub instanceof INode) {
final INode<K, V> in = (INode<K, V>) sub;
if (ct.isReadOnly() || (startgen == in.gen)) {
return in.rec_lookup(k, hc, lev + LEVEL_BITS, this, startgen, ct);
}
if (GCAS(cn, cn.renewed(startgen, ct), ct)) {
// Tail recursion: return rec_lookup(k, hc, lev, parent, startgen, ct);
continue;
}
return RESTART;
} else if (sub instanceof SNode) {
// 2) singleton node
final SNode<K, V> sn = (SNode<K, V>) sub;
if (sn.hc == hc && ct.equal(sn.k, k)) {
return sn.v;
}
return null;
} else {
throw CNode.invalidElement(sub);
}
} else if (m instanceof TNode) {
// 3) non-live node
return cleanReadOnly((TNode<K, V>) m, lev, parent, ct, k, hc);
} else if (m instanceof LNode) {
// 5) an l-node
final LNodeEntry<K, V> entry = ((LNode<K, V>) m).get(ct.equiv(), k);
return entry != null ? entry.getValue() : null;
} else {
throw invalidElement(m);
}
}
}
private Object cleanReadOnly(final TNode<K, V> tn, final int lev, final INode<K, V> parent,
final TrieMap<K, V> ct, final K k, final int hc) {
if (ct.isReadOnly()) {
if (tn.hc == hc && ct.equal(tn.k, k)) {
return tn.v;
}
return null;
}
clean(parent, ct, lev - LEVEL_BITS);
return RESTART;
}
/**
* Removes the key associated with the given value.
*
* @param cond
* if null, will remove the key regardless of the value;
* otherwise removes only if binding contains that exact key
* and value
* @return null if not successful, an Optional indicating the previous
* value otherwise
*/
Optional<V> rec_remove(final K k, final Object cond, final int hc, final int lev, final INode<K, V> parent,
final TrieMap<K, V> ct) {
return rec_remove(k, cond, hc, lev, parent, gen, ct);
}
@SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
justification = "Returning null Optional indicates the need to restart.")
private Optional<V> rec_remove(final K k, final Object cond, final int hc, final int lev, final INode<K, V> parent,
final Gen startgen, final TrieMap<K, V> ct) {
final MainNode<K, V> m = GCAS_READ(ct); // use -Yinline!
if (m instanceof CNode) {
final CNode<K, V> cn = (CNode<K, V>) m;
final int idx = (hc >>> lev) & 0x1f;
final int bmp = cn.bitmap;
final int flag = 1 << idx;
if ((bmp & flag) == 0) {
return Optional.empty();
}
final int pos = Integer.bitCount(bmp & (flag - 1));
final BasicNode sub = cn.array[pos];
final Optional<V> res;
if (sub instanceof INode) {
final INode<K, V> in = (INode<K, V>) sub;
if (startgen == in.gen) {
res = in.rec_remove(k, cond, hc, lev + LEVEL_BITS, this, startgen, ct);
} else {
if (GCAS(cn, cn.renewed(startgen, ct), ct)) {
res = rec_remove(k, cond, hc, lev, parent, startgen, ct);
} else {
res = null;
}
}
} else if (sub instanceof SNode) {
final SNode<K, V> sn = (SNode<K, V>) sub;
if (sn.hc == hc && ct.equal(sn.k, k) && (cond == null || cond.equals(sn.v))) {
final MainNode<K, V> ncn = cn.removedAt(pos, flag, gen).toContracted(lev);
if (GCAS(cn, ncn, ct)) {
res = Optional.of(sn.v);
} else {
res = null;
}
} else {
res = Optional.empty();
}
} else {
throw CNode.invalidElement(sub);
}
if (res == null || !res.isPresent()) {
return res;
}
if (parent != null) {
// never tomb at root
final MainNode<K, V> n = GCAS_READ(ct);
if (n instanceof TNode) {
cleanParent(n, parent, ct, hc, lev, startgen);
}
}
return res;
} else if (m instanceof TNode) {
clean(parent, ct, lev - LEVEL_BITS);
return null;
} else if (m instanceof LNode) {
final LNode<K, V> ln = (LNode<K, V>) m;
final LNodeEntry<K, V> entry = ln.get(ct.equiv(), k);
if (entry == null) {
// Key was not found, hence no modification is needed
return Optional.empty();
}
final V value = entry.getValue();
if (cond != null && !cond.equals(value)) {
// Value does not match
return Optional.empty();
}
return GCAS(ln, ln.removeChild(entry, hc), ct) ? Optional.of(value) : null;
} else {
throw invalidElement(m);
}
}
private void cleanParent(final Object nonlive, final INode<K, V> parent, final TrieMap<K, V> ct, final int hc,
final int lev, final Gen startgen) {
while (true) {
final MainNode<K, V> pm = parent.GCAS_READ(ct);
if ((!(pm instanceof CNode))) {
// parent is no longer a cnode, we're done
return;
}
final CNode<K, V> cn = (CNode<K, V>) pm;
final int idx = (hc >>> (lev - LEVEL_BITS)) & 0x1f;
final int bmp = cn.bitmap;
final int flag = 1 << idx;
if ((bmp & flag) == 0) {
// somebody already removed this i-node, we're done
return;
}
final int pos = Integer.bitCount(bmp & (flag - 1));
final BasicNode sub = cn.array[pos];
if (sub == this) {
if (nonlive instanceof TNode) {
final TNode<?, ?> tn = (TNode<?, ?>) nonlive;
final MainNode<K, V> ncn = cn.updatedAt(pos, tn.copyUntombed(), gen).toContracted(lev - LEVEL_BITS);
if (!parent.GCAS(cn, ncn, ct)) {
if (ct.readRoot().gen == startgen) {
// Tail recursion: cleanParent(nonlive, parent, ct, hc, lev, startgen);
continue;
}
}
}
}
break;
}
}
private void clean(final INode<K, V> nd, final TrieMap<K, V> ct, final int lev) {
final MainNode<K, V> m = nd.GCAS_READ(ct);
if (m instanceof CNode) {
final CNode<K, V> cn = (CNode<K, V>) m;
nd.GCAS(cn, cn.toCompressed(ct, lev, gen), ct);
}
}
int size(final ImmutableTrieMap<?, ?> ct) {
return GCAS_READ(ct).size(ct);
}
// /* this is a quiescent method! */
// def string(lev: Int) = "%sINode -> %s".format(" " * lev, mainnode
// match {
// case null => "<null>"
// case tn: TNode[_, _] => "TNode(%s, %s, %d, !)".format(tn.k, tn.v,
// tn.hc)
// case cn: CNode[_, _] => cn.string(lev)
// case ln: LNode[_, _] => ln.string(lev)
// case x => "<elem: %s>".format(x)
// })
@Override
String string(final int lev) {
return "INode";
}
}