// Copyright (C) 2013 The Android Open Source Project
//
// 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 com.google.gerrit.server.index.change;
import static com.google.gerrit.server.query.change.ChangeStatusPredicate.open;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.Change.Status;
import com.google.gerrit.server.index.FieldDef;
import com.google.gerrit.server.index.IndexConfig;
import com.google.gerrit.server.index.IndexPredicate;
import com.google.gerrit.server.index.IndexRewriter;
import com.google.gerrit.server.index.QueryOptions;
import com.google.gerrit.server.index.Schema;
import com.google.gerrit.server.query.AndPredicate;
import com.google.gerrit.server.query.LimitPredicate;
import com.google.gerrit.server.query.NotPredicate;
import com.google.gerrit.server.query.OrPredicate;
import com.google.gerrit.server.query.Predicate;
import com.google.gerrit.server.query.QueryParseException;
import com.google.gerrit.server.query.change.AndChangeSource;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.query.change.ChangeDataSource;
import com.google.gerrit.server.query.change.ChangeQueryBuilder;
import com.google.gerrit.server.query.change.ChangeStatusPredicate;
import com.google.gerrit.server.query.change.OrSource;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.util.BitSet;
import java.util.EnumSet;
import java.util.List;
import java.util.Set;
import org.eclipse.jgit.util.MutableInteger;
/** Rewriter that pushes boolean logic into the secondary index. */
@Singleton
public class ChangeIndexRewriter implements IndexRewriter<ChangeData> {
/** Set of all open change statuses. */
public static final Set<Change.Status> OPEN_STATUSES;
/** Set of all closed change statuses. */
public static final Set<Change.Status> CLOSED_STATUSES;
static {
EnumSet<Change.Status> open = EnumSet.noneOf(Change.Status.class);
EnumSet<Change.Status> closed = EnumSet.noneOf(Change.Status.class);
for (Change.Status s : Change.Status.values()) {
if (s.isOpen()) {
open.add(s);
} else {
closed.add(s);
}
}
OPEN_STATUSES = Sets.immutableEnumSet(open);
CLOSED_STATUSES = Sets.immutableEnumSet(closed);
}
/**
* Get the set of statuses that changes matching the given predicate may have.
*
* @param in predicate
* @return the maximal set of statuses that any changes matching the input predicates may have,
* based on examining boolean and {@link ChangeStatusPredicate}s.
*/
public static EnumSet<Change.Status> getPossibleStatus(Predicate<ChangeData> in) {
EnumSet<Change.Status> s = extractStatus(in);
return s != null ? s : EnumSet.allOf(Change.Status.class);
}
private static EnumSet<Change.Status> extractStatus(Predicate<ChangeData> in) {
if (in instanceof ChangeStatusPredicate) {
return EnumSet.of(((ChangeStatusPredicate) in).getStatus());
} else if (in instanceof NotPredicate) {
EnumSet<Status> s = extractStatus(in.getChild(0));
return s != null ? EnumSet.complementOf(s) : null;
} else if (in instanceof OrPredicate) {
EnumSet<Change.Status> r = null;
int childrenWithStatus = 0;
for (int i = 0; i < in.getChildCount(); i++) {
EnumSet<Status> c = extractStatus(in.getChild(i));
if (c != null) {
if (r == null) {
r = EnumSet.noneOf(Change.Status.class);
}
r.addAll(c);
childrenWithStatus++;
}
}
if (r != null && childrenWithStatus < in.getChildCount()) {
// At least one child supplied a status but another did not.
// Assume all statuses for the children that did not feed a
// status at this part of the tree. This matches behavior if
// the child was used at the root of a query.
return EnumSet.allOf(Change.Status.class);
}
return r;
} else if (in instanceof AndPredicate) {
EnumSet<Change.Status> r = null;
for (int i = 0; i < in.getChildCount(); i++) {
EnumSet<Change.Status> c = extractStatus(in.getChild(i));
if (c != null) {
if (r == null) {
r = EnumSet.allOf(Change.Status.class);
}
r.retainAll(c);
}
}
return r;
}
return null;
}
private final ChangeIndexCollection indexes;
private final IndexConfig config;
@Inject
ChangeIndexRewriter(ChangeIndexCollection indexes, IndexConfig config) {
this.indexes = indexes;
this.config = config;
}
@Override
public Predicate<ChangeData> rewrite(Predicate<ChangeData> in, QueryOptions opts)
throws QueryParseException {
Predicate<ChangeData> s = rewriteImpl(in, opts);
if (!(s instanceof ChangeDataSource)) {
in = Predicate.and(open(), in);
s = rewriteImpl(in, opts);
}
if (!(s instanceof ChangeDataSource)) {
throw new QueryParseException("invalid query: " + s);
}
return s;
}
private Predicate<ChangeData> rewriteImpl(Predicate<ChangeData> in, QueryOptions opts)
throws QueryParseException {
ChangeIndex index = indexes.getSearchIndex();
MutableInteger leafTerms = new MutableInteger();
Predicate<ChangeData> out = rewriteImpl(in, index, opts, leafTerms);
if (in == out || out instanceof IndexPredicate) {
return new IndexedChangeQuery(index, out, opts);
} else if (out == null /* cannot rewrite */) {
return in;
} else {
return out;
}
}
/**
* Rewrite a single predicate subtree.
*
* @param in predicate to rewrite.
* @param index index whose schema determines which fields are indexed.
* @param opts other query options.
* @param leafTerms number of leaf index query terms encountered so far.
* @return {@code null} if no part of this subtree can be queried in the index directly. {@code
* in} if this subtree and all its children can be queried directly in the index. Otherwise, a
* predicate that is semantically equivalent, with some of its subtrees wrapped to query the
* index directly.
* @throws QueryParseException if the underlying index implementation does not support this
* predicate.
*/
private Predicate<ChangeData> rewriteImpl(
Predicate<ChangeData> in, ChangeIndex index, QueryOptions opts, MutableInteger leafTerms)
throws QueryParseException {
if (isIndexPredicate(in, index)) {
if (++leafTerms.value > config.maxTerms()) {
throw new QueryParseException("too many terms in query");
}
return in;
} else if (in instanceof LimitPredicate) {
// Replace any limits with the limit provided by the caller. The caller
// should have already searched the predicate tree for limit predicates
// and included that in their limit computation.
return new LimitPredicate<>(ChangeQueryBuilder.FIELD_LIMIT, opts.limit());
} else if (!isRewritePossible(in)) {
if (in instanceof IndexPredicate) {
throw new QueryParseException("Unsupported index predicate: " + in.toString());
}
return null; // magic to indicate "in" cannot be rewritten
}
int n = in.getChildCount();
BitSet isIndexed = new BitSet(n);
BitSet notIndexed = new BitSet(n);
BitSet rewritten = new BitSet(n);
List<Predicate<ChangeData>> newChildren = Lists.newArrayListWithCapacity(n);
for (int i = 0; i < n; i++) {
Predicate<ChangeData> c = in.getChild(i);
Predicate<ChangeData> nc = rewriteImpl(c, index, opts, leafTerms);
if (nc == c) {
isIndexed.set(i);
newChildren.add(c);
} else if (nc == null /* cannot rewrite c */) {
notIndexed.set(i);
newChildren.add(c);
} else {
rewritten.set(i);
newChildren.add(nc);
}
}
if (isIndexed.cardinality() == n) {
return in; // All children are indexed, leave as-is for parent.
} else if (notIndexed.cardinality() == n) {
return null; // Can't rewrite any children, so cannot rewrite in.
} else if (rewritten.cardinality() == n) {
return in.copy(newChildren); // All children were rewritten.
}
return partitionChildren(in, newChildren, isIndexed, index, opts);
}
private boolean isIndexPredicate(Predicate<ChangeData> in, ChangeIndex index) {
if (!(in instanceof IndexPredicate)) {
return false;
}
IndexPredicate<ChangeData> p = (IndexPredicate<ChangeData>) in;
FieldDef<ChangeData, ?> def = p.getField();
Schema<ChangeData> schema = index.getSchema();
return schema.hasField(def);
}
private Predicate<ChangeData> partitionChildren(
Predicate<ChangeData> in,
List<Predicate<ChangeData>> newChildren,
BitSet isIndexed,
ChangeIndex index,
QueryOptions opts)
throws QueryParseException {
if (isIndexed.cardinality() == 1) {
int i = isIndexed.nextSetBit(0);
newChildren.add(0, new IndexedChangeQuery(index, newChildren.remove(i), opts));
return copy(in, newChildren);
}
// Group all indexed predicates into a wrapped subtree.
List<Predicate<ChangeData>> indexed = Lists.newArrayListWithCapacity(isIndexed.cardinality());
List<Predicate<ChangeData>> all =
Lists.newArrayListWithCapacity(newChildren.size() - isIndexed.cardinality() + 1);
for (int i = 0; i < newChildren.size(); i++) {
Predicate<ChangeData> c = newChildren.get(i);
if (isIndexed.get(i)) {
indexed.add(c);
} else {
all.add(c);
}
}
all.add(0, new IndexedChangeQuery(index, in.copy(indexed), opts));
return copy(in, all);
}
private Predicate<ChangeData> copy(Predicate<ChangeData> in, List<Predicate<ChangeData>> all) {
if (in instanceof AndPredicate) {
return new AndChangeSource(all);
} else if (in instanceof OrPredicate) {
return new OrSource(all);
}
return in.copy(all);
}
private static boolean isRewritePossible(Predicate<ChangeData> p) {
return p.getChildCount() > 0
&& (p instanceof AndPredicate || p instanceof OrPredicate || p instanceof NotPredicate);
}
}