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// 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.closed;
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.common.Nullable;
import com.google.gerrit.entities.Change;
import com.google.gerrit.entities.Change.Status;
import com.google.gerrit.index.IndexConfig;
import com.google.gerrit.index.IndexRewriter;
import com.google.gerrit.index.QueryOptions;
import com.google.gerrit.index.Schema;
import com.google.gerrit.index.SchemaFieldDefs.SchemaField;
import com.google.gerrit.index.query.AndCardinalPredicate;
import com.google.gerrit.index.query.AndPredicate;
import com.google.gerrit.index.query.HasCardinality;
import com.google.gerrit.index.query.IndexPredicate;
import com.google.gerrit.index.query.LimitPredicate;
import com.google.gerrit.index.query.NotPredicate;
import com.google.gerrit.index.query.OrCardinalPredicate;
import com.google.gerrit.index.query.OrPredicate;
import com.google.gerrit.index.query.Predicate;
import com.google.gerrit.index.query.QueryParseException;
import com.google.gerrit.index.query.TooManyTermsInQueryException;
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.IsSubmittablePredicate;
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.Optional;
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 {
/** Set of all open change statuses. */
public static final Set OPEN_STATUSES;
/** Set of all closed change statuses. */
public static final Set CLOSED_STATUSES;
static {
EnumSet open = EnumSet.noneOf(Change.Status.class);
EnumSet 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 Set getPossibleStatus(Predicate in) {
EnumSet s = extractStatus(in);
return s != null ? s : EnumSet.allOf(Change.Status.class);
}
private static @Nullable EnumSet extractStatus(Predicate in) {
if (in instanceof ChangeStatusPredicate) {
Status status = ((ChangeStatusPredicate) in).getStatus();
return status != null ? EnumSet.of(status) : null;
} else if (in instanceof NotPredicate) {
EnumSet s = extractStatus(in.getChild(0));
return s != null ? EnumSet.complementOf(s) : null;
} else if (in instanceof OrPredicate) {
EnumSet r = null;
int childrenWithStatus = 0;
for (int i = 0; i < in.getChildCount(); i++) {
EnumSet 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 r = null;
for (int i = 0; i < in.getChildCount(); i++) {
EnumSet 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 rewrite(Predicate in, QueryOptions opts)
throws QueryParseException {
Predicate s = rewriteImpl(in, opts);
if (!(s instanceof ChangeDataSource)) {
in = Predicate.and(Predicate.or(open(), closed()), in);
s = rewriteImpl(in, opts);
}
if (!(s instanceof ChangeDataSource)) {
throw new QueryParseException("invalid query: " + s);
}
return s;
}
private Predicate rewriteImpl(Predicate in, QueryOptions opts)
throws QueryParseException {
ChangeIndex index = indexes.getSearchIndex();
MutableInteger leafTerms = new MutableInteger();
Predicate out = rewriteImpl(in, index, opts, leafTerms);
if (leafTerms.value > config.maxTerms()) {
throw new TooManyTermsInQueryException(leafTerms.value, config.maxTerms());
}
if (isSameInstance(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.
*/
@Nullable
private Predicate rewriteImpl(
Predicate in, ChangeIndex index, QueryOptions opts, MutableInteger leafTerms)
throws QueryParseException {
in = IsSubmittablePredicate.rewrite(in);
if (isIndexPredicate(in, index)) {
++leafTerms.value;
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);
BitSet changeSource = new BitSet(n);
List> newChildren = Lists.newArrayListWithCapacity(n);
for (int i = 0; i < n; i++) {
Predicate c = in.getChild(i);
Predicate nc = rewriteImpl(c, index, opts, leafTerms);
if (isSameInstance(nc, c)) {
isIndexed.set(i);
newChildren.add(c);
} else if (nc == null /* cannot rewrite c */) {
if (c instanceof ChangeDataSource) {
changeSource.set(i);
}
notIndexed.set(i);
newChildren.add(c);
} else {
if (nc instanceof ChangeDataSource) {
changeSource.set(i);
}
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) {
if (changeSource.cardinality() == n) {
return copy(in, newChildren);
}
return null; // Can't rewrite any children, so cannot rewrite in.
} else if (rewritten.cardinality() == n) {
// All children were rewritten.
if (changeSource.cardinality() == n) {
return copy(in, newChildren);
}
return in.copy(newChildren);
}
return partitionChildren(in, newChildren, isIndexed, index, opts);
}
private boolean isIndexPredicate(Predicate in, ChangeIndex index) {
if (!(in instanceof IndexPredicate)) {
return false;
}
IndexPredicate p = (IndexPredicate) in;
SchemaField field = p.getField();
Schema schema = index.getSchema();
return schema.hasField(field);
}
private Predicate partitionChildren(
Predicate in,
List> newChildren,
BitSet isIndexed,
ChangeIndex index,
QueryOptions opts)
throws QueryParseException {
if (isIndexed.cardinality() == 1) {
int i = isIndexed.nextSetBit(0);
Predicate indexed = newChildren.remove(i);
newChildren.add(0, new IndexedChangeQuery(index, copy(indexed, indexed.getChildren()), opts));
return copy(in, newChildren);
}
// Group all indexed predicates into a wrapped subtree.
List> indexed = Lists.newArrayListWithCapacity(isIndexed.cardinality());
List> all =
Lists.newArrayListWithCapacity(newChildren.size() - isIndexed.cardinality() + 1);
for (int i = 0; i < newChildren.size(); i++) {
Predicate c = newChildren.get(i);
if (isIndexed.get(i)) {
indexed.add(c);
} else {
all.add(c);
}
}
all.add(0, new IndexedChangeQuery(index, copy(in, indexed), opts));
return copy(in, all);
}
private Predicate copy(Predicate in, List> all) {
if (in instanceof AndPredicate) {
Optional> atLeastOneChangeDataSource =
all.stream().filter(p -> (p instanceof ChangeDataSource)).findAny();
if (atLeastOneChangeDataSource.isPresent()) {
return new AndChangeSource(all, config);
}
Optional> atLeastOneCardinalPredicate =
all.stream().filter(p -> (p instanceof HasCardinality)).findAny();
if (atLeastOneCardinalPredicate.isPresent()) {
return new AndCardinalPredicate<>(all);
}
} else if (in instanceof OrPredicate) {
Optional> nonChangeDataSource =
all.stream().filter(p -> !(p instanceof ChangeDataSource)).findAny();
if (!nonChangeDataSource.isPresent()) {
return new OrSource(all);
}
Optional> nonHasCardinality =
all.stream().filter(p -> !(p instanceof HasCardinality)).findAny();
if (!nonHasCardinality.isPresent()) {
return new OrCardinalPredicate<>(all);
}
}
return in.copy(all);
}
private static boolean isRewritePossible(Predicate p) {
return p.getChildCount() > 0
&& (p instanceof AndPredicate || p instanceof OrPredicate || p instanceof NotPredicate);
}
@SuppressWarnings("ReferenceEquality")
private static boolean isSameInstance(T a, T b) {
return a == b;
}
}
