com.google.gerrit.index.query.QueryProcessor Maven / Gradle / Ivy
// Copyright (C) 2016 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.index.query;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.flogger.LazyArgs.lazy;
import static java.util.stream.Collectors.toList;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Ordering;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.index.Index;
import com.google.gerrit.index.IndexCollection;
import com.google.gerrit.index.IndexConfig;
import com.google.gerrit.index.IndexRewriter;
import com.google.gerrit.index.QueryOptions;
import com.google.gerrit.index.SchemaDefinitions;
import com.google.gerrit.metrics.Description;
import com.google.gerrit.metrics.Field;
import com.google.gerrit.metrics.MetricMaker;
import com.google.gerrit.metrics.Timer1;
import com.google.gerrit.server.logging.CallerFinder;
import com.google.gerrit.server.logging.Metadata;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.IntSupplier;
import java.util.stream.IntStream;
/**
* Lower-level implementation for executing a single query over a secondary index.
*
* Instances are one-time-use. Other singleton classes should inject a Provider rather than
* holding on to a single instance.
*/
public abstract class QueryProcessor {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
protected static class Metrics {
final Timer1 executionTime;
Metrics(MetricMaker metricMaker) {
executionTime =
metricMaker.newTimer(
"query/query_latency",
new Description("Successful query latency, accumulated over the life of the process")
.setCumulative()
.setUnit(Description.Units.MILLISECONDS),
Field.ofString("index", Metadata.Builder::indexName)
.description("index name")
.build());
}
}
private final Metrics metrics;
private final SchemaDefinitions schemaDef;
private final IndexConfig indexConfig;
private final IndexCollection> indexes;
private final IndexRewriter rewriter;
private final String limitField;
private final IntSupplier permittedLimit;
private final CallerFinder callerFinder;
// This class is not generally thread-safe, but programmer error may result in it being shared
// across threads. At least ensure the bit for checking if it's been used is threadsafe.
private final AtomicBoolean used;
protected int start;
private boolean enforceVisibility = true;
private int userProvidedLimit;
private boolean isNoLimit;
private Set requestedFields;
protected QueryProcessor(
MetricMaker metricMaker,
SchemaDefinitions schemaDef,
IndexConfig indexConfig,
IndexCollection> indexes,
IndexRewriter rewriter,
String limitField,
IntSupplier permittedLimit) {
this.metrics = new Metrics(metricMaker);
this.schemaDef = schemaDef;
this.indexConfig = indexConfig;
this.indexes = indexes;
this.rewriter = rewriter;
this.limitField = limitField;
this.permittedLimit = permittedLimit;
this.used = new AtomicBoolean(false);
this.callerFinder =
CallerFinder.builder()
.addTarget(InternalQuery.class)
.addTarget(QueryProcessor.class)
.matchSubClasses(true)
.skip(1)
.build();
}
public QueryProcessor setStart(int n) {
start = n;
return this;
}
/**
* Specify whether to enforce visibility by filtering out results that are not visible to the
* user.
*
* Enforcing visibility may have performance consequences, as the index system may need to
* post-filter a large number of results to fill even a modest limit.
*
*
If visibility is enforced, the user's {@code queryLimit} global capability is also used to
* bound the total number of results. If this capability is non-positive, this results in the
* entire query processor being {@link #isDisabled() disabled}.
*
* @param enforce whether to enforce visibility.
* @return this.
*/
public QueryProcessor enforceVisibility(boolean enforce) {
enforceVisibility = enforce;
return this;
}
/**
* Set an end-user-provided limit on the number of results returned.
*
* Since this limit is provided by an end user, it may exceed the limit that they are
* authorized to use. This is allowed; the processor will take multiple possible limits into
* account and choose the one that makes the most sense.
*
* @param n limit; zero or negative means no limit.
* @return this.
*/
public QueryProcessor setUserProvidedLimit(int n) {
userProvidedLimit = n;
return this;
}
public QueryProcessor setNoLimit(boolean isNoLimit) {
this.isNoLimit = isNoLimit;
return this;
}
public QueryProcessor setRequestedFields(Set fields) {
requestedFields = fields;
return this;
}
/**
* Query for entities that match a structured query.
*
* @see #query(List)
* @param query the query.
* @return results of the query.
*/
public QueryResult query(Predicate query) throws QueryParseException {
return query(ImmutableList.of(query)).get(0);
}
/**
* Perform multiple queries in parallel.
*
* If querying is disabled, short-circuits the index and returns empty results. Callers that
* wish to distinguish this case from a query returning no results from the index may call {@link
* #isDisabled()} themselves.
*
* @param queries list of queries.
* @return results of the queries, one QueryResult per input query, in the same order as the
* input.
*/
public List> query(List> queries) throws QueryParseException {
try {
return query(null, queries);
} catch (StorageException e) {
if (e.getCause() != null) {
Throwables.throwIfInstanceOf(e.getCause(), QueryParseException.class);
}
throw e;
}
}
private List> query(
@Nullable List queryStrings, List> queries) throws QueryParseException {
long startNanos = System.nanoTime();
checkState(!used.getAndSet(true), "%s has already been used", getClass().getSimpleName());
int cnt = queries.size();
if (queryStrings != null) {
int qs = queryStrings.size();
checkArgument(qs == cnt, "got %s query strings but %s predicates", qs, cnt);
}
if (cnt == 0) {
return ImmutableList.of();
}
if (isDisabled()) {
return disabledResults(queryStrings, queries);
}
logger.atFine().log(
"Executing %d %s index queries for %s",
cnt, schemaDef.getName(), callerFinder.findCallerLazy());
List> out;
try {
// Parse and rewrite all queries.
List limits = new ArrayList<>(cnt);
List> predicates = new ArrayList<>(cnt);
List> sources = new ArrayList<>(cnt);
int queryCount = 0;
for (Predicate q : queries) {
int limit = getEffectiveLimit(q);
limits.add(limit);
if (limit == getBackendSupportedLimit()) {
limit--;
}
int page = (start / limit) + 1;
if (page > indexConfig.maxPages()) {
throw new QueryParseException(
"Cannot go beyond page " + indexConfig.maxPages() + " of results");
}
// Always bump limit by 1, even if this results in exceeding the permitted
// max for this user. The only way to see if there are more entities is to
// ask for one more result from the query.
QueryOptions opts = createOptions(indexConfig, start, limit + 1, getRequestedFields());
logger.atFine().log("Query options: " + opts);
Predicate pred = rewriter.rewrite(q, opts);
if (enforceVisibility) {
pred = enforceVisibility(pred);
}
predicates.add(pred);
logger.atFine().log(
"%s index query[%d]:\n%s",
schemaDef.getName(),
queryCount++,
pred instanceof IndexedQuery ? pred.getChild(0) : pred);
@SuppressWarnings("unchecked")
DataSource s = (DataSource) pred;
sources.add(s);
}
// Run each query asynchronously, if supported.
List> matches = new ArrayList<>(cnt);
for (DataSource s : sources) {
matches.add(s.read());
}
out = new ArrayList<>(cnt);
for (int i = 0; i < cnt; i++) {
ImmutableList matchesList = matches.get(i).toList();
logger.atFine().log(
"Matches[%d]:\n%s",
i, lazy(() -> matchesList.stream().map(this::formatForLogging).collect(toList())));
out.add(
QueryResult.create(
queryStrings != null ? queryStrings.get(i) : null,
predicates.get(i),
limits.get(i),
matchesList));
}
// Only measure successful queries that actually touched the index.
metrics.executionTime.record(
schemaDef.getName(), System.nanoTime() - startNanos, TimeUnit.NANOSECONDS);
} catch (StorageException e) {
Optional qpe = findQueryParseException(e);
if (qpe.isPresent()) {
throw new QueryParseException(qpe.get().getMessage(), e);
}
throw e;
}
return out;
}
private static ImmutableList> disabledResults(
List queryStrings, List> queries) {
return IntStream.range(0, queries.size())
.mapToObj(
i ->
QueryResult.create(
queryStrings != null ? queryStrings.get(i) : null,
queries.get(i),
0,
ImmutableList.of()))
.collect(toImmutableList());
}
protected QueryOptions createOptions(
IndexConfig indexConfig, int start, int limit, Set requestedFields) {
return QueryOptions.create(indexConfig, start, limit, requestedFields);
}
/**
* Invoked after the query was rewritten. Subclasses must overwrite this method to filter out
* results that are not visible to the calling user.
*
* @param pred the query
* @return the modified query
*/
protected abstract Predicate enforceVisibility(Predicate pred);
private Set getRequestedFields() {
if (requestedFields != null) {
return requestedFields;
}
Index index = indexes.getSearchIndex();
return index != null ? index.getSchema().getStoredFields().keySet() : ImmutableSet.of();
}
/**
* Check whether querying should be disabled.
*
* Currently, the only condition that can disable the whole query processor is if both {@link
* #enforceVisibility(boolean) visibility is enforced} and the user has a non-positive maximum
* value for the {@code queryLimit} capability.
*
*
If querying is disabled, all calls to {@link #query(Predicate)} and {@link #query(List)}
* will return empty results. This method can be used if callers wish to distinguish this case
* from a query returning no results from the index.
*
* @return true if querying should be disabled.
*/
public boolean isDisabled() {
return enforceVisibility && getPermittedLimit() <= 0;
}
private int getPermittedLimit() {
return enforceVisibility ? permittedLimit.getAsInt() : Integer.MAX_VALUE;
}
private int getBackendSupportedLimit() {
return indexConfig.maxLimit();
}
private int getEffectiveLimit(Predicate p) {
if (isNoLimit == true) {
return Integer.MAX_VALUE;
}
List possibleLimits = new ArrayList<>(4);
possibleLimits.add(getBackendSupportedLimit());
possibleLimits.add(getPermittedLimit());
if (userProvidedLimit > 0) {
possibleLimits.add(userProvidedLimit);
}
if (limitField != null) {
Integer limitFromPredicate = LimitPredicate.getLimit(limitField, p);
if (limitFromPredicate != null) {
possibleLimits.add(limitFromPredicate);
}
}
int result = Ordering.natural().min(possibleLimits);
// Should have short-circuited from #query or thrown some other exception before getting here.
checkState(result > 0, "effective limit should be positive");
return result;
}
private static Optional findQueryParseException(Throwable t) {
return Throwables.getCausalChain(t).stream()
.filter(c -> c instanceof QueryParseException)
.map(QueryParseException.class::cast)
.findFirst();
}
protected abstract String formatForLogging(T t);
}