Java tutorial
/* * Copyright 2017-present Facebook, Inc. * * 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.facebook.buck.rules.query; import com.facebook.buck.core.model.targetgraph.TargetGraph; import com.facebook.buck.query.CachingQueryEvaluator; import com.facebook.buck.query.QueryEvaluator; import com.facebook.buck.query.QueryException; import com.facebook.buck.query.QueryExpression; import com.google.common.annotations.VisibleForTesting; import com.google.common.cache.CacheBuilder; import com.google.common.cache.CacheLoader; import com.google.common.cache.LoadingCache; import java.util.Objects; import java.util.concurrent.ExecutionException; /** Cache that evaluates and stores the result of a dependency {@link Query}. */ public class QueryCache { private final LoadingCache<TargetGraph, CachingQueryEvaluator> evaluators; public QueryCache() { evaluators = CacheBuilder.newBuilder().build(CacheLoader.from(CachingQueryEvaluator::new)); } QueryEvaluator getQueryEvaluator(TargetGraph targetGraph) { try { return evaluators.get(targetGraph); } catch (ExecutionException e) { throw new RuntimeException("Failed to obtain query evaluator", e); } } @VisibleForTesting boolean isPresent(TargetGraph targetGraph, GraphEnhancementQueryEnvironment env, Query query) throws QueryException { CachingQueryEvaluator evaluator = evaluators.getIfPresent(targetGraph); return Objects.nonNull(evaluator) && evaluator.isPresent(QueryExpression.parse(query.getQuery(), env)); } }