| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to you 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.apache.calcite.rel.metadata; |
| |
| import org.apache.calcite.rel.RelNode; |
| import org.apache.calcite.util.Pair; |
| import org.apache.calcite.util.Util; |
| |
| import com.google.common.cache.CacheBuilder; |
| import com.google.common.cache.CacheLoader; |
| import com.google.common.cache.LoadingCache; |
| import com.google.common.util.concurrent.UncheckedExecutionException; |
| |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| |
| import java.util.concurrent.ExecutionException; |
| |
| /** |
| * Implementation of {@link MetadataFactory} that gets providers from a |
| * {@link RelMetadataProvider} and stores them in a cache. |
| * |
| * <p>The cache does not store metadata. It remembers which providers can |
| * provide which kinds of metadata, for which kinds of relational |
| * expressions.</p> |
| * |
| * @deprecated Use {@link RelMetadataQuery}. |
| */ |
| @Deprecated // to be removed before 2.0 |
| public class MetadataFactoryImpl implements MetadataFactory { |
| @SuppressWarnings("unchecked") |
| public static final UnboundMetadata<@Nullable Metadata> DUMMY = (rel, mq) -> null; |
| |
| private final LoadingCache< |
| Pair<Class<RelNode>, Class<Metadata>>, |
| UnboundMetadata<@Nullable Metadata>> cache; |
| |
| public MetadataFactoryImpl(RelMetadataProvider provider) { |
| this.cache = CacheBuilder.newBuilder().build(loader(provider)); |
| } |
| |
| private static CacheLoader<Pair<Class<RelNode>, Class<Metadata>>, |
| UnboundMetadata<@Nullable Metadata>> loader(final RelMetadataProvider provider) { |
| //noinspection RedundantTypeArguments |
| return CacheLoader.<Pair<Class<RelNode>, Class<Metadata>>, |
| UnboundMetadata<@Nullable Metadata>>from(key -> { |
| final UnboundMetadata<@Nullable Metadata> function = |
| provider.apply(key.left, key.right); |
| // Return DUMMY, not null, so the cache knows to not ask again. |
| return function != null ? function : DUMMY; |
| }); |
| } |
| |
| @Override public <@Nullable M extends @Nullable Metadata> M query( |
| RelNode rel, RelMetadataQuery mq, |
| Class<M> metadataClazz) { |
| try { |
| //noinspection unchecked |
| final Pair<Class<RelNode>, Class<Metadata>> key = |
| Pair.of((Class<RelNode>) rel.getClass(), (Class<Metadata>) metadataClazz); |
| final Metadata apply = cache.get(key).bind(rel, mq); |
| return metadataClazz.cast(apply); |
| } catch (UncheckedExecutionException | ExecutionException e) { |
| throw Util.throwAsRuntime(Util.causeOrSelf(e)); |
| } |
| } |
| } |