[CALCITE-4882] Introduce new Lambda-based Metadata framework

core/src/main/java/org/apache/calcite/rel/metadata/JaninoRelMetadataProvider.java

@@ -26,13 +26,15 @@
 import org.apache.calcite.util.ControlFlowException;
 import org.apache.calcite.util.Util;
 
+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 com.google.common.collect.ImmutableList;
 import com.google.common.collect.Multimap;
 import com.google.common.util.concurrent.UncheckedExecutionException;
 
+import org.apiguardian.api.API;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.codehaus.commons.compiler.CompileException;
 import org.codehaus.commons.compiler.CompilerFactoryFactory;
@@ -425,4 +427,10 @@ private Key(Class<? extends MetadataHandler<?>> handlerClass,
           && ((Key) obj).provider.equals(provider);
     }
   }
+
+  @API(status = API.Status.INTERNAL)
+  @VisibleForTesting
+  public static void clearStaticCache() {
+    HANDLERS.invalidateAll();
+  }
 }

core/src/main/java/org/apache/calcite/rel/metadata/lambda/CachingLambdaProvider.java

@@ -0,0 +1,61 @@
+/*
+ * 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.lambda;
+
+import org.apache.calcite.rel.RelNode;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+import javax.annotation.concurrent.ThreadSafe;
+
+/**
+ * A LambdaProvider that maintains a cache for each RelNode class/Lambda class combination,
+ * delegating to an underlying LambdaProvider to do actual work.
+ */
+@ThreadSafe
+class CachingLambdaProvider implements LambdaProvider {
+
+  private final LambdaProvider provider;
+  private final LoadingCache<Class<? extends RelNode>, LoadingCache<Class, Object>> cache;
+
+  CachingLambdaProvider(final LambdaProvider provider) {
+    this.provider = provider;
+    this.cache = CacheBuilder.newBuilder()
+        .build(new CacheLoader<Class, LoadingCache<Class, Object>>() {
+          @Override public LoadingCache<Class, Object> load(final Class relNodeClazz)
+              throws Exception {
+            return CacheBuilder.<Class, Object>newBuilder().build(
+                new CacheLoader<Class, Object>() {
+                  @Override public Object load(final Class lambdaClazz) throws Exception {
+                    return provider.get((Class<? extends RelNode>) relNodeClazz, lambdaClazz);
+                  }
+                });
+          }
+        });
+  }
+
+  public <R extends RelNode, T extends MetadataLambda> List<T> get(
+      Class<R> relNodeClazz,
+      Class<T> lambdaClazz) throws ExecutionException {
+    return (List<T>) cache.get(relNodeClazz).get(lambdaClazz);
+  }
+
+}

core/src/main/java/org/apache/calcite/rel/metadata/lambda/CanonicalizingIRMQ.java

@@ -0,0 +1,82 @@
+/*
+ * 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.lambda;
+
+import org.apache.calcite.plan.RelOptPredicateList;
+import org.apache.calcite.rel.RelDistribution;
+import org.apache.calcite.rel.RelDistributions;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.metadata.RelMdUtil;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlExplainLevel;
+import org.apache.calcite.util.ImmutableBitSet;
+
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import static org.apache.calcite.linq4j.Nullness.castNonNull;
+
+/**
+ * Canonicalizes methods from null to other standard outputs.
+ */
+class CanonicalizingIRMQ extends DelegatingIRMQ {
+  CanonicalizingIRMQ(IRelMetadataQuery delegate) {
+    super(delegate);
+  }
+
+  @Override public @Nullable RelDistribution distribution(final RelNode rel) {
+    RelDistribution distribution = super.distribution(rel);
+    if (distribution == null) {
+      return RelDistributions.ANY;
+    }
+    return distribution;
+  }
+
+  public Double getRowCount(RelNode rel) {
+    return RelMdUtil.validateResult(castNonNull(super.getRowCount(rel)));
+  }
+
+  public @Nullable Double getPopulationSize(RelNode rel, ImmutableBitSet groupKey) {
+    return RelMdUtil.validateResult(super.getPopulationSize(rel, groupKey));
+  }
+
+  public @Nullable Double getPercentageOriginalRows(RelNode rel) {
+    Double result = super.getPercentageOriginalRows(rel);
+    return RelMdUtil.validatePercentage(result);
+  }
+
+  public @Nullable Double getSelectivity(RelNode rel, @Nullable RexNode predicate) {
+    return RelMdUtil.validatePercentage(super.getSelectivity(rel, predicate));
+  }
+
+  public @Nullable Double getDistinctRowCount(
+      RelNode rel,
+      ImmutableBitSet groupKey,
+      @Nullable RexNode predicate) {
+    return RelMdUtil.validateResult(super.getDistinctRowCount(rel, groupKey, predicate));
+  }
+
+  public RelOptPredicateList getPulledUpPredicates(RelNode rel) {
+    RelOptPredicateList result = super.getPulledUpPredicates(rel);
+    return result != null ? result : RelOptPredicateList.EMPTY;
+  }
+
+  public Boolean isVisibleInExplain(RelNode rel,
+      SqlExplainLevel explainLevel) {
+    Boolean b = super.isVisibleInExplain(rel, explainLevel);
+    return b == null || b;
+  }
+}