com.hazelcast.shaded.org.apache.calcite.materialize.CachingLatticeStatisticProvider Maven / Gradle / Ivy
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* 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 com.hazelcast.shaded.org.apache.calcite.materialize;
import com.hazelcast.shaded.org.apache.calcite.util.Util;
import com.hazelcast.shaded.com.google.common.cache.CacheBuilder;
import com.hazelcast.shaded.com.google.common.cache.CacheLoader;
import com.hazelcast.shaded.com.google.common.cache.LoadingCache;
import com.hazelcast.shaded.com.google.common.collect.ImmutableList;
import com.hazelcast.shaded.com.google.common.util.concurrent.UncheckedExecutionException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
/**
* Implementation of {@link LatticeStatisticProvider} that caches single-column
* statistics and computes multi-column statistics from these.
*/
class CachingLatticeStatisticProvider implements LatticeStatisticProvider {
private final Lattice lattice;
private final LoadingCache cache;
/** Creates a CachingStatisticProvider. */
CachingLatticeStatisticProvider(final Lattice lattice,
final LatticeStatisticProvider provider) {
this.lattice = lattice;
cache =
CacheBuilder.newBuilder().build(
CacheLoader.from(key ->
provider.cardinality(ImmutableList.of(key))));
}
@Override public double cardinality(List columns) {
final List counts = new ArrayList<>();
for (Lattice.Column column : columns) {
try {
counts.add(cache.get(column));
} catch (UncheckedExecutionException | ExecutionException e) {
throw Util.throwAsRuntime(Util.causeOrSelf(e));
}
}
return (int) Lattice.getRowCount(lattice.getFactRowCount(), counts);
}
}
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