Github user kchilton2 commented on a diff in the pull request: https://github.com/apache/incubator-rya/pull/251#discussion_r153274991 --- Diff: extras/rya.pcj.fluo/pcj.fluo.app/src/main/java/org/apache/rya/indexing/pcj/fluo/app/query/FluoQueryMetadataCache.java --- @@ -0,0 +1,247 @@ +/* + * 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.rya.indexing.pcj.fluo.app.query; + +import static com.google.common.base.Preconditions.checkArgument; + +import java.util.concurrent.Callable; + +import org.apache.fluo.api.client.SnapshotBase; +import org.apache.fluo.api.data.Bytes; +import org.apache.fluo.api.data.Column; +import org.apache.rya.indexing.pcj.fluo.app.NodeType; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import com.google.common.base.Optional; +import com.google.common.cache.Cache; +import com.google.common.cache.CacheBuilder; + +/** + * Wrapper for {@link FluoQueryMetadataDAO} that caches any metadata that has been retrieved from Fluo. This class first + * checks the cache to see if the metadata is present before delegating to the underlying DAO method to retrieve the + * data. + * + */ +public class FluoQueryMetadataCache extends FluoQueryMetadataDAO { + + private static final Logger LOG = LoggerFactory.getLogger(FluoQueryMetadataCache.class); + private final FluoQueryMetadataDAO dao; + private final Cache<String, CommonNodeMetadata> commonNodeMetadataCache; + private final Cache<String, Bytes> metadataCache; + private int capacity; + private int concurrencyLevel; + + /** + * Creates a FluoQueryMetadataCache with the specified capacity. Old, unused results are evicted as necessary. + * + * @param capacity - max size of the cache + */ + public FluoQueryMetadataCache(FluoQueryMetadataDAO dao, int capacity, int concurrencyLevel) { + this.dao = dao; + commonNodeMetadataCache = CacheBuilder.newBuilder().concurrencyLevel(concurrencyLevel).maximumSize(capacity).build(); + metadataCache = CacheBuilder.newBuilder().concurrencyLevel(concurrencyLevel).maximumSize(capacity).build(); + this.capacity = capacity; + this.concurrencyLevel = concurrencyLevel; + } + + /** + * @return - capacity of this cache in terms of max number of entries + */ + public int getCapacity() { + return capacity; + } + + /** + * @return - concurrencyLevel of this cache,in terms of number of partitions that distinct threads can operate on + * without waiting for other threads + */ + public int getConcurrencyLevel() { + return concurrencyLevel; + } + + + @Override + public StatementPatternMetadata readStatementPatternMetadata(SnapshotBase tx, String nodeId) { --- End diff -- This comment applies for all the methods.
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