[GitHub] accumulo pull request #256: ACCUMULO-4463: Make block cache implementation c...

[keith-turner <gi...@git.apache.org>]

Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/256#discussion_r115578473
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/file/blockfile/cache/BlockCacheFactory.java ---
    @@ -0,0 +1,121 @@
    +/*
    + * 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.accumulo.core.file.blockfile.cache;
    +
    +import java.util.HashMap;
    +import java.util.Map;
    +
    +import org.apache.accumulo.core.conf.AccumuloConfiguration;
    +import org.apache.accumulo.core.conf.ConfigurationCopy;
    +import org.apache.accumulo.core.conf.Property;
    +import org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +public abstract class BlockCacheFactory<B extends BlockCache,C extends BlockCacheConfiguration> {
    --- End diff --
    
    There are two significant changes that I am wondering what the motivations for was.  First, this factory seems to cahce cahces and now be responsible for starting and stopping them.  Earlier you had the start and stop method on the cache itself.  Why make the BlockCacheFactory stateful?
    
    Second, BlockCacheConfiguration used to be a helper class that someone implementing a BlockCacheFactory could optionally use.  Why tightly couple these?


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