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From kaspersorensen <...@git.apache.org>
Subject [GitHub] metamodel-membrane pull request #1: Initial codebase
Date Thu, 27 Jul 2017 01:13:19 GMT
Github user kaspersorensen commented on a diff in the pull request:

    https://github.com/apache/metamodel-membrane/pull/1#discussion_r129734366
  
    --- Diff: core/src/main/java/org/apache/metamodel/membrane/app/CachedDataSourceRegistryWrapper.java
---
    @@ -0,0 +1,109 @@
    +/**
    + * 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.metamodel.membrane.app;
    +
    +import java.util.List;
    +import java.util.concurrent.ExecutionException;
    +import java.util.concurrent.TimeUnit;
    +
    +import org.apache.metamodel.DataContext;
    +import org.apache.metamodel.MetaModelException;
    +import org.apache.metamodel.factory.DataContextProperties;
    +import org.apache.metamodel.membrane.app.exceptions.DataSourceAlreadyExistException;
    +import org.apache.metamodel.membrane.app.exceptions.NoSuchDataSourceException;
    +import org.apache.metamodel.util.FileHelper;
    +
    +import com.google.common.cache.CacheBuilder;
    +import com.google.common.cache.CacheLoader;
    +import com.google.common.cache.LoadingCache;
    +import com.google.common.cache.RemovalListener;
    +import com.google.common.cache.RemovalNotification;
    +
    +/**
    + * A wrapper that adds a cache around a {@link DataSourceRegistry} in order to
    + * prevent re-connecting all the time to the same data source.
    + */
    +public class CachedDataSourceRegistryWrapper implements DataSourceRegistry {
    +
    +    /**
    +     * The default timeout (in seconds) before the cache evicts and closes the
    +     * created {@link DataContext}s.
    +     */
    +    public static final int DEFAULT_TIMEOUT_SECONDS = 60;
    +
    +    private final DataSourceRegistry delegate;
    +    private final LoadingCache<String, DataContext> loadingCache;
    +
    +    public CachedDataSourceRegistryWrapper(DataSourceRegistry delegate) {
    +        this(delegate, DEFAULT_TIMEOUT_SECONDS, TimeUnit.SECONDS);
    +    }
    +
    +    public CachedDataSourceRegistryWrapper(DataSourceRegistry delegate, long cacheTimeout,
TimeUnit cacheTimeoutUnit) {
    +        this.delegate = delegate;
    +        this.loadingCache = CacheBuilder.newBuilder().expireAfterAccess(cacheTimeout,
cacheTimeoutUnit).removalListener(
    +                createRemovalListener()).build(createCacheLoader());
    +    }
    +
    +    private RemovalListener<String, DataContext> createRemovalListener() {
    +        return new RemovalListener<String, DataContext>() {
    +            @Override
    +            public void onRemoval(RemovalNotification<String, DataContext> notification)
{
    --- End diff --
    
    Hmm I started fixing this but it's ... everywhere. Do you know of a tool that can automate
it?


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