Randgalt commented on a change in pull request #335: [CURATOR-549] Recipes based on Persistent Recursive Watchers URL: https://github.com/apache/curator/pull/335#discussion_r398522314
########## File path: curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCache.java ########## @@ -0,0 +1,133 @@ +/** + * 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.curator.framework.recipes.cache; + +import org.apache.curator.framework.CuratorFramework; +import org.apache.curator.framework.listen.Listenable; +import java.io.Closeable; +import java.util.Optional; +import java.util.stream.Stream; + +/** + * <p> + * A utility that attempts to keep the data from a node locally cached. Optionally the entire + * tree of children below the node can also be cached. Will respond to update/create/delete events, pull + * down the data, etc. You can register listeners that will get notified when changes occur. + * </p> + * + * <p> + * <b>IMPORTANT</b> - it's not possible to stay transactionally in sync. Users of this class must + * be prepared for false-positives and false-negatives. Additionally, always use the version number + * when updating data to avoid overwriting another process' change. + * </p> + */ +public interface CuratorCache extends Closeable, CuratorCacheAccessor +{ + /** + * cache build options + */ + enum Options + { + /** + * Normally the entire tree of nodes starting at the given node are cached. This option + * causes only the given node to be cached (i.e. a single node cache) + */ + SINGLE_NODE_CACHE, + + /** + * Decompress data via {@link org.apache.curator.framework.api.GetDataBuilder#decompressed()} + */ + COMPRESSED_DATA, + + /** + * Normally, when the cache is closed via {@link CuratorCache#close()}, the storage is cleared + * via {@link CuratorCacheStorage#clear()}. This option prevents the storage from being cleared. + */ + DO_NOT_CLEAR_ON_CLOSE + } + + /** + * Return a Curator Cache for the given path with the given options using a standard storage instance + * + * @param client Curator client + * @param path path to cache + * @param options any options + * @return cache (note it must be started via {@link #start()} + */ + static CuratorCache build(CuratorFramework client, String path, Options... options) + { + return builder(client, path).withOptions(options).build(); + } + + /** + * Start a Curator Cache builder + * + * @param client Curator client + * @param path path to cache + * @return builder + */ + static CuratorCacheBuilder builder(CuratorFramework client, String path) + { + return new CuratorCacheBuilderImpl(client, path); + } + + /** + * Start the cache. This will cause a complete refresh from the cache's root node and generate + * events for all nodes found, etc. + */ + void start(); + + /** + * Close the cache, stop responding to events, etc. + */ + @Override + void close(); + + /** + * Return the listener container so that listeners can be registered to be notified of changes to the cache + * + * @return listener container + */ + Listenable<CuratorCacheListener> listenable(); + + /** + * {@inheritDoc} + */ + @Override + Optional<ChildData> get(String path); + + /** + * {@inheritDoc} + */ + @Override + int size(); + + /** + * {@inheritDoc} + */ + @Override + Stream<ChildData> stream(); + + /** + * {@inheritDoc} + */ + @Override + Stream<ChildData> streamImmediateChildren(String fromParent); Review comment: I'm not happy with this API. I'm going to change it. Please refer to the next commit. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
