[GitHub] [curator] Randgalt commented on a change in pull request #335: [CURATOR-549] Recipes based on Persistent Recursive Watchers

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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
 
 

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 File path: curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCache.java
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 @@ -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.

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