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/**
* 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.v2.recipes.cache;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.listen.Listenable;
import org.apache.curator.v2.CuratorFrameworkV2;
import java.io.Closeable;
/**
* <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
{
/**
* 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);
}
/**
* 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(CuratorFrameworkV2 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(CuratorFrameworkV2 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 storage instance being used
*
* @return storage
*/
CuratorCacheStorage storage();
/**
* Return the listener container so that listeners can be registered to be notified of changes to the cache
*
* @return listener container
*/
Listenable<CuratorCacheListener> listenable();
}