Github user ottobackwards commented on a diff in the pull request:
https://github.com/apache/incubator-metron/pull/395#discussion_r93092757
--- Diff:
metron-platform/metron-common/src/main/java/org/apache/metron/common/configuration/manager/ZkConfigurationManager.java
---
@@ -0,0 +1,129 @@
+/*
+ *
+ * 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.metron.common.configuration.manager;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.recipes.cache.NodeCache;
+import org.apache.curator.utils.CloseableUtils;
+import org.apache.metron.common.utils.JSONUtils;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+import static org.apache.commons.lang.ArrayUtils.isNotEmpty;
+
+/**
+ * Responsible for managing configuration values that are created,
persisted, and updated
+ * in Zookeeper.
+ */
+public class ZkConfigurationManager implements ConfigurationManager {
+
+ /**
+ * A Zookeeper client.
+ */
+ private CuratorFramework zookeeperClient;
+
+ /**
+ * The configuration values under management. Maps the path to the
configuration values
+ * in Zookeeper to the cache of its values.
+ */
+ private Map<String, NodeCache> valuesCache;
+
+ /**
+ * @param zookeeperClient The client used to communicate with Zookeeper.
The client is not
+ * closed. It must be managed externally.
+ */
+ public ZkConfigurationManager(CuratorFramework zookeeperClient) {
+ this.zookeeperClient = zookeeperClient;
+ this.valuesCache = Collections.synchronizedMap(new HashMap<>());
+ }
+
+ /**
+ * Define the paths within Zookeeper that contains configuration values
that need managed.
+ * @param zookeeperPath The Zookeeper path.
+ */
+ @Override
+ public ZkConfigurationManager with(String zookeeperPath) {
+ NodeCache cache = new NodeCache(zookeeperClient, zookeeperPath);
+ valuesCache.put(zookeeperPath, cache);
+ return this;
+ }
+
+ /**
+ * Open a connection to Zookeeper and retrieve the initial configuration
value.
+ */
+ @Override
+ public synchronized ZkConfigurationManager open() throws IOException {
+ try {
+ doOpen();
+ } catch(Exception e) {
+ throw new IOException(e);
+ }
+
+ return this;
+ }
+
+ private void doOpen() throws Exception {
+ for (NodeCache cache : valuesCache.values()) {
+ cache.start(true);
+ }
+ }
+
+ /**
+ * Retrieve the configuration object.
+ */
+ @Override
+ public synchronized <T> Optional<T> get(String key, Class<T> clazz)
throws IOException {
+ T result = null;
+
+ NodeCache cache = valuesCache.get(key);
+ if(cache != null && cache.getCurrentData() != null &&
isNotEmpty(cache.getCurrentData().getData())) {
+ result = deserialize(cache.getCurrentData().getData(), clazz);
+ }
+
+ return Optional.ofNullable(result);
+ }
+
+ /**
+ * Close the configuration manager.
+ *
+ * Does not close the zookeeperClient that was passed in to the
constructor.
+ */
+ @Override
+ public synchronized void close() {
+ for (NodeCache cache : valuesCache.values()) {
+ CloseableUtils.closeQuietly(cache);
--- End diff --
my apologies
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