add client for bks metrics

rubix-client/src/main/java/com/qubole/rubix/metrics/BookKeeperMetricsClient.java

@@ -0,0 +1,61 @@
+/**
+ * Copyright (c) 2019. Qubole Inc
+ * Licensed 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. See accompanying LICENSE file.
+ */
+package com.qubole.rubix.metrics;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.qubole.rubix.spi.BookKeeperFactory;
+import com.qubole.rubix.spi.RetryingPooledBookkeeperClient;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+
+import java.util.Map;
+
+public class BookKeeperMetricsClient
+{
+    private static Configuration conf = new Configuration();
+    private static BookKeeperFactory factory;
+    private static final Log log = LogFactory.getLog(BookKeeperMetricsClient.class);
+
+    public BookKeeperMetricsClient(Configuration conf)
+    {
+        this(conf, new BookKeeperFactory());
+    }
+
+    public BookKeeperMetricsClient(Configuration conf, BookKeeperFactory factory)
+    {
+        this.conf = conf;
+        this.factory = factory;
+    }
+
+    public static void main(String[] args)
+    {
+        BookKeeperMetricsClient metricsClient = new BookKeeperMetricsClient(conf);
+        Gson gson = new GsonBuilder().serializeSpecialFloatingPointValues().create();
+        System.out.println(gson.toJson(metricsClient.getMetrics()));
+    }
+
+    public static Map<String, Double> getMetrics()
+    {
+        try (RetryingPooledBookkeeperClient rclient = factory.createBookKeeperClient(conf))
+        {
+            return rclient.getCacheMetrics();
+        }
+        catch (Exception e)
+        {
+            log.error("Bookkeeper is not responding", e);
+        }
+        return null;
+    }
+}