Github user HeartSaVioR commented on a diff in the pull request:
https://github.com/apache/storm/pull/2504#discussion_r162319081
--- Diff:
storm-server/src/main/java/org/apache/storm/metricstore/rocksdb/RocksDbMetricsWriter.java
---
@@ -0,0 +1,306 @@
+/**
+ * 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.storm.metricstore.rocksdb;
+
+import com.codahale.metrics.Meter;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.ListIterator;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ThreadLocalRandom;
+import org.apache.storm.metricstore.AggLevel;
+import org.apache.storm.metricstore.Metric;
+import org.apache.storm.metricstore.MetricException;
+import org.rocksdb.FlushOptions;
+import org.rocksdb.RocksDBException;
+import org.rocksdb.WriteBatch;
+import org.rocksdb.WriteOptions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Class designed to perform all metrics inserts into RocksDB. Metrics
are processed from the a blocking queue.
+ * </P>
+ * A writable LRU StringMetadataCache is used to minimize looking up
metadata string Ids. As entries are added to the full cache, older
+ * entries are evicted from the cache and need to be written to the
database. This happens as the handleEvictedMetadata()
+ * method callback.
+ */
+public class RocksDbMetricsWriter implements Runnable, AutoCloseable {
+ private static final Logger LOG =
LoggerFactory.getLogger(RocksDbMetricsWriter.class);
+ private RocksDbStore store;
+ private BlockingQueue queue;
+ private WritableStringMetadataCache stringMetadataCache;
+ private Set<Integer> unusedIds = new HashSet<>();
+ private TreeMap<RocksDbKey, RocksDbValue> insertBatch = new
TreeMap<>(); // RocksDB should insert in sorted key order
--- End diff --
Maybe better to describe the intention, especially regarding thread-safety.
---
