[GitHub] [cassandra] yifan-c commented on a change in pull request #831: CASSANDRA-16095 - Nodetool tablestats WriteLatency error

[GitBox <gi...@apache.org>]

yifan-c commented on a change in pull request #831:
URL: https://github.com/apache/cassandra/pull/831#discussion_r528031218



##########
File path: src/java/org/apache/cassandra/metrics/TableMetrics.java
##########
@@ -62,7 +62,17 @@
  */
 public class TableMetrics
 {
+    /**
+     * stores metrics that will be rolled into a single global metric
+     */
+    private static final ConcurrentMap<String, Set<Metric>> ALL_TABLE_METRICS = Maps.newConcurrentMap();
     public static final long[] EMPTY = new long[0];
+    private static final MetricNameFactory GLOBAL_FACTORY = new AllTableMetricNameFactory("Table");
+    private static final MetricNameFactory GLOBAL_ALIAS_FACTORY = new AllTableMetricNameFactory("ColumnFamily");
+
+    public final static LatencyMetrics GLOBAL_READ_LATENCY = new LatencyMetrics(GLOBAL_FACTORY, GLOBAL_ALIAS_FACTORY, "Read");
+    public final static LatencyMetrics GLOBAL_WRITE_LATENCY = new LatencyMetrics(GLOBAL_FACTORY, GLOBAL_ALIAS_FACTORY, "Write");
+    public final static LatencyMetrics GLOBAL_RANGE_LATENCY = new LatencyMetrics(GLOBAL_FACTORY, GLOBAL_ALIAS_FACTORY, "Range");

Review comment:
       great to group the static variable together. 

##########
File path: src/java/org/apache/cassandra/metrics/TableMetrics.java
##########
@@ -609,7 +609,7 @@ public Long getValue()
             public Long getValue()
             {
                 long min = Long.MAX_VALUE;
-                for (Metric cfGauge : allTableMetrics.get("MinPartitionSize"))
+                for (Metric cfGauge : ALL_TABLE_METRICS.get("MinPartitionSize"))

Review comment:
       nit: maybe also create constants for the metrics names? since this patch is doing some code cleanup already. 
   (Maybe too much work. your call)

##########
File path: src/java/org/apache/cassandra/config/CassandraRelevantProperties.java
##########
@@ -196,6 +199,28 @@ public String getString()
         return value == null ? defaultVal : STRING_CONVERTER.convert(value);
     }
 
+    /**

Review comment:
       The get with overrideDefaultValue methods are not used. Not a big problem if the other patch referenced is to be merged. 

##########
File path: test/distributed/org/apache/cassandra/distributed/test/metric/TableMetricTest.java
##########
@@ -0,0 +1,210 @@
+/*
+ * 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.cassandra.distributed.test.metric;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import javax.management.InstanceAlreadyExistsException;
+import javax.management.InstanceNotFoundException;
+import javax.management.ObjectName;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import org.junit.Assert;
+import org.junit.Test;
+
+import org.apache.cassandra.db.ColumnFamilyStore;
+import org.apache.cassandra.distributed.Cluster;
+import org.apache.cassandra.distributed.api.IInvokableInstance;
+import org.apache.cassandra.distributed.test.TestBaseImpl;
+import org.apache.cassandra.utils.MBeanWrapper;
+
+import static org.apache.cassandra.config.CassandraRelevantProperties.IS_DISABLED_MBEAN_REGISTRATION;
+import static org.apache.cassandra.config.CassandraRelevantProperties.MBEAN_REGISTRATION_CLASS;
+
+public class TableMetricTest extends TestBaseImpl
+{
+    static
+    {
+        MBEAN_REGISTRATION_CLASS.setString(MapMBeanWrapper.class.getName());
+        IS_DISABLED_MBEAN_REGISTRATION.setBoolean(false);
+    }
+
+    private static Map<String, Collection<String>> SYSTEM_TABLES = ImmutableMap.of(
+    "system", ImmutableSet.of("available_ranges", "available_ranges_v2", "batches", "built_views", "compaction_history", "IndexInfo", "local",

Review comment:
       I think it is better to load the tables programmatically. So compiler prompts when code changes. It can be done via
   
   ```java
           Map<String, Collection<String>> systemTables = new HashMap<>();
           Consumer<KeyspaceMetadata> loader = meta ->
           {
               Set<String> tables = meta.tables.stream().map(t -> t.name).collect(Collectors.toSet());
               systemTables.put(meta.name, tables);
           };
           Arrays.asList(SystemKeyspace.metadata(), AuthKeyspace.metadata(), SystemDistributedKeyspace.metadata(),
                         SchemaKeyspace.metadata(), TraceKeyspace.metadata())
                 .forEach(loader);
   ```




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