Github user anmolnar commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/440#discussion_r163458563
--- Diff:
src/java/main/org/apache/zookeeper/server/quorum/ProposalStats.java ---
@@ -0,0 +1,70 @@
+/**
+ * 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.zookeeper.server.quorum;
+
+import com.codahale.metrics.ExponentiallyDecayingReservoir;
+import com.codahale.metrics.Histogram;
+import com.codahale.metrics.JmxReporter;
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.Reservoir;
+import com.codahale.metrics.Snapshot;
+import org.apache.zookeeper.jmx.CommonNames;
+import org.apache.zookeeper.jmx.MBeanRegistry;
+
+import static com.codahale.metrics.MetricRegistry.name;
+
+/**
+ * Provides real-time metrics on Leader's proposal size.
+ * The class uses a histogram included in Dropwizard metrics library with
ExponentiallyDecayingReservoir.
+ * It provides stats of proposal sizes from the last 5 minutes with
acceptable cpu/memory footprint optimized for streaming data.
+ */
+public class ProposalStats {
+ private final Histogram proposalSizes;
+
+ ProposalStats() {
+ final MetricRegistry metrics = new MetricRegistry();
+ Reservoir reservoir = new ExponentiallyDecayingReservoir();
--- End diff --
http://metrics.dropwizard.io/3.1.0/apidocs/com/codahale/metrics/ExponentiallyDecayingReservoir.html
Default constructor:
> Creates a new ExponentiallyDecayingReservoir of 1028 elements, which
offers a 99.9% confidence level with a 5% margin of error assuming a normal
distribution, and an alpha factor of 0.015, which heavily biases the reservoir
to the past 5 minutes of measurements.
There're 2 other constructors which the reservoir can be configured with by
size, alpha and clock. So, the window can be extended, though it's not as
obvious as with `SlidingWindow`.
Let's go with that as you suggested.
---
