You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@iceberg.apache.org by GitBox <gi...@apache.org> on 2022/07/29 16:25:45 UTC
[GitHub] [iceberg] kbendick commented on a diff in pull request #5348: API: define Gauge and Histogram metrics with default implementations
kbendick commented on code in PR #5348:
URL: https://github.com/apache/iceberg/pull/5348#discussion_r933435663
##########
api/src/main/java/org/apache/iceberg/metrics/DefaultHistogram.java:
##########
@@ -0,0 +1,145 @@
+/*
+ * 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.iceberg.metrics;
+
+import java.util.Arrays;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+
+/**
+ * A default {@link Histogram} implementation that uses a fixed size reservoir like circular buffer.
+ * Oldest observation is replaced by latest observation.
+ */
+public class DefaultHistogram implements Histogram {
+ private final long[] measurements;
+ private long count;
+
+ public DefaultHistogram(int reservoirSize) {
+ this.measurements = new long[reservoirSize];
+ this.count = 0L;
+ }
+
+ @Override
+ public synchronized long count() {
+ return count;
+ }
+
+ @Override
+ public synchronized void update(long value) {
+ int index = (int) (count % measurements.length);
+ measurements[index] = value;
+ count++;
+ }
+
+ @Override
+ public Statistics statistics() {
+ int size = measurements.length;
+ if (count < (long) measurements.length) {
+ size = (int) count;
+ }
+
+ long[] values = new long[size];
+ for (int i = 0; i < values.length; ++i) {
+ synchronized (this) {
+ values[i] = measurements[i];
+ }
+ }
+
+ return new UniformWeightStatistics(values);
+ }
+
+ private static class UniformWeightStatistics implements Statistics {
+ private final long[] values;
+
+ private UniformWeightStatistics(long[] values) {
+ // since the input values is already a copied array,
+ // there is no need to copy again.
+ this.values = values;
+ Arrays.sort(this.values);
+ }
+
+ @Override
+ public long size() {
+ return values.length;
+ }
+
+ @Override
+ public double mean() {
+ if (values.length == 0) {
+ return 0.0;
+ } else {
+ double sum = 0.0;
+ for (int i = 0; i < values.length; ++i) {
+ sum += values[i];
+ }
+
+ return sum / values.length;
+ }
+ }
+
+ @Override
+ public double stdDev() {
+ if (this.values.length <= 1) {
+ return 0.0;
+ } else {
+ double mean = mean();
+ double sumOfDiffSquares = 0.0;
+ for (int i = 0; i < values.length; ++i) {
+ double diff = values[i] - mean;
+ sumOfDiffSquares += diff * diff;
+ }
+
+ double variance = sumOfDiffSquares / values.length;
+ return Math.sqrt(variance);
+ }
+ }
+
+ @Override
+ public long max() {
+ return values.length == 0 ? 0L : values[values.length - 1];
+ }
+
+ @Override
+ public long min() {
+ return values.length == 0 ? 0L : values[0];
+ }
+
+ @Override
+ public double percentile(double percentile) {
+ Preconditions.checkArgument(
+ !Double.isNaN(percentile) && percentile >= 0.0 && percentile <= 1.0,
+ "Percentile point cannot be outside the range of [0.0 - 1.10]: %s",
Review Comment:
Nit: `range of [0.0 - 1.0]`, not `1.10`. Either the string has a typo or the boolean logic should be `percentile <= 1.10` but I assume it's a string typo.
##########
api/src/main/java/org/apache/iceberg/metrics/DefaultHistogram.java:
##########
@@ -0,0 +1,145 @@
+/*
+ * 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.iceberg.metrics;
+
+import java.util.Arrays;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+
+/**
+ * A default {@link Histogram} implementation that uses a fixed size reservoir like circular buffer.
+ * Oldest observation is replaced by latest observation.
+ */
+public class DefaultHistogram implements Histogram {
+ private final long[] measurements;
+ private long count;
+
+ public DefaultHistogram(int reservoirSize) {
+ this.measurements = new long[reservoirSize];
+ this.count = 0L;
+ }
+
+ @Override
+ public synchronized long count() {
+ return count;
+ }
+
+ @Override
+ public synchronized void update(long value) {
+ int index = (int) (count % measurements.length);
+ measurements[index] = value;
+ count++;
+ }
+
+ @Override
+ public Statistics statistics() {
+ int size = measurements.length;
+ if (count < (long) measurements.length) {
+ size = (int) count;
+ }
+
+ long[] values = new long[size];
+ for (int i = 0; i < values.length; ++i) {
+ synchronized (this) {
+ values[i] = measurements[i];
+ }
+ }
+
+ return new UniformWeightStatistics(values);
+ }
+
+ private static class UniformWeightStatistics implements Statistics {
+ private final long[] values;
+
+ private UniformWeightStatistics(long[] values) {
+ // since the input values is already a copied array,
+ // there is no need to copy again.
+ this.values = values;
+ Arrays.sort(this.values);
+ }
+
+ @Override
+ public long size() {
+ return values.length;
+ }
+
+ @Override
+ public double mean() {
+ if (values.length == 0) {
+ return 0.0;
+ } else {
+ double sum = 0.0;
+ for (int i = 0; i < values.length; ++i) {
+ sum += values[i];
+ }
+
+ return sum / values.length;
+ }
+ }
+
+ @Override
+ public double stdDev() {
+ if (this.values.length <= 1) {
+ return 0.0;
+ } else {
+ double mean = mean();
+ double sumOfDiffSquares = 0.0;
+ for (int i = 0; i < values.length; ++i) {
+ double diff = values[i] - mean;
+ sumOfDiffSquares += diff * diff;
+ }
+
+ double variance = sumOfDiffSquares / values.length;
+ return Math.sqrt(variance);
+ }
+ }
+
+ @Override
+ public long max() {
+ return values.length == 0 ? 0L : values[values.length - 1];
+ }
+
+ @Override
+ public long min() {
+ return values.length == 0 ? 0L : values[0];
+ }
+
+ @Override
+ public double percentile(double percentile) {
+ Preconditions.checkArgument(
+ !Double.isNaN(percentile) && percentile >= 0.0 && percentile <= 1.0,
+ "Percentile point cannot be outside the range of [0.0 - 1.10]: %s",
+ percentile);
+ if (values.length == 0) {
+ return 0.0;
+ } else {
+ double position = percentile * values.length;
+ int index = (int) position;
+ if (index < 1) {
+ return values[0];
+ } else if (index >= values.length) {
+ return values[values.length - 1];
Review Comment:
Are these two blocks needed? Particularly the `index < 1` block.
I'm ok with it as defensive coding, but wondering how practical it is or what made you think to add these blocks (e.g. can these situations occur?).
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: issues-unsubscribe@iceberg.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@iceberg.apache.org
For additional commands, e-mail: issues-help@iceberg.apache.org