Polish "Add expiry and bufferLength configuration properties"

See gh-27584

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsProperties.java

@@ -30,7 +30,6 @@
  * @author Jon Schneider
  * @author Alexander Abramov
  * @author Tadaya Tsuyukubo
- * @author Leo Li
  * @since 2.0.0
  */
 @ConfigurationProperties("management.metrics")
@@ -299,16 +298,16 @@ public static class Distribution {
 		private final Map<String, String> maximumExpectedValue = new LinkedHashMap<>();
 
 		/**
-		 * Specific statistic's expiry for meter IDs starting-with the specified name.
-		 * Values should be a Duration value, the key `all` can also be used to configure
-		 * all meters.
+		 * Maximum amount of time that samples for meter IDs starting with the specified
+		 * name are accumulated to decaying distribution statistics before they are reset
+		 * and rotated. The longest match wins, the key `all` can also be used to
+		 * configure all meters.
 		 */
 		private final Map<String, Duration> expiry = new LinkedHashMap<>();
 
 		/**
-		 * Specific statistic's bufferLength for meter IDs starting-with the specified
-		 * name. Samples are accumulated to statistics in ring buffers, and bufferLength
-		 * is the number to keep in the ring buffer, the key `all` can also be used to
+		 * Number of histograms for meter IDs starting with the specified name to keep in
+		 * the ring buffer. The longest match wins, the key `all` can also be used to
 		 * configure all meters.
 		 */
 		private final Map<String, Integer> bufferLength = new LinkedHashMap<>();

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/PropertiesMeterFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,6 @@
  * @author Stephane Nicoll
  * @author Artsiom Yudovin
  * @author Alexander Abramov
- * @author Leo Li
  * @since 2.0.0
  */
 public class PropertiesMeterFilter implements MeterFilter {
@@ -84,15 +83,14 @@ public DistributionStatisticConfig configure(Meter.Id id, DistributionStatisticC
 		return DistributionStatisticConfig.builder()
 				.percentilesHistogram(lookupWithFallbackToAll(distribution.getPercentilesHistogram(), id, null))
 				.percentiles(lookupWithFallbackToAll(distribution.getPercentiles(), id, null))
-				.expiry(lookupWithFallbackToAll(distribution.getExpiry(), id, null))
-				.bufferLength(lookupWithFallbackToAll(distribution.getBufferLength(), id, null))
 				.serviceLevelObjectives(
 						convertServiceLevelObjectives(id.getType(), lookup(distribution.getSlo(), id, null)))
 				.minimumExpectedValue(
 						convertMeterValue(id.getType(), lookup(distribution.getMinimumExpectedValue(), id, null)))
 				.maximumExpectedValue(
 						convertMeterValue(id.getType(), lookup(distribution.getMaximumExpectedValue(), id, null)))
-				.build().merge(config);
+				.expiry(lookupWithFallbackToAll(distribution.getExpiry(), id, null))
+				.bufferLength(lookupWithFallbackToAll(distribution.getBufferLength(), id, null)).build().merge(config);
 	}
 
 	private double[] convertServiceLevelObjectives(Meter.Type meterType, ServiceLevelObjectiveBoundary[] slo) {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/PropertiesMeterFilterTests.java

@@ -309,7 +309,7 @@ void configureWhenAllExpirySetShouldSetExpiryToValue() {
 	@Test
 	void configureWhenHasBufferLengthShouldSetBufferLengthToValue() {
 		PropertiesMeterFilter filter = new PropertiesMeterFilter(
-				createProperties("distribution.bufferLength[spring.boot]=3"));
+				createProperties("distribution.buffer-length.spring.boot=3"));
 		assertThat(
 				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
 						.isEqualTo(3);
@@ -318,7 +318,7 @@ void configureWhenHasBufferLengthShouldSetBufferLengthToValue() {
 	@Test
 	void configureWhenHasHigherBufferLengthShouldSetBufferLengthToValue() {
 		PropertiesMeterFilter filter = new PropertiesMeterFilter(
-				createProperties("distribution.bufferLength.spring=3"));
+				createProperties("distribution.buffer-length.spring=3"));
 		assertThat(
 				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
 						.isEqualTo(3);
@@ -327,15 +327,15 @@ void configureWhenHasHigherBufferLengthShouldSetBufferLengthToValue() {
 	@Test
 	void configureWhenHasHigherBufferLengthAndLowerShouldSetBufferLengthToHigher() {
 		PropertiesMeterFilter filter = new PropertiesMeterFilter(
-				createProperties("distribution.bufferLength.spring=2", "distribution.bufferLength[spring.boot]=3"));
+				createProperties("distribution.buffer-length.spring=2", "distribution.buffer-length.spring.boot=3"));
 		assertThat(
 				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
 						.isEqualTo(3);
 	}
 
 	@Test
 	void configureWhenAllBufferLengthSetShouldSetBufferLengthToValue() {
-		PropertiesMeterFilter filter = new PropertiesMeterFilter(createProperties("distribution.bufferLength.all=3"));
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(createProperties("distribution.buffer-length.all=3"));
 		assertThat(
 				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
 						.isEqualTo(3);

spring-boot-project/spring-boot-docs/src/docs/asciidoc/actuator/metrics.adoc

@@ -1153,6 +1153,10 @@ The following properties allow per-meter customization:
 | configprop:management.metrics.distribution.percentiles[]
 | Publish percentile values computed in your application
 
+| configprop:management.metrics.distribution.expiry[], configprop:management.metrics.distribution.buffer-length[]
+| Give greater weight to recent samples by accumulating them in ring buffers which rotate after a configurable expiry, with a
+configurable buffer length.
+
 | configprop:management.metrics.distribution.slo[]
 | Publish a cumulative histogram with buckets defined by your service-level objectives.
 |===