Provide expiry and bufferLength configuration properties for configuring a distribution statistic

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.autoconfigure.metrics;
 
+import java.time.Duration;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
@@ -29,6 +30,7 @@
  * @author Jon Schneider
  * @author Alexander Abramov
  * @author Tadaya Tsuyukubo
+ * @author Leo Li
  * @since 2.0.0
  */
 @ConfigurationProperties("management.metrics")
@@ -296,6 +298,21 @@ 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.
+		 */
+		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
+		 * configure all meters.
+		 */
+		private final Map<String, Integer> bufferLength = new LinkedHashMap<>();
+
 		public Map<String, Boolean> getPercentilesHistogram() {
 			return this.percentilesHistogram;
 		}
@@ -316,6 +333,14 @@ public Map<String, String> getMaximumExpectedValue() {
 			return this.maximumExpectedValue;
 		}
 
+		public Map<String, Duration> getExpiry() {
+			return this.expiry;
+		}
+
+		public Map<String, Integer> getBufferLength() {
+			return this.bufferLength;
+		}
+
 	}
 
 }

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

@@ -42,6 +42,7 @@
  * @author Stephane Nicoll
  * @author Artsiom Yudovin
  * @author Alexander Abramov
+ * @author Leo Li
  * @since 2.0.0
  */
 public class PropertiesMeterFilter implements MeterFilter {
@@ -83,6 +84,8 @@ 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(

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

@@ -41,6 +41,7 @@
  * @author Phillip Webb
  * @author Jon Schneider
  * @author Artsiom Yudovin
+ * @author Leo Li
  */
 class PropertiesMeterFilterTests {
 
@@ -275,6 +276,71 @@ void configureWhenHasHigherMaximumExpectedValueAndLowerShouldSetMaximumExpectedV
 				.getMaximumExpectedValueAsDouble()).isEqualTo(Duration.ofMillis(10000).toNanos());
 	}
 
+	@Test
+	void configureWhenHasExpiryShouldSetExpiryToValue() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(
+				createProperties("distribution.expiry[spring.boot]=5ms"));
+		assertThat(filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getExpiry())
+				.isEqualTo(Duration.ofMillis(5));
+	}
+
+	@Test
+	void configureWhenHasHigherExpiryShouldSetExpiryToValue() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(createProperties("distribution.expiry.spring=5ms"));
+		assertThat(filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getExpiry())
+				.isEqualTo(Duration.ofMillis(5));
+	}
+
+	@Test
+	void configureWhenHasHigherExpiryAndLowerShouldSetExpiryToHigher() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(
+				createProperties("distribution.expiry.spring=5ms", "distribution.expiry[spring.boot]=10ms"));
+		assertThat(filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getExpiry())
+				.isEqualTo(Duration.ofMillis(10));
+	}
+
+	@Test
+	void configureWhenAllExpirySetShouldSetExpiryToValue() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(createProperties("distribution.expiry.all=5ms"));
+		assertThat(filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getExpiry())
+				.isEqualTo(Duration.ofMillis(5));
+	}
+
+	@Test
+	void configureWhenHasBufferLengthShouldSetBufferLengthToValue() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(
+				createProperties("distribution.bufferLength[spring.boot]=3"));
+		assertThat(
+				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
+						.isEqualTo(3);
+	}
+
+	@Test
+	void configureWhenHasHigherBufferLengthShouldSetBufferLengthToValue() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(
+				createProperties("distribution.bufferLength.spring=3"));
+		assertThat(
+				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
+						.isEqualTo(3);
+	}
+
+	@Test
+	void configureWhenHasHigherBufferLengthAndLowerShouldSetBufferLengthToHigher() {
+		PropertiesMeterFilter filter = new PropertiesMeterFilter(
+				createProperties("distribution.bufferLength.spring=2", "distribution.bufferLength[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"));
+		assertThat(
+				filter.configure(createMeterId("spring.boot"), DistributionStatisticConfig.DEFAULT).getBufferLength())
+						.isEqualTo(3);
+	}
+
 	private Id createMeterId(String name) {
 		Meter.Type meterType = Type.TIMER;
 		return createMeterId(name, meterType);