Note that the default max elapsed time is {@link Long#MAX_VALUE}. Use - * {@link #setMaxElapsedTime(long)} to limit the maximum length of time - * that an instance should accumulate before returning - * {@link BackOffExecution#STOP}. + *
Note that the default max elapsed time and maximum number of attempts are both
+ * {@link Long#MAX_VALUE}. Use {@link #setMaxElapsedTime(long)} to limit the maximum
+ * length of time that an instance should accumulate before returning
+ * {@link BackOffExecution#STOP}. Alternatively, use {@link #setMaxAttempts} to limit
+ * the number of attempts. The execution stops when any of those two limit is reached.
*
* @author Stephane Nicoll
+ * @author Gary Russell
* @since 4.1
*/
public class ExponentialBackOff implements BackOff {
@@ -74,6 +76,10 @@ public class ExponentialBackOff implements BackOff {
*/
public static final long DEFAULT_MAX_ELAPSED_TIME = Long.MAX_VALUE;
+ /**
+ * The default maximum attempts.
+ */
+ public static final int DEFAULT_MAX_ATTEMPTS = Integer.MAX_VALUE;
private long initialInterval = DEFAULT_INITIAL_INTERVAL;
@@ -83,6 +89,8 @@ public class ExponentialBackOff implements BackOff {
private long maxElapsedTime = DEFAULT_MAX_ELAPSED_TIME;
+ private int maxAttempts = DEFAULT_MAX_ATTEMPTS;
+
/**
* Create an instance with the default settings.
@@ -90,6 +98,7 @@ public class ExponentialBackOff implements BackOff {
* @see #DEFAULT_MULTIPLIER
* @see #DEFAULT_MAX_INTERVAL
* @see #DEFAULT_MAX_ELAPSED_TIME
+ * @see #DEFAULT_MAX_ATTEMPTS
*/
public ExponentialBackOff() {
}
@@ -152,6 +161,8 @@ public class ExponentialBackOff implements BackOff {
/**
* The maximum elapsed time in milliseconds after which a call to
* {@link BackOffExecution#nextBackOff()} returns {@link BackOffExecution#STOP}.
+ * @param maxElapsedTime the maximum elapsed time
+ * @see #setMaxAttempts(int)
*/
public void setMaxElapsedTime(long maxElapsedTime) {
this.maxElapsedTime = maxElapsedTime;
@@ -160,11 +171,35 @@ public class ExponentialBackOff implements BackOff {
/**
* Return the maximum elapsed time in milliseconds after which a call to
* {@link BackOffExecution#nextBackOff()} returns {@link BackOffExecution#STOP}.
+ * @return the maximum elapsed time
+ * @see #getMaxAttempts()
*/
public long getMaxElapsedTime() {
return this.maxElapsedTime;
}
+ /**
+ * The maximum number of attempts after which a call to
+ * {@link BackOffExecution#nextBackOff()} returns {@link BackOffExecution#STOP}.
+ * @param maxAttempts the maximum number of attempts.
+ * @since 6.1
+ * @see #setMaxElapsedTime(long)
+ */
+ public void setMaxAttempts(int maxAttempts) {
+ this.maxAttempts = maxAttempts;
+ }
+
+ /**
+ * Return the maximum number of attempts after which a call to
+ * {@link BackOffExecution#nextBackOff()} returns {@link BackOffExecution#STOP}.
+ * @return the maximum number of attempts
+ * @since 6.1
+ * @see #getMaxElapsedTime()
+ */
+ public int getMaxAttempts() {
+ return this.maxAttempts;
+ }
+
@Override
public BackOffExecution start() {
return new ExponentialBackOffExecution();
@@ -182,14 +217,18 @@ public class ExponentialBackOff implements BackOff {
private long currentElapsedTime = 0;
+ private int attempts;
+
@Override
public long nextBackOff() {
- if (this.currentElapsedTime >= maxElapsedTime) {
+ if (this.currentElapsedTime >= getMaxElapsedTime()
+ || this.attempts >= getMaxAttempts()) {
return STOP;
}
long nextInterval = computeNextInterval();
this.currentElapsedTime += nextInterval;
+ this.attempts++;
return nextInterval;
}
diff --git a/spring-core/src/test/java/org/springframework/util/ExponentialBackOffTests.java b/spring-core/src/test/java/org/springframework/util/ExponentialBackOffTests.java
index 8080f82fe0a..a539479c77c 100644
--- a/spring-core/src/test/java/org/springframework/util/ExponentialBackOffTests.java
+++ b/spring-core/src/test/java/org/springframework/util/ExponentialBackOffTests.java
@@ -1,5 +1,5 @@
/*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -16,6 +16,10 @@
package org.springframework.util;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.IntStream;
+
import org.junit.jupiter.api.Test;
import org.springframework.util.backoff.BackOffExecution;
@@ -25,6 +29,8 @@ import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
/**
+ * Tests for {@link ExponentialBackOff}.
+ *
* @author Stephane Nicoll
*/
class ExponentialBackOffTests {
@@ -131,4 +137,17 @@ class ExponentialBackOffTests {
assertThat(execution.toString()).isEqualTo("ExponentialBackOff{currentInterval=4000ms, multiplier=2.0}");
}
+ @Test
+ void maxAttempts() {
+ ExponentialBackOff backOff = new ExponentialBackOff();
+ backOff.setInitialInterval(1000L);
+ backOff.setMultiplier(2.0);
+ backOff.setMaxInterval(10000L);
+ backOff.setMaxAttempts(6);
+ List