Prevent CachedSupplier jitter from cycling through low values (#6811)

* Prevent CachedSupplier.maxStaleFailureJitter() from cycling through low values

* Update CachedSupplierTest

Author: davidh44

.changes/2.42.18.json

@@ -31,6 +31,12 @@
             "category": "AWS SDK for Java v2",
             "contributor": "",
             "description": "Updated endpoint and partition metadata."
+        },
+        {
+            "type": "bugfix",
+            "category": "AWS SDK for Java v2",
+            "contributor": "",
+            "description": "Fix bug in CachedSupplier that disabled InstanceProfileCredentialsProvider credential refreshing after 58 consecutive failures."
         }
     ]
 }

.changes/next-release/bugfix-AWSSDKforJavav2-a3a0e71.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Fix bug in CachedSupplier that retries aggressively after many consecutive failures"
+}

utils/src/main/java/software/amazon/awssdk/utils/cache/CachedSupplier.java

@@ -334,13 +334,22 @@ private Duration maxPrefetchJitter(RefreshResult<T> result) {
     }
 
     private Duration maxStaleFailureJitter(int numFailures) {
+        // prevent cycling back through low values
+        if (numFailures > 63) {
+            return Duration.ofSeconds(10);
+        }
         long exponentialBackoffMillis = (1L << numFailures - 1) * 100;
         if (exponentialBackoffMillis <= 0) {
             exponentialBackoffMillis = Long.MAX_VALUE;
         }
         return ComparableUtils.minimum(Duration.ofMillis(exponentialBackoffMillis), Duration.ofSeconds(10));
     }
 
+    @SdkTestInternalApi
+    protected Duration maxStaleFailureJitterTest(int numFailures) {
+        return maxStaleFailureJitter(numFailures);
+    }
+
     private Instant jitterTime(Instant time, Duration jitterStart, Duration jitterEnd) {
         long jitterRange = jitterEnd.minus(jitterStart).toMillis();
         long jitterAmount = Math.abs(jitterRandom.nextLong() % jitterRange);

utils/src/test/java/software/amazon/awssdk/utils/cache/CachedSupplierTest.java

@@ -27,6 +27,7 @@
 
 import java.io.Closeable;
 import java.time.Clock;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
@@ -362,6 +363,28 @@ public void throwIsHiddenIfValueIsStaleInAllowMode() throws InterruptedException
         }
     }
 
+    @Test
+    public void maxStaleFailureJitter_shouldNotReturnNegativeOrCycleLowValues() {
+        CachedSupplier<String> supplier = CachedSupplier.builder(() -> RefreshResult.builder("v")
+                                                                                    .staleTime(Instant.MAX)
+                                                                                    .build())
+                                                        .build();
+
+        for (int i = 1; i <= 70; i++) {
+            Duration jitter = supplier.maxStaleFailureJitterTest(i);
+            assertThat(jitter)
+                .as("numFailures=%d: jitter must be positive", i)
+                .isPositive();
+
+            if (i > 64) {
+                assertThat(jitter)
+                    .isEqualTo(Duration.ofSeconds(10));
+            }
+        }
+
+        supplier.close();
+    }
+
     @Test
     public void basicCachingWorks() {
         try (WaitingSupplier waitingSupplier = new WaitingSupplier(future(), future())) {