fix(bucket-retriever): Fix flaky tests by removing dependency on slee…

…ping in tests (#7223)

atlasdb-impl-shared/src/main/java/com/palantir/atlasdb/sweep/asts/ShardedSweepableBucketRetriever.java

@@ -21,13 +21,13 @@
 import com.palantir.atlasdb.sweep.asts.SweepStateCoordinator.SweepableBucket;
 import com.palantir.atlasdb.sweep.queue.ShardAndStrategy;
 import com.palantir.atlasdb.table.description.SweeperStrategy;
+import com.palantir.common.base.RunnableCheckedException;
 import com.palantir.refreshable.Refreshable;
 import com.palantir.tracing.CloseableTracer;
 import java.time.Duration;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.ThreadLocalRandom;
-import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
@@ -41,10 +41,8 @@ public final class ShardedSweepableBucketRetriever implements SweepableBucketRet
 
     private final Refreshable<Integer> maxParallelism;
 
-    private final Refreshable<Duration> maxBackoff;
-
-    // Exists to facilitate testing in unit tests, rather than needing to mock out ThreadLocalRandom.
-    private final Supplier<Long> backoffMillisGenerator;
+    // Exists to facilitate testing in unit tests, rather than needing to mock out ThreadLocalRandom and Thread#sleep.
+    private final RunnableCheckedException<InterruptedException> sleeper;
 
     @VisibleForTesting
     ShardedSweepableBucketRetriever(
@@ -54,16 +52,14 @@ public final class ShardedSweepableBucketRetriever implements SweepableBucketRet
             ShardedSweepTimestampManager sweepTimestampManager,
             ParallelTaskExecutor parallelTaskExecutor,
             Refreshable<Integer> maxParallelism,
-            Refreshable<Duration> maxBackoff,
-            Supplier<Long> backoffMillisGenerator) {
+            RunnableCheckedException<InterruptedException> sleeper) {
         this.numShards = numShards;
         this.shardedRetrievalStrategy = shardedRetrievalStrategy;
         this.strategy = strategy;
         this.sweepTimestampManager = sweepTimestampManager;
         this.parallelTaskExecutor = parallelTaskExecutor;
         this.maxParallelism = maxParallelism;
-        this.maxBackoff = maxBackoff;
-        this.backoffMillisGenerator = backoffMillisGenerator;
+        this.sleeper = sleeper;
     }
 
     public static SweepableBucketRetriever create(
@@ -81,9 +77,9 @@ public static SweepableBucketRetriever create(
                 sweepTimestampManager,
                 parallelTaskExecutor,
                 maxParallelism,
-                maxBackoff,
                 // We want _some_ backoff, hence the minimum is 1, rather than the standard 0.
-                () -> ThreadLocalRandom.current().nextLong(1, maxBackoff.get().toMillis()));
+                () -> Thread.sleep(
+                        ThreadLocalRandom.current().nextLong(1, maxBackoff.get().toMillis())));
     }
 
     @Override
@@ -117,7 +113,7 @@ public Set<SweepableBucket> getSweepableBuckets() {
      */
     private List<SweepableBucket> getSweepableBucketsForShardWithJitter(int shard) {
         try {
-            Thread.sleep(backoffMillisGenerator.get());
+            sleeper.run();
             return getSweepableBucketsForShard(shard);
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();

atlasdb-impl-shared/src/test/java/com/palantir/atlasdb/sweep/asts/ShardedSweepableBucketRetrieverTest.java

@@ -35,6 +35,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -52,10 +53,11 @@ public class ShardedSweepableBucketRetrieverTest {
             SweepTimestamps.builder().sweepTimestamp(1).lastSweptTimestamp(12).build();
     private final SettableRefreshable<Integer> numShards = Refreshable.create(1);
     private final SettableRefreshable<Integer> maxParallelism = Refreshable.create(1);
-    private final SettableRefreshable<Duration> maxBackoff = Refreshable.create(Duration.ofMillis(0));
     private final TestShardedRetrievalStrategy strategy = new TestShardedRetrievalStrategy();
     private final TestParallelTaskExecutor parallelTaskExecutor = new TestParallelTaskExecutor();
     private final ExecutorService executorService = PTExecutors.newSingleThreadScheduledExecutor();
+    private final AtomicBoolean wasSleepCalled = new AtomicBoolean(false);
+
     private SweepableBucketRetriever retriever;
 
     @BeforeEach
@@ -67,11 +69,7 @@ public void before() {
                 shardAndStrategy -> SWEEP_TIMESTAMPS,
                 parallelTaskExecutor,
                 maxParallelism,
-                maxBackoff,
-
-                // The tests that rely on this are based off the sleep duration being equal to the maxBackoff.
-                // so for simplicity, it's set to that for all tests.
-                () -> maxBackoff.get().toMillis());
+                () -> wasSleepCalled.set(true));
     }
 
     @AfterEach
@@ -106,27 +104,22 @@ public void updatesToMaxParallelismAreReflectedInSubsequentRequests() {
     }
 
     @Test
-    public void boundedBackoffBetweenRequests() throws InterruptedException {
-        Duration backoff = Duration.ofMillis(100);
-        maxBackoff.update(backoff);
-        CountDownLatch latch = new CountDownLatch(1);
-        Future<?> future = executorService.submit(() -> {
-            latch.countDown();
-            retriever.getSweepableBuckets();
-        });
-        latch.await(); // reduce flakes from delay caused by executor not starting
-
-        Awaitility.await()
-                .atLeast(backoff)
-                // add an extra leeway to account for any context switching.
-                .atMost(backoff.plus(Duration.ofMillis(20)))
-                .pollInterval(Duration.ofMillis(10))
-                .until(future::isDone);
+    public void callsSleeperBetweenRequests() {
+        retriever.getSweepableBuckets();
+        assertThat(wasSleepCalled).isTrue();
     }
 
     @Test
-    public void backoffCanBeInterrupted() throws InterruptedException {
-        maxBackoff.update(Duration.ofSeconds(10));
+    public void defaultSleeperCanBeInterrupted() throws InterruptedException {
+        retriever = ShardedSweepableBucketRetriever.create(
+                numShards,
+                SweeperStrategy.CONSERVATIVE,
+                strategy,
+                shardAndStrategy -> SWEEP_TIMESTAMPS,
+                parallelTaskExecutor,
+                maxParallelism,
+                Refreshable.only(Duration.ofMinutes(10)));
+
         CountDownLatch latch = new CountDownLatch(1);
         Future<?> future = executorService.submit(() -> {
             latch.countDown();
@@ -136,8 +129,8 @@ public void backoffCanBeInterrupted() throws InterruptedException {
         future.cancel(true);
         executorService.shutdown();
 
-        // Even though the backoff in 10s, interrupting the task should make it finish much faster.
-        Awaitility.await().atMost(Duration.ofMillis(200)).untilAsserted(() -> assertThat(
+        // Even though the backoff is up to 10 minutes, interrupting the task should make it finish much faster.
+        Awaitility.await().atMost(Duration.ofSeconds(1)).untilAsserted(() -> assertThat(
                         executorService.awaitTermination(0, TimeUnit.MILLISECONDS))
                 .isTrue());
     }