Fix flakyness in RemoteStoreRefreshListenerIT (opensearch-project#8547)

---------

Signed-off-by: Ashish Singh <ssashish@amazon.com>

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreRefreshListenerIT.java

@@ -27,7 +27,6 @@
 @OpenSearchIntegTestCase.ClusterScope(scope = OpenSearchIntegTestCase.Scope.TEST, numDataNodes = 0)
 public class RemoteStoreRefreshListenerIT extends AbstractRemoteStoreMockRepositoryIntegTestCase {
 
-    @AwaitsFix(bugUrl = "https://github.com/opensearch-project/OpenSearch/issues/7703")
     public void testRemoteRefreshRetryOnFailure() throws Exception {
 
         Path location = randomRepoPath().toAbsolutePath();

server/src/main/java/org/opensearch/index/shard/RemoteStoreRefreshListener.java

@@ -47,7 +47,6 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.stream.Collectors;
@@ -96,9 +95,9 @@ public final class RemoteStoreRefreshListener implements ReferenceManager.Refres
     private long primaryTerm;
 
     /**
-     * Semaphore that ensures there is only 1 retry scheduled at any time.
+     * This boolean is used to ensure that there is only 1 retry scheduled/running at any time.
      */
-    private final Semaphore SCHEDULE_RETRY_PERMITS = new Semaphore(1);
+    private final AtomicBoolean retryScheduled = new AtomicBoolean(false);
 
     private volatile Iterator<TimeValue> backoffDelayIterator;
 
@@ -321,6 +320,9 @@ private void onSuccessfulSegmentsSync(
     private void cancelAndResetScheduledCancellableRetry() {
         if (scheduledCancellableRetry != null && scheduledCancellableRetry.getDelay(TimeUnit.NANOSECONDS) > 0) {
             scheduledCancellableRetry.cancel();
+            // Since we are cancelling the retry attempt as an internal/external refresh happened already before the retry job could be
+            // started and the current run successfully uploaded the segments.
+            retryScheduled.set(false);
         }
         scheduledCancellableRetry = null;
     }
@@ -333,14 +335,14 @@ private void resetBackOffDelayIterator() {
     }
 
     private void afterSegmentsSync(boolean isRetry, boolean shouldRetry) {
-        // If this was a retry attempt, then we release the semaphore at the end so that further retries can be scheduled
+        // If this was a retry attempt, then we set the retryScheduled to false so that the next retry (if needed) can be scheduled
         if (isRetry) {
-            SCHEDULE_RETRY_PERMITS.release();
+            retryScheduled.set(false);
         }
 
         // If there are failures in uploading segments, then we should retry as search idle can lead to
         // refresh not occurring until write happens.
-        if (shouldRetry && indexShard.state() != IndexShardState.CLOSED && SCHEDULE_RETRY_PERMITS.tryAcquire()) {
+        if (shouldRetry && indexShard.state() != IndexShardState.CLOSED && retryScheduled.compareAndSet(false, true)) {
             scheduledCancellableRetry = indexShard.getThreadPool()
                 .schedule(() -> this.syncSegments(true), backoffDelayIterator.next(), ThreadPool.Names.REMOTE_REFRESH);
         }