[Remote Store] Emit correct global checkpoint during translog upload

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

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

@@ -18,6 +18,7 @@
 import org.opensearch.action.admin.indices.settings.put.UpdateSettingsRequest;
 import org.opensearch.action.index.IndexResponse;
 import org.opensearch.action.search.SearchPhaseExecutionException;
+import org.opensearch.client.Requests;
 import org.opensearch.cluster.health.ClusterHealthStatus;
 import org.opensearch.cluster.metadata.IndexMetadata;
 import org.opensearch.cluster.routing.RecoverySource;
@@ -202,7 +203,7 @@ public void testRemoteTranslogCleanup() throws Exception {
 
     public void testStaleCommitDeletionWithInvokeFlush() throws Exception {
         String dataNode = internalCluster().startNode();
-        createIndex(INDEX_NAME, remoteStoreIndexSettings(1, 10000l, -1));
+        createIndex(INDEX_NAME, remoteStoreIndexSettings(1, 10000L, -1));
         int numberOfIterations = randomIntBetween(5, 15);
         indexData(numberOfIterations, true, INDEX_NAME);
         String segmentsPathFixedPrefix = RemoteStoreSettings.CLUSTER_REMOTE_STORE_SEGMENTS_PATH_PREFIX.get(getNodeSettings());
@@ -1011,4 +1012,73 @@ public void testAsyncTranslogDurabilityRestrictionsThroughIdxTemplates() throws
                 .get()
         );
     }
+
+    public void testCloseIndexWithNoOpSyncAndFlushForSyncTranslog() throws InterruptedException {
+        internalCluster().startNodes(3);
+        client().admin()
+            .cluster()
+            .prepareUpdateSettings()
+            .setTransientSettings(Settings.builder().put(CLUSTER_REMOTE_TRANSLOG_BUFFER_INTERVAL_SETTING.getKey(), "5s"))
+            .get();
+        Settings.Builder settings = Settings.builder()
+            .put(remoteStoreIndexSettings(0, 10000L, -1))
+            .put(IndexSettings.INDEX_REFRESH_INTERVAL_SETTING.getKey(), "1s");
+        createIndex(INDEX_NAME, settings.build());
+        CountDownLatch latch = new CountDownLatch(1);
+        new Thread(() -> {
+            if (randomBoolean()) {
+                for (int i = 0; i < randomIntBetween(1, 5); i++) {
+                    indexSingleDoc(INDEX_NAME);
+                }
+                flushAndRefresh(INDEX_NAME);
+            }
+            // Index single doc to start the asyn io processor to run which will lead to 10s wait time before the next sync.
+            indexSingleDoc(INDEX_NAME);
+            // Reduce the latch for the main thread to flush after some sleep.
+            latch.countDown();
+            // Index another doc and in this case the flush would have happened before the sync.
+            indexSingleDoc(INDEX_NAME);
+        }).start();
+        // Wait for atleast one doc to be ingested.
+        latch.await();
+        // Sleep for some time for the next doc to be present in lucene buffer. If flush happens first before the doc #2
+        // gets indexed, then it goes into the happy case where the close index happens succefully.
+        Thread.sleep(1000);
+        // Flush so that the subsequent sync or flushes are no-op.
+        flush(INDEX_NAME);
+        // Closing the index involves translog.sync and shard.flush which are now no-op.
+        client().admin().indices().close(Requests.closeIndexRequest(INDEX_NAME)).actionGet();
+        Thread.sleep(10000);
+        ensureGreen(INDEX_NAME);
+    }
+
+    public void testCloseIndexWithNoOpSyncAndFlushForAsyncTranslog() throws InterruptedException {
+        internalCluster().startNodes(3);
+        Settings.Builder settings = Settings.builder()
+            .put(remoteStoreIndexSettings(0, 10000L, -1))
+            .put(IndexSettings.INDEX_REFRESH_INTERVAL_SETTING.getKey(), "1s")
+            .put(IndexSettings.INDEX_TRANSLOG_DURABILITY_SETTING.getKey(), Durability.ASYNC)
+            .put(IndexSettings.INDEX_TRANSLOG_SYNC_INTERVAL_SETTING.getKey(), "10s");
+        createIndex(INDEX_NAME, settings.build());
+        CountDownLatch latch = new CountDownLatch(1);
+        new Thread(() -> {
+            // Index some docs to start the asyn io processor to run which will lead to 10s wait time before the next sync.
+            indexSingleDoc(INDEX_NAME);
+            indexSingleDoc(INDEX_NAME);
+            indexSingleDoc(INDEX_NAME);
+            // Reduce the latch for the main thread to flush after some sleep.
+            latch.countDown();
+        }).start();
+        // Wait for atleast one doc to be ingested.
+        latch.await();
+        // Sleep for some time for the next doc to be present in lucene buffer. If flush happens first before the doc #2
+        // gets indexed, then it goes into the happy case where the close index happens succefully.
+        Thread.sleep(1000);
+        // Flush so that the subsequent sync or flushes are no-op.
+        flush(INDEX_NAME);
+        // Closing the index involves translog.sync and shard.flush which are now no-op.
+        client().admin().indices().close(Requests.closeIndexRequest(INDEX_NAME)).actionGet();
+        Thread.sleep(10000);
+        ensureGreen(INDEX_NAME);
+    }
 }