Add missing javadocs

Signed-off-by: Bhumika Saini <sabhumik@amazon.com>

server/src/main/java/org/opensearch/action/admin/cluster/remotestore/stats/RemoteStoreStats.java

@@ -24,8 +24,14 @@
  * @opensearch.internal
  */
 public class RemoteStoreStats implements Writeable, ToXContentFragment {
-
+    /**
+     * Stats related to Remote Segment Store operations
+     */
     private final RemoteRefreshSegmentTracker.Stats remoteSegmentUploadShardStats;
+
+    /**
+     * Stats related to Remote Translog Store operations
+     */
     private final RemoteTranslogTracker.Stats remoteTranslogShardStats;
 
     public RemoteStoreStats(

server/src/main/java/org/opensearch/index/remote/RemoteTranslogTracker.java

@@ -22,6 +22,9 @@
  * Stores Remote Translog Store-related stats for a given IndexShard.
  */
 public class RemoteTranslogTracker {
+    /**
+     * The shard that this tracker is associated with
+     */
     public final ShardId shardId;
 
     /**
@@ -267,6 +270,10 @@ void updateUploadTimeMsMovingAverageWindowSize(int updatedSize) {
         }
     }
 
+    /**
+     * Gets the tracker's state as seen in the stats API
+     * @return Stats object with the tracker's stats
+     */
     public RemoteTranslogTracker.Stats stats() {
         return new RemoteTranslogTracker.Stats(
             shardId,
@@ -284,6 +291,13 @@ public RemoteTranslogTracker.Stats stats() {
         );
     }
 
+    /**
+     * Validates that the sum of successful operations, failed operations, and the number of operations to add (irrespective of failed/successful) does not exceed the number of operations originally started
+     * @param startedCount Number of operations started
+     * @param failedCount Number of operations failed
+     * @param succeededCount Number of operations successful
+     * @param countToAdd Number of operations to add
+     */
     private void checkTotal(long startedCount, long failedCount, long succeededCount, long countToAdd) {
         long delta = startedCount - (failedCount + succeededCount + countToAdd);
         assert delta >= 0 : "Sum of failure count ("
@@ -445,6 +459,11 @@ public boolean equals(Object obj) {
         }
     }
 
+    /**
+     * Validates if the stats in this tracker and the stats contained in the given stats object are same or not
+     * @param other Stats object to compare this tracker against
+     * @return true if stats are same and false otherwise
+     */
     boolean hasSameStatsAs(RemoteTranslogTracker.Stats other) {
         return this.getShardId().toString().equals(other.shardId.toString())
             && this.getLastUploadTimestamp() == other.lastUploadTimestamp

server/src/main/java/org/opensearch/index/translog/RemoteFsTranslog.java

@@ -273,35 +273,30 @@ private boolean upload(Long primaryTerm, Long generation) throws IOException {
             Releasable transferReleasable = Releasables.wrap(deletionPolicy.acquireTranslogGen(getMinFileGeneration()));
             return translogTransferManager.transferSnapshot(transferSnapshotProvider, new TranslogTransferListener() {
                 /**
-                 *
+                 * Tracker holding stats related to Remote Translog Store operations
                  */
                 final RemoteTranslogTracker remoteTranslogTracker = RemoteFsTranslog.this.remoteTranslogTracker;
 
                 /**
-                 *
+                 * Files (.tlog, .ckp, metadata) to upload to Remote Translog Store
                  */
                 Set<FileSnapshot.TransferFileSnapshot> toUpload;
 
                 /**
-                 *
+                 * Total bytes to be uploaded to Remote Translog Store
                  */
                 long uploadBytes;
 
                 /**
-                 *
+                 * System nano time when the Remote Translog Store upload is started
                  */
                 long uploadStartTime;
 
                 /**
-                 *
+                 * System nano time when the Remote Translog Store upload is completed
                  */
                 long uploadEndTime;
 
-                /**
-                 *
-                 * @param transferSnapshot the transfer snapshot
-                 * @throws IOException
-                 */
                 @Override
                 public void beforeUpload(TransferSnapshot transferSnapshot) throws IOException {
                     toUpload = RemoteStoreUtils.getUploadBlobsFromSnapshot(transferSnapshot, fileTransferTracker);
@@ -311,11 +306,6 @@ public void beforeUpload(TransferSnapshot transferSnapshot) throws IOException {
                     captureStatsBeforeUpload();
                 }
 
-                /**
-                 *
-                 * @param transferSnapshot the transfer snapshot
-                 * @throws IOException
-                 */
                 @Override
                 public void onUploadComplete(TransferSnapshot transferSnapshot) throws IOException {
                     uploadEndTime = RemoteStoreUtils.getCurrentSystemNanoTime();
@@ -328,12 +318,6 @@ public void onUploadComplete(TransferSnapshot transferSnapshot) throws IOExcepti
                     logger.trace("uploaded translog for {} {} ", primaryTerm, generation);
                 }
 
-                /**
-                 *
-                 * @param transferSnapshot the transfer snapshot
-                 * @param ex the exception while processing the {@link TransferSnapshot}
-                 * @throws IOException
-                 */
                 @Override
                 public void onUploadFailed(TransferSnapshot transferSnapshot, Exception ex) throws IOException {
                     uploadEndTime = RemoteStoreUtils.getCurrentSystemNanoTime();
@@ -349,11 +333,17 @@ public void onUploadFailed(TransferSnapshot transferSnapshot, Exception ex) thro
                     }
                 }
 
+                /**
+                 * Adds relevant stats to the tracker when an upload is started
+                 */
                 private void captureStatsBeforeUpload() {
                     remoteTranslogTracker.incrementUploadsStarted();
                     remoteTranslogTracker.addUploadBytesStarted(uploadBytes);
                 }
 
+                /**
+                 * Adds relevant stats to the tracker when an upload is successfully completed
+                 */
                 private void captureStatsOnUploadSuccess() {
                     long uploadDurationInMillis = (uploadEndTime - uploadStartTime) / 1_000_000L;
                     remoteTranslogTracker.incrementUploadsSucceeded();
@@ -369,6 +359,9 @@ private void captureStatsOnUploadSuccess() {
                     remoteTranslogTracker.updateUploadTimeMovingAverage(uploadDurationInMillis);
                 }
 
+                /**
+                 * Adds relevant stats to the tracker when an upload has failed
+                 */
                 private void captureStatsOnUploadFailure() {
                     remoteTranslogTracker.incrementUploadsFailed();
                     remoteTranslogTracker.addUploadTimeInMillis((uploadEndTime - uploadStartTime) / 1_000_000L);