Update IndicesRequestCache.java

Signed-off-by: Kiran Prakash <awskiran@amazon.com>

server/src/main/java/org/opensearch/indices/IndicesRequestCache.java

@@ -465,6 +465,8 @@ public int hashCode() {
      *
      * It also keeps track of the number of stale keys in the cache (staleKeysCount) and a staleness threshold,
      * which is used to determine when the cache should be cleaned.
+     *
+     * If Staleness threshold is 0, we do not keep track of stale keys in the cache
      * */
     class IndicesRequestCacheCleanupManager {
         private final Set<CleanupKey> keysToClean;
@@ -475,10 +477,10 @@ class IndicesRequestCacheCleanupManager {
         private final Lock writeLock;
 
         IndicesRequestCacheCleanupManager(double stalenessThreshold) {
+            this.stalenessThreshold = stalenessThreshold;
             this.keysToClean = ConcurrentCollections.newConcurrentSet();
             this.cleanupKeyToCountMap = ConcurrentCollections.newConcurrentMap();
             this.staleKeysCount = new AtomicInteger(0);
-            this.stalenessThreshold = stalenessThreshold;
             ReadWriteLock rwLock = new ReentrantReadWriteLock();
             this.readLock = rwLock.readLock();
             this.writeLock = rwLock.writeLock();
@@ -507,7 +509,10 @@ void enqueueCleanupKey(CleanupKey cleanupKey) {
          *
          * @param cleanupKey the CleanupKey to be updated in the map
          */
-        private void updateCleanupKeyToCountMap(CleanupKey cleanupKey) { // TODO call this oncached
+        private void updateCleanupKeyToCountMap(CleanupKey cleanupKey) {
+            if(stalenessThreshold == 0.0) {
+                return;
+            }
             IndexShard indexShard = (IndexShard) cleanupKey.entity.getCacheIdentity();
             if (indexShard == null) {
                 logger.warn("IndexShard is null for CleanupKey: {} while cleaning Indices Request Cache", cleanupKey.readerCacheKeyId);
@@ -524,13 +529,17 @@ private void updateCleanupKeyToCountMap(CleanupKey cleanupKey) { // TODO call th
         /**
          * Updates the count of stale keys in the cache.
          * This method is called when a CleanupKey is added to the keysToClean set.
+         *
          * It increments the staleKeysCount by the count of the CleanupKey in the cleanupKeyToCountMap.
          * If the CleanupKey's readerCacheKeyId is null or the CleanupKey's entity is not open, it increments the staleKeysCount
          * by the total count of keys associated with the CleanupKey's ShardId in the cleanupKeyToCountMap and removes the ShardId from the map.
          *
          * @param cleanupKey the CleanupKey that has been marked for cleanup
          */
         private void updateStaleKeysCount(CleanupKey cleanupKey) {
+            if(stalenessThreshold == 0.0) {
+                return;
+            }
             IndexShard indexShard = (IndexShard) cleanupKey.entity.getCacheIdentity();
             if (indexShard == null) {
                 logger.warn("IndexShard is null for CleanupKey: {}", cleanupKey.readerCacheKeyId);
@@ -686,6 +695,9 @@ private boolean shouldRemoveKey(Key key, Set<CleanupKey> cleanupKeysFromOutdated
          * @return true if the cache cleanup process can be skipped, false otherwise.
          */
         private boolean canSkipCacheCleanup(double cleanThresholdPercent) {
+            if(cleanThresholdPercent == 0.0) {
+                return false;
+            }
             readLock.lock();
             try {
                 if (staleKeysInCachePercentage() < cleanThresholdPercent) {