Refactor Cache.CacheStats with Builder pattern

CHANGELOG.md

@@ -59,6 +59,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Update NoOpResult constructors in the Engine to be public ([#19950](https://github.com/opensearch-project/OpenSearch/pull/19950))
 - Refactor the TranslogStats and RequestCacheStats class to use the Builder pattern instead of constructors ([#19961](https://github.com/opensearch-project/OpenSearch/pull/19961))
 - Refactor the IndexPressutreStats, DeviceStats and TransportStats class to use the Builder pattern instead of constructors ([#19991](https://github.com/opensearch-project/OpenSearch/pull/19991))
+- Refactor the Cache.CacheStats class to use the Builder pattern instead of constructors ([#20015](https://github.com/opensearch-project/OpenSearch/pull/20015))
 
 ### Fixed
 - Fix Allocation and Rebalance Constraints of WeightFunction are incorrectly reset ([#19012](https://github.com/opensearch-project/OpenSearch/pull/19012))
@@ -122,6 +123,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Deprecated existing constructors in FieldDataStats and CompletionStats in favor of the new Builder ([#19936](https://github.com/opensearch-project/OpenSearch/pull/19936))
 - Deprecated existing constructors in TranslogStats and RequestCacheStats in favor of the new Builder ([#19961](https://github.com/opensearch-project/OpenSearch/pull/19961))
 - Deprecated existing constructors in IndexPressutreStats, DeviceStats and TransportStats in favor of the new Builder ([#19991](https://github.com/opensearch-project/OpenSearch/pull/19991))
+- Deprecated existing constructors in Cache.CacheStats in favor of the new Builder ([#20015](https://github.com/opensearch-project/OpenSearch/pull/20015))
 
 ### Removed
 

server/src/main/java/org/opensearch/common/cache/Cache.java

@@ -790,7 +790,7 @@ public CacheStats stats() {
             misses += segments[i].segmentStats.misses.longValue();
             evictions += segments[i].segmentStats.evictions.longValue();
         }
-        return new CacheStats(hits, misses, evictions);
+        return new CacheStats.Builder().hits(hits).misses(misses).evictions(evictions).build();
     }
 
     /**
@@ -804,6 +804,22 @@ public static class CacheStats {
         private long misses;
         private long evictions;
 
+        /**
+         * Private constructor that takes a builder.
+         * This is the sole entry point for creating a new CacheStats object.
+         * @param builder The builder instance containing all the values.
+         */
+        private CacheStats(Builder builder) {
+            this.hits = builder.hits;
+            this.misses = builder.misses;
+            this.evictions = builder.evictions;
+        }
+
+        /**
+         * This constructor will be deprecated starting in version 3.4.0.
+         * Use {@link CacheStats} instead.
+         */
+        @Deprecated
         public CacheStats(long hits, long misses, long evictions) {
             this.hits = hits;
             this.misses = misses;
@@ -821,6 +837,41 @@ public long getMisses() {
         public long getEvictions() {
             return evictions;
         }
+
+        /**
+         * Builder for the {@link CacheStats} class.
+         * Provides a fluent API for constructing a CacheStats object.
+         */
+        public static class Builder {
+            private long hits = 0;
+            private long misses = 0;
+            private long evictions = 0;
+
+            public Builder() {}
+
+            public Builder hits(long hits) {
+                this.hits = hits;
+                return this;
+            }
+
+            public Builder misses(long misses) {
+                this.misses = misses;
+                return this;
+            }
+
+            public Builder evictions(long evictions) {
+                this.evictions = evictions;
+                return this;
+            }
+
+            /**
+             * Creates a {@link CacheStats} object from the builder's current state.
+             * @return A new CacheStats instance.
+             */
+            public CacheStats build() {
+                return new CacheStats(this);
+            }
+        }
     }
 
     /**