Fix getTime field name to time in GetStats (#16894) (#17009)

* Fix getTime field name to time in GetStats (#16894)

Signed-off-by: hye-on <ain0103@naver.com>

* Update PR number in changelog

Signed-off-by: hye-on <ain0103@naver.com>

* Deprecate getTime field and add time field in GetStats for backward compatibility

Signed-off-by: hye-on <ain0103@naver.com>

* Add forRemoval flag to getTime field for future removal

Signed-off-by: hye-on <ain0103@naver.com>

* Changed to use field instead of humanReadableField for GET_TIME in JSON response

Replaced the use of builder.humanReadableField for the GET_TIME field with builder.field(Fields.GET_TIME, Objects.toString(getTime())). This prevents the duplication of the time_in_millis field.

Signed-off-by: hye-on <ain0103@naver.com>

* Add test to validate getTime and time fields in _stats API response

getTime and time fields are verified to be included in the _stats API response and correctly aligned.

Signed-off-by: hye-on <ain0103@naver.com>

* Fix formatting in GetStats.java

Signed-off-by: hye-on <ain0103@naver.com>

* Rename test file to better reflect test purpose

Signed-off-by: hye-on <ain0103@naver.com>

* Test Add skip version for stats API human filter test under 2.19.99

Signed-off-by: hye-on <ain0103@naver.com>

* Remove unnecessary changelog entries

Signed-off-by: hye-on <ain0103@naver.com>

* Add a line for styling purposes

Signed-off-by: hye-on <ain0103@naver.com>

---------

Signed-off-by: hye-on <ain0103@naver.com>
(cherry picked from commit fe1f0d8)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -23,6 +23,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add search replica stats to segment replication stats API ([#16678](https://github.com/opensearch-project/OpenSearch/pull/16678))
 - Introduce framework for auxiliary transports and an experimental gRPC transport plugin ([#16534](https://github.com/opensearch-project/OpenSearch/pull/16534))
 - Support searching from doc_value using termQueryCaseInsensitive/termQuery in flat_object/keyword field([#16974](https://github.com/opensearch-project/OpenSearch/pull/16974/))
+- Added a new `time` field to replace the deprecated `getTime` field in `GetStats`. ([#17009](https://github.com/opensearch-project/OpenSearch/pull/17009))
 
 ### Dependencies
 - Bump `com.google.cloud:google-cloud-core-http` from 2.23.0 to 2.47.0 ([#16504](https://github.com/opensearch-project/OpenSearch/pull/16504))
@@ -69,6 +70,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Deprecated
 - Performing update operation with default pipeline or final pipeline is deprecated ([#16712](https://github.com/opensearch-project/OpenSearch/pull/16712))
+- Marked `getTime` field as deprecated in favor of the new `time` field. ([#17009](https://github.com/opensearch-project/OpenSearch/pull/17009))
 
 ### Removed
 

rest-api-spec/src/main/resources/rest-api-spec/test/indices.stats/60_include_both_time_and_gettime_in_stats.yml

@@ -0,0 +1,36 @@
+---
+setup:
+  - do:
+      indices.create:
+        index: test1
+        body:
+          settings:
+            number_of_shards: 1
+            number_of_replicas: 0
+        wait_for_active_shards: all
+
+  - do:
+      index:
+        index: test1
+        id: 1
+        body: { "foo": "bar" }
+
+  - do:
+      indices.refresh:
+        index: test1
+
+---
+"Test _stats API includes both time and getTime metrics with human filter":
+  - skip:
+      version: " - 2.19.99"
+      reason: "this change is added in 3.0.0"
+
+  - do:
+      indices.stats:
+        metric: [ get ]
+        human: true
+
+  - is_true: _all.primaries.get.time
+  - is_true: _all.primaries.get.getTime
+  - match: { _all.primaries.get.time: "0s" }
+  - match: { _all.primaries.get.getTime: "0s" }

server/src/main/java/org/opensearch/index/get/GetStats.java

@@ -41,6 +41,7 @@
 import org.opensearch.core.xcontent.XContentBuilder;
 
 import java.io.IOException;
+import java.util.Objects;
 
 /**
  * Stats for a search get
@@ -137,6 +138,7 @@ public long current() {
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(Fields.GET);
         builder.field(Fields.TOTAL, getCount());
+        builder.field(Fields.GET_TIME, Objects.toString(getTime()));
         builder.humanReadableField(Fields.TIME_IN_MILLIS, Fields.TIME, getTime());
         builder.field(Fields.EXISTS_TOTAL, existsCount);
         builder.humanReadableField(Fields.EXISTS_TIME_IN_MILLIS, Fields.EXISTS_TIME, getExistsTime());
@@ -155,7 +157,12 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
     static final class Fields {
         static final String GET = "get";
         static final String TOTAL = "total";
-        static final String TIME = "getTime";
+        /**
+         * Deprecated field name for time. Use {@link #TIME} instead.
+         */
+        @Deprecated(forRemoval = true)
+        static final String GET_TIME = "getTime";
+        static final String TIME = "time";
         static final String TIME_IN_MILLIS = "time_in_millis";
         static final String EXISTS_TOTAL = "exists_total";
         static final String EXISTS_TIME = "exists_time";