Add methods for adding generation listeners with primary term (elasti…

…c#100899)

Provide a facility to supply the primary term for the engine for a more precise comparison of generations. Deprecate existing `addSegmentGenerationListener` and `waitForSegmentGeneration` methods

Prerequisite for elastic#99752

docs/changelog/100899.yaml

@@ -0,0 +1,5 @@
+pr: 100899
+summary: Add methods for adding generation listeners with primary term
+area: Store
+type: enhancement
+issues: []

server/src/main/java/org/elasticsearch/index/engine/Engine.java

@@ -111,6 +111,7 @@ public abstract class Engine implements Closeable {
     public static final String SEARCH_SOURCE = "search"; // TODO: Make source of search enum?
     public static final String CAN_MATCH_SEARCH_SOURCE = "can_match";
     protected static final String DOC_STATS_SOURCE = "doc_stats";
+    public static final long UNKNOWN_PRIMARY_TERM = -1L;
 
     protected final ShardId shardId;
     protected final Logger logger;
@@ -2114,8 +2115,19 @@ public final EngineConfig getEngineConfig() {
 
     /**
      * Allows registering a listener for when the index shard is on a segment generation >= minGeneration.
+     *
+     * @deprecated use {@link #addPrimaryTermAndGenerationListener(long, long, ActionListener)} instead.
      */
+    @Deprecated
     public void addSegmentGenerationListener(long minGeneration, ActionListener<Long> listener) {
+        addPrimaryTermAndGenerationListener(UNKNOWN_PRIMARY_TERM, minGeneration, listener);
+    }
+
+    /**
+     * Allows registering a listener for when the index shard is on a primary term >= minPrimaryTerm
+     * and a segment generation >= minGeneration.
+     */
+    public void addPrimaryTermAndGenerationListener(long minPrimaryTerm, long minGeneration, ActionListener<Long> listener) {
         throw new UnsupportedOperationException();
     }
 

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -4173,7 +4173,18 @@ public String toString() {
         return "IndexShard(shardRouting=" + shardRouting + ")";
     }
 
+    /**
+     * @deprecated use {@link #waitForPrimaryTermAndGeneration(long, long, ActionListener)} instead.
+     */
+    @Deprecated
     public void waitForSegmentGeneration(long segmentGeneration, ActionListener<Long> listener) {
-        getEngine().addSegmentGenerationListener(segmentGeneration, listener);
+        waitForPrimaryTermAndGeneration(getOperationPrimaryTerm(), segmentGeneration, listener);
+    }
+
+    /**
+     * Registers a listener for an event when the shard advances to the provided primary term and segment generation
+     */
+    public void waitForPrimaryTermAndGeneration(long primaryTerm, long segmentGeneration, ActionListener<Long> listener) {
+        getEngine().addPrimaryTermAndGenerationListener(primaryTerm, segmentGeneration, listener);
     }
 }