Remove LegacyClusterTaskResultActionListener (#89459)

Also removes the now-unused legacy method
`ClusterStateTaskListener#onClusterStateProcessed`.

Closes #83784

server/src/main/java/org/elasticsearch/action/admin/indices/create/AutoCreateAction.java

@@ -161,11 +161,6 @@ public void onFailure(Exception e) {
                 listener.onFailure(e);
             }
 
-            @Override
-            public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-                assert false : "should not be called";
-            }
-
             private ClusterStateAckListener getAckListener(String indexName) {
                 return new ClusterStateAckListener() {
                     @Override

server/src/main/java/org/elasticsearch/action/admin/indices/rollover/TransportRolloverAction.java

@@ -241,16 +241,10 @@ record RolloverTask(
         RolloverResponse trialRolloverResponse,
         ActionListener<RolloverResponse> listener
     ) implements ClusterStateTaskListener {
-
         @Override
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     record RolloverExecutor(

server/src/main/java/org/elasticsearch/cluster/ClusterStateTaskExecutor.java

@@ -73,23 +73,6 @@ default String describeTasks(List<T> tasks) {
         return output.toString();
     }
 
-    /**
-     * A {@link Consumer} for passing to {@link ClusterStateTaskExecutor.TaskContext#success} which preserves the
-     * legacy behaviour of calling {@link ClusterStateTaskListener#clusterStateProcessed} or {@link ClusterStateTaskListener#onFailure}.
-     * <p>
-     * New implementations should use a dedicated listener rather than relying on this legacy behaviour.
-     */
-    // TODO remove all remaining usages of this listener
-    @Deprecated
-    record LegacyClusterTaskResultActionListener(ClusterStateTaskListener task, ClusterState originalState)
-        implements
-            Consumer<ClusterState> {
-        @Override
-        public void accept(ClusterState publishedState) {
-            task.clusterStateProcessed(originalState, publishedState);
-        }
-    }
-
     /**
      * A task to be executed, along with callbacks for the executor to record the outcome of this task's execution. The executor must
      * call exactly one of these methods for every task in its batch.
@@ -108,10 +91,7 @@ interface TaskContext<T extends ClusterStateTaskListener> {
          * method and must instead call {@link #success(Runnable, ClusterStateAckListener)}, passing the task itself as the {@code
          * clusterStateAckListener} argument.
          *
-         * @param onPublicationSuccess An action executed when (if?) the cluster state update succeeds. The task's {@link
-         *                             ClusterStateTaskListener#clusterStateProcessed} method is not called directly by the master
-         *                             service once the task execution has succeeded, but legacy implementations may supply a listener
-         *                             which calls this methods.
+         * @param onPublicationSuccess An action executed when (if?) the cluster state update succeeds.
          */
         void success(Runnable onPublicationSuccess);
 
@@ -122,10 +102,7 @@ interface TaskContext<T extends ClusterStateTaskListener> {
          * method and must instead call {@link #success(Consumer, ClusterStateAckListener)}, passing the task itself as the {@code
          * clusterStateAckListener} argument.
          *
-         * @param publishedStateConsumer A consumer of the cluster state that was ultimately published. The task's {@link
-         *                               ClusterStateTaskListener#clusterStateProcessed} method is not called directly by the master
-         *                               service once the task execution has succeeded, but legacy implementations may supply a listener
-         *                               which calls this methods.
+         * @param publishedStateConsumer A consumer of the cluster state that was ultimately published.
          *                               <p>
          *                               The consumer should prefer not to use the published state for things like determining the result
          *                               of a task. The task may have been executed as part of a batch, and later tasks in the batch may
@@ -143,10 +120,7 @@ interface TaskContext<T extends ClusterStateTaskListener> {
          * Note that some tasks implement {@link ClusterStateAckListener} and can listen for acks themselves. If so, you must pass the task
          * itself as the {@code clusterStateAckListener} argument.
          *
-         * @param onPublicationSuccess An action executed when (if?) the cluster state update succeeds. The task's {@link
-         *                             ClusterStateTaskListener#clusterStateProcessed} method is not called directly by the master
-         *                             service once the task execution has succeeded, but legacy implementations may supply a listener
-         *                             which calls this methods.
+         * @param onPublicationSuccess An action executed when (if?) the cluster state update succeeds.
          *
          * @param clusterStateAckListener A listener for acknowledgements from nodes. If the publication succeeds then this listener is
          *                                completed as nodes ack the state update. If the publication fails then the failure
@@ -160,10 +134,7 @@ interface TaskContext<T extends ClusterStateTaskListener> {
          * Note that some tasks implement {@link ClusterStateAckListener} and can listen for acks themselves. If so, you must pass the task
          * itself as the {@code clusterStateAckListener} argument.
          *
-         * @param publishedStateConsumer A consumer of the cluster state that was ultimately published. The task's {@link
-         *                               ClusterStateTaskListener#clusterStateProcessed} method is not called directly by the master
-         *                               service once the task execution has succeeded, but legacy implementations may supply a listener
-         *                               which calls this methods.
+         * @param publishedStateConsumer A consumer of the cluster state that was ultimately published.
          *                               <p>
          *                               The consumer should prefer not to use the published state for things like determining the result
          *                               of a task. The task may have been executed as part of a batch, and later tasks in the batch may

server/src/main/java/org/elasticsearch/cluster/ClusterStateTaskListener.java

@@ -12,7 +12,6 @@
 import org.elasticsearch.cluster.service.MasterService;
 
 public interface ClusterStateTaskListener {
-
     /**
      * A callback for when task execution fails. May receive a {@link NotMasterException} if this node stopped being the master before this
      * task was executed or a {@link ProcessClusterEventTimeoutException} if the task timed out before it was executed. If the task fails
@@ -28,19 +27,4 @@ public interface ClusterStateTaskListener {
      * implementations must do so themselves, typically using a more specific logger and at a less dramatic log level.
      */
     void onFailure(Exception e);
-
-    /**
-     * Called when the result of the {@link ClusterStateTaskExecutor#execute} method has been processed properly by all listeners.
-     *
-     * The {@param newState} parameter is the state that was ultimately published. This can lead to surprising behaviour if tasks are
-     * batched together: a later task in the batch may undo or overwrite the changes made by an earlier task. In general you should prefer
-     * to ignore the published state and instead handle the success of a publication via the listener that the executor passes to
-     * {@link ClusterStateTaskExecutor.TaskContext#success}.
-     *
-     * Implementations of this callback must not throw exceptions: an exception thrown here is logged by the master service at {@code ERROR}
-     * level and otherwise ignored, except in tests where it raises an {@link AssertionError}. If log-and-ignore is the right behaviour then
-     * implementations must do so themselves, typically using a more specific logger and at a less dramatic log level.
-     */
-    // TODO: replace all remaining usages of this method with dedicated listeners and then remove it.
-    default void clusterStateProcessed(ClusterState oldState, ClusterState newState) {}
 }

server/src/main/java/org/elasticsearch/cluster/ClusterStateUpdateTask.java

@@ -8,9 +8,6 @@
 
 package org.elasticsearch.cluster;
 
-import org.elasticsearch.cluster.coordination.FailedToCommitClusterStateException;
-import org.elasticsearch.cluster.metadata.ProcessClusterEventTimeoutException;
-import org.elasticsearch.cluster.service.MasterService;
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.core.TimeValue;
@@ -50,20 +47,15 @@ public ClusterStateUpdateTask(Priority priority, TimeValue timeout) {
     public abstract ClusterState execute(ClusterState currentState) throws Exception;
 
     /**
-     * A callback for when task execution fails. May receive a {@link NotMasterException} if this node stopped being the master before this
-     * task was executed or a {@link ProcessClusterEventTimeoutException} if the task timed out before it was executed. If the task fails
-     * during execution then this method receives the corresponding exception. If the task executes successfully but the resulting cluster
-     * state publication fails then this method receives a {@link FailedToCommitClusterStateException}. If publication fails then a new
-     * master is elected and the update might or might not take effect, depending on whether or not the newly-elected master accepted the
-     * published state that failed to be committed.
-     * <p>
-     * Use {@link MasterService#isPublishFailureException} to detect the "expected" master failure cases if needed.
-     * <p>
-     * Implementations of this callback should not throw exceptions: an exception thrown here is logged by the master service at {@code
-     * ERROR} level and otherwise ignored. If log-and-ignore is the right behaviour then implementations should do so themselves, typically
-     * using a more specific logger and at a less dramatic log level.
+     * Called when the result of the {@link #execute} method has been processed properly by all listeners.
+     *
+     * The {@param newState} parameter is the state that was ultimately published.
+     *
+     * Implementations of this callback must not throw exceptions: an exception thrown here is logged by the master service at {@code ERROR}
+     * level and otherwise ignored, except in tests where it raises an {@link AssertionError}. If log-and-ignore is the right behaviour then
+     * implementations must do so themselves, typically using a more specific logger and at a less dramatic log level.
      */
-    public abstract void onFailure(Exception e);
+    public void clusterStateProcessed(ClusterState initialState, ClusterState newState) {}
 
     /**
      * If the cluster state update task wasn't processed by the provided timeout, call

server/src/main/java/org/elasticsearch/cluster/LocalMasterServiceTask.java

@@ -25,11 +25,6 @@ public LocalMasterServiceTask(Priority priority) {
 
     protected void execute(ClusterState currentState) {}
 
-    @Override
-    public final void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-        assert false : "not called";
-    }
-
     protected void onPublicationComplete() {}
 
     public void submit(MasterService masterService, String source) {

server/src/main/java/org/elasticsearch/cluster/action/shard/ShardStateAction.java

@@ -538,7 +538,6 @@ public int hashCode() {
     public record FailedShardUpdateTask(FailedShardEntry entry, ActionListener<TransportResponse.Empty> listener)
         implements
             ClusterStateTaskListener {
-
         @Override
         public void onFailure(Exception e) {
             logger.log(
@@ -548,11 +547,6 @@ public void onFailure(Exception e) {
             );
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "should not be called";
-        }
     }
 
     public void shardStarted(
@@ -859,11 +853,6 @@ public void onFailure(Exception e) {
             listener.onFailure(e);
         }
 
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "should not be called";
-        }
-
         @Override
         public String toString() {
             return "StartedShardUpdateTask{entry=" + entry + ", listener=" + listener + "}";

server/src/main/java/org/elasticsearch/cluster/coordination/JoinTask.java

@@ -9,7 +9,6 @@
 package org.elasticsearch.cluster.coordination;
 
 import org.elasticsearch.action.ActionListener;
-import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.ClusterStateTaskListener;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 
@@ -38,11 +37,6 @@ public void onFailure(Exception e) {
         }
     }
 
-    @Override
-    public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-        assert false : "not called";
-    }
-
     @Override
     public String toString() {
         final StringBuilder stringBuilder = new StringBuilder();

server/src/main/java/org/elasticsearch/cluster/coordination/NodeRemovalClusterStateTaskExecutor.java

@@ -32,11 +32,6 @@ public void onFailure(final Exception e) {
             logger.log(MasterService.isPublishFailureException(e) ? Level.DEBUG : Level.ERROR, "unexpected failure during [node-left]", e);
         }
 
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
-
         @Override
         public String toString() {
             final StringBuilder stringBuilder = new StringBuilder();

server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexStateService.java

@@ -211,16 +211,10 @@ public ClusterState execute(BatchExecutionContext<AddBlocksToCloseTask> batchExe
     private record AddBlocksToCloseTask(CloseIndexClusterStateUpdateRequest request, ActionListener<CloseIndexResponse> listener)
         implements
             ClusterStateTaskListener {
-
         @Override
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     private class CloseIndicesExecutor implements ClusterStateTaskExecutor<CloseIndicesTask> {
@@ -292,16 +286,10 @@ private record CloseIndicesTask(
         Map<Index, CloseIndexResponse.IndexResult> verifyResults,
         ActionListener<CloseIndexResponse> listener
     ) implements ClusterStateTaskListener {
-
         @Override
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     /**
@@ -547,11 +535,6 @@ private record AddBlocksTask(AddIndexBlockClusterStateUpdateRequest request, Act
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     private static class FinalizeBlocksExecutor implements ClusterStateTaskExecutor<FinalizeBlocksTask> {
@@ -592,16 +575,10 @@ private record FinalizeBlocksTask(
         Map<Index, AddBlockResult> verifyResults,
         ActionListener<AddIndexBlockResponse> listener
     ) implements ClusterStateTaskListener {
-
         @Override
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     /**
@@ -1243,10 +1220,5 @@ public void onAckTimeout() {
         public TimeValue ackTimeout() {
             return request.ackTimeout();
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 }

server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java

@@ -158,11 +158,6 @@ private abstract static class TemplateClusterStateUpdateTask implements ClusterS
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "not called";
-        }
     }
 
     @Inject

server/src/main/java/org/elasticsearch/cluster/metadata/MetadataUpdateSettingsService.java

@@ -136,11 +136,6 @@ public void onFailure(Exception e) {
             listener.onFailure(e);
         }
 
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "should not be called";
-        }
-
         ClusterState execute(ClusterState currentState) {
             final Settings normalizedSettings = Settings.builder()
                 .put(request.settings())

server/src/main/java/org/elasticsearch/health/metadata/HealthMetadataService.java

@@ -155,11 +155,6 @@ public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
      */
     abstract static class UpsertHealthMetadataTask implements ClusterStateTaskListener {
 
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "never called";
-        }
-
         @Override
         public void onFailure(@Nullable Exception e) {
             logger.error("failure during health metadata update", e);

server/src/main/java/org/elasticsearch/ingest/IngestService.java

@@ -146,11 +146,6 @@ abstract static class PipelineClusterStateUpdateTask implements ClusterStateTask
         public void onFailure(Exception e) {
             listener.onFailure(e);
         }
-
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "should not be called";
-        }
     }
 
     public IngestService(

server/src/main/java/org/elasticsearch/snapshots/SnapshotsService.java

@@ -3381,11 +3381,6 @@ public void onFailure(Exception e) {
             listener.onFailure(e);
         }
 
-        @Override
-        public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
-            assert false : "never called";
-        }
-
         @Override
         public boolean equals(Object other) {
             if (this == other) {