REST high-level client: add force merge API (#28896)

Relates to #27205

client/rest-high-level/src/main/java/org/elasticsearch/client/IndicesClient.java

@@ -34,15 +34,17 @@
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexResponse;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
 import org.elasticsearch.action.admin.indices.flush.FlushResponse;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingResponse;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexResponse;
-import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
-import org.elasticsearch.action.admin.indices.rollover.RolloverResponse;
 import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
 import org.elasticsearch.action.admin.indices.refresh.RefreshResponse;
+import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
+import org.elasticsearch.action.admin.indices.rollover.RolloverResponse;
 import org.elasticsearch.action.admin.indices.shrink.ResizeRequest;
 import org.elasticsearch.action.admin.indices.shrink.ResizeResponse;
 
@@ -261,6 +263,28 @@ public void flushAsync(FlushRequest flushRequest, ActionListener<FlushResponse>
                 listener, emptySet(), headers);
     }
 
+    /**
+     * Force merge one or more indices using the Force Merge API
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html">
+     * Force Merge API on elastic.co</a>
+     */
+    public ForceMergeResponse forceMerge(ForceMergeRequest forceMergeRequest, Header... headers) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(forceMergeRequest, Request::forceMerge, ForceMergeResponse::fromXContent,
+            emptySet(), headers);
+    }
+
+    /**
+     * Asynchronously force merge one or more indices using the Force Merge API
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html">
+     * Force Merge API on elastic.co</a>
+     */
+    public void forceMergeAsync(ForceMergeRequest forceMergeRequest, ActionListener<ForceMergeResponse> listener, Header... headers) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(forceMergeRequest, Request::forceMerge, ForceMergeResponse::fromXContent,
+                listener, emptySet(), headers);
+    }
+
     /**
      * Clears the cache of one or more indices using the Clear Cache API
      * <p>

client/rest-high-level/src/main/java/org/elasticsearch/client/Request.java

@@ -37,6 +37,7 @@
 import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
@@ -235,6 +236,17 @@ static Request flush(FlushRequest flushRequest) {
         return new Request(HttpPost.METHOD_NAME, endpoint, parameters.getParams(), null);
     }
 
+    static Request forceMerge(ForceMergeRequest forceMergeRequest) {
+        String[] indices = forceMergeRequest.indices() == null ? Strings.EMPTY_ARRAY : forceMergeRequest.indices();
+        String endpoint = endpoint(indices, "_forcemerge");
+        Params parameters = Params.builder();
+        parameters.withIndicesOptions(forceMergeRequest.indicesOptions());
+        parameters.putParam("max_num_segments", Integer.toString(forceMergeRequest.maxNumSegments()));
+        parameters.putParam("only_expunge_deletes", Boolean.toString(forceMergeRequest.onlyExpungeDeletes()));
+        parameters.putParam("flush", Boolean.toString(forceMergeRequest.flush()));
+        return new Request(HttpPost.METHOD_NAME, endpoint, parameters.getParams(), null);
+    }
+
     static Request clearCache(ClearIndicesCacheRequest clearIndicesCacheRequest) {
         String[] indices = clearIndicesCacheRequest.indices() == null ? Strings.EMPTY_ARRAY :clearIndicesCacheRequest.indices();
         String endpoint = endpoint(indices, "_cache/clear");

client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesClientIT.java

@@ -38,6 +38,8 @@
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexResponse;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
 import org.elasticsearch.action.admin.indices.flush.FlushResponse;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingResponse;
@@ -469,6 +471,32 @@ public void testClearCache() throws IOException {
         }
     }
 
+    public void testForceMerge() throws IOException {
+        {
+            String index = "index";
+            Settings settings = Settings.builder()
+                .put("number_of_shards", 1)
+                .put("number_of_replicas", 0)
+                .build();
+            createIndex(index, settings);
+            ForceMergeRequest forceMergeRequest = new ForceMergeRequest(index);
+            ForceMergeResponse forceMergeResponse =
+                execute(forceMergeRequest, highLevelClient().indices()::forceMerge, highLevelClient().indices()::forceMergeAsync);
+            assertThat(forceMergeResponse.getTotalShards(), equalTo(1));
+            assertThat(forceMergeResponse.getSuccessfulShards(), equalTo(1));
+            assertThat(forceMergeResponse.getFailedShards(), equalTo(0));
+            assertThat(forceMergeResponse.getShardFailures(), equalTo(BroadcastResponse.EMPTY));
+        }
+        {
+            String nonExistentIndex = "non_existent_index";
+            assertFalse(indexExists(nonExistentIndex));
+            ForceMergeRequest forceMergeRequest = new ForceMergeRequest(nonExistentIndex);
+            ElasticsearchException exception = expectThrows(ElasticsearchException.class,
+                () -> execute(forceMergeRequest, highLevelClient().indices()::forceMerge, highLevelClient().indices()::forceMergeAsync));
+            assertEquals(RestStatus.NOT_FOUND, exception.status());
+        }
+    }
+
     public void testExistsAlias() throws IOException {
         GetAliasesRequest getAliasesRequest = new GetAliasesRequest("alias");
         assertFalse(execute(getAliasesRequest, highLevelClient().indices()::existsAlias, highLevelClient().indices()::existsAliasAsync));

client/rest-high-level/src/test/java/org/elasticsearch/client/RequestTests.java

@@ -40,6 +40,7 @@
 import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
@@ -623,6 +624,43 @@ public void testFlush() {
         assertThat(request.getMethod(), equalTo(HttpPost.METHOD_NAME));
     }
 
+    public void testForceMerge() {
+        String[] indices = randomBoolean() ? null : randomIndicesNames(0, 5);
+        ForceMergeRequest forceMergeRequest;
+        if (randomBoolean()) {
+            forceMergeRequest = new ForceMergeRequest(indices);
+        } else {
+            forceMergeRequest = new ForceMergeRequest();
+            forceMergeRequest.indices(indices);
+        }
+
+        Map<String, String> expectedParams = new HashMap<>();
+        setRandomIndicesOptions(forceMergeRequest::indicesOptions, forceMergeRequest::indicesOptions, expectedParams);
+        if (randomBoolean()) {
+            forceMergeRequest.maxNumSegments(randomInt());
+        }
+        expectedParams.put("max_num_segments", Integer.toString(forceMergeRequest.maxNumSegments()));
+        if (randomBoolean()) {
+            forceMergeRequest.onlyExpungeDeletes(randomBoolean());
+        }
+        expectedParams.put("only_expunge_deletes", Boolean.toString(forceMergeRequest.onlyExpungeDeletes()));
+        if (randomBoolean()) {
+            forceMergeRequest.flush(randomBoolean());
+        }
+        expectedParams.put("flush", Boolean.toString(forceMergeRequest.flush()));
+
+        Request request = Request.forceMerge(forceMergeRequest);
+        StringJoiner endpoint = new StringJoiner("/", "/", "");
+        if (indices != null && indices.length > 0) {
+            endpoint.add(String.join(",", indices));
+        }
+        endpoint.add("_forcemerge");
+        assertThat(request.getEndpoint(), equalTo(endpoint.toString()));
+        assertThat(request.getParameters(), equalTo(expectedParams));
+        assertThat(request.getEntity(), nullValue());
+        assertThat(request.getMethod(), equalTo(HttpPost.METHOD_NAME));
+    }
+
     public void testClearCache() {
         String[] indices = randomBoolean() ? null : randomIndicesNames(0, 5);
         ClearIndicesCacheRequest clearIndicesCacheRequest;

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/IndicesClientDocumentationIT.java

@@ -37,6 +37,8 @@
 import org.elasticsearch.action.admin.indices.delete.DeleteIndexResponse;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
 import org.elasticsearch.action.admin.indices.flush.FlushResponse;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
+import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
 import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.action.admin.indices.mapping.put.PutMappingResponse;
@@ -771,6 +773,79 @@ public void onFailure(Exception e) {
         }
     }
 
+    public void testForceMergeIndex() throws Exception {
+        RestHighLevelClient client = highLevelClient();
+
+        {
+            createIndex("index", Settings.EMPTY);
+        }
+
+        {
+            // tag::force-merge-request
+            ForceMergeRequest request = new ForceMergeRequest("index1"); // <1>
+            ForceMergeRequest requestMultiple = new ForceMergeRequest("index1", "index2"); // <2>
+            ForceMergeRequest requestAll = new ForceMergeRequest(); // <3>
+            // end::force-merge-request
+
+            // tag::force-merge-request-indicesOptions
+            request.indicesOptions(IndicesOptions.lenientExpandOpen()); // <1>
+            // end::force-merge-request-indicesOptions
+
+            // tag::force-merge-request-segments-num
+            request.maxNumSegments(1); // <1>
+            // end::force-merge-request-segments-num
+
+            // tag::force-merge-request-only-expunge-deletes
+            request.onlyExpungeDeletes(true); // <1>
+            // end::force-merge-request-only-expunge-deletes
+
+            // tag::force-merge-request-flush
+            request.flush(true); // <1>
+            // end::force-merge-request-flush
+
+            // tag::force-merge-execute
+            ForceMergeResponse forceMergeResponse = client.indices().forceMerge(request);
+            // end::force-merge-execute
+
+            // tag::force-merge-response
+            int totalShards = forceMergeResponse.getTotalShards(); // <1>
+            int successfulShards = forceMergeResponse.getSuccessfulShards(); // <2>
+            int failedShards = forceMergeResponse.getFailedShards(); // <3>
+            DefaultShardOperationFailedException[] failures = forceMergeResponse.getShardFailures(); // <4>
+            // end::force-merge-response
+
+            // tag::force-merge-execute-listener
+            ActionListener<ForceMergeResponse> listener = new ActionListener<ForceMergeResponse>() {
+                @Override
+                public void onResponse(ForceMergeResponse forceMergeResponse) {
+                    // <1>
+                }
+
+                @Override
+                public void onFailure(Exception e) {
+                    // <2>
+                }
+            };
+            // end::force-merge-execute-listener
+
+            // tag::force-merge-execute-async
+            client.indices().forceMergeAsync(request, listener); // <1>
+            // end::force-merge-execute-async
+        }
+        {
+            // tag::force-merge-notfound
+            try {
+                ForceMergeRequest request = new ForceMergeRequest("does_not_exist");
+                client.indices().forceMerge(request);
+            } catch (ElasticsearchException exception) {
+                if (exception.status() == RestStatus.NOT_FOUND) {
+                    // <1>
+                }
+            }
+            // end::force-merge-notfound
+        }
+    }
+
     public void testClearCache() throws Exception {
         RestHighLevelClient client = highLevelClient();
 
@@ -855,7 +930,6 @@ public void onFailure(Exception e) {
         }
     }
 
-
     public void testCloseIndex() throws Exception {
         RestHighLevelClient client = highLevelClient();
 

docs/java-rest/high-level/indices/force_merge.asciidoc

@@ -0,0 +1,102 @@
+[[java-rest-high-force-merge]]
+=== Force Merge API
+
+[[java-rest-high-force-merge-request]]
+==== Force merge Request
+
+A `ForceMergeRequest` can be applied to one or more indices, or even on `_all` the indices:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-request]
+--------------------------------------------------
+<1> Force merge one index
+<2> Force merge multiple indices
+<3> Force merge all the indices
+
+==== Optional arguments
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-request-indicesOptions]
+--------------------------------------------------
+<1> Setting `IndicesOptions` controls how unavailable indices are resolved and
+how wildcard expressions are expanded
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-request-segments-num]
+--------------------------------------------------
+<1> Set `max_num_segments` to control the number of segments to merge down to.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-request-only-expunge-deletes]
+--------------------------------------------------
+<1> Set the `only_expunge_deletes` flag to `true`
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-request-flush]
+--------------------------------------------------
+<1> Set the `flush` flag to `true`
+
+[[java-rest-high-force-merge-sync]]
+==== Synchronous Execution
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-execute]
+--------------------------------------------------
+
+[[java-rest-high-force-merge-async]]
+==== Asynchronous Execution
+
+The asynchronous execution of a force merge request requires both the `ForceMergeRequest`
+instance and an `ActionListener` instance to be passed to the asynchronous
+method:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-execute-async]
+--------------------------------------------------
+<1> The `ForceMergeRequest` to execute and the `ActionListener` to use when
+the execution completes
+
+The asynchronous method does not block and returns immediately. Once it is
+completed the `ActionListener` is called back using the `onResponse` method
+if the execution successfully completed or using the `onFailure` method if
+it failed.
+
+A typical listener for `ForceMergeResponse` looks like:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-execute-listener]
+--------------------------------------------------
+<1> Called when the execution is successfully completed. The response is
+provided as an argument
+<2> Called in case of failure. The raised exception is provided as an argument
+
+[[java-rest-high-force-merge-response]]
+==== Force Merge Response
+
+The returned `ForceMergeResponse` allows to retrieve information about the
+executed operation as follows:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-response]
+--------------------------------------------------
+<1> Total number of shards hit by the force merge request
+<2> Number of shards where the force merge has succeeded
+<3> Number of shards where the force merge has failed
+<4> A list of failures if the operation failed on one or more shards
+
+By default, if the indices were not found, an `ElasticsearchException` will be thrown:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[force-merge-notfound]
+--------------------------------------------------
+<1> Do something if the indices to be force merged were not found

docs/java-rest/high-level/supported-apis.asciidoc

@@ -60,6 +60,7 @@ Index Management::
 * <<java-rest-high-refresh>>
 * <<java-rest-high-flush>>
 * <<java-rest-high-clear-cache>>
+* <<java-rest-high-force-merge>>
 * <<java-rest-high-rollover-index>>
 
 Mapping Management::
@@ -79,6 +80,7 @@ include::indices/split_index.asciidoc[]
 include::indices/refresh.asciidoc[]
 include::indices/flush.asciidoc[]
 include::indices/clear_cache.asciidoc[]
+include::indices/force_merge.asciidoc[]
 include::indices/rollover.asciidoc[]
 include::indices/put_mapping.asciidoc[]
 include::indices/update_aliases.asciidoc[]