Add some docs

Author: thecoop

client/client-benchmark-noop-api-plugin/src/main/java/org/elasticsearch/plugin/noop/action/search/TransportNoopSearchAction.java

@@ -9,10 +9,10 @@
 package org.elasticsearch.plugin.noop.action.search;
 
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.action.support.HandledTransportAction;
 import org.elasticsearch.common.util.concurrent.EsExecutors;

docs/reference/search/retriever.asciidoc

@@ -610,6 +610,14 @@ Note that score calculations vary depending on the model used.
 Applies the specified <<query-dsl-bool-query, boolean query filter>> to the child  <<retriever, retriever>>.
 If the child retriever already specifies any filters, then this top-level filter is applied in conjuction with the filter defined in the child retriever.
 
+`allow_rerank_failures`::
+(Optional, `boolean`)
++
+If `true`, a failure during reranking will not fail the whole query. Instead, the documents
+from the preceding steps are passed-through unmodified to subsequent retriever steps.
+The failure exception will be available in the <<search-api-phase-failures, `phase_failures`>> field of the search response.
+Defaults to `false`.
+
 [discrete]
 [[text-similarity-reranker-retriever-example-elastic-rerank]]
 ==== Example: Elastic Rerank

docs/reference/search/search.asciidoc

@@ -782,6 +782,14 @@ Took time does *not* include:
 If `true`,
 the request timed out before completion;
 returned results may be partial or empty.
+--
+
+[[search-api-phase-failures]]
+`phase_failures`::
+(object)
+If present, contains information on any failures in specific search phases
+that did not prevent some results from being returned.
+In such cases, search results may be different to those expected.
 
 [[search-api-shards]]
 `_shards`::

modules/lang-mustache/src/test/java/org/elasticsearch/script/mustache/SearchTemplateResponseTests.java

@@ -10,9 +10,9 @@
 package org.elasticsearch.script.mustache;
 
 import org.apache.lucene.search.TotalHits;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.search.SearchHit;

server/src/main/java/org/elasticsearch/action/search/SearchResponse.java

@@ -106,10 +106,7 @@ public SearchResponse(StreamInput in) throws IOException {
             s -> s == 0 ? ShardSearchFailure.EMPTY_ARRAY : new ShardSearchFailure[s]
         );
         if (in.getTransportVersion().onOrAfter(TransportVersions.SEARCH_SUBSIDIARY_FAILURES)) {
-            phaseFailures = in.readArray(
-                PhaseFailure::new,
-                s -> s == 0 ? PhaseFailure.EMPTY_ARRAY : new PhaseFailure[s]
-            );
+            phaseFailures = in.readArray(PhaseFailure::new, s -> s == 0 ? PhaseFailure.EMPTY_ARRAY : new PhaseFailure[s]);
         } else {
             phaseFailures = PhaseFailure.EMPTY_ARRAY;
         }

server/src/test/java/org/elasticsearch/action/search/SearchResponseMergerTests.java

@@ -170,7 +170,7 @@ public void testMergePhaseFailures() throws InterruptedException {
                     0,
                     100L,
                     ShardSearchFailure.EMPTY_ARRAY,
-                        phaseFailures,
+                    phaseFailures,
                     SearchResponse.Clusters.EMPTY
                 );
                 try {

test/framework/src/main/java/org/elasticsearch/search/SearchResponseUtils.java

@@ -13,11 +13,11 @@
 import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.action.search.MultiSearchResponse;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchRequestBuilder;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.SearchResponse.Clusters;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.client.Response;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.common.ParsingException;

x-pack/plugin/async-search/src/main/java/org/elasticsearch/xpack/search/MutableSearchResponse.java

@@ -9,11 +9,11 @@
 import org.apache.lucene.search.TotalHits;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.ExceptionsHelper;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.SearchResponse.Clusters;
 import org.elasticsearch.action.search.SearchResponseMerger;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.util.concurrent.AtomicArray;

x-pack/plugin/async-search/src/test/java/org/elasticsearch/xpack/search/AsyncSearchResponseTests.java

@@ -10,9 +10,9 @@
 import org.apache.lucene.index.CorruptIndexException;
 import org.elasticsearch.TransportVersion;
 import org.elasticsearch.action.OriginalIndices;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;

x-pack/plugin/enrich/src/main/java/org/elasticsearch/xpack/enrich/action/EnrichShardMultiSearchAction.java

@@ -17,10 +17,10 @@
 import org.elasticsearch.action.ValidateActions;
 import org.elasticsearch.action.search.MultiSearchRequest;
 import org.elasticsearch.action.search.MultiSearchResponse;
+import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.ShardSearchFailure;
-import org.elasticsearch.action.search.PhaseFailure;
 import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.action.support.single.shard.SingleShardRequest;
 import org.elasticsearch.action.support.single.shard.TransportSingleShardAction;