Addresses code review comments

core/src/main/java/org/elasticsearch/cluster/metadata/IndexGraveyard.java

@@ -68,14 +68,16 @@ final public class IndexGraveyard implements MetaData.Custom {
     public static final IndexGraveyard PROTO = new IndexGraveyard(new ArrayList<>());
     public static final String TYPE = "index-graveyard";
     private static final ParseField TOMBSTONES_FIELD = new ParseField("tombstones");
-    private static final ObjectParser<List<Tombstone>, Void> GRAVEYARD_PARSER = new ObjectParser<>("index_graveyard", ArrayList::new);
+    private static final ObjectParser<List<Tombstone>, Void> GRAVEYARD_PARSER;
     static {
+        GRAVEYARD_PARSER = new ObjectParser<>("index_graveyard", ArrayList::new);
         GRAVEYARD_PARSER.declareObjectArray(List::addAll, Tombstone.getParser(), TOMBSTONES_FIELD);
     }
 
     private final List<Tombstone> tombstones;
 
     private IndexGraveyard(final List<Tombstone> list) {
+        assert list != null;
         tombstones = Collections.unmodifiableList(list);
     }
 
@@ -109,7 +111,7 @@ public boolean equals(Object obj) {
 
     @Override
     public int hashCode() {
-        return Objects.hash(tombstones);
+        return tombstones.hashCode();
     }
 
     /**
@@ -175,6 +177,7 @@ public static IndexGraveyard.Builder builder(final IndexGraveyard graveyard) {
     final public static class Builder {
         private List<Tombstone> tombstones;
         private int numPurged = -1;
+        private long currentTime = System.currentTimeMillis();
 
         private Builder() {
             tombstones = new ArrayList<>();
@@ -195,7 +198,7 @@ public List<Tombstone> tombstones() {
          * Add a deleted index to the list of tombstones in the cluster state.
          */
         public Builder addTombstone(final Index index) {
-            tombstones.add(new Tombstone(index, System.currentTimeMillis()));
+            tombstones.add(new Tombstone(index, currentTime));
             return this;
         }
 
@@ -309,11 +312,10 @@ public void writeTo(final StreamOutput out) throws IOException {
 
         @Override
         public IndexGraveyard apply(final MetaData.Custom previous) {
-            @SuppressWarnings("unchecked")
-            final IndexGraveyard old = (IndexGraveyard) previous;
+            @SuppressWarnings("unchecked") final IndexGraveyard old = (IndexGraveyard) previous;
             if (removedCount > old.tombstones.size()) {
-                throw new IllegalStateException("IndexGraveyardDiff cannot remove " + removedCount + " entries from " +
-                                                old.tombstones.size() + " tombstones.");
+                throw new IllegalStateException("IndexGraveyardDiff cannot remove [" + removedCount + "] entries from [" +
+                                                old.tombstones.size() + "] tombstones.");
             }
             final List<Tombstone> newTombstones = new ArrayList<>(old.tombstones.subList(removedCount, old.tombstones.size()));
             for (Tombstone tombstone : added) {
@@ -341,16 +343,16 @@ final public static class Tombstone implements ToXContent, Writeable<Tombstone>
         private static final String INDEX_KEY = "index";
         private static final String DELETE_DATE_IN_MILLIS_KEY = "delete_date_in_millis";
         private static final String DELETE_DATE_KEY = "delete_date";
-        private static final ObjectParser<Tombstone.Builder, Void> TOMBSTONE_PARSER =
-            new ObjectParser<>("tombstoneEntry", Tombstone.Builder::new);
+        private static final ObjectParser<Tombstone.Builder, Void> TOMBSTONE_PARSER;
         static {
+            TOMBSTONE_PARSER = new ObjectParser<>("tombstoneEntry", Tombstone.Builder::new);
             TOMBSTONE_PARSER.declareObject(Tombstone.Builder::index, Index::parseIndex, new ParseField(INDEX_KEY));
             TOMBSTONE_PARSER.declareLong(Tombstone.Builder::deleteDateInMillis, new ParseField(DELETE_DATE_IN_MILLIS_KEY));
-            TOMBSTONE_PARSER.declareString((b,s) -> {}, new ParseField(DELETE_DATE_KEY));
+            TOMBSTONE_PARSER.declareString((b, s) -> {}, new ParseField(DELETE_DATE_KEY));
         }
 
         static BiFunction<XContentParser, Void, Tombstone> getParser() {
-            return (p,c) -> TOMBSTONE_PARSER.apply(p, c).build();
+            return (p, c) -> TOMBSTONE_PARSER.apply(p, c).build();
         }
 
         private final Index index;
@@ -404,8 +406,7 @@ public boolean equals(final Object other) {
             if (other == null || getClass() != other.getClass()) {
                 return false;
             }
-            @SuppressWarnings("unchecked")
-            Tombstone that = (Tombstone) other;
+            @SuppressWarnings("unchecked") Tombstone that = (Tombstone) other;
             if (index.equals(that.index) == false) {
                 return false;
             }

core/src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -931,8 +931,7 @@ public Builder indexGraveyard(final IndexGraveyard indexGraveyard) {
         }
 
         public IndexGraveyard indexGraveyard() {
-            @SuppressWarnings("unchecked")
-            IndexGraveyard graveyard = (IndexGraveyard) getCustom(IndexGraveyard.TYPE);
+            @SuppressWarnings("unchecked") IndexGraveyard graveyard = (IndexGraveyard) getCustom(IndexGraveyard.TYPE);
             return graveyard;
         }
 

core/src/main/java/org/elasticsearch/index/Index.java

@@ -50,10 +50,8 @@ public class Index implements Writeable<Index>, ToXContent {
     private final String uuid;
 
     public Index(String name, String uuid) {
-        Objects.requireNonNull(name);
-        Objects.requireNonNull(uuid);
-        this.name = name.intern();
-        this.uuid = uuid.intern();
+        this.name = Objects.requireNonNull(name).intern();
+        this.uuid = Objects.requireNonNull(uuid).intern();
     }
 
     public Index(StreamInput in) throws IOException {

core/src/main/java/org/elasticsearch/indices/IndicesService.java

@@ -112,7 +112,6 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.function.BiFunction;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -567,11 +566,11 @@ void deleteIndexStore(String reason, IndexMetaData metaData, ClusterState cluste
     }
 
     private void deleteIndexStore(String reason, Index index, IndexSettings indexSettings) throws IOException {
-       deleteIndexStoreWithPredicate(reason, index, indexSettings, DEFAULT_INDEX_DELETION_PREDICATE);
+       deleteIndexStoreIfDeletionAllowed(reason, index, indexSettings, DEFAULT_INDEX_DELETION_PREDICATE);
     }
 
-    private void deleteIndexStoreWithPredicate(final String reason, final Index index, final IndexSettings indexSettings,
-                                               final IndexDeletionPredicate predicate) throws IOException {
+    private void deleteIndexStoreIfDeletionAllowed(final String reason, final Index index, final IndexSettings indexSettings,
+                                                   final IndexDeletionAllowedPredicate predicate) throws IOException {
         boolean success = false;
         try {
             // we are trying to delete the index store here - not a big deal if the lock can't be obtained
@@ -696,9 +695,9 @@ public IndexMetaData verifyIndexIsDeleted(final Index index, final ClusterState
             }
             final IndexSettings indexSettings = buildIndexSettings(metaData);
             try {
-                deleteIndexStoreWithPredicate("stale deleted index", index, indexSettings, ALWAYS_TRUE);
+                deleteIndexStoreIfDeletionAllowed("stale deleted index", index, indexSettings, ALWAYS_TRUE);
             } catch (IOException e) {
-                // we just warn about the exception here because if deleteIndexStoreWithPredicate
+                // we just warn about the exception here because if deleteIndexStoreIfDeletionAllowed
                 // throws an exception, it gets added to the list of pending deletes to be tried again
                 logger.warn("[{}] failed to delete index on disk", e, metaData.getIndex());
             }
@@ -1119,12 +1118,12 @@ public void onRemoval(RemovalNotification<IndicesRequestCache.Key, IndicesReques
     }
 
     @FunctionalInterface
-    interface IndexDeletionPredicate extends BiFunction<Index, IndexSettings, Boolean> {
-        Boolean apply(Index index, IndexSettings indexSettings);
+    interface IndexDeletionAllowedPredicate {
+        boolean apply(Index index, IndexSettings indexSettings);
     }
 
-    private final IndexDeletionPredicate DEFAULT_INDEX_DELETION_PREDICATE =
+    private final IndexDeletionAllowedPredicate DEFAULT_INDEX_DELETION_PREDICATE =
         (Index index, IndexSettings indexSettings) -> canDeleteIndexContents(index, indexSettings);
-    private final IndexDeletionPredicate ALWAYS_TRUE = (Index index, IndexSettings indexSettings) -> true;
+    private final IndexDeletionAllowedPredicate ALWAYS_TRUE = (Index index, IndexSettings indexSettings) -> true;
 
 }

core/src/test/java/org/elasticsearch/cluster/ClusterChangedEventTests.java

@@ -386,10 +386,19 @@ private static ClusterState executeIndicesChangesTest(final ClusterState previou
         }
         final int numDel;
         switch (deletionQuantity) {
-            case DELETE_ALL: numDel = stateIndices.size(); break;
-            case DELETE_NONE: numDel = 0; break;
-            case DELETE_RANDOM: numDel = randomIntBetween(0, Math.max(stateIndices.size() - 1, 0)); break;
-            default: throw new IllegalArgumentException("Unhandled mode " + deletionQuantity);
+            case DELETE_ALL: {
+                numDel = stateIndices.size();
+                break;
+            }
+            case DELETE_NONE: {
+                numDel = 0;
+                break;
+            }
+            case DELETE_RANDOM: {
+                numDel = randomIntBetween(0, Math.max(stateIndices.size() - 1, 0));
+                break;
+            }
+            default: throw new AssertionError("Unhandled mode [" + deletionQuantity + "]");
         }
         final List<Index> addedIndices = addIndices(numAdd, randomAsciiOfLengthBetween(5, 10));
         List<Index> delIndices = delIndices(numDel, stateIndices);

core/src/test/java/org/elasticsearch/gateway/GatewayIndexStateIT.java

@@ -49,11 +49,13 @@
 import org.elasticsearch.test.InternalTestCluster.RestartCallback;
 
 import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
 
 import static org.elasticsearch.index.query.QueryBuilders.matchAllQuery;
 import static org.elasticsearch.index.query.QueryBuilders.matchQuery;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.nullValue;
@@ -555,4 +557,23 @@ public void testArchiveBrokenClusterSettings() throws Exception {
             + ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey()));
         assertHitCount(client().prepareSearch().setQuery(matchAllQuery()).get(), 1L);
     }
+
+
+    /**
+     * Creates a shadow replica index and asserts that the index creation was acknowledged.
+     * Can only be invoked on a cluster where each node has been configured with shared data
+     * paths and the other necessary settings for shadow replicas.
+     */
+    private void createShadowReplicaIndex(final String name, final Path dataPath, final int numReplicas) {
+        assert Files.exists(dataPath);
+        assert numReplicas >= 0;
+        final Settings idxSettings = Settings.builder()
+                                         .put(IndexMetaData.SETTING_NUMBER_OF_SHARDS, 1)
+                                         .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, numReplicas)
+                                         .put(IndexMetaData.SETTING_DATA_PATH, dataPath.toAbsolutePath().toString())
+                                         .put(IndexMetaData.SETTING_SHADOW_REPLICAS, true)
+                                         .build();
+        assertAcked(prepareCreate(name).setSettings(idxSettings).get());
+    }
+
 }

test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java

@@ -708,23 +708,6 @@ public final void createIndex(String... names) {
         }
     }
 
-    /**
-     * Creates a shadow replica index and asserts that the index creation was acknowledged.
-     * Can only be invoked on a cluster where each node has been configured with shared data
-     * paths and the other necessary settings for shadow replicas.
-     */
-    public final void createShadowReplicaIndex(final String name, final Path dataPath, final int numReplicas) {
-        assert Files.exists(dataPath);
-        assert numReplicas >= 0;
-        final Settings idxSettings = Settings.builder()
-                                             .put(IndexMetaData.SETTING_NUMBER_OF_SHARDS, 1)
-                                             .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, numReplicas)
-                                             .put(IndexMetaData.SETTING_DATA_PATH, dataPath.toAbsolutePath().toString())
-                                             .put(IndexMetaData.SETTING_SHADOW_REPLICAS, true)
-                                             .build();
-        assertAcked(prepareCreate(name).setSettings(idxSettings).get());
-    }
-
     /**
      * Creates a new {@link CreateIndexRequestBuilder} with the settings obtained from {@link #indexSettings()}.
      */