Updates for changes in hppc classes

There are 3 changes in hppc that impact OpenSearch:

- ObjectIntScatterMap has been removed. I could have replaced it with
ObjectIntHashMap, but a plain java.util.HashMap seems to solve the
problem well so I used that instead.

- `indexRemove(int index)` is a new method in two interfaces that we
extend in a delegate pattern, so I have had to add that method as a
pass-through in two places.

- The seeded version of `BitMixer.mix(int, int)` [has been removed][1].
The implementation that was removed simply xor'd the value to the seed
before calling the single-int variant of the method. I have changed the
OpenSearch code to do the xor directly, so this should be equivalent to
the previous implementation.

[1]: carrotsearch/hppc#10

Signed-off-by: Andrew Ross <[email protected]>

server/src/main/java/org/opensearch/common/collect/ImmutableOpenIntMap.java

@@ -390,6 +390,11 @@ public void indexInsert(int index, int key, VType value) {
             map.indexInsert(index, key, value);
         }
 
+        @Override
+        public VType indexRemove(int index) {
+            return map.indexRemove(index);
+        }
+
         @Override
         public void release() {
             map.release();

server/src/main/java/org/opensearch/common/collect/ImmutableOpenMap.java

@@ -409,6 +409,11 @@ public void indexInsert(int index, KType key, VType value) {
             map.indexInsert(index, key, value);
         }
 
+        @Override
+        public VType indexRemove(int index) {
+            return map.indexRemove(index);
+        }
+
         @Override
         public void release() {
             map.release();

server/src/main/java/org/opensearch/common/lucene/search/function/RandomScoreFunction.java

@@ -75,7 +75,7 @@ public RandomScoreFunction(int seed, int salt, IndexFieldData<?> uidFieldData) {
     public RandomScoreFunction(int seed, int salt, IndexFieldData<?> uidFieldData, @Nullable String functionName) {
         super(CombineFunction.MULTIPLY);
         this.originalSeed = seed;
-        this.saltedSeed = BitMixer.mix(seed, salt);
+        this.saltedSeed = BitMixer.mix(seed ^ salt);
         this.fieldData = uidFieldData;
         this.functionName = functionName;
     }
@@ -97,7 +97,7 @@ public LeafScoreFunction getLeafScoreFunction(LeafReaderContext ctx) {
             public double score(int docId, float subQueryScore) throws IOException {
                 int hash;
                 if (values == null) {
-                    hash = BitMixer.mix(ctx.docBase + docId, saltedSeed);
+                    hash = BitMixer.mix((ctx.docBase + docId) ^ saltedSeed);
                 } else if (values.advanceExact(docId)) {
                     hash = StringHelper.murmurhash3_x86_32(values.nextValue(), saltedSeed);
                 } else {

server/src/main/java/org/opensearch/rest/action/cat/RestAllocationAction.java

@@ -32,7 +32,6 @@
 
 package org.opensearch.rest.action.cat;
 
-import com.carrotsearch.hppc.ObjectIntScatterMap;
 import org.opensearch.action.admin.cluster.node.stats.NodeStats;
 import org.opensearch.action.admin.cluster.node.stats.NodesStatsRequest;
 import org.opensearch.action.admin.cluster.node.stats.NodesStatsResponse;
@@ -51,7 +50,9 @@
 import org.opensearch.rest.action.RestActionListener;
 import org.opensearch.rest.action.RestResponseListener;
 
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import static java.util.Arrays.asList;
 import static java.util.Collections.unmodifiableList;
@@ -129,7 +130,7 @@ protected Table getTableWithHeader(final RestRequest request) {
     }
 
     private Table buildTable(RestRequest request, final ClusterStateResponse state, final NodesStatsResponse stats) {
-        final ObjectIntScatterMap<String> allocs = new ObjectIntScatterMap<>();
+        final Map<String, Integer> allocs = new HashMap<>();
 
         for (ShardRouting shard : state.getState().routingTable().allShards()) {
             String nodeId = "UNASSIGNED";
@@ -138,7 +139,7 @@ private Table buildTable(RestRequest request, final ClusterStateResponse state,
                 nodeId = shard.currentNodeId();
             }
 
-            allocs.addTo(nodeId, 1);
+            allocs.merge(nodeId, 1, Integer::sum);
         }
 
         Table table = getTableWithHeader(request);