Remove Countable interface and dry up ShardsIterator (#121923) (#122519)

The size method is needed only in SearchShardIterator and PlainIterator.
An interface is not really needed, we can just rather add the size method
where needed.

Also, there's a couple of methods in the ShardsIterator interface that are
not needed that this commit removes: size, reset and remaining.

Author: javanna

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

@@ -12,7 +12,6 @@
 import org.elasticsearch.action.OriginalIndices;
 import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.cluster.routing.ShardsIterator;
-import org.elasticsearch.common.util.Countable;
 import org.elasticsearch.common.util.PlainIterator;
 import org.elasticsearch.core.Nullable;
 import org.elasticsearch.core.TimeValue;
@@ -29,7 +28,7 @@
  * the cluster alias.
  * @see OriginalIndices
  */
-public final class SearchShardIterator implements Comparable<SearchShardIterator>, Countable {
+public final class SearchShardIterator implements Comparable<SearchShardIterator> {
 
     private final OriginalIndices originalIndices;
     private final String clusterAlias;
@@ -171,7 +170,6 @@ boolean prefiltered() {
      *
      * @return number of shard routing instances in this iterator
      */
-    @Override
     public int size() {
         return targetNodesIterator.size();
     }

server/src/main/java/org/elasticsearch/cluster/routing/ShardsIterator.java

@@ -8,26 +8,12 @@
  */
 package org.elasticsearch.cluster.routing;
 
-import org.elasticsearch.common.util.Countable;
-
 import java.util.List;
 
 /**
  * Allows to iterate over unrelated shards.
  */
-public interface ShardsIterator extends Iterable<ShardRouting>, Countable {
-
-    /**
-     * Resets the iterator to its initial state.
-     */
-    void reset();
-
-    /**
-     * The number of shard routing instances.
-     *
-     * @return number of shard routing instances in this iterator
-     */
-    int size();
+public interface ShardsIterator extends Iterable<ShardRouting> {
 
     /**
      * The number of active shard routing instances
@@ -41,13 +27,6 @@ public interface ShardsIterator extends Iterable<ShardRouting>, Countable {
      */
     ShardRouting nextOrNull();
 
-    /**
-     * Return the number of shards remaining in this {@link ShardsIterator}
-     *
-     * @return number of shard remaining
-     */
-    int remaining();
-
     @Override
     int hashCode();
 

server/src/main/java/org/elasticsearch/common/util/Countable.java

@@ -13,7 +13,7 @@
 import java.util.Iterator;
 import java.util.List;
 
-public class PlainIterator<T> implements Iterable<T>, Countable {
+public class PlainIterator<T> implements Iterable<T> {
     private final List<T> elements;
 
     // Calls to nextOrNull might be performed on different threads in the transport actions so we need the volatile
@@ -43,7 +43,6 @@ public T nextOrNull() {
         }
     }
 
-    @Override
     public int size() {
         return elements.size();
     }

server/src/main/java/org/elasticsearch/common/util/PlainIterator.java

@@ -312,18 +312,21 @@ public void testAllAssignedShardsGrouped() {
     }
 
     public void testAllShardsForMultipleIndices() {
-        assertThat(this.emptyRoutingTable.allShards(new String[0]).size(), is(0));
+        assertThat(this.emptyRoutingTable.allShards(new String[0]).getShardRoutings().size(), is(0));
 
-        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).size(), is(this.shardsPerIndex));
+        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).getShardRoutings().size(), is(this.shardsPerIndex));
 
         initPrimaries();
-        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).size(), is(this.shardsPerIndex));
+        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).getShardRoutings().size(), is(this.shardsPerIndex));
 
         startInitializingShards(TEST_INDEX_1);
-        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).size(), is(this.shardsPerIndex));
+        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1 }).getShardRoutings().size(), is(this.shardsPerIndex));
 
         startInitializingShards(TEST_INDEX_2);
-        assertThat(clusterState.routingTable().allShards(new String[] { TEST_INDEX_1, TEST_INDEX_2 }).size(), is(this.totalNumberOfShards));
+        assertThat(
+            clusterState.routingTable().allShards(new String[] { TEST_INDEX_1, TEST_INDEX_2 }).getShardRoutings().size(),
+            is(this.totalNumberOfShards)
+        );
 
         try {
             clusterState.routingTable().allShards(new String[] { TEST_INDEX_1, "not_exists" });