Improve RoutingNodes API

Currently the RoutingNodes API allows modification of it's internal state outside of the class.
This commit improves the APIs of `RoutingNode` and `RoutingNode` to change internal state
only within the classes itself.

Closes #4458

src/main/java/org/elasticsearch/action/mlt/TransportMoreLikeThisAction.java

@@ -35,10 +35,7 @@
 import org.elasticsearch.cluster.ClusterService;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.node.DiscoveryNode;
-import org.elasticsearch.cluster.routing.MutableShardRouting;
-import org.elasticsearch.cluster.routing.RoutingNode;
-import org.elasticsearch.cluster.routing.ShardIterator;
-import org.elasticsearch.cluster.routing.ShardRouting;
+import org.elasticsearch.cluster.routing.*;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.engine.DocumentMissingException;
@@ -96,13 +93,13 @@ protected void doExecute(final MoreLikeThisRequest request, final ActionListener
         // update to the concrete index
         final String concreteIndex = clusterState.metaData().concreteIndex(request.index());
 
-        RoutingNode routingNode = clusterState.getRoutingNodes().nodesToShards().get(clusterService.localNode().getId());
+        Iterable<MutableShardRouting> routingNode = clusterState.getRoutingNodes().routingNodeIter(clusterService.localNode().getId());
         if (routingNode == null) {
             redirect(request, concreteIndex, listener, clusterState);
             return;
         }
         boolean hasIndexLocally = false;
-        for (MutableShardRouting shardRouting : routingNode.shards()) {
+        for (MutableShardRouting shardRouting : routingNode) {
             if (concreteIndex.equals(shardRouting.index())) {
                 hasIndexLocally = true;
                 break;

src/main/java/org/elasticsearch/cluster/routing/RoutingNode.java

@@ -19,10 +19,12 @@
 
 package org.elasticsearch.cluster.routing;
 
+import com.google.common.collect.Iterators;
 import org.elasticsearch.ElasticSearchIllegalStateException;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 
@@ -52,6 +54,10 @@ public RoutingNode(String nodeId, DiscoveryNode node, List<MutableShardRouting>
 
     @Override
     public Iterator<MutableShardRouting> iterator() {
+        return Iterators.unmodifiableIterator(shards.iterator());
+    }
+
+    Iterator<MutableShardRouting> mutableIterator() {
         return shards.iterator();
     }
 
@@ -72,12 +78,8 @@ public String nodeId() {
         return this.nodeId;
     }
 
-    /**
-     * Get a list of shards hosted on this node  
-     * @return list of shards
-     */
-    public List<MutableShardRouting> shards() {
-        return this.shards;
+    public int size() {
+        return shards.size();
     }
 
     /**
@@ -150,21 +152,6 @@ public List<MutableShardRouting> shardsWithState(String index, ShardRoutingState
         return shards;
     }
 
-    /**
-     * Get the number of shard that not match the given states
-     * @param state set states to exclude
-     * @return number of shards which state is listed
-     */
-    public int numberOfShardsNotWithState(ShardRoutingState state) {
-        int count = 0;
-        for (MutableShardRouting shardEntry : this) {
-            if (shardEntry.state() != state) {
-                count++;
-            }
-        }
-        return count;
-    }
-
     /**
      * The number of shards on this node that will not be eventually relocated.
      */
@@ -187,4 +174,16 @@ public String prettyPrint() {
         }
         return sb.toString();
     }
+
+    public MutableShardRouting get(int i) {
+        return shards.get(i) ;
+    }
+
+    public Collection<MutableShardRouting> copyShards() {
+        return new ArrayList<MutableShardRouting>(shards);
+    }
+
+    public boolean isEmpty() {
+        return shards.isEmpty();
+    }
 }