From 24a841a07567f781a2d5f7cd6e2d5b7dcec6c0fc Mon Sep 17 00:00:00 2001
From: Jason Tedor <jason@tedor.me>
Date: Fri, 29 Jan 2016 13:57:18 -0500
Subject: [PATCH] ShardId equality and hash code inconsistency

This commit fixes an inconsistency between ShardId#equals(Object),
ShardId#hashCode, and ShardId#compareTo(ShardId). In particular,
ShardId#equals(Object) compared only the numerical shard ID and the
index name, but did not compare the index UUID; a similar situation
applies to ShardId#compareTo(ShardId). However, ShardId#hashCode
incorporated the indexUUID into its calculation. This can lead to
situations where two ShardIds compare as equal yet have different hash
codes.

Closes #16319
---
 .../java/org/elasticsearch/index/shard/ShardId.java    | 10 +++++++---
 .../org/elasticsearch/index/shard/IndexShardTests.java |  3 ++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/org/elasticsearch/index/shard/ShardId.java b/core/src/main/java/org/elasticsearch/index/shard/ShardId.java
index f021cb4c162..3dea5501c62 100644
--- a/core/src/main/java/org/elasticsearch/index/shard/ShardId.java
+++ b/core/src/main/java/org/elasticsearch/index/shard/ShardId.java
@@ -76,7 +76,7 @@ public class ShardId implements Streamable, Comparable<ShardId> {
         if (this == o) return true;
         if (o == null) return false;
         ShardId shardId1 = (ShardId) o;
-        return shardId == shardId1.shardId && index.getName().equals(shardId1.index.getName());
+        return shardId == shardId1.shardId && index.equals(shardId1.index);
     }
 
     @Override
@@ -112,8 +112,12 @@ public class ShardId implements Streamable, Comparable<ShardId> {
     @Override
     public int compareTo(ShardId o) {
         if (o.getId() == shardId) {
-            return index.getName().compareTo(o.getIndex().getName());
+            int compare = index.getName().compareTo(o.getIndex().getName());
+            if (compare != 0) {
+                return compare;
+            }
+            return index.getUUID().compareTo(o.getIndex().getUUID());
         }
         return Integer.compare(shardId, o.getId());
     }
-}
\ No newline at end of file
+}
diff --git a/core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java b/core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java
index ca0069e4eda..9a4e6a814a3 100644
--- a/core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java
+++ b/core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java
@@ -68,6 +68,7 @@ import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.env.Environment;
 import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.env.ShardLock;
+import org.elasticsearch.index.Index;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.NodeServicesProvider;
@@ -250,7 +251,7 @@ public class IndexShardTests extends ESSingleNodeTestCase {
         ShardStateMetaData shardStateMetaData = load(logger, env.availableShardPaths(shard.shardId));
         assertEquals(shardStateMetaData, getShardStateMetadata(shard));
 
-        routing = TestShardRouting.newShardRouting(shard.shardId.getIndexName(), shard.shardId.id(), routing.currentNodeId(), null, routing.primary(), ShardRoutingState.INITIALIZING, shard.shardRouting.allocationId(), shard.shardRouting.version() + 1);
+        routing = TestShardRouting.newShardRouting(shard.shardId.getIndex(), shard.shardId.id(), routing.currentNodeId(), null, routing.primary(), ShardRoutingState.INITIALIZING, shard.shardRouting.allocationId(), shard.shardRouting.version() + 1);
         shard.updateRoutingEntry(routing, true);
         shard.deleteShardState();