[GATEWAY] Move GatewayShardsState logic into IndexShard

The index shard should take care of shard state persistence since it has
all the information and the gateway concept has been removed in master.

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

@@ -301,19 +301,21 @@ public boolean equals(Object o) {
         if (shardId != that.shardId) {
             return false;
         }
-        if (currentNodeId != null ? !currentNodeId.equals(that.currentNodeId) : that.currentNodeId != null)
+        if (currentNodeId != null ? !currentNodeId.equals(that.currentNodeId) : that.currentNodeId != null) {
             return false;
+        }
         if (index != null ? !index.equals(that.index) : that.index != null) {
             return false;
         }
-        if (relocatingNodeId != null ? !relocatingNodeId.equals(that.relocatingNodeId) : that.relocatingNodeId != null)
+        if (relocatingNodeId != null ? !relocatingNodeId.equals(that.relocatingNodeId) : that.relocatingNodeId != null) {
             return false;
+        }
         if (state != that.state) {
             return false;
         }
-        if (restoreSource != null ? !restoreSource.equals(that.restoreSource) : that.restoreSource != null)
+        if (restoreSource != null ? !restoreSource.equals(that.restoreSource) : that.restoreSource != null) {
             return false;
-
+        }
         return true;
     }
 

src/main/java/org/elasticsearch/gateway/Gateway.java

@@ -31,6 +31,7 @@
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.env.NodeEnvironment;
+import org.elasticsearch.indices.IndicesService;
 
 import java.nio.file.Path;
 
@@ -43,7 +44,6 @@ public class Gateway extends AbstractComponent implements ClusterStateListener {
 
     private final NodeEnvironment nodeEnv;
 
-    private final GatewayShardsState shardsState;
     private final GatewayMetaState metaState;
 
     private final TransportNodesListGatewayMetaState listGatewayMetaState;
@@ -52,8 +52,7 @@ public class Gateway extends AbstractComponent implements ClusterStateListener {
     private final ClusterName clusterName;
 
     @Inject
-    public Gateway(Settings settings, ClusterService clusterService, NodeEnvironment nodeEnv,
-                   GatewayShardsState shardsState, GatewayMetaState metaState,
+    public Gateway(Settings settings, ClusterService clusterService, NodeEnvironment nodeEnv, GatewayMetaState metaState,
                    TransportNodesListGatewayMetaState listGatewayMetaState, ClusterName clusterName) {
         super(settings);
         this.clusterService = clusterService;
@@ -62,8 +61,6 @@ public Gateway(Settings settings, ClusterService clusterService, NodeEnvironment
         this.listGatewayMetaState = listGatewayMetaState;
         this.clusterName = clusterName;
 
-        this.shardsState = shardsState;
-
         clusterService.addLast(this);
 
         // we define what is our minimum "master" nodes, use that to allow for recovery
@@ -180,7 +177,6 @@ public void clusterChanged(final ClusterChangedEvent event) {
         // order is important, first metaState, and then shardsState
         // so dangling indices will be recorded
         metaState.clusterChanged(event);
-        shardsState.clusterChanged(event);
     }
 
     public interface GatewayStateRecoveredListener {

src/main/java/org/elasticsearch/gateway/GatewayMetaState.java

@@ -37,6 +37,7 @@
 import org.elasticsearch.common.settings.ImmutableSettings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.discovery.Discovery;
 import org.elasticsearch.env.NodeEnvironment;
 
 import java.io.IOException;
@@ -68,6 +69,9 @@ public GatewayMetaState(Settings settings, NodeEnvironment nodeEnv, MetaStateSer
         this.danglingIndicesState = danglingIndicesState;
         nodesListGatewayMetaState.init(this);
 
+        if (DiscoveryNode.dataNode(settings)) {
+            ensureNoPre019ShardState(nodeEnv);
+        }
 
         if (DiscoveryNode.masterNode(settings) || DiscoveryNode.dataNode(settings)) {
             nodeEnv.ensureAtomicMoveSupported();
@@ -230,4 +234,21 @@ private void pre20Upgrade() throws Exception {
                     + "used some custom routing logic, you can now remove these settings from your `elasticsearch.yml` file", DEPRECATED_SETTING_ROUTING_HASH_FUNCTION, DEPRECATED_SETTING_ROUTING_USE_TYPE);
         }
     }
+
+
+    // shard state BWC
+    private void ensureNoPre019ShardState(NodeEnvironment nodeEnv) throws Exception {
+        for (Path dataLocation : nodeEnv.nodeDataPaths()) {
+            final Path stateLocation = dataLocation.resolve(MetaDataStateFormat.STATE_DIR_NAME);
+            if (Files.exists(stateLocation)) {
+                try (DirectoryStream<Path> stream = Files.newDirectoryStream(stateLocation, "shards-*")) {
+                    for (Path stateFile : stream) {
+                        throw new ElasticsearchIllegalStateException("Detected pre 0.19 shard state file please upgrade to a version before "
+                                + Version.CURRENT.minimumCompatibilityVersion()
+                                + " first to upgrade state structures - shard state found: [" + stateFile.getParent().toAbsolutePath());
+                    }
+                }
+            }
+        }
+    }
 }

src/main/java/org/elasticsearch/gateway/GatewayModule.java

@@ -32,7 +32,6 @@ protected void configure() {
         bind(DanglingIndicesState.class).asEagerSingleton();
         bind(GatewayService.class).asEagerSingleton();
         bind(Gateway.class).asEagerSingleton();
-        bind(GatewayShardsState.class).asEagerSingleton();
         bind(TransportNodesListGatewayMetaState.class).asEagerSingleton();
         bind(GatewayMetaState.class).asEagerSingleton();
         bind(TransportNodesListGatewayStartedShards.class).asEagerSingleton();