Switches UpdateManagedIndexMetaData to batch tasks using custom execu…

…tor (opendistro-for-elasticsearch#209)

* Switches UpdateManagedIndexMetaData to batch tasks using custom executor

* Removes unneeded type

src/main/kotlin/com/amazon/opendistroforelasticsearch/indexstatemanagement/transport/action/updateindexmetadata/TransportUpdateManagedIndexMetaDataAction.kt

@@ -28,18 +28,24 @@ import org.elasticsearch.action.support.ActionFilters
 import org.elasticsearch.action.support.master.AcknowledgedResponse
 import org.elasticsearch.action.support.master.TransportMasterNodeAction
 import org.elasticsearch.client.Client
-import org.elasticsearch.cluster.AckedClusterStateUpdateTask
 import org.elasticsearch.cluster.ClusterState
+import org.elasticsearch.cluster.ClusterStateTaskConfig
+import org.elasticsearch.cluster.ClusterStateTaskExecutor
+import org.elasticsearch.cluster.ClusterStateTaskExecutor.ClusterTasksResult
+import org.elasticsearch.cluster.ClusterStateTaskListener
 import org.elasticsearch.cluster.block.ClusterBlockException
 import org.elasticsearch.cluster.block.ClusterBlockLevel
 import org.elasticsearch.cluster.metadata.IndexMetaData
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver
 import org.elasticsearch.cluster.metadata.MetaData
 import org.elasticsearch.cluster.service.ClusterService
+import org.elasticsearch.common.Priority
 import org.elasticsearch.common.inject.Inject
 import org.elasticsearch.common.io.stream.StreamInput
+import org.elasticsearch.index.Index
 import org.elasticsearch.threadpool.ThreadPool
 import org.elasticsearch.transport.TransportService
+import java.lang.Exception
 import java.util.function.Supplier
 
 class TransportUpdateManagedIndexMetaDataAction : TransportMasterNodeAction<UpdateManagedIndexMetaDataRequest, AcknowledgedResponse> {
@@ -69,6 +75,7 @@ class TransportUpdateManagedIndexMetaDataAction : TransportMasterNodeAction<Upda
     private val log = LogManager.getLogger(javaClass)
     private val client: Client
     private val indexStateManagementHistory: IndexStateManagementHistory
+    private val executor = ManagedIndexMetaDataExecutor()
 
     override fun checkBlock(request: UpdateManagedIndexMetaDataRequest, state: ClusterState): ClusterBlockException? {
         // https://github.com/elastic/elasticsearch/commit/ae14b4e6f96b554ca8f4aaf4039b468f52df0123
@@ -87,45 +94,14 @@ class TransportUpdateManagedIndexMetaDataAction : TransportMasterNodeAction<Upda
     ) {
         clusterService.submitStateUpdateTask(
             IndexStateManagementPlugin.PLUGIN_NAME,
-            object : AckedClusterStateUpdateTask<AcknowledgedResponse>(request, listener) {
-                override fun execute(currentState: ClusterState): ClusterState {
-                    // If there are no indices to make changes to, return early.
-                    // Also doing this because when creating a metaDataBuilder and making no changes to it, for some
-                    // reason the task does not complete, leading to indefinite suspension.
-                    if (request.indicesToAddManagedIndexMetaDataTo.isEmpty() &&
-                        request.indicesToRemoveManagedIndexMetaDataFrom.isEmpty()
-                    ) {
-                        return currentState
-                    }
-
-                    val metaDataBuilder = MetaData.builder(currentState.metaData)
-
-                    for (pair in request.indicesToAddManagedIndexMetaDataTo) {
-                        if (currentState.metaData.hasIndex(pair.first.name)) {
-                            metaDataBuilder.put(IndexMetaData.builder(currentState.metaData.index(pair.first))
-                                .putCustom(ManagedIndexMetaData.MANAGED_INDEX_METADATA, pair.second.toMap()))
-                        } else {
-                            log.debug("No IndexMetaData found for [${pair.first.name}] when updating ManagedIndexMetaData")
-                        }
-                    }
-
-                    for (index in request.indicesToRemoveManagedIndexMetaDataFrom) {
-                        if (currentState.metaData.hasIndex(index.name)) {
-                            val indexMetaDataBuilder = IndexMetaData.builder(currentState.metaData.index(index))
-                            indexMetaDataBuilder.removeCustom(ManagedIndexMetaData.MANAGED_INDEX_METADATA)
-
-                            metaDataBuilder.put(indexMetaDataBuilder)
-                        } else {
-                            log.debug("No IndexMetaData found for [${index.name}] when removing ManagedIndexMetaData")
-                        }
-                    }
-
-                    return ClusterState.builder(currentState).metaData(metaDataBuilder).build()
-                }
-
-                override fun newResponse(acknowledged: Boolean): AcknowledgedResponse {
-                    return AcknowledgedResponse(acknowledged)
-                }
+            ManagedIndexMetaDataTask(request.indicesToAddManagedIndexMetaDataTo, request.indicesToRemoveManagedIndexMetaDataFrom),
+            ClusterStateTaskConfig.build(Priority.NORMAL),
+            executor,
+            object : ClusterStateTaskListener {
+                override fun onFailure(source: String, e: Exception) = listener.onFailure(e)
+
+                override fun clusterStateProcessed(source: String, oldState: ClusterState, newState: ClusterState) =
+                    listener.onResponse(AcknowledgedResponse(true))
             }
         )
 
@@ -147,4 +123,55 @@ class TransportUpdateManagedIndexMetaDataAction : TransportMasterNodeAction<Upda
     override fun executor(): String {
         return ThreadPool.Names.SAME
     }
+
+    inner class ManagedIndexMetaDataExecutor : ClusterStateTaskExecutor<ManagedIndexMetaDataTask> {
+
+        override fun execute(currentState: ClusterState, tasks: List<ManagedIndexMetaDataTask>): ClusterTasksResult<ManagedIndexMetaDataTask> {
+            val newClusterState = getUpdatedClusterState(currentState, tasks)
+            return ClusterTasksResult.builder<ManagedIndexMetaDataTask>().successes(tasks).build(newClusterState)
+        }
+    }
+
+    fun getUpdatedClusterState(currentState: ClusterState, tasks: List<ManagedIndexMetaDataTask>): ClusterState {
+        // If there are no indices to make changes to, return early.
+        // Also doing this because when creating a metaDataBuilder and making no changes to it, for some
+        // reason the task does not complete, leading to indefinite suspension.
+        if (tasks.all { it.indicesToAddManagedIndexMetaDataTo.isEmpty() && it.indicesToRemoveManagedIndexMetaDataFrom.isEmpty() }
+        ) {
+            return currentState
+        }
+        log.trace("Start of building new cluster state")
+        val metaDataBuilder = MetaData.builder(currentState.metaData)
+        for (task in tasks) {
+            for (pair in task.indicesToAddManagedIndexMetaDataTo) {
+                if (currentState.metaData.hasIndex(pair.first.name)) {
+                    metaDataBuilder.put(IndexMetaData.builder(currentState.metaData.index(pair.first))
+                            .putCustom(ManagedIndexMetaData.MANAGED_INDEX_METADATA, pair.second.toMap()))
+                } else {
+                    log.debug("No IndexMetaData found for [${pair.first.name}] when updating ManagedIndexMetaData")
+                }
+            }
+
+            for (index in task.indicesToRemoveManagedIndexMetaDataFrom) {
+                if (currentState.metaData.hasIndex(index.name)) {
+                    val indexMetaDataBuilder = IndexMetaData.builder(currentState.metaData.index(index))
+                    indexMetaDataBuilder.removeCustom(ManagedIndexMetaData.MANAGED_INDEX_METADATA)
+
+                    metaDataBuilder.put(indexMetaDataBuilder)
+                } else {
+                    log.debug("No IndexMetaData found for [${index.name}] when removing ManagedIndexMetaData")
+                }
+            }
+        }
+        log.trace("End of building new cluster state")
+
+        return ClusterState.builder(currentState).metaData(metaDataBuilder).build()
+    }
+
+    companion object {
+        data class ManagedIndexMetaDataTask(
+            val indicesToAddManagedIndexMetaDataTo: List<Pair<Index, ManagedIndexMetaData>>,
+            val indicesToRemoveManagedIndexMetaDataFrom: List<Index>
+        )
+    }
 }