Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/2315#discussion_r75119617
--- Diff:
flink-mesos/src/main/java/org/apache/flink/mesos/runtime/clusterframework/store/ZooKeeperMesosWorkerStore.java
---
@@ -0,0 +1,290 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.mesos.runtime.clusterframework.store;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.recipes.shared.SharedCount;
+import org.apache.curator.framework.recipes.shared.SharedValue;
+import org.apache.curator.framework.recipes.shared.VersionedValue;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.configuration.ConfigConstants;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.runtime.state.StateHandle;
+import org.apache.flink.runtime.util.ZooKeeperUtils;
+import org.apache.flink.runtime.zookeeper.StateStorageHelper;
+import org.apache.flink.runtime.zookeeper.ZooKeeperStateHandleStore;
+import org.apache.mesos.Protos;
+import org.apache.zookeeper.KeeperException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import scala.Option;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.ConcurrentModificationException;
+import java.util.List;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+import static org.apache.flink.util.Preconditions.checkState;
+
+/**
+ * A ZooKeeper-backed Mesos worker store.
+ */
+public class ZooKeeperMesosWorkerStore implements MesosWorkerStore {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(ZooKeeperMesosWorkerStore.class);
+
+ private final Object cacheLock = new Object();
+
+ /** Client (not a namespace facade) */
+ private final CuratorFramework client;
+
+ /** Flag indicating whether this instance is running. */
+ private boolean isRunning;
+
+ /** A persistent value of the assigned framework ID */
+ private final SharedValue frameworkIdInZooKeeper;
+
+ /** A persistent count of all tasks created, for generating unique IDs
*/
+ private final SharedCount totalTaskCountInZooKeeper;
+
+ /** A persistent store of serialized workers */
+ private final ZooKeeperStateHandleStore<MesosWorkerStore.Worker>
workersInZooKeeper;
+
+ @SuppressWarnings("unchecked")
+ ZooKeeperMesosWorkerStore(
+ CuratorFramework client,
+ String storePath,
+ StateStorageHelper<MesosWorkerStore.Worker> stateStorage
+ ) throws Exception {
+ checkNotNull(storePath, "storePath");
+ checkNotNull(stateStorage, "stateStorage");
+
+ // Keep a reference to the original client and not the
namespace facade. The namespace
+ // facade cannot be closed.
+ this.client = checkNotNull(client, "client");
+
+ // All operations will have the given path as root
+
client.newNamespaceAwareEnsurePath(storePath).ensure(client.getZookeeperClient());
+ CuratorFramework facade =
client.usingNamespace(client.getNamespace() + storePath);
+
+ // Track the assignd framework ID.
+ frameworkIdInZooKeeper = new SharedValue(facade,
"/frameworkId", new byte[0]);
+
+ // Keep a count of all tasks created ever, as the basis for a
unique ID.
+ totalTaskCountInZooKeeper = new SharedCount(facade, "/count",
0);
+
+ // Keep track of the workers in state handle storage.
+
facade.newNamespaceAwareEnsurePath("/workers").ensure(client.getZookeeperClient());
+ CuratorFramework storeFacade =
client.usingNamespace(facade.getNamespace() + "/workers");
+
+ this.workersInZooKeeper = ZooKeeperStateHandleStore.class
+ .getConstructor(CuratorFramework.class,
StateStorageHelper.class)
+ .newInstance(storeFacade, stateStorage);
+ }
+
+ @Override
+ public void start() throws Exception {
+ synchronized (cacheLock) {
+ if (!isRunning) {
+ isRunning = true;
+ frameworkIdInZooKeeper.start();
+ totalTaskCountInZooKeeper.start();
+ }
+ }
+ }
+
+ public void stop() throws Exception {
+ synchronized (cacheLock) {
+ if (isRunning) {
+ frameworkIdInZooKeeper.close();
+ totalTaskCountInZooKeeper.close();
+ client.close();
+ isRunning = false;
+ }
+ }
+ }
+
+ /**
+ * Verifies that the state is running.
+ */
+ private void verifyIsRunning() {
+ checkState(isRunning, "Not running. Forgot to call start()?");
+ }
+
+ /**
+ * Get the persisted framework ID.
+ * @return the current ID or empty if none is yet persisted.
+ * @throws Exception on ZK failures, interruptions.
+ */
+ @Override
+ public Option<Protos.FrameworkID> getFrameworkID() throws Exception {
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ Option<Protos.FrameworkID> frameworkID;
+ byte[] value = frameworkIdInZooKeeper.getValue();
+ if (value.length == 0) {
+ frameworkID = Option.empty();
+ } else {
+ frameworkID =
Option.apply(Protos.FrameworkID.newBuilder().setValue(new
String(value)).build());
+ }
+
+ return frameworkID;
+ }
+ }
+
+ /**
+ * Update the persisted framework ID.
+ * @param frameworkID the new ID or empty to remove the persisted ID.
+ * @throws Exception on ZK failures, interruptions.
+ */
+ @Override
+ public void setFrameworkID(Option<Protos.FrameworkID> frameworkID)
throws Exception {
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ byte[] value = frameworkID.isDefined() ?
frameworkID.get().getValue().getBytes() : new byte[0];
+ frameworkIdInZooKeeper.setValue(value);
+ }
+ }
+
+ /**
+ * Generates a new task ID.
+ */
+ @Override
+ public Protos.TaskID newTaskID() throws Exception {
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ int nextCount;
+ boolean success;
+ do {
+ VersionedValue<Integer> count =
totalTaskCountInZooKeeper.getVersionedValue();
+ nextCount = count.getValue() + 1;
+ success =
totalTaskCountInZooKeeper.trySetCount(count, nextCount);
+ }
+ while (!success);
+
+ Protos.TaskID taskID =
Protos.TaskID.newBuilder().setValue(TASKID_FORMAT.format(nextCount)).build();
+ return taskID;
+ }
+ }
+
+ @Override
+ public List<MesosWorkerStore.Worker> recoverWorkers() throws Exception {
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ List<Tuple2<StateHandle<MesosWorkerStore.Worker>,
String>> handles = workersInZooKeeper.getAll();
+
+ if(handles.size() != 0) {
+ List<MesosWorkerStore.Worker> workers = new
ArrayList<>(handles.size());
+ for
(Tuple2<StateHandle<MesosWorkerStore.Worker>, String> handle : handles) {
+ Worker worker =
handle.f0.getState(ClassLoader.getSystemClassLoader());
+
+ workers.add(worker);
+ }
+
+ return workers;
+ }
+ else {
+ return Collections.emptyList();
+ }
+ }
+ }
+
+ @Override
+ public void putWorker(MesosWorkerStore.Worker worker) throws Exception {
+
+ checkNotNull(worker, "worker");
+ String path = getPathForWorker(worker.taskID());
+
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ int currentVersion = workersInZooKeeper.exists(path);
+ if (currentVersion == -1) {
+ try {
+ workersInZooKeeper.add(path, worker);
+ LOG.debug("Added {} in ZooKeeper.",
worker);
+ } catch (KeeperException.NodeExistsException
ex) {
+ throw new
ConcurrentModificationException("ZooKeeper unexpectedly modified", ex);
+ }
+ } else {
+ try {
+ workersInZooKeeper.replace(path,
currentVersion, worker);
+ LOG.debug("Updated {} in ZooKeeper.",
worker);
+ } catch (KeeperException.NoNodeException ex) {
+ throw new
ConcurrentModificationException("ZooKeeper unexpectedly modified", ex);
+ }
+ }
+ }
+ }
+
+ @Override
+ public void removeWorker(Protos.TaskID taskID) throws Exception {
+ checkNotNull(taskID, "taskID");
+ String path = getPathForWorker(taskID);
+ synchronized (cacheLock) {
+ verifyIsRunning();
+
+ workersInZooKeeper.remove(path);
+ LOG.debug("Removed worker {} from ZooKeeper.", taskID);
+ }
+ }
+
+ @Override
+ public void cleanup() throws Exception {
+ // TODO
--- End diff --
Can we resolve this TODO?
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