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https://issues.apache.org/jira/browse/STORM-885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15018658#comment-15018658
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ASF GitHub Bot commented on STORM-885:
--------------------------------------
Github user d2r commented on a diff in the pull request:
https://github.com/apache/storm/pull/838#discussion_r45510536
--- Diff: storm-core/src/jvm/backtype/storm/cluster/ClusterState.java ---
@@ -0,0 +1,209 @@
+/**
+ * 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 backtype.storm.cluster;
+
+import clojure.lang.APersistentMap;
+import clojure.lang.IFn;
+import java.util.List;
+import org.apache.zookeeper.data.ACL;
+
+/**
+ * ClusterState provides the API for the pluggable state store used by the
+ * Storm daemons. Data is stored in path/value format, and the store
supports
+ * listing sub-paths at a given path.
+ * All data should be available across all nodes with eventual consistency.
+ *
+ * IMPORTANT NOTE:
+ * Heartbeats have different api calls used to interact with them. The root
+ * path (/) may or may not be the same as the root path for the other api
calls.
+ *
+ * For example, performing these two calls:
+ * set_data("/path", data, acls);
+ * void set_worker_hb("/path", heartbeat, acls);
+ * may or may not cause a collision in "/path".
+ * Never use the same paths with the *_hb* methods as you do with the
others.
+ */
+public interface ClusterState {
+
+ /**
+ * Registers a callback function that gets called when CuratorEvents
happen.
+ * @param callback is a clojure IFn that accepts the type - translated
to
+ * clojure keyword as in zookeeper.clj - and the path: (callback type
path)
+ * @return is an id that can be passed to unregister(...) to
unregister the
+ * callback.
+ */
+ String register(IFn callback);
+
+ /**
+ * Unregisters a callback function that was registered with
register(...).
+ * @param id is the String id that was returned from register(...).
+ */
+ void unregister(String id);
+
+ /**
+ * Path will be appended with a monotonically increasing integer, a
new node
+ * will be created there, and data will be put at that node.
+ * @param path The path that the monotonically increasing integer
suffix will
+ * be added to.
+ * @param data The data that will be written at the suffixed path's
node.
+ * @param acls The acls to apply to the path. May be null.
+ * @return The path with the integer suffix appended.
+ */
+ String create_sequential(String path, byte[] data, List<ACL> acls);
+
+ /**
+ * Creates nodes for path and all its parents. Path elements are
separated by
+ * a "/", as in *nix filesystem notation. Equivalent to mkdir -p in
*nix.
+ * @param path The path to create, along with all its parents.
+ * @param acls The acls to apply to the path. May be null.
+ * @return path
+ */
+ String mkdirs(String path, List<ACL> acls);
+
+ /**
+ * Deletes the node at a given path, and any child nodes that may
exist.
+ * @param path The path to delete
+ */
+ void delete_node(String path);
+
+ /**
+ * Creates an ephemeral node at path. Ephemeral nodes are destroyed
+ * by the store when the client disconnects.
+ * @param path The path where a node will be created.
+ * @param data The data to be written at the node.
+ * @param acls The acls to apply to the path. May be null.
+ * @return path
+ */
+ void set_ephemeral_node(String path, byte[] data, List<ACL> acls);
+
+ /**
+ * Gets the 'version' of the node at a path. Optionally sets a watch
+ * on that node. The version should increase whenever a write happens.
+ * @param path The path to get the version of.
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return The integer version of this node.
+ */
+ Integer get_version(String path, boolean watch);
+
+ /**
+ * Check if a node exists and optionally set a watch on the path.
+ * @param path The path to check for the existence of a node.
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return Whether or not a node exists at path.
+ */
+ boolean node_exists(String path, boolean watch);
+
+ /**
+ * Get a list of paths of all the child nodes which exist immediately
+ * under path.
+ * @param path The path to look under
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return list of string paths under path.
+ */
+ List<String> get_children(String path, boolean watch);
+
+ /**
+ * Close the connection to the data store.
+ */
+ void close();
+
+ /**
+ * Set the value of the node at path to data.
+ * @param path The path whose node we want to set.
+ * @param data The data to put in the node.
+ * @param acls The acls to apply to the path. May be null.
+ */
+ void set_data(String path, byte[] data, List<ACL> acls);
+
+ /**
+ * Get the data from the node at path
+ * @param path The path to look under
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return The data at the node.
+ */
+ byte[] get_data(String path, boolean watch);
+
+ /**
+ * Get the data at the node along with its version. Data is returned
+ * in an APersistentMap with clojure keyword keys :data and :version.
+ * @param path The path to look under
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return An APersistentMap in the form {:data data :version version}
+ */
+ APersistentMap get_data_with_version(String path, boolean watch);
+
+ /**
+ * Write a worker heartbeat at the path.
+ * @param path The path whose node we want to set.
+ * @param data The data to put in the node.
+ * @param acls The acls to apply to the path. May be null.
+ */
+ void set_worker_hb(String path, byte[] data, List<ACL> acls);
+
+ /**
+ * Get the heartbeat from the node at path
+ * @param path The path to look under
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return The heartbeat at the node.
+ */
+ byte[] get_worker_hb(String path, boolean watch);
+
+ /**
+ * Get a list of paths of all the child nodes which exist immediately
+ * under path. This is similar to get_children, but must be used for
+ * any nodes
+ * @param path The path to look under
+ * @param watch Whether or not to set a watch on the path. Watched
paths
+ * emit events which are consumed by functions registered with the
+ * register method. Very useful for catching updates to nodes.
+ * @return list of string paths under path.
+ */
+ List<String> get_worker_hb_children(String path, boolean watch);
+
+ /**
+ * Deletes the heartbeat at a given path, and any child nodes that may
exist.
+ * @param path The path to delete.
+ */
+ void delete_worker_hb(String path);
+
+ /**
+ * Add a ClusterStateListener to the connection.
+ * @param listener A ClusterStateListener to handle changing cluster
state
+ * events.
+ */
+ void add_listener(ClusterStateListener listener);
+
+ /**
+ * Force consistency on a path. Any writes committed on the path before
+ * this call will be completely propagated when it returns.
+ * @param The path to synchronize.
--- End diff --
minor: `path to synchronize` (evidently the first word is the param name
here)
> Heartbeat Server (Pacemaker)
> ----------------------------
>
> Key: STORM-885
> URL: https://issues.apache.org/jira/browse/STORM-885
> Project: Apache Storm
> Issue Type: Improvement
> Components: storm-core
> Reporter: Robert Joseph Evans
> Assignee: Kyle Nusbaum
>
> Large highly connected topologies and large clusters write a lot of data into
> ZooKeeper. The heartbeats, that make up the majority of this data, do not
> need to be persisted to disk. Pacemaker is intended to be a secure
> replacement for storing the heartbeats without changing anything within the
> heartbeats. In the future as more metrics are added in, we may want to look
> into switching it over to look more like Heron, where a metrics server is
> running for each node/topology. And can be used to aggregate/per-aggregate
> them in a more scalable manor.
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