ClusterState (Storm 1.2.3 API)

```
public interface ClusterState
```
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.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`add_listener(ClusterStateListener listener)` Add a ClusterStateListener to the connection.
`void`	`close()` Close the connection to the data store.
`String`	`create_sequential(String path, byte[] data, List<org.apache.zookeeper.data.ACL> acls)` Path will be appended with a monotonically increasing integer, a new node will be created there, and data will be put at that node.
`void`	`delete_node_blobstore(String path, String nimbusHostPortInfo)` Allows us to delete the znodes within /storm/blobstore/key_name whose znodes start with the corresponding nimbusHostPortInfo
`void`	`delete_node(String path)` Deletes the node at a given path, and any child nodes that may exist.
`void`	`delete_worker_hb(String path)` Deletes the heartbeat at a given path, and any child nodes that may exist.
`List<String>`	`get_children(String path, boolean watch)` Get a list of paths of all the child nodes which exist immediately under path.
`clojure.lang.APersistentMap`	`get_data_with_version(String path, boolean watch)` Get the data at the node along with its version.
`byte[]`	`get_data(String path, boolean watch)` Get the data from the node at path
`Integer`	`get_version(String path, boolean watch)` Gets the ‘version’ of the node at a path.
`List<String>`	`get_worker_hb_children(String path, boolean watch)` Get a list of paths of all the child nodes which exist immediately under path.
`byte[]`	`get_worker_hb(String path, boolean watch)` Get the heartbeat from the node at path
`String`	`mkdirs(String path, List<org.apache.zookeeper.data.ACL> acls)` Creates nodes for path and all its parents.
`boolean`	`node_exists(String path, boolean watch)` Check if a node exists and optionally set a watch on the path.
`String`	`register(clojure.lang.IFn callback)` Registers a callback function that gets called when CuratorEvents happen.
`void`	`set_data(String path, byte[] data, List<org.apache.zookeeper.data.ACL> acls)` Set the value of the node at path to data.
`void`	`set_ephemeral_node(String path, byte[] data, List<org.apache.zookeeper.data.ACL> acls)` Creates an ephemeral node at path.
`void`	`set_worker_hb(String path, byte[] data, List<org.apache.zookeeper.data.ACL> acls)` Write a worker heartbeat at the path.
`void`	`sync_path(String path)` Force consistency on a path.
`void`	`unregister(String id)` Unregisters a callback function that was registered with register(…).

- Method Detail
  - register
```
String register(clojure.lang.IFn callback)
```
    Registers a callback function that gets called when CuratorEvents happen.
    
    Parameters:
    
    callback - is a clojure IFn that accepts the type - translated to clojure keyword as in zookeeper.clj - and the path: (callback type path)
    
    Returns:
    
    is an id that can be passed to unregister(…) to unregister the callback.
  - unregister
```
void unregister(String id)
```
    Unregisters a callback function that was registered with register(…).
    
    Parameters:
    
    id - is the String id that was returned from register(…).
  - create_sequential
```
String create_sequential(String path,
                         byte[] data,
                         List<org.apache.zookeeper.data.ACL> acls)
```
    Path will be appended with a monotonically increasing integer, a new node will be created there, and data will be put at that node.
    
    Parameters:
    
    path - The path that the monotonically increasing integer suffix will be added to.
    
    data - The data that will be written at the suffixed path’s node.
    
    acls - The acls to apply to the path. May be null.
    
    Returns:
    
    The path with the integer suffix appended.
  - mkdirs
```
String mkdirs(String path,
              List<org.apache.zookeeper.data.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.
    
    Parameters:
    
    path - The path to create, along with all its parents.
    
    acls - The acls to apply to the path. May be null.
    
    Returns:
    
    path
  - delete_node
```
void delete_node(String path)
```
    Deletes the node at a given path, and any child nodes that may exist.
    
    Parameters:
    
    path - The path to delete
  - set_ephemeral_node
```
void set_ephemeral_node(String path,
                        byte[] data,
                        List<org.apache.zookeeper.data.ACL> acls)
```
    Creates an ephemeral node at path. Ephemeral nodes are destroyed by the store when the client disconnects.
    
    Parameters:
    
    path - The path where a node will be created.
    
    data - The data to be written at the node.
    
    acls - The acls to apply to the path. May be null.
  - get_version
```
Integer get_version(String path,
                    boolean watch)
```
    Gets the ‘version’ of the node at a path. Optionally sets a watch on that node. The version should increase whenever a write happens.
    
    Parameters:
    
    path - The path to get the version of.
    
    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.
    
    Returns:
    
    The integer version of this node.
  - node_exists
```
boolean node_exists(String path,
                    boolean watch)
```
    Check if a node exists and optionally set a watch on the path.
    
    Parameters:
    
    path - The path to check for the existence of a node.
    
    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.
    
    Returns:
    
    Whether or not a node exists at path.
  - get_children
```
List<String> get_children(String path,
                          boolean watch)
```
    Get a list of paths of all the child nodes which exist immediately under path.
    
    Parameters:
    
    path - The path to look under
    
    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.
    
    Returns:
    
    list of string paths under path.
  - close
```
void close()
```
    Close the connection to the data store.
  - set_data
```
void set_data(String path,
              byte[] data,
              List<org.apache.zookeeper.data.ACL> acls)
```
    Set the value of the node at path to data.
    
    Parameters:
    
    path - The path whose node we want to set.
    
    data - The data to put in the node.
    
    acls - The acls to apply to the path. May be null.
  - get_data
```
byte[] get_data(String path,
                boolean watch)
```
    Get the data from the node at path
    
    Parameters:
    
    path - The path to look under
    
    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.
    
    Returns:
    
    The data at the node.
  - get_data_with_version
```
clojure.lang.APersistentMap get_data_with_version(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.
    
    Parameters:
    
    path - The path to look under
    
    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.
    
    Returns:
    
    An APersistentMap in the form {:data data :version version}
  - set_worker_hb
```
void set_worker_hb(String path,
                   byte[] data,
                   List<org.apache.zookeeper.data.ACL> acls)
```
    Write a worker heartbeat at the path.
    
    Parameters:
    
    path - The path whose node we want to set.
    
    data - The data to put in the node.
    
    acls - The acls to apply to the path. May be null.
  - get_worker_hb
```
byte[] get_worker_hb(String path,
                     boolean watch)
```
    Get the heartbeat from the node at path
    
    Parameters:
    
    path - The path to look under
    
    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.
    
    Returns:
    
    The heartbeat at the node.
  - get_worker_hb_children
```
List<String> get_worker_hb_children(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
    
    Parameters:
    
    path - The path to look under
    
    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.
    
    Returns:
    
    list of string paths under path.
  - delete_worker_hb
```
void delete_worker_hb(String path)
```
    Deletes the heartbeat at a given path, and any child nodes that may exist.
    
    Parameters:
    
    path - The path to delete.
  - add_listener
```
void add_listener(ClusterStateListener listener)
```
    Add a ClusterStateListener to the connection.
    
    Parameters:
    
    listener - A ClusterStateListener to handle changing cluster state events.
  - sync_path
```
void sync_path(String path)
```
    Force consistency on a path. Any writes committed on the path before this call will be completely propagated when it returns.
    
    Parameters:
    
    path - The path to synchronize.
  - delete_node_blobstore
```
void delete_node_blobstore(String path,
                           String nimbusHostPortInfo)
```
    Allows us to delete the znodes within /storm/blobstore/key_name whose znodes start with the corresponding nimbusHostPortInfo
    
    Parameters:
    
    path - /storm/blobstore/key_name
    
    nimbusHostPortInfo - Contains the host port information of a nimbus node.

Interface ClusterState

Method Summary

Method Detail

register

unregister

create_sequential

mkdirs

delete_node

set_ephemeral_node

get_version

node_exists

get_children

close

set_data

get_data

get_data_with_version

set_worker_hb

get_worker_hb

get_worker_hb_children

delete_worker_hb

add_listener

sync_path

delete_node_blobstore