org.apache.storm.cluster

Interface IStateStorage

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

PaceMakerStateStorage, ZKStateStorage

public interface IStateStorage
extends Closeable

StateStorage 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

Modifier and Type	Method and Description
void	add_listener(org.apache.storm.shade.org.apache.curator.framework.state.ConnectionStateListener listener) Add a StateStorageListener to the connection.
void	close() Close the connection to the data store.
String	create_sequential(String path, byte[] data, List<org.apache.storm.shade.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.
VersionedData<byte[]>	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
void	mkdirs(String path, List<org.apache.storm.shade.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(ZKStateChangedCallback callback) Registers a callback function that gets called when CuratorEvents happen.
void	set_data(String path, byte[] data, List<org.apache.storm.shade.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.storm.shade.org.apache.zookeeper.data.ACL> acls) Creates an ephemeral node at path.
void	set_worker_hb(String path, byte[] data, List<org.apache.storm.shade.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(ZKStateChangedCallback 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 - 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.storm.shade.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

void mkdirs(String path,
            List<org.apache.storm.shade.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.

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.storm.shade.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)
             throws Exception

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.

Throws:

Exception

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.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

set_data

void set_data(String path,
              byte[] data,
              List<org.apache.storm.shade.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

VersionedData<byte[]> get_data_with_version(String path,
                                            boolean watch)

Get the data at the node along with its version. Data is returned in an Map with the 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:

the data with a version

set_worker_hb

void set_worker_hb(String path,
                   byte[] data,
                   List<org.apache.storm.shade.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(org.apache.storm.shade.org.apache.curator.framework.state.ConnectionStateListener listener)

Add a StateStorageListener to the connection.

Parameters:

listener - A StateStorageListener 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.