net.dempsy.cluster.zookeeper

Class ZookeeperSession

java.lang.Object

net.dempsy.cluster.zookeeper.ZookeeperSession

All Implemented Interfaces:

AutoCloseable, ClusterInfoSession, DisruptibleSession

public class ZookeeperSession
extends Object
implements ClusterInfoSession, DisruptibleSession

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	ZookeeperSession.WatcherProxy
protected static class	ZookeeperSession.ZkWatcher

Field Summary

Fields

Modifier and Type	Field and Description
protected String	connectString
protected long	resetDelay
protected int	sessionTimeout

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ZookeeperSession(Serializer serializer, String connectString, int sessionTimeout)

Method Summary

Modifier and Type	Method and Description
void	disrupt()
boolean	exists(String ppath, ClusterInfoWatcher watcher) Check if a path has already been created.
Object	getData(String ppath, ClusterInfoWatcher watcher) If data is stored at the node indicated by the path, then the data will be returned.
Collection<String>	getSubdirs(String ppath, ClusterInfoWatcher pwatcher) Show all of the subdirectories of the given directory.
protected ZookeeperSession.WatcherProxy	makeWatcherProxy(ClusterInfoWatcher watcher)
protected org.apache.zookeeper.ZooKeeper	makeZooKeeperClient(String connectString, int sessionTimeout) This is defined here to be overridden in a test.
String	mkdir(String path, Object data, DirMode mode) This will create a node at the given path.
void	rmdir(String ppath) This will remove the directory stored at the path.
void	setData(String ppath, Object info) Set the data associated with the tree node identified by the path.
void	stop() Stop the session.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.dempsy.cluster.ClusterInfoSession

close, recursiveMkdir

Field Detail

resetDelay

protected long resetDelay

connectString

protected String connectString

sessionTimeout

protected int sessionTimeout

Constructor Detail

ZookeeperSession

protected ZookeeperSession(Serializer serializer,
                           String connectString,
                           int sessionTimeout)
                    throws IOException

Throws:

IOException

Method Detail

mkdir

public String mkdir(String path,
                    Object data,
                    DirMode mode)
             throws ClusterInfoException

Description copied from interface: ClusterInfoSession

This will create a node at the given path. A node must be created before it can be used. This method is not recursive so parent directories will need to be created before this one is created.

Specified by:

mkdir in interface ClusterInfoSession

Parameters:

path - a '/' separated path to a directory in the cluster information manager to create.

data - optional data to set for that directory

mode - is the mode to set for the new directory. See DirMode.

Returns:

directory path if the directory was created. null if the directory cannot be created or already exists. If the DirMode is sequential then the result will satisfy the SEQUENTIAL requirements (see DirMode for the details).

Throws:

ClusterInfoException - on an error which can include the fact that the parent directory doesn't exist (when it should throw a ClusterInfoException.NoParentException) or if you add a directory as a subdir of an EPHEMERAL directory.

rmdir

public void rmdir(String ppath)
           throws ClusterInfoException

Description copied from interface: ClusterInfoSession

This will remove the directory stored at the path. The directory can be deleted if there is a data object stored in it but it cannot be deleted it it has children. They should be removed first.

Specified by:

rmdir in interface ClusterInfoSession

Parameters:

ppath - is the directory to delete.

Throws:

ClusterInfoException - if there is no node at the given path.

exists

public boolean exists(String ppath,
                      ClusterInfoWatcher watcher)
               throws ClusterInfoException

Description copied from interface: ClusterInfoSession

Check if a path has already been created. If the path exists, and if watcher is non-null then the watcher will be called back when the node at the path has data added removed or changed. Once the notification takes place the watch is unregistered.

Specified by:

exists in interface ClusterInfoSession

Parameters:

ppath - is the directory to check

watcher - if non-null, and the path exists, then the watcher will be called back whenever the node at the path has data added to it, or is deleted.

Returns:

true if the node exists, false otherwise.

Throws:

ClusterInfoException - if there is an unforeseen problem.

getData

public Object getData(String ppath,
                      ClusterInfoWatcher watcher)
               throws ClusterInfoException

Description copied from interface: ClusterInfoSession

If data is stored at the node indicated by the path, then the data will be returned. If the node exists, and if watcher is non-null then the watcher will be called back when the node at the path has data added removed or changed. Once the notification takes place the watch is unregistered.

Specified by:

getData in interface ClusterInfoSession

Parameters:

ppath - place to put the data.

watcher - if non-null, and the path exists, then the watcher will be called back whenever the node at the path has data added to it, or is deleted.

Returns:

the Object stored at the location.

Throws:

ClusterInfoException

setData

public void setData(String ppath,
                    Object info)
             throws ClusterInfoException

Description copied from interface: ClusterInfoSession

Set the data associated with the tree node identified by the path. Any data watches set will be triggered.

Specified by:

setData in interface ClusterInfoSession

Parameters:

ppath - identify the directory/tree node of the place to store the data

info - the data to put at the given location.

Throws:

ClusterInfoException

getSubdirs

public Collection<String> getSubdirs(String ppath,
                                     ClusterInfoWatcher pwatcher)
                              throws ClusterInfoException

Description copied from interface: ClusterInfoSession

Show all of the subdirectories of the given directory. If the path exists, and if watcher is non-null then the watcher will be called back when any subdirectories are added removed or changed. Once the notification takes place the watch is unregistered.

Specified by:

getSubdirs in interface ClusterInfoSession

Parameters:

ppath - where the subdirectories to show are.

pwatcher - if non-null, and the path exists, then the watcher will be called back whenever the node at the path has data added to it, or is deleted.

Returns:

the list of subdirectories. These strings WILL NOT contain the full path. They will only contain the subdirectory name. If they are versions of the same SEQUENTIAL directory then they will be lexographically sortable.

Throws:

ClusterInfoException

stop

public void stop()

Description copied from interface: ClusterInfoSession

Stop the session. Stopping the session should cause all EPHEMERAL nodes that were created by the session to be removed. stop() must be implemented such that it doesn't throw an exception no matter what but forces the stopping of any underlying resources that require stopping. Stop is expected to manage the stopping of all underlying MpClusters that it created and once complete no more MpWatcher callbacks should be, or be able to, execute. NOTE: stop() must be idempotent.

Specified by:

stop in interface ClusterInfoSession

disrupt

public void disrupt()

Specified by:

disrupt in interface DisruptibleSession

makeZooKeeperClient

protected org.apache.zookeeper.ZooKeeper makeZooKeeperClient(String connectString,
                                                             int sessionTimeout)
                                                      throws IOException

This is defined here to be overridden in a test.

Throws:

IOException

makeWatcherProxy

protected ZookeeperSession.WatcherProxy makeWatcherProxy(ClusterInfoWatcher watcher)