com.netflix.curator.framework.recipes.shared

Class SharedCount

java.lang.Object

com.netflix.curator.framework.recipes.shared.SharedCount

All Implemented Interfaces:

Listenable<SharedCountListener>, SharedCountReader, java.io.Closeable, java.lang.AutoCloseable

public class SharedCount
extends java.lang.Object
implements java.io.Closeable, SharedCountReader, Listenable<SharedCountListener>

Manages a shared integer. All clients watching the same path will have the up-to-date value of the shared integer (considering ZK's normal consistency guarantees).

Constructor Summary

Constructors

Constructor and Description
SharedCount(CuratorFramework client, java.lang.String path, int seedValue)

Method Summary

Methods

Modifier and Type	Method and Description
void	addListener(SharedCountListener listener) Add the given listener.
void	addListener(SharedCountListener listener, java.util.concurrent.Executor executor) Add the given listener.
void	close()
int	getCount() Return the current value of the count
void	removeListener(SharedCountListener listener) Remove the given listener
void	setCount(int newCount) Change the shared count value irrespective of its previous state
void	start() The shared count must be started before it can be used.
boolean	trySetCount(int newCount) Changes the shared count only if its value has not changed since this client last read it.

Methods inherited from class java.lang.Object

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

Constructor Detail

SharedCount

public SharedCount(CuratorFramework client,
           java.lang.String path,
           int seedValue)

Parameters:

client - the client

path - the shared path - i.e. where the shared count is stored

seedValue - the initial value for the count if/f the path has not yet been created

Method Detail

getCount

public int getCount()

Description copied from interface: SharedCountReader

Return the current value of the count

Specified by:

getCount in interface SharedCountReader

Returns:

count

setCount

public void setCount(int newCount)
              throws java.lang.Exception

Change the shared count value irrespective of its previous state

Parameters:

newCount - new value

Throws:

java.lang.Exception - ZK errors, interruptions, etc.

trySetCount

public boolean trySetCount(int newCount)
                    throws java.lang.Exception

Changes the shared count only if its value has not changed since this client last read it. If the count has changed, the value is not set and this client's view of the value is updated. i.e. if the count is not successful you can get the updated value by calling getCount().

Parameters:

newCount - the new value to attempt

Returns:

true if the change attempt was successful, false if not. If the change was not successful, getCount() will return the updated value

Throws:

java.lang.Exception - ZK errors, interruptions, etc.

addListener

public void addListener(SharedCountListener listener)

Description copied from interface: Listenable

Add the given listener. The listener will be executed in the containing instance's thread.

Specified by:

addListener in interface Listenable<SharedCountListener>

Parameters:

listener - listener to add

addListener

public void addListener(SharedCountListener listener,
               java.util.concurrent.Executor executor)

Description copied from interface: Listenable

Add the given listener. The listener will be executed using the given executor

Specified by:

addListener in interface Listenable<SharedCountListener>

Parameters:

listener - listener to add

executor - executor to run listener in

removeListener

public void removeListener(SharedCountListener listener)

Description copied from interface: Listenable

Remove the given listener

Specified by:

removeListener in interface Listenable<SharedCountListener>

Parameters:

listener - listener to remove

start

public void start()
           throws java.lang.Exception

The shared count must be started before it can be used. Call close() when you are finished with the shared count

Throws:

java.lang.Exception - ZK errors, interruptions, etc.

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.io.IOException