Package org.infinispan.counter.impl.weak

Class WeakCounterImpl

java.lang.Object

org.infinispan.counter.impl.weak.WeakCounterImpl

All Implemented Interfaces:

WeakCounter, CounterEventGenerator, TopologyChangeListener, InternalCounterAdmin

public class WeakCounterImpl
extends Object
implements WeakCounter, CounterEventGenerator, TopologyChangeListener, InternalCounterAdmin

A weak consistent counter implementation.

Implementation: The counter is split in multiple keys and they are stored in the cache.

Write: A write operation will pick a key to update. If the node is a primary owner of one of the key, that key is chosen based on thread-id. This will take advantage of faster write operations. If the node is not a primary owner, one of the key in key set is chosen.

Read: A read operation needs to read all the key set (including the remote keys). This is slower than atomic counter.

Weak Read: A snapshot of all the keys values is kept locally and they are updated via cluster listeners.

Reset: The reset operation is not atomic and intermediate results may be observed.

Since:

9.0

Author:

Pedro Ruivo

Constructor Summary

Constructors

Constructor	Description
WeakCounterImpl(String counterName, org.infinispan.AdvancedCache<WeakCounterKey,CounterValue> cache, CounterConfiguration configuration, CounterManagerNotificationManager notificationManager)

Method Summary

Modifier and Type	Method	Description
CompletableFuture<Void>	add(long delta)	Adds the given value to the new value.
<T extends CounterListener> Handle<T>	addListener(T listener)	Adds a CounterListener to this counter.
WeakCounter	asWeakCounter()
CompletionStage<Void>	destroy()	Destroys the counter.
CounterEvent	generate(CounterKey key, CounterValue value)	It generates the CounterEvent.
CounterConfiguration	getConfiguration()
WeakCounterKey[]	getKeys()	Debug only!
String	getName()
WeakCounterKey[]	getPreferredKeys()	Debug only!
long	getValue()	It returns the counter's value.
CompletionStage<InternalCounterAdmin>	init()	Initializes the key set.
boolean	isWeakCounter()	Checks if the counter is a WeakCounter.
CompletableFuture<Void>	remove()	It removes this counter from the cluster.
static CompletionStage<Void>	removeWeakCounter(org.infinispan.Cache<WeakCounterKey,CounterValue> cache, CounterConfiguration configuration, String counterName)	It removes a weak counter from the cache, identified by the counterName.
CompletableFuture<Void>	reset()	Resets the counter to its initial value.
SyncWeakCounter	sync()	It returns a synchronous weak counter for this instance.
void	topologyChanged()	It notifies the cache topology change.
String	toString()
CompletionStage<Long>	value()	Returns the counter's value.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.infinispan.counter.impl.manager.InternalCounterAdmin

asStrongCounter

Methods inherited from interface org.infinispan.counter.api.WeakCounter

decrement, increment

Constructor Details

WeakCounterImpl

public WeakCounterImpl(String counterName,
 org.infinispan.AdvancedCache<WeakCounterKey,CounterValue> cache,
 CounterConfiguration configuration,
 CounterManagerNotificationManager notificationManager)

Method Details

removeWeakCounter

public static CompletionStage<Void> removeWeakCounter(org.infinispan.Cache<WeakCounterKey,CounterValue> cache,
 CounterConfiguration configuration,
 String counterName)

It removes a weak counter from the cache, identified by the counterName.

Parameters:

cache - The Cache to remove the counter from.

configuration - The counter's configuration.

counterName - The counter's name.

init

public CompletionStage<InternalCounterAdmin> init()

Initializes the key set.

Only one key will have the initial value and the remaining is zero.

getName

public String getName()

Specified by:

getName in interface WeakCounter

Returns:

The counter name.

getValue

public long getValue()

Description copied from interface: WeakCounter

It returns the counter's value.

This value may be not the mot up-to-data value.

Specified by:

getValue in interface WeakCounter

Returns:

The counter's value.

add

public CompletableFuture<Void> add(long delta)

Description copied from interface: WeakCounter

Adds the given value to the new value.

Specified by:

add in interface WeakCounter

Parameters:

delta - the value to add.

asWeakCounter

public WeakCounter asWeakCounter()

Specified by:

asWeakCounter in interface InternalCounterAdmin

Returns:

The WeakCounter instance or throws an CounterException if the counter is not a WeakCounter.

destroy

public CompletionStage<Void> destroy()

Description copied from interface: InternalCounterAdmin

Destroys the counter.

It drops the counter's value and all listeners registered.

Specified by:

destroy in interface InternalCounterAdmin

Returns:

A CompletionStage instance which is completed when the operation finishes.

reset

public CompletableFuture<Void> reset()

Description copied from interface: WeakCounter

Resets the counter to its initial value.

Specified by:

reset in interface InternalCounterAdmin

Specified by:

reset in interface WeakCounter

Returns:

A CompletionStage instance which is completed when the operation finishes.

value

public CompletionStage<Long> value()

Description copied from interface: InternalCounterAdmin

Returns the counter's value.

Specified by:

value in interface InternalCounterAdmin

Returns:

A CompletionStage instance which is completed when the operation finishes.

isWeakCounter

public boolean isWeakCounter()

Description copied from interface: InternalCounterAdmin

Checks if the counter is a WeakCounter.

If true, ensures InternalCounterAdmin.asWeakCounter() never throws an CounterException. Otherwise, it ensures InternalCounterAdmin.asStrongCounter() never throws an CounterException.

Specified by:

isWeakCounter in interface InternalCounterAdmin

Returns:

true if the counter is WeakCounter.

addListener

public <T extends CounterListener> Handle<T> addListener(T listener)

Description copied from interface: WeakCounter

Adds a CounterListener to this counter.

Specified by:

addListener in interface WeakCounter

Type Parameters:

T - The type of the listener. It must implement CounterListener.

Parameters:

listener - The listener to add.

Returns:

A Handle that allows to remove the listener via Handle.remove() ()}.

getConfiguration

public CounterConfiguration getConfiguration()

Specified by:

getConfiguration in interface WeakCounter

Returns:

the CounterConfiguration used by this counter.

generate

public CounterEvent generate(CounterKey key,
 CounterValue value)

Description copied from interface: CounterEventGenerator

It generates the CounterEvent.

The value is the new value of CounterEvent.

Specified by:

generate in interface CounterEventGenerator

Parameters:

key - The counter's key.

value - The counter's most recent CounterValue.

Returns:

The CounterEvent with the updated value.

remove

public CompletableFuture<Void> remove()

Description copied from interface: WeakCounter

It removes this counter from the cluster.

Note that it doesn't remove the counter from the CounterManager. If you want to remove the counter from the CounterManager use CounterManager.remove(String).

Specified by:

remove in interface WeakCounter

Returns:

The CompletableFuture that is completed when the counter is removed from the cluster.

sync

public SyncWeakCounter sync()

Description copied from interface: WeakCounter

It returns a synchronous weak counter for this instance.

Specified by:

sync in interface WeakCounter

Returns:

a SyncWeakCounter.

topologyChanged

public void topologyChanged()

Description copied from interface: TopologyChangeListener

It notifies the cache topology change.

Specified by:

topologyChanged in interface TopologyChangeListener

getPreferredKeys

public WeakCounterKey[] getPreferredKeys()

Debug only!

getKeys

public WeakCounterKey[] getKeys()

Debug only!

toString

public String toString()

Overrides:

toString in class Object