Package org.infinispan.counter.impl.weak

Class WeakCounterImpl

java.lang.Object

org.infinispan.counter.impl.weak.WeakCounterImpl

All Implemented Interfaces:

org.infinispan.counter.api.WeakCounter, CounterEventGenerator, TopologyChangeListener, InternalCounterAdmin

public class WeakCounterImpl
extends Object
implements org.infinispan.counter.api.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, org.infinispan.counter.api.CounterConfiguration configuration, CounterManagerNotificationManager notificationManager)

Method Summary

Modifier and Type	Method	Description
CompletableFuture<Void>	add(long delta)
<T extends org.infinispan.counter.api.CounterListener> org.infinispan.counter.api.Handle<T>	addListener(T listener)
org.infinispan.counter.api.WeakCounter	asWeakCounter()
CompletionStage<Void>	destroy()	Destroys the counter.
org.infinispan.counter.api.CounterEvent	generate(CounterKey key, CounterValue value)	It generates the CounterEvent.
org.infinispan.counter.api.CounterConfiguration	getConfiguration()
WeakCounterKey[]	getKeys()	Debug only!
String	getName()
WeakCounterKey[]	getPreferredKeys()	Debug only!
long	getValue()
CompletionStage<InternalCounterAdmin>	init()	Initializes the key set.
boolean	isWeakCounter()	Checks if the counter is a WeakCounter.
CompletableFuture<Void>	remove()
static CompletionStage<Void>	removeWeakCounter(org.infinispan.Cache<WeakCounterKey,CounterValue> cache, org.infinispan.counter.api.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.
org.infinispan.counter.api.SyncWeakCounter	sync()
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 Detail

WeakCounterImpl

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

Method Detail

removeWeakCounter

public static CompletionStage<Void> removeWeakCounter(org.infinispan.Cache<WeakCounterKey,CounterValue> cache,
                                                      org.infinispan.counter.api.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 org.infinispan.counter.api.WeakCounter

getValue

public long getValue()

Specified by:

getValue in interface org.infinispan.counter.api.WeakCounter

add

public CompletableFuture<Void> add(long delta)

Specified by:

add in interface org.infinispan.counter.api.WeakCounter

asWeakCounter

public org.infinispan.counter.api.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: InternalCounterAdmin

Resets the counter to its initial value.

Specified by:

reset in interface InternalCounterAdmin

Specified by:

reset in interface org.infinispan.counter.api.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 org.infinispan.counter.api.CounterListener> org.infinispan.counter.api.Handle<T> addListener(T listener)

Specified by:

addListener in interface org.infinispan.counter.api.WeakCounter

getConfiguration

public org.infinispan.counter.api.CounterConfiguration getConfiguration()

Specified by:

getConfiguration in interface org.infinispan.counter.api.WeakCounter

generate

public org.infinispan.counter.api.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()

Specified by:

remove in interface org.infinispan.counter.api.WeakCounter

sync

public org.infinispan.counter.api.SyncWeakCounter sync()

Specified by:

sync in interface org.infinispan.counter.api.WeakCounter

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