Package org.infinispan.counter.impl.strong

Class AbstractStrongCounter

java.lang.Object

org.infinispan.counter.impl.strong.AbstractStrongCounter

All Implemented Interfaces:

StrongCounter, CounterEventGenerator, InternalCounterAdmin

Direct Known Subclasses:

BoundedStrongCounter, UnboundedStrongCounter

public abstract class AbstractStrongCounter
extends Object
implements StrongCounter, CounterEventGenerator, InternalCounterAdmin

A base strong consistent counter implementation.

Implementation: The value is stored in a single key and it uses the Infinispan's concurrency control and distribution to apply the write and reads. It uses the functional API.

Writes: The writes are performed by the functional API in order. The single key approach allows us to provide atomic properties for the counter value.

Reads: The reads read the value from the cache and it can go remotely.

Weak Reads: This implementation supports weak cached reads. It uses clustered listeners to receive the notifications of the actual value to store it locally.

Since:

9.0

Author:

Pedro Ruivo

Method Summary

Modifier and Type	Method	Description
final CompletableFuture<Long>	addAndGet(long delta)	Atomically adds the given value and return the new value.
final <T extends CounterListener> Handle<T>	addListener(T listener)	Registers a CounterListener to this counter.
StrongCounter	asStrongCounter()
CompletableFuture<Long>	compareAndSwap(long expect, long update)	Atomically sets the value to the given updated value if the current value == the expected value.
CompletionStage<Void>	destroy()	Destroys the counter.
CounterEvent	generate(CounterKey key, CounterValue value)	It generates the CounterEvent.
CompletableFuture<Long>	getAndSet(long value)	Atomically sets the value to the given updated value
final CounterConfiguration	getConfiguration()
final String	getName()
final CompletableFuture<Long>	getValue()	It fetches the current value.
protected abstract long	handleAddResult(CounterValue counterValue)	Extracts and validates the value after a read.
protected abstract Long	handleCASResult(Object state)
protected abstract Long	handleSetResult(Object state)
final CompletionStage<InternalCounterAdmin>	init()
boolean	isWeakCounter()	Checks if the counter is a WeakCounter.
CompletableFuture<Void>	remove()	It removes this counter from the cluster.
static CompletionStage<Void>	removeStrongCounter(org.infinispan.Cache<StrongCounterKey,CounterValue> cache, String counterName)	It removes a strong counter from the cache, identified by the counterName.
final CompletableFuture<Void>	reset()	Resets the counter to its initial value.
SyncStrongCounter	sync()	It returns a synchronous strong counter for this instance.
CompletionStage<Long>	value()	Returns the counter's value.

Methods inherited from class java.lang.Object

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

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

asWeakCounter

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

compareAndSet, decrementAndGet, incrementAndGet

Method Details

removeStrongCounter

public static CompletionStage<Void> removeStrongCounter(org.infinispan.Cache<StrongCounterKey,CounterValue> cache,
 String counterName)

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

Parameters:

cache - The Cache to remove the counter from.

counterName - The counter's name.

init

public final CompletionStage<InternalCounterAdmin> init()

asStrongCounter

public StrongCounter asStrongCounter()

Specified by:

asStrongCounter in interface InternalCounterAdmin

Returns:

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

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.

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.

getName

public final String getName()

Specified by:

getName in interface StrongCounter

Returns:

The counter name.

getValue

public final CompletableFuture<Long> getValue()

Description copied from interface: StrongCounter

It fetches the current value.

It may go remotely to fetch the current value.

Specified by:

getValue in interface StrongCounter

Returns:

The current value.

addAndGet

public final CompletableFuture<Long> addAndGet(long delta)

Description copied from interface: StrongCounter

Atomically adds the given value and return the new value.

Specified by:

addAndGet in interface StrongCounter

Parameters:

delta - The non-zero value to add. It can be negative.

Returns:

The new value.

reset

public final CompletableFuture<Void> reset()

Description copied from interface: StrongCounter

Resets the counter to its initial value.

Specified by:

reset in interface InternalCounterAdmin

Specified by:

reset in interface StrongCounter

Returns:

A CompletionStage instance which is completed when the operation finishes.

addListener

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

Description copied from interface: StrongCounter

Registers a CounterListener to this counter.

Specified by:

addListener in interface StrongCounter

Type Parameters:

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

Parameters:

listener - The listener to register.

Returns:

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

compareAndSwap

public CompletableFuture<Long> compareAndSwap(long expect,
 long update)

Description copied from interface: StrongCounter

Atomically sets the value to the given updated value if the current value == the expected value.

The operation is successful if the return value is equals to the expected value.

Specified by:

compareAndSwap in interface StrongCounter

Parameters:

expect - the expected value.

update - the new value.

Returns:

the previous counter's value.

getAndSet

public CompletableFuture<Long> getAndSet(long value)

Description copied from interface: StrongCounter

Atomically sets the value to the given updated value

Specified by:

getAndSet in interface StrongCounter

Parameters:

value - the expected value.

Returns:

the previous counter's value.

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: StrongCounter

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 StrongCounter

Returns:

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

getConfiguration

public final CounterConfiguration getConfiguration()

Specified by:

getConfiguration in interface StrongCounter

Returns:

the CounterConfiguration used by this counter.

sync

public SyncStrongCounter sync()

Description copied from interface: StrongCounter

It returns a synchronous strong counter for this instance.

Specified by:

sync in interface StrongCounter

Returns:

a SyncStrongCounter.

handleCASResult

protected abstract Long handleCASResult(Object state)

handleAddResult

protected abstract long handleAddResult(CounterValue counterValue)

Extracts and validates the value after a read.

Any exception should be thrown using CompletionException.

Parameters:

counterValue - The new CounterValue.

Returns:

The new value stored in CounterValue.

handleSetResult

protected abstract Long handleSetResult(Object state)