org.jgroups.blocks.atomic.AsyncCounter Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of wildfly-client-all

This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 34.0.0.Final

Show newest version

package org.jgroups.blocks.atomic;

import org.jgroups.annotations.Experimental;
import org.jgroups.util.LongSizeStreamable;
import org.jgroups.util.Streamable;

import java.util.concurrent.CompletionStage;

/**
 * An asynchronous counter interface.
 *
 * @author Pedro Ruivo
 * @since 5.2
 */
public interface AsyncCounter {

    /**
     * @return The counter's name.
     */
    String getName();

    /**
     * Gets the current value of the counter.
     *
     * @return A {@link CompletionStage} that is completed with the counter's value.
     */
    default CompletionStage get() {
        return addAndGet(0);
    }

    /**
     * Sets the counter to a new value.
     *
     * @return A {@link CompletionStage} that is completed with the counter's value is updated.
     */
    CompletionStage set(long new_value);

    /**
     * Atomically updates the counter using a compare-and-set operation.
     *
     * @param expect The expected value of the counter
     * @param update The new value of the counter
     * @return A {@link CompletionStage} that is completed with {@code true} if the counter is updated and {@link false} otherwise.
     */
    default CompletionStage compareAndSet(long expect, long update) {
        return compareAndSwap(expect, update).thenApply(value -> value == expect);
    }

    /**
     * Atomically updates the counter using a compare-and-swap operation.
     *
     * @param expect The expected value of the counter
     * @param update The new value of the counter
     * @return A {@link CompletionStage} that is completed with the current counter's value.
     */
    CompletionStage compareAndSwap(long expect, long update);

    /**
     * Atomically increments the counter and returns the new value
     *
     * @return A {@link CompletionStage} that is completed with the new counter's value.
     */
    default CompletionStage incrementAndGet() {
        return addAndGet(1);
    }

    /**
     * Atomically decrements the counter and returns the new value
     *
     * @return A {@link CompletionStage} that is completed with the new counter's value.
     */
    default CompletionStage decrementAndGet() {
        return addAndGet(-1);
    }


    /**
     * Atomically adds the given value to the current value.
     *
     * @param delta the value to add
     * @return A {@link CompletionStage} that is completed with the updated counter's value.
     */
    CompletionStage addAndGet(long delta);

    /**
     * Atomically updates the counter's value.
     * 
     * Both {@link CounterFunction} and return value must implement {@link Streamable} to be sent over the network.
     * The function should not block thread since it can cause deadlocks neither invoke any operation over the {@link AsyncCounter}.
     * 
     * The {@link CounterView} is a copy of the counter's value and the last {@link CounterView#set(long)} will be applied to the counter.
     *
     * @param updateFunction The update {@link CounterFunction}.
     * @param             The return value type.
     * @return The {@link CompletionStage} which will be completed with the {@link CounterFunction} return value.
     * @see CounterFunction
     * @see CounterView
     * @see LongSizeStreamable
     */
    @Experimental
    default  CompletionStage update(CounterFunction updateFunction) {
        throw new UnsupportedOperationException();
    }

    /**
     * @return a synchronous wrapper around this instance.
     */
    SyncCounter sync();

}