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Kubernetes Service Discovery for Hazelcast Discovery SPI
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/*
 * Copyright 2020 Hazelcast Inc.
 *
 * Licensed under the Hazelcast Community License (the "License"); you may not use
 * this file except in compliance with the License. You may obtain a copy of the
 * License at
 *
 * http://hazelcast.com/hazelcast-community-license
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */

package com.hazelcast.hibernate.serialization;

import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;

import java.io.IOException;
import java.util.Comparator;
import java.util.Objects;

/**
 * A container class which represents an entry in a region cache which can be marked for expiration
 */
public abstract class Expirable implements IdentifiedDataSerializable {

    protected Object version;

    protected Expirable() {
    }

    protected Expirable(Object version) {
        this.version = version;
    }

    /**
     * Determine if the current entry can be overridden with a value corresponding to the given new version
     * and the transaction timestamp.
     *
     * @param txTimestamp       the timestamp of the transaction
     * @param newVersion        the new version for the replacement value
     * @param versionComparator the comparator to use for the version
     *
     * @return {@code true} if the value can be replaced, {@code false} otherwise
     */
    public abstract boolean isReplaceableBy(long txTimestamp, Object newVersion, Comparator versionComparator);

    /**
     * @return the value contained, or {@code null} if none exists
     */
    public abstract Object getValue();

    /**
     * @param txTimestamp the timestamp of the transaction
     *
     * @return the value contained if it was created before the transaction timestamp or {@code null}
     */
    public abstract Object getValue(long txTimestamp);

    /**
     * @return the version representing the value of {@code null} if the entry is not versioned
     */
    public Object getVersion() {
        return version;
    }

    /**
     * @return {@code true} if the {@link Expirable} matches using the specified lock, {@code false} otherwise
     *
     * @see ExpiryMarker#expire(long)
     */
    public abstract boolean matches(ExpiryMarker lock);

    /**
     * Mark the entry for expiration with the given timeout and marker id.
     * 
     * For every invocation a corresponding call to {@link ExpiryMarker#expire(long)} should be made, provided that
     * the returned marker {@link #matches(ExpiryMarker)}
     *
     * @param timeout      the timestamp in which the lock times out
     * @param nextMarkerId the next lock id to use if creating a new lock
     *
     * @return the newly created marker, or the current marker with a higher multiplicity
     *
     * @see ExpiryMarker#expire(long)
     */
    public abstract ExpiryMarker markForExpiration(long timeout, String nextMarkerId);

    @Override
    public void writeData(ObjectDataOutput out) throws IOException {
        out.writeObject(version);
    }

    @Override
    public void readData(ObjectDataInput in) throws IOException {
        version = in.readObject();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        Expirable expirable = (Expirable) o;
        return Objects.equals(version, expirable.version);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(version);
    }
}