com.linecorp.centraldogma.client.Latest Maven / Gradle / Ivy

Go to download

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

Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2 (centraldogma-client)

The newest version!

/*
 * Copyright 2017 LINE Corporation
 *
 * LINE Corporation licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package com.linecorp.centraldogma.client;

import static java.util.Objects.requireNonNull;

import java.util.Objects;

import javax.annotation.Nullable;

import com.google.common.base.MoreObjects;

import com.linecorp.centraldogma.common.Revision;

/**
 * An immutable holder of the latest known value and its {@link Revision} retrieved by a {@link Watcher}.
 *
 * @param  the value type
 */
public final class Latest {

    private final Revision revision;
    @Nullable
    private final U value;

    /**
     * Creates a new instance with the specified {@link Revision} and value.
     */
    public Latest(Revision revision, @Nullable U value) {
        this.revision = requireNonNull(revision, "revision");
        this.value = value;
    }

    /**
     * Returns the {@link Revision} of the latest known value.
     */
    public Revision revision() {
        return revision;
    }

    /**
     * Returns the latest known value.
     */
    @Nullable
    public U value() {
        return value;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof Latest)) {
            return false;
        }
        final Latest that = (Latest) o;
        return revision.equals(that.revision) && Objects.equals(value, that.value);
    }

    @Override
    public int hashCode() {
        return revision.hashCode() * 31 + Objects.hashCode(value);
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(this)
                          .add("revision", revision)
                          .add("value", value)
                          .toString();
    }
}