kafka TimelineObject 源码

kafka TimelineObject 代码

文件路径：/metadata/src/main/java/org/apache/kafka/timeline/TimelineObject.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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
 *
 *    http://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 org.apache.kafka.timeline;

import java.util.Iterator;
import java.util.Objects;


/**
 * This is a mutable reference to an immutable object. It can be snapshotted.
 *
 * This class requires external synchronization.
 */
public class TimelineObject<T> implements Revertable {
    static class ObjectContainer<T> implements Delta {
        private T value;

        ObjectContainer(T initialValue) {
            this.value = initialValue;
        }

        T value() {
            return value;
        }

        void setValue(T value) {
            this.value = value;
        }

        @Override
        public void mergeFrom(long destinationEpoch, Delta delta) {
            // Nothing to do
        }
    }

    private final SnapshotRegistry snapshotRegistry;
    private final T initialValue;
    private T value;

    public TimelineObject(SnapshotRegistry snapshotRegistry, T initialValue) {
        Objects.requireNonNull(initialValue);
        this.snapshotRegistry = snapshotRegistry;
        this.initialValue = initialValue;
        this.value = initialValue;
        snapshotRegistry.register(this);
    }

    public T get() {
        return value;
    }

    public T get(long epoch) {
        if (epoch == SnapshotRegistry.LATEST_EPOCH) return value;
        Iterator<Snapshot> iterator = snapshotRegistry.iterator(epoch);
        while (iterator.hasNext()) {
            Snapshot snapshot = iterator.next();
            ObjectContainer<T> container = snapshot.getDelta(TimelineObject.this);
            if (container != null) return container.value();
        }
        return value;
    }

    public void set(T newValue) {
        Objects.requireNonNull(newValue);
        Iterator<Snapshot> iterator = snapshotRegistry.reverseIterator();
        if (iterator.hasNext()) {
            Snapshot snapshot = iterator.next();
            ObjectContainer<T> prevContainer = snapshot.getDelta(TimelineObject.this);
            if (prevContainer == null) {
                prevContainer = new ObjectContainer<>(initialValue);
                snapshot.setDelta(TimelineObject.this, prevContainer);
                prevContainer.setValue(value);
            }
        }
        this.value = newValue;
    }

    @SuppressWarnings("unchecked")
    @Override
    public void executeRevert(long targetEpoch, Delta delta) {
        ObjectContainer<T> container = (ObjectContainer<T>) delta;
        this.value = container.value();
    }

    @Override
    public void reset() {
        set(initialValue);
    }

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

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof TimelineObject)) return false;
        TimelineObject other = (TimelineObject) o;
        return value.equals(other.value);
    }

    @Override
    public String toString() {
        return value.toString();
    }
}

相关信息

kafka 源码目录

相关文章

kafka BaseHashTable 源码

kafka Delta 源码

kafka Revertable 源码

kafka Snapshot 源码

kafka SnapshotRegistry 源码

kafka SnapshottableHashTable 源码

kafka TimelineHashMap 源码

kafka TimelineHashSet 源码

kafka TimelineInteger 源码

kafka TimelineLong 源码