kafka TimelineLong 源码
kafka TimelineLong 代码
文件路径:/metadata/src/main/java/org/apache/kafka/timeline/TimelineLong.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;
/**
* This is a mutable long which can be snapshotted.
*
* This class requires external synchronization.
*/
public class TimelineLong implements Revertable {
public static final long INIT = 0;
static class LongContainer implements Delta {
private long value = INIT;
long value() {
return value;
}
void setValue(long value) {
this.value = value;
}
@Override
public void mergeFrom(long destinationEpoch, Delta delta) {
// Nothing to do
}
}
private final SnapshotRegistry snapshotRegistry;
private long value;
public TimelineLong(SnapshotRegistry snapshotRegistry) {
this.snapshotRegistry = snapshotRegistry;
this.value = INIT;
snapshotRegistry.register(this);
}
public long get() {
return value;
}
public long get(long epoch) {
if (epoch == SnapshotRegistry.LATEST_EPOCH) return value;
Iterator<Snapshot> iterator = snapshotRegistry.iterator(epoch);
while (iterator.hasNext()) {
Snapshot snapshot = iterator.next();
LongContainer container = snapshot.getDelta(TimelineLong.this);
if (container != null) return container.value();
}
return value;
}
public void set(long newValue) {
Iterator<Snapshot> iterator = snapshotRegistry.reverseIterator();
if (iterator.hasNext()) {
Snapshot snapshot = iterator.next();
LongContainer prevContainer = snapshot.getDelta(TimelineLong.this);
if (prevContainer == null) {
prevContainer = new LongContainer();
snapshot.setDelta(TimelineLong.this, prevContainer);
prevContainer.setValue(value);
}
}
this.value = newValue;
}
public void increment() {
set(get() + 1L);
}
public void decrement() {
set(get() - 1L);
}
@SuppressWarnings("unchecked")
@Override
public void executeRevert(long targetEpoch, Delta delta) {
LongContainer container = (LongContainer) delta;
this.value = container.value();
}
@Override
public void reset() {
set(INIT);
}
@Override
public int hashCode() {
return ((int) value) ^ (int) (value >>> 32);
}
@Override
public boolean equals(Object o) {
if (!(o instanceof TimelineLong)) return false;
TimelineLong other = (TimelineLong) o;
return value == other.value;
}
@Override
public String toString() {
return Long.toString(value);
}
}
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