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