org.apache.flink.runtime.state.gemini.engine.rm.AbstractReferenceCountable Maven / Gradle / Ivy
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* 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.flink.runtime.state.gemini.engine.rm;
import org.apache.flink.runtime.state.gemini.engine.page.bmap.UnsafeHelp;
import sun.misc.Unsafe;
/**
* An abstract implement for {@link ReferenceCountable}.
*/
public abstract class AbstractReferenceCountable implements ReferenceCountable {
private static final Unsafe unsafe;
private static final long valueOffset;
static {
try {
unsafe = UnsafeHelp.getUnsafe();
valueOffset = unsafe.objectFieldOffset
(AbstractReferenceCountable.class.getDeclaredField("referenceCount"));
} catch (Exception ex) {
throw new Error(ex);
}
}
private volatile int referenceCount = 0;
@Override
public void retain() {
unsafe.getAndAddInt(this, valueOffset, 1);
}
@Override
public void release() {
unsafe.getAndAddInt(this, valueOffset, -1);
}
@Override
public int refCnt() {
return referenceCount;
}
protected int decrementAndGetRefCnt() {
return unsafe.getAndAddInt(this, valueOffset, -1) - 1;
}
}