80 lines
2.4 KiB
Java
80 lines
2.4 KiB
Java
/*
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* Copyright 2021 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.buffer.api.internal;
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import io.netty.buffer.api.Drop;
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import java.lang.ref.Cleaner;
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import java.util.concurrent.atomic.AtomicReference;
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/**
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* A drop implementation that delegates to another drop instance, either when called directly, or when it becomes
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* cleanable. This ensures that objects are dropped even if they leak.
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*/
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public final class CleanerDrop<T> implements Drop<T> {
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private Cleaner.Cleanable cleanable;
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private GatedRunner<T> runner;
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/**
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* Wrap the given drop instance, and produce a new drop instance that will also call the delegate drop instance if
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* it becomes cleanable.
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*/
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public static <T> Drop<T> wrap(Drop<T> drop) {
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CleanerDrop<T> cleanerDrop = new CleanerDrop<>();
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GatedRunner<T> runner = new GatedRunner<>(drop);
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cleanerDrop.cleanable = Statics.CLEANER.register(cleanerDrop, runner);
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cleanerDrop.runner = runner;
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return cleanerDrop;
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}
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private CleanerDrop() {
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}
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@Override
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public void attach(T obj) {
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runner.set(obj);
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runner.drop.attach(obj);
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}
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@Override
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public void drop(T obj) {
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attach(obj);
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cleanable.clean();
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}
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@Override
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public String toString() {
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return "CleanerDrop(" + runner.drop + ')';
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}
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private static final class GatedRunner<T> extends AtomicReference<T> implements Runnable {
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private static final long serialVersionUID = 2685535951915798850L;
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final Drop<T> drop;
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private GatedRunner(Drop<T> drop) {
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this.drop = drop;
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}
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@Override
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public void run() {
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T obj = getAndSet(null); // Make absolutely sure we only delegate once.
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if (obj != null) {
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drop.drop(obj);
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}
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}
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}
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}
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