jnr.ffi.util.ref.internal.Finalizer Maven / Gradle / Ivy
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/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed 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 jnr.ffi.util.ref.internal;
import java.lang.ref.PhantomReference;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Thread that finalizes referents. All references should implement
* {@code com.datastax.driver.$internal.com.google.common.base.FinalizableReference}.
*
* While this class is public, we consider it to be *internal* and not part
* of our published API. It is public so we can access it reflectively across
* class loaders in secure environments.
*
*
This class can't depend on other Google Collections code. If we were
* to load this class in the same class loader as the rest of
* Google Collections, this thread would keep an indirect strong reference
* to the class loader and prevent it from being garbage collected. This
* poses a problem for environments where you want to throw away the class
* loader. For example, dynamically reloading a web application or unloading
* an OSGi bundle.
*
*
{@code com.datastax.driver.$internal.com.google.common.base.FinalizableReferenceQueue} loads this class
* in its own class loader. That way, this class doesn't prevent the main
* class loader from getting garbage collected, and this class can detect when
* the main class loader has been garbage collected and stop itself.
*/
public class Finalizer extends Thread {
private static final Logger logger
= Logger.getLogger(Finalizer.class.getName());
/** Name of FinalizableReference.class. */
private static final String FINALIZABLE_REFERENCE
= "jnr.ffi.util.ref.FinalizableReference";
/**
* Starts the Finalizer thread. FinalizableReferenceQueue calls this method
* reflectively.
*
* @param finalizableReferenceClass FinalizableReference.class
* @param frq reference to instance of FinalizableReferenceQueue that started
* this thread
* @return ReferenceQueue which Finalizer will poll
*/
public static ReferenceQueue