ObjectCleaner.java — netty Source File

Source Code

/*
 * Copyright 2017 The Netty Project
 *
 * The Netty Project 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:
 *
 *   https://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 io.netty.util.internal;

import io.netty.util.concurrent.FastThreadLocalThread;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;

import static io.netty.util.internal.SystemPropertyUtil.getInt;
import static java.lang.Math.max;

/**
 * Allows a way to register some {@link Runnable} that will executed once there are no references to an {@link Object}
 * anymore.
 */
public final class ObjectCleaner {
    private static final int REFERENCE_QUEUE_POLL_TIMEOUT_MS =
            max(500, getInt("io.netty.util.internal.ObjectCleaner.refQueuePollTimeout", 10000));

    // Package-private for testing
    static final String CLEANER_THREAD_NAME = ObjectCleaner.class.getSimpleName() + "Thread";
    // This will hold a reference to the AutomaticCleanerReference which will be removed once we called cleanup()
    private static final Set<AutomaticCleanerReference> LIVE_SET = ConcurrentHashMap.newKeySet();
    private static final ReferenceQueue<Object> REFERENCE_QUEUE = new ReferenceQueue<>();
    private static final AtomicBoolean CLEANER_RUNNING = new AtomicBoolean(false);
    private static final Runnable CLEANER_TASK = new Runnable() {
        @Override
        public void run() {
            boolean interrupted = false;
            for (;;) {
                // Keep on processing as long as the LIVE_SET is not empty and once it becomes empty
                // See if we can let this thread complete.
                while (!LIVE_SET.isEmpty()) {
                    final AutomaticCleanerReference reference;
                    try {
                        reference = (AutomaticCleanerReference) REFERENCE_QUEUE.remove(REFERENCE_QUEUE_POLL_TIMEOUT_MS);
                    } catch (InterruptedException ex) {
                        // Just consume and move on
                        interrupted = true;
                        continue;
                    }
// ... (99 more lines)