/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * 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 org.teiid.common.buffer;

import java.lang.ref.PhantomReference;
import java.lang.ref.ReferenceQueue;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Set;

import org.teiid.logging.LogConstants;
import org.teiid.logging.LogManager;

public class AutoCleanupUtil {
	
	public interface Removable {
		public void remove();
	}
	
	static final class PhantomCleanupReference extends PhantomReference<Object> {
		
		private Removable removable;
		
		public PhantomCleanupReference(Object referent, Removable removable) {
			super(referent, QUEUE);
			this.removable = removable;
		}
		
		public void cleanup() {
			try {
				this.removable.remove();
			} finally {
				this.removable = null;
				this.clear();
			}
		}
	}

	private static ReferenceQueue<Object> QUEUE = new ReferenceQueue<Object>();
	private static final Set<PhantomReference<Object>> REFERENCES = Collections.synchronizedSet(Collections.newSetFromMap(new IdentityHashMap<PhantomReference<Object>, Boolean>()));

	public static PhantomReference<Object> setCleanupReference(Object o, Removable r) {
		PhantomCleanupReference ref = new PhantomCleanupReference(o, r);
		REFERENCES.add(ref);
		doCleanup(true);
		return ref;
	}
	
	public static void removeCleanupReference(PhantomReference<Object> ref) {
		if (ref == null) {
			return;
		}
		REFERENCES.remove(ref);
		ref.clear();
	}

	public static void doCleanup(boolean quick) {
		int max = quick?10:Integer.MAX_VALUE;
		for (int i = 0; i < max; i++) {
			PhantomCleanupReference ref = (PhantomCleanupReference)QUEUE.poll();
			if (ref == null) {
				break;
			}
			try {
				ref.cleanup();
			} catch (Throwable e) {
				LogManager.logWarning(LogConstants.CTX_DQP, e, "Error cleaning up."); //$NON-NLS-1$
			}
			REFERENCES.remove(ref);
		}
	}
}
