/*
 * 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.nifi.nar;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.Set;

public class SharedInstanceClassLoader extends InstanceClassLoader {
    private long referenceCount = 0L;
    private boolean closed = false;

    public SharedInstanceClassLoader(final String identifier, final String type, final Set<URL> instanceUrls, final Set<URL> additionalResourceUrls,
                                     final Set<File> narNativeLibDirs, final ClassLoader parent) {
        super(identifier, type, instanceUrls, additionalResourceUrls, narNativeLibDirs, parent);
    }

    @Override
    public synchronized void close() throws IOException {
        referenceCount--;

        if (referenceCount <= 0) {
            closed = true;
            super.close();
        }
    }

    public synchronized boolean incrementReferenceCount() {
        if (closed) {
            return false;
        }

        referenceCount++;
        return true;
    }
}
