/*
 * Copyright 2017 NAVER Corp.
 *
 * 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 com.navercorp.pinpoint.bootstrap.classloader;

import java.net.URL;
import java.net.URLClassLoader;

/**
 * @author Taejin Koo
 */
class ParallelCapablePinpointURLClassLoader extends URLClassLoader {

    private static final LibClass PROFILER_LIB_CLASS = new ProfilerLibClass();

    private final ClassLoader parent;

    private final LibClass libClass;

    static {
        ClassLoader.registerAsParallelCapable();
    }

    public ParallelCapablePinpointURLClassLoader(URL[] urls, ClassLoader parent) {
        this(urls, parent, PROFILER_LIB_CLASS);
    }

    public ParallelCapablePinpointURLClassLoader(URL[] urls, ClassLoader parent, LibClass libClass) {
        super(urls, parent);

        if (parent == null) {
            throw new NullPointerException("parent must not be null");
        }
        if (libClass == null) {
            throw new NullPointerException("libClass must not be null");
        }

        this.parent = parent;
        this.libClass = libClass;
    }

    @Override
    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        synchronized (getClassLoadingLock(name)) {
            // First, check if the class has already been loaded
            Class clazz = findLoadedClass(name);
            if (clazz == null) {
                if (onLoadClass(name)) {
                    // load a class used for Pinpoint itself by this PinpointURLClassLoader
                    clazz = findClass(name);
                } else {
                    try {
                        // load a class by parent ClassLoader
                        clazz = parent.loadClass(name);
                    } catch (ClassNotFoundException ignore) {
                    }
                    if (clazz == null) {
                        // if not found, try to load a class by this PinpointURLClassLoader
                        clazz = findClass(name);
                    }
                }
            }
            if (resolve) {
                resolveClass(clazz);
            }
            return clazz;
        }
    }

    // for test
    boolean onLoadClass(String name) {
        return libClass.onLoadClass(name);
    }

}