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Open source Reference Implementation of JSR-224: Java API for XML Web Services

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/*
 * Copyright (c) 2014, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package com.sun.tools.ws.wsdl.parser;

import com.sun.tools.ws.resources.ContextClassloaderLocalMessages;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.WeakHashMap;

/**
 * Simple utility ensuring that the value is cached only in case it is non-internal implementation
 */
abstract class ContextClassloaderLocal {

    private WeakHashMap CACHE = new WeakHashMap<>();

    public V get() throws Error {
        ClassLoader tccl = getContextClassLoader();
        V instance = CACHE.get(tccl);
        if (instance == null) {
            instance = createNewInstance();
            CACHE.put(tccl, instance);
        }
        return instance;
    }

    public void set(V instance) {
        CACHE.put(getContextClassLoader(), instance);
    }

    protected abstract V initialValue() throws Exception;

    private V createNewInstance() {
        try {
            return initialValue();
        } catch (Exception e) {
            throw new Error(ContextClassloaderLocalMessages.FAILED_TO_CREATE_NEW_INSTANCE(getClass().getName()), e);
        }
    }

    private static ClassLoader getContextClassLoader() {
        return AccessController.doPrivileged((PrivilegedAction) () -> {
            ClassLoader cl = null;
            try {
                cl = Thread.currentThread().getContextClassLoader();
            } catch (SecurityException ex) {
            }
            return cl;
        });
    }
}