

package org.apache.derbyTesting.junit;

import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import junit.framework.Test;
import org.apache.derbyTesting.functionTests.tests.upgradeTests.UpgradeClassLoader;

/**
 * A decorator that changes the context class loader for the current
 * configuration and resets it afterwards.
 */
public class ClassLoaderTestSetup extends BaseJDBCTestSetup {

    private ClassLoader oldLoader;

    /**
     * Create a decorator that makes {@code test} run with non-default
     * class loader. It also shuts down the engine so Derby classes will
     * be loaded with the new class loader.
     *
     * @param test the test to decorate
     */
    public ClassLoaderTestSetup(Test test) {
        super(test);
    }

    private static ClassLoader makeClassLoader(final ClassLoader old) {
        return AccessController.doPrivileged(
            new PrivilegedAction<URLClassLoader>() {
                @Override
                public URLClassLoader run() {
                        URL[] jars = ((URLClassLoader)old).getURLs();
                        return new URLClassLoader(jars, null);
                }
            });
    }

    @Override
    protected void setUp() throws Exception {
        super.setUp();
        TestConfiguration.getCurrent().shutdownEngine();
        oldLoader = getThreadLoader();
        setThreadLoader(makeClassLoader(oldLoader));
    }

    @Override
    protected void tearDown() throws Exception {
        setThreadLoader(oldLoader);
        super.tearDown();
    }

    /**
     * Force this thread to use a specific class loader.
     * @param which class loader to set
     *
     * @throws  SecurityException
     *          if the current thread cannot set the context ClassLoader
     */
    public static void setThreadLoader(final ClassLoader which) {
        AccessController.doPrivileged(new PrivilegedAction<Void>() {
            @Override
            public Void run() {
                java.lang.Thread.currentThread().setContextClassLoader(which);
              return null;
            }
        });
    }

    /**
     * <p>
     * Retrieve the class loader currently being used by this thread.
     * </p>
     * @return the current context class loader
     */
    public static ClassLoader getThreadLoader() {
        return AccessController.doPrivileged(
                new PrivilegedAction<ClassLoader>() {
            public ClassLoader run() {
                return Thread.currentThread().getContextClassLoader();
            }
        });
    }

}
