/*

 * Copyright 2015 Google Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.File;

import java.io.FileWriter;

import java.io.PrintStream;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Type;

import java.net.URL;

import java.net.URLClassLoader;

import java.util.Arrays;

import java.util.List;

import javax.tools.JavaCompiler;

import javax.tools.StandardJavaFileManager;

import javax.tools.ToolProvider;

/**

 * A manual benchmark of the JVMTI RedefineClasses when a

 * single class (and its parent) contains many methods.

 */

public class ManyMethodsBenchmarkApp {

     // Limit is 64k but we can not put such many as the CP limit is 32k.

     // In practice, it means a real limit is much lower (less than 22000).

    static final int METHOD_COUNT = 20000;

    static Class<?> loadClassInNewClassLoader(String className) throws Exception {

        URL[] urls = { new File(".").toURI().toURL() };

        URLClassLoader ucl = new URLClassLoader(urls, null);

        Class<?> klazz = Class.forName(className, true, ucl);

        return klazz;

    }

    static void benchmarkClassOperations(String className) throws Exception {

        Class<?> klazz = loadClassInNewClassLoader(className);

        Method[] methods = klazz.getDeclaredMethods();

        if (methods.length != METHOD_COUNT) {

            throw new AssertionError("unexpected method count: " + methods.length +

                                     " expected: " + METHOD_COUNT);

        }

        methods = klazz.getMethods();

        // returned methods includes those inherited from Object

        int objectMethodSlop = 100;

        if (methods.length <= METHOD_COUNT ||

            methods.length >= METHOD_COUNT + objectMethodSlop) {

            throw new AssertionError("unexpected method count: " + methods.length);

        }

        // Invoke methods to make them appear in the constant pool cache

        Object obj = klazz.newInstance();

        Object[] args = new Object[0];

        for (Method m: methods) {

            try {

                Class<?>[] types = m.getParameterTypes();

                String     name  = m.getName();

             // System.out.println("method: " + name + "; argno: " + types.length);

                if (types.length == 0 && name.length() == 2 && name.startsWith("f")) {

                    m.invoke(obj, args);

                }

            } catch (InvocationTargetException ex) {

                ex.printStackTrace();

            }

        }

    }

    public static void main(String[] args) throws Exception {

        System.out.println("test started: ManyMethodsBenchmarkApp");

        // Create source files with many methods

        File base = new File("Base.java");

        try (FileWriter fw = new FileWriter(base)) {

            fw.write("public class Base {\n");

            final int L = 10;

            // Each of the first L methods makes calls to its own chunk of METHOD_COUNT/L methods

            for (int k = 0; k < L; k++) {

                fw.write("    public void f" + k + "() {\n");

                int shift = (k == 0) ? L : 0;

                for (int i = (k * (METHOD_COUNT/L)) + shift; i < (k + 1) * METHOD_COUNT/L; i++) {

                    fw.write("        f" + i + "();\n");

                }

                fw.write("    }\n");

            }

            // The rest of (METHOD_COUNT - L) methods have empty body

            for (int i = L; i < METHOD_COUNT; i++) {

                fw.write("    public static void f" + i + "() {}\n");

            }

            fw.write("}\n");

        }

        // Compile the generated source files.

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

        List<File> files = Arrays.asList(new File[] { base });

        try (StandardJavaFileManager fileManager =

             compiler.getStandardFileManager(null, null, null)) {

            compiler.getTask(null, fileManager, null, null, null,

                fileManager.getJavaFileObjectsFromFiles(files))

                .call();

        }

        benchmarkClassOperations("Base");

        ManyMethodsBenchmarkAgent.instr();

        // Cleanup

        base.delete();

        new File("Base.class").delete();

        if (!ManyMethodsBenchmarkAgent.completed) {

            throw new Exception("ERROR: ManyMethodsBenchmarkAgent did not complete.");

        }

        if (ManyMethodsBenchmarkAgent.fail) {

            throw new Exception("ERROR: ManyMethodsBenchmarkAgent failed.");

        } else {

            System.out.println("ManyMethodsBenchmarkAgent succeeded.");

        }

        System.out.println("test finished: ManyMethodsBenchmarkApp");

    }

}