/*
 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. 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.
 */
package demo;

import com.sun.max.unsafe.*;
import com.sun.max.vm.jdk.*;
import com.sun.max.vm.runtime.*;
import com.sun.max.vm.stack.*;
import com.sun.max.vm.thread.*;

import demo.VmOperationDemoHelper.DemoRunnable;

/**
 * Demonstrates usage of the {@link VmOperation} mechanism.
 * This demo starts a number of threads that spin in a loop
 * that allocates object arrays of length 1024, thus creating
 * garbage quickly. The main thread also spins in a loop for
 * a specified number of seconds, printing a stack trace of
 * all the other spinning threads.
 *
 * This demo also shows what happens if a VM operation
 * triggers a GC.
 *
 * Like all VmOperations, this class must be in the boot image.
 * This is achieved by adding 'demo.VmOperationDemo' to the end
 * of a 'max image' command.
 */
public class StackTraceVmOperationDemo extends VmOperation {

    private static VmOperationDemoHelper demoHelper;

    StackTraceVmOperationDemo() {
        super("StackTraceDemo", null, Mode.Safepoint);
    }

    @Override
    protected boolean operateOnThread(VmThread thread) {
        return demoHelper.operateOnThread(thread);
    }

    @Override
    public void doThread(VmThread vmThread, Pointer ip, Pointer sp, Pointer fp) {
        Thread thread = vmThread.javaThread();
        assert !ip.isZero() : " [not yet executing Java]";
        VmStackFrameWalker sfw = new VmStackFrameWalker(vmThread.tla());
        StackTraceElement[] trace = JDK_java_lang_Throwable.getStackTrace(sfw, ip, sp, fp, null, Integer.MAX_VALUE);
        System.out.println(thread + " [stack depth: " + trace.length + "]");
        for (StackTraceElement e : trace) {
            System.out.println("\tat " + e);
        }
    }

    static volatile boolean done;

    static class Allocator extends DemoRunnable {
        static int i = 0;
        @Override
        public void run() {
            runEntered();
            while (!done) {
                Object[] o = new Object[1024];
                o[0] = o;
            }
        }

        @Override
        protected void customize(Thread thread) {
            thread.setName("Allocator-" + i++);
        }
    }

    public static void main(String[] args) {
        VmOperationDemoHelper.parseArguments(args);
        demoHelper = new VmOperationDemoHelper(new Allocator());
        StackTraceVmOperationDemo stackTraceDumper = new StackTraceVmOperationDemo();

        long start = System.currentTimeMillis();
        int time;
        try {
            do {
                time = (int) (System.currentTimeMillis() - start) / 1000;
                try {
                    System.out.println("---- Dumping stacks of spinning threads ----");
                    stackTraceDumper.submit();
                } catch (VmOperationThread.HoldsThreadLockError e) {
                    System.out.println("VM operation triggered while dumping stack traces");
                    break;
                }
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while (time < VmOperationDemoHelper.runTime);
        } finally {
            done = true;
        }
    }
}