/*
 * Copyright (c) 2014, 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.
 *
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 */

/*
 * @test WBStackSize
 * @summary verify that whitebox functions getThreadFullStackSize() and getThreadRemainingStackSize are working
 * @library /testlibrary /testlibrary/whitebox
 * @build WBStackSize
 * @run main ClassFileInstaller sun.hotspot.WhiteBox
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xss512k WBStackSize 
 */

import com.sun.management.HotSpotDiagnosticMXBean;
import sun.hotspot.WhiteBox;

public class WBStackSize {

    static final long MIN_STACK_SIZE = 8 * 1024;
    static final long MAX_STACK_SIZE_ALLOCATED_IN_MAIN = 200 * 1024; // current value is about 130k on 64-bit platforms

    static final WhiteBox wb = WhiteBox.getWhiteBox();

    static long stackRemainingSize = -1;

    static int eatAllStack() {
        return eatAllStack() * 2;
    }
    
    static void testStackOverflow() {

        stackRemainingSize = wb.getThreadRemainingStackSize();

        if (stackRemainingSize > MIN_STACK_SIZE) {

            try {
                testStackOverflow();
            } catch (StackOverflowError e) {
                // We caught SOE too early. The error will be reported in main()
            }

        } else {

            try {
                eatAllStack();
                throw new RuntimeException("Haven't caught StackOverflowError at all. Is 2*2==4 on this machine?");
            } catch (StackOverflowError e) {
                // OK: we caught the anticipated error
            }
        }
    }

    public static void main(String[] args) {
        HotSpotDiagnosticMXBean bean = sun.management.ManagementFactoryHelper.getDiagnosticMXBean();
        long tss = Long.valueOf(bean.getVMOption("ThreadStackSize").getValue()) * 1024;

        System.out.println("ThreadStackSize VM option = " + tss);

        long fss = wb.getThreadFullStackSize();
        System.out.println("Full stack size " + fss);

        if (fss < tss * 0.9 || fss > tss * 1.1) {
            throw new RuntimeException("getThreadFullStackSize value [" + fss 
                                     + "] should be within 90%..110% of the value returned by HotSpotDiagnosticMXBean");
        }

        long rss = wb.getThreadRemainingStackSize();
        System.out.println("Remaining stack size " + rss);
        
        // Up to 200k can be already allocated by VM
        if (rss > tss || (tss > MAX_STACK_SIZE_ALLOCATED_IN_MAIN && rss < tss - MAX_STACK_SIZE_ALLOCATED_IN_MAIN)) {
            throw new RuntimeException("getThreadRemainingStackSize value [" + rss 
                                     + "] should be at least ThreadStackSize value [" + tss + "] minus [" 
                                     + MAX_STACK_SIZE_ALLOCATED_IN_MAIN + "]");
        }

        testStackOverflow();

        if (stackRemainingSize > MIN_STACK_SIZE) {
            throw new RuntimeException("Caught StackOverflowError too early: when there were " 
                                     + stackRemainingSize + " bytes in stack");
        } else if (stackRemainingSize < 0) {
            throw new RuntimeException("Internal test error: stackRemainingSize < 0");
        } else {
            System.out.println("Caught StackOverflowError as expected");
        }
    }
}