/*
 * Copyright (c) 1996, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 sun.misc;

import static java.lang.Thread.State.*;
import java.io.IOException;
import java.security.AccessControlException;
import java.util.Properties;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class VM {

    /* The following methods used to be native methods that instruct
     * the VM to selectively suspend certain threads in low-memory
     * situations. They are inherently dangerous and not implementable
     * on native threads. We removed them in JDK 1.2. The skeletons
     * remain so that existing applications that use these methods
     * will still work.
     */
    private static boolean suspended = false;

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static boolean threadsSuspended() {
        return suspended;
    }

    public static boolean allowThreadSuspension(ThreadGroup g, boolean b) {
        return g.allowThreadSuspension(b);
    }

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static boolean suspendThreads() {
        suspended = true;
        return true;
    }

    // Causes any suspended threadgroups to be resumed.
    
Deprecated:
/** @deprecated */
    @Deprecated
    public static void unsuspendThreads() {
        suspended = false;
    }

    // Causes threadgroups no longer marked suspendable to be resumed.
    
Deprecated:
/** @deprecated */
    @Deprecated
    public static void unsuspendSomeThreads() {
    }

    /* Deprecated fields and methods -- Memory advice not supported in 1.2 */

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static final int STATE_GREEN = 1;

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static final int STATE_YELLOW = 2;

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static final int STATE_RED = 3;

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static final int getState() {
        return STATE_GREEN;
    }

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static void registerVMNotification(VMNotification n) { }

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static void asChange(int as_old, int as_new) { }

    
Deprecated:
/** @deprecated */
    @Deprecated
    public static void asChange_otherthread(int as_old, int as_new) { }

    /*
     * Not supported in 1.2 because these will have to be exported as
     * JVM functions, and we are not sure we want do that. Leaving
     * here so it can be easily resurrected -- just remove the //
     * comments.
     */

    /**
     * Resume Java profiling.  All profiling data is added to any
     * earlier profiling, unless <code>resetJavaProfiler</code> is
     * called in between.  If profiling was not started from the
     * command line, <code>resumeJavaProfiler</code> will start it.
     * <p>
     *
     * NOTE: Profiling must be enabled from the command line for a
     * java.prof report to be automatically generated on exit; if not,
     * writeJavaProfilerReport must be invoked to write a report.
     *
     * @see     resetJavaProfiler
     * @see     writeJavaProfilerReport
     */

    // public native static void resumeJavaProfiler();

    /**
     * Suspend Java profiling.
     */
    // public native static void suspendJavaProfiler();

    /**
     * Initialize Java profiling.  Any accumulated profiling
     * information is discarded.
     */
    // public native static void resetJavaProfiler();

    
Write the current profiling contents to the file "java.prof".
If the file already exists, it will be overwritten.
/**
     * Write the current profiling contents to the file "java.prof".
     * If the file already exists, it will be overwritten.
     */
    // public native static void writeJavaProfilerReport();


    private static volatile boolean booted = false;
    private static final Object lock = new Object();

    // Invoked by by System.initializeSystemClass just before returning.
    // Subsystems that are invoked during initialization can check this
    // property in order to avoid doing things that should wait until the
    // application class loader has been set up.
    //
    public static void booted() {
        synchronized (lock) {
            booted = true;
            lock.notifyAll();
        }
    }

    public static boolean isBooted() {
        return booted;
    }

    // Waits until VM completes initialization
    //
    // This method is invoked by the Finalizer thread
    public static void awaitBooted() throws InterruptedException {
        synchronized (lock) {
            while (!booted) {
                lock.wait();
            }
        }
    }

    // A user-settable upper limit on the maximum amount of allocatable direct
    // buffer memory.  This value may be changed during VM initialization if
    // "java" is launched with "-XX:MaxDirectMemorySize=<size>".
    //
    // The initial value of this field is arbitrary; during JRE initialization
    // it will be reset to the value specified on the command line, if any,
    // otherwise to Runtime.getRuntime.maxDirectMemory().
    //
    private static long directMemory = 64 * 1024 * 1024;

    // Returns the maximum amount of allocatable direct buffer memory.
    // The directMemory variable is initialized during system initialization
    // in the saveAndRemoveProperties method.
    //
    public static long maxDirectMemory() {
        return directMemory;
    }

    // User-controllable flag that determines if direct buffers should be page
    // aligned. The "-XX:+PageAlignDirectMemory" option can be used to force
    // buffers, allocated by ByteBuffer.allocateDirect, to be page aligned.
    private static boolean pageAlignDirectMemory;

    // Returns {@code true} if the direct buffers should be page aligned. This
    // variable is initialized by saveAndRemoveProperties.
    public static boolean isDirectMemoryPageAligned() {
        return pageAlignDirectMemory;
    }

    // A user-settable boolean to determine whether ClassLoader.loadClass should
    // accept array syntax.  This value may be changed during VM initialization
    // via the system property "sun.lang.ClassLoader.allowArraySyntax".
    //
    // The default for 1.5 is "true", array syntax is allowed.  In 1.6, the
    // default will be "false".  The presence of this system property to
    // control array syntax allows applications the ability to preview this new
    // behaviour.
    //
    private static boolean defaultAllowArraySyntax = false;
    private static boolean allowArraySyntax = defaultAllowArraySyntax;

    // The allowArraySyntax boolean is initialized during system initialization
    // in the saveAndRemoveProperties method.
    //
    // It is initialized based on the value of the system property
    // "sun.lang.ClassLoader.allowArraySyntax".  If the system property is not
    // provided, the default for 1.5 is "true".  In 1.6, the default will be
    // "false".  If the system property is provided, then the value of
    // allowArraySyntax will be equal to "true" if Boolean.parseBoolean()
    // returns "true".   Otherwise, the field will be set to "false".
    //
    public static boolean allowArraySyntax() {
        return allowArraySyntax;
    }

    private static boolean allowGetCallerClass = true;

    // Reflection.getCallerClass(int) is enabled by default.
    // It can be disabled by setting the system property
    // "jdk.reflect.allowGetCallerClass" to "false". It cannot be
    // disabled if the logging stack walk (to find resource bundles)
    // is enabled.
    public static boolean allowGetCallerClass() {
        return allowGetCallerClass;
    }

    
Returns the system property of the specified key saved at
system initialization time.  This method should only be used
for the system properties that are not changed during runtime.
It accesses a private copy of the system properties so
that user's locking of the system properties object will not
cause the library to deadlock.
Note that the saved system properties do not include
the ones set by sun.misc.Version.init().
/**
     * Returns the system property of the specified key saved at
     * system initialization time.  This method should only be used
     * for the system properties that are not changed during runtime.
     * It accesses a private copy of the system properties so
     * that user's locking of the system properties object will not
     * cause the library to deadlock.
     *
     * Note that the saved system properties do not include
     * the ones set by sun.misc.Version.init().
     *
     */
    public static String getSavedProperty(String key) {
        if (savedProps.isEmpty())
            throw new IllegalStateException("Should be non-empty if initialized");

        return savedProps.getProperty(key);
    }

    // TODO: the Property Management needs to be refactored and
    // the appropriate prop keys need to be accessible to the
    // calling classes to avoid duplication of keys.
    private static final Properties savedProps = new Properties();

    // Save a private copy of the system properties and remove
    // the system properties that are not intended for public access.
    //
    // This method can only be invoked during system initialization.
    public static void saveAndRemoveProperties(Properties props) {
        if (booted)
            throw new IllegalStateException("System initialization has completed");

        savedProps.putAll(props);

        // Set the maximum amount of direct memory.  This value is controlled
        // by the vm option -XX:MaxDirectMemorySize=<size>.
        // The maximum amount of allocatable direct buffer memory (in bytes)
        // from the system property sun.nio.MaxDirectMemorySize set by the VM.
        // The system property will be removed.
        String s = (String)props.remove("sun.nio.MaxDirectMemorySize");
        if (s != null) {
            if (s.equals("-1")) {
                // -XX:MaxDirectMemorySize not given, take default
                directMemory = Runtime.getRuntime().maxMemory();
            } else {
                long l = Long.parseLong(s);
                if (l > -1)
                    directMemory = l;
            }
        }

        // Check if direct buffers should be page aligned
        s = (String)props.remove("sun.nio.PageAlignDirectMemory");
        if ("true".equals(s))
            pageAlignDirectMemory = true;

        // Set a boolean to determine whether ClassLoader.loadClass accepts
        // array syntax.  This value is controlled by the system property
        // "sun.lang.ClassLoader.allowArraySyntax".
        s = props.getProperty("sun.lang.ClassLoader.allowArraySyntax");
        allowArraySyntax = (s == null
                               ? defaultAllowArraySyntax
                               : Boolean.parseBoolean(s));

        // Reflection.getCallerClass(int) is enabled by default.
        // It can be disabled by setting a system property (but only if
        // the logging stack walk is not enabled)
        s = props.getProperty("jdk.reflect.allowGetCallerClass");
        allowGetCallerClass = (s != null
                                   ? (s.isEmpty() || Boolean.parseBoolean(s))
                                   : true) ||
             Boolean.valueOf(props.getProperty("jdk.logging.allowStackWalkSearch"));

        // Remove other private system properties
        // used by java.lang.Integer.IntegerCache
        props.remove("java.lang.Integer.IntegerCache.high");

        // used by java.util.zip.ZipFile
        props.remove("sun.zip.disableMemoryMapping");

        // used by sun.launcher.LauncherHelper
        props.remove("sun.java.launcher.diag");
    }

    // Initialize any miscellenous operating system settings that need to be
    // set for the class libraries.
    //
    public static void initializeOSEnvironment() {
        if (!booted) {
            OSEnvironment.initialize();
        }
    }

    /* Current count of objects pending for finalization */
    private static volatile int finalRefCount = 0;

    /* Peak count of objects pending for finalization */
    private static volatile int peakFinalRefCount = 0;

    /*
     * Gets the number of objects pending for finalization.
     *
     * @return the number of objects pending for finalization.
     */
    public static int getFinalRefCount() {
        return finalRefCount;
    }

    /*
     * Gets the peak number of objects pending for finalization.
     *
     * @return the peak number of objects pending for finalization.
     */
    public static int getPeakFinalRefCount() {
        return peakFinalRefCount;
    }

    /*
     * Add <tt>n</tt> to the objects pending for finalization count.
     *
     * @param n an integer value to be added to the objects pending
     * for finalization count
     */
    public static void addFinalRefCount(int n) {
        // The caller must hold lock to synchronize the update.

        finalRefCount += n;
        if (finalRefCount > peakFinalRefCount) {
            peakFinalRefCount = finalRefCount;
        }
    }

    
Returns Thread.State for the given threadStatus
/**
     * Returns Thread.State for the given threadStatus
     */
    public static Thread.State toThreadState(int threadStatus) {
        if ((threadStatus & JVMTI_THREAD_STATE_RUNNABLE) != 0) {
            return RUNNABLE;
        } else if ((threadStatus & JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER) != 0) {
            return BLOCKED;
        } else if ((threadStatus & JVMTI_THREAD_STATE_WAITING_INDEFINITELY) != 0) {
            return WAITING;
        } else if ((threadStatus & JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT) != 0) {
            return TIMED_WAITING;
        } else if ((threadStatus & JVMTI_THREAD_STATE_TERMINATED) != 0) {
            return TERMINATED;
        } else if ((threadStatus & JVMTI_THREAD_STATE_ALIVE) == 0) {
            return NEW;
        } else {
            return RUNNABLE;
        }
    }

    /* The threadStatus field is set by the VM at state transition
     * in the hotspot implementation. Its value is set according to
     * the JVM TI specification GetThreadState function.
     */
    private final static int JVMTI_THREAD_STATE_ALIVE = 0x0001;
    private final static int JVMTI_THREAD_STATE_TERMINATED = 0x0002;
    private final static int JVMTI_THREAD_STATE_RUNNABLE = 0x0004;
    private final static int JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER = 0x0400;
    private final static int JVMTI_THREAD_STATE_WAITING_INDEFINITELY = 0x0010;
    private final static int JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT = 0x0020;

    /*
     * Returns first non-privileged class loader on the stack (excluding
     * reflection generated frames) or the extension class loader if only
     * class loaded by the boot class loader and extension class loader are
     * found on the stack.
     */
    public static native ClassLoader latestUserDefinedLoader0();
    public static ClassLoader latestUserDefinedLoader() {
        ClassLoader loader = latestUserDefinedLoader0();
        if (loader != null) {
            return loader;
        }
        try {
            return Launcher.ExtClassLoader.getExtClassLoader();
        } catch (IOException e) {
            return null;
        }
    }

    static {
        initialize();
    }
    private native static void initialize();
}