/*

 * Copyright (c) 2007, 2015, 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.java2d.marlin;

import java.lang.ref.PhantomReference;

import java.lang.ref.ReferenceQueue;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Vector;

import static sun.java2d.marlin.MarlinConst.logUnsafeMalloc;

import sun.misc.ThreadGroupUtils;

import sun.misc.Unsafe;

/**

 *

 * @author bourgesl

 */

final class OffHeapArray  {

    // unsafe reference

    static final Unsafe unsafe;

    // size of int / float

    static final int SIZE_INT;

    // RendererContext reference queue

    private static final ReferenceQueue<Object> rdrQueue

        = new ReferenceQueue<Object>();

    // reference list

    private static final Vector<OffHeapReference> refList

        = new Vector<OffHeapReference>(32);

    static {

        unsafe   = Unsafe.getUnsafe();

        SIZE_INT = Unsafe.ARRAY_INT_INDEX_SCALE;

        // Mimics Java2D Disposer:

        AccessController.doPrivileged(

            (PrivilegedAction<Void>) () -> {

                /*

                 * The thread must be a member of a thread group

                 * which will not get GCed before VM exit.

                 * Make its parent the top-level thread group.

                 */

                final ThreadGroup rootTG

                    = ThreadGroupUtils.getRootThreadGroup();

                final Thread t = new Thread(rootTG, new OffHeapDisposer(),

                    "MarlinRenderer Disposer");

                t.setContextClassLoader(null);

                t.setDaemon(true);

                t.setPriority(Thread.MAX_PRIORITY);

                t.start();

                return null;

            }

        );

    }

    /* members */

    long address;

    long length;

    int  used;

    OffHeapArray(final Object parent, final long len) {

        // note: may throw OOME:

        this.address = unsafe.allocateMemory(len);

        this.length  = len;

        this.used    = 0;

        if (logUnsafeMalloc) {

            MarlinUtils.logInfo(System.currentTimeMillis()

                                + ": OffHeapArray.allocateMemory = "

                                + len + " to addr = " + this.address);

        }

        // Create the phantom reference to ensure freeing off-heap memory:

        refList.add(new OffHeapReference(parent, this));

    }

    /*

     * As realloc may change the address, updating address is MANDATORY

     * @param len new array length

     * @throws OutOfMemoryError if the allocation is refused by the system

     */

    void resize(final long len) {

        // note: may throw OOME:

        this.address = unsafe.reallocateMemory(address, len);

        this.length  = len;

        if (logUnsafeMalloc) {

            MarlinUtils.logInfo(System.currentTimeMillis()

                                + ": OffHeapArray.reallocateMemory = "

                                + len + " to addr = " + this.address);

        }

    }

    void free() {

        unsafe.freeMemory(this.address);

        if (logUnsafeMalloc) {

            MarlinUtils.logInfo(System.currentTimeMillis()

                                + ": OffHeapEdgeArray.free = "

                                + this.length

                                + " at addr = " + this.address);

        }

    }

    void fill(final byte val) {

        unsafe.setMemory(this.address, this.length, val);

    }

    static final class OffHeapReference extends PhantomReference<Object> {

        private final OffHeapArray array;

        OffHeapReference(final Object parent, final OffHeapArray edges) {

            super(parent, rdrQueue);

            this.array = edges;

        }

        void dispose() {

            // free off-heap blocks

            this.array.free();

        }

    }

    static final class OffHeapDisposer implements Runnable {

        @Override

        public void run() {

            final Thread currentThread = Thread.currentThread();

            OffHeapReference ref;

            // check interrupted:

            for (; !currentThread.isInterrupted();) {

                try {

                    ref = (OffHeapReference)rdrQueue.remove();

                    ref.dispose();

                    refList.remove(ref);

                } catch (InterruptedException ie) {

                    MarlinUtils.logException("OffHeapDisposer interrupted:",

                                             ie);

                }

            }

        }

    }

}