/*
 * Copyright (C) 2009, 2011 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef MarkStack_h
#define MarkStack_h

#if ENABLE(OBJECT_MARK_LOGGING)
#define MARK_LOG_MESSAGE0(message) dataLog(message)
#define MARK_LOG_MESSAGE1(message, arg1) dataLog(message, arg1)
#define MARK_LOG_MESSAGE2(message, arg1, arg2) dataLog(message, arg1, arg2)
#define MARK_LOG_ROOT(visitor, rootName) \
    dataLog("\n%s: ", rootName); \
    (visitor).resetChildCount()
#define MARK_LOG_PARENT(visitor, parent) \
    dataLog("\n%p (%s): ", parent, parent->className() ? parent->className() : "unknown"); \
    (visitor).resetChildCount()
#define MARK_LOG_CHILD(visitor, child) \
    if ((visitor).childCount()) \
    dataLogString(", "); \
    dataLog("%p", child); \
    (visitor).incrementChildCount()
#else
#define MARK_LOG_MESSAGE0(message) do { } while (false)
#define MARK_LOG_MESSAGE1(message, arg1) do { } while (false)
#define MARK_LOG_MESSAGE2(message, arg1, arg2) do { } while (false)
#define MARK_LOG_ROOT(visitor, rootName) do { } while (false)
#define MARK_LOG_PARENT(visitor, parent) do { } while (false)
#define MARK_LOG_CHILD(visitor, child) do { } while (false)
#endif

#include <wtf/StdLibExtras.h>
#include <wtf/TCSpinLock.h>

namespace JSC {

class JSCell;

struct MarkStackSegment {
    MarkStackSegment* m_previous;
#if !ASSERT_DISABLED
    size_t m_top;
#endif
        
    const JSCell** data()
    {
        return bitwise_cast<const JSCell**>(this + 1);
    }
    
    static size_t capacityFromSize(size_t size)
    {
        return (size - sizeof(MarkStackSegment)) / sizeof(const JSCell*);
    }
    
    static size_t sizeFromCapacity(size_t capacity)
    {
        return sizeof(MarkStackSegment) + capacity * sizeof(const JSCell*);
    }
};

class MarkStackSegmentAllocator {
public:
    MarkStackSegmentAllocator();
    ~MarkStackSegmentAllocator();
    
    MarkStackSegment* allocate();
    void release(MarkStackSegment*);
    
    void shrinkReserve();
    
private:
    SpinLock m_lock;
    MarkStackSegment* m_nextFreeSegment;
};

class MarkStackArray {
public:
    MarkStackArray(MarkStackSegmentAllocator&);
    ~MarkStackArray();

    void append(const JSCell*);

    bool canRemoveLast();
    const JSCell* removeLast();
    bool refill();
    
    void donateSomeCellsTo(MarkStackArray& other);
    void stealSomeCellsFrom(MarkStackArray& other, size_t idleThreadCount);

    size_t size();
    bool isEmpty();

private:
    JS_EXPORT_PRIVATE void expand();
    
    size_t postIncTop();
    size_t preDecTop();
    void setTopForFullSegment();
    void setTopForEmptySegment();
    size_t top();
    
    void validatePrevious();

    MarkStackSegment* m_topSegment;
    MarkStackSegmentAllocator& m_allocator;

    size_t m_segmentCapacity;
    size_t m_top;
    size_t m_numberOfPreviousSegments;
   
};

} // namespace JSC

#endif