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 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2016, NVIDIA CORPORATION.  All rights reserved.
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/**
 * \file
 * cub::GridQueue is a descriptor utility for dynamic queue management.
 */

#pragma once

#include "../util_namespace.cuh"
#include "../util_debug.cuh"

/// Optional outer namespace(s)
CUB_NS_PREFIX

/// CUB namespace
namespace cub {


/**
 * \addtogroup GridModule
 * @{
 */


/**
 * \brief GridQueue is a descriptor utility for dynamic queue management.
 *
 * \par Overview
 * GridQueue descriptors provides abstractions for "filling" or
 * "draining" globally-shared vectors.
 *
 * \par
 * A "filling" GridQueue works by atomically-adding to a zero-initialized counter,
 * returning a unique offset for the calling thread to write its items.
 * The GridQueue maintains the total "fill-size".  The fill counter must be reset
 * using GridQueue::ResetFill by the host or kernel instance prior to the kernel instance that
 * will be filling.
 *
 * \par
 * Similarly, a "draining" GridQueue works by works by atomically-incrementing a
 * zero-initialized counter, returning a unique offset for the calling thread to
 * read its items. Threads can safely drain until the array's logical fill-size is
 * exceeded.  The drain counter must be reset using GridQueue::ResetDrain or
 * GridQueue::FillAndResetDrain by the host or kernel instance prior to the kernel instance that
 * will be filling.  (For dynamic work distribution of existing data, the corresponding fill-size
 * is simply the number of elements in the array.)
 *
 * \par
 * Iterative work management can be implemented simply with a pair of flip-flopping
 * work buffers, each with an associated set of fill and drain GridQueue descriptors.
 *
 * \tparam OffsetT Signed integer type for global offsets
 */
template <typename OffsetT>
class GridQueue
{
private:

    /// Counter indices
    enum
    {
        FILL    = 0,
        DRAIN   = 1,
    };

    /// Pair of counters
    OffsetT *d_counters;

public: