WinAggHistogram.h

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/*
// $Id: //open/dev/fennel/calculator/WinAggHistogram.h#2 $
// Fennel is a library of data storage and processing components.
// Copyright (C) 2006-2009 The Eigenbase Project
// Copyright (C) 2006-2009 SQLstream, Inc.
// Copyright (C) 2009-2009 LucidEra, Inc.
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version approved by The Eigenbase Project.
//
// This program 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// WinAggHistogram - Windowed Aggregation Histogram object.
*/

#ifndef Fennel_WinAggHistogram_Included
#define Fennel_WinAggHistogram_Included

#include "fennel/tuple/TupleDescriptor.h"
#include "fennel/calculator/CalcCommon.h"
#include "fennel/common/TraceSource.h"

#include <utility>
#include <set>
#include <deque>
#include <list>

FENNEL_BEGIN_NAMESPACE

template <typename STDTYPE>
class WinAggHistogram
{

public:
    WinAggHistogram()
        : currentWindow(),
          nullRows(0),
          currentSum(0),
          queue()
    {}

    ~WinAggHistogram()
    {}

    typedef multiset<STDTYPE> WinAggData;

    // REVIEW: jhyde, 2006/6/14: We don't need a double-ended queue. We only
    // add to the tail, and remove from the head.
    typedef list<STDTYPE> WinAggQueue;

    //
    void addRow(RegisterRef<STDTYPE>* node)
    {
        // Add the new node to the histogram strucuture

        if (!node->isNull()) {
            STDTYPE val = node->value();
            (void) currentWindow.insert(val);
            currentSum += val;

            // Add to the FIFO queue.
            queue.push_back(val);

        } else {
            ++nullRows;
        }
    }

    //
    void dropRow(RegisterRef<STDTYPE>* node)
    {
        if (!node->isNull()) {
            assert(0 != currentWindow.size());
            STDTYPE* pData = node->refer();

            pair<
                typename WinAggData::iterator,
                typename WinAggData::iterator> entries =
                currentWindow.equal_range(*pData);

            assert(entries.first != entries.second);
            if (entries.first != entries.second) {
                currentWindow.erase(entries.first);
                currentSum -= *pData;
            }

            // Remove from the FIFO queue.
            queue.pop_front();
        } else {
            assert(0 != nullRows);
            --nullRows;
        }
    }

    void getMin(RegisterRef<STDTYPE>* node)
    {
        if (0 != currentWindow.size()) {
            node->value(*(currentWindow.begin()));
        } else {
            node->toNull();
        }
    }

    void getMax(RegisterRef<STDTYPE>* node)
    {
        if (0 != currentWindow.size()) {
            node->value(*(--(currentWindow.end())));
        } else {
            node->toNull();
        }
    }

    void getSum(RegisterRef<STDTYPE>* node)
    {
        if (0 != currentWindow.size()) {
            node->value(currentSum);
        } else {
            node->toNull();
        }
    }

    void getCount(RegisterRef<int64_t>* node)
    {
        node->value(currentWindow.size() + nullRows);
    }

    void getAvg(RegisterRef<STDTYPE>* node)
    {
        node->value(
            (0 != currentWindow.size()) ?
            (currentSum / static_cast<STDTYPE>(currentWindow.size())) :
            0);
    }

    void getFirstValue(RegisterRef<STDTYPE>* node)
    {
        if (queue.empty()) {
            node->toNull();
        } else {
            node->value(queue.front());
        }
    }

    void getLastValue(RegisterRef<STDTYPE>* node)
    {
        if (queue.empty()) {
            node->toNull();
        } else {
            node->value(queue.back());
        }
    }

private:

    WinAggData currentWindow;   // Holds the values currently in the window.
    int64_t nullRows;           // Couunt of null entries

    // REVIEW (jhyde, 2006/6/14): We need to support char datatypes, so it's
    // not appropriate that sum has the same type as the values in the
    // window. Maybe break histogram into a base class only min/max support,
    // and a derived class with sum. The sum type will be an extra template
    // parameter.

    STDTYPE currentSum;

    WinAggQueue queue;
};

FENNEL_END_NAMESPACE

#endif

// End WinAggHistogram.h

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