SegPageEntryIter.h

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00001 /*
00002 // $Id: //open/dev/fennel/segment/SegPageEntryIter.h#3 $
00003 // Fennel is a library of data storage and processing components.
00004 // Copyright (C) 2005-2009 The Eigenbase Project
00005 // Copyright (C) 2005-2009 SQLstream, Inc.
00006 // Copyright (C) 2005-2009 LucidEra, Inc.
00007 // Portions Copyright (C) 1999-2009 John V. Sichi
00008 //
00009 // This program is free software; you can redistribute it and/or modify it
00010 // under the terms of the GNU General Public License as published by the Free
00011 // Software Foundation; either version 2 of the License, or (at your option)
00012 // any later version approved by The Eigenbase Project.
00013 //
00014 // This program is distributed in the hope that it will be useful,
00015 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00016 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00017 // GNU General Public License for more details.
00018 //
00019 // You should have received a copy of the GNU General Public License
00020 // along with this program; if not, write to the Free Software
00021 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00022 */
00023 
00024 #ifndef Fennel_SegPageEntryIter_Included
00025 #define Fennel_SegPageEntryIter_Included
00026 
00027 #include <vector>
00028 #include "fennel/segment/SegPageIter.h"
00029 #include "fennel/segment/SegPageEntryIterSource.h"
00030 #include "fennel/common/CircularBuffer.h"
00031 
00032 FENNEL_BEGIN_NAMESPACE
00033 
00041 template <class EntryT>
00042 class SegPageEntryIter : public SegPageIter
00043 {
00050     CircularBuffer<std::pair<PageId, EntryT> > entryQueue;
00051 
00056     SegPageEntryIterSource<EntryT> *pPrefetchSource;
00057 
00061     void init();
00062 
00072     void prefetchPages(PageId prevPageId, bool oneIter);
00073 
00074 public:
00079     explicit SegPageEntryIter<EntryT>();
00080 
00086     explicit SegPageEntryIter<EntryT>(uint nEntriesInit);
00087 
00093     void resize(uint nEntries);
00094 
00100     void setPrefetchSource(SegPageEntryIterSource<EntryT> &prefetchSource);
00101 
00117     void mapRange(
00118         SegmentAccessor const &segmentAccessor,
00119         PageId beginPageId,
00120         PageId endPageId = NULL_PAGE_ID);
00121 
00125     std::pair<PageId, EntryT> & operator * ()
00126     {
00127         assert(!isSingular());
00128         std::pair<PageId, EntryT> &entryPair = entryQueue.reference_front();
00129         assert(entryPair.first == prefetchQueue[iFetch]);
00130         return entryPair;
00131     }
00132 
00137     void operator ++ ();
00138 
00142     void makeSingular()
00143     {
00144         SegPageIter::makeSingular();
00145         pPrefetchSource = NULL;
00146     }
00147 
00151     bool isSingular() const
00152     {
00153         return (pPrefetchSource == NULL || SegPageIter::isSingular());
00154     }
00155 };
00156 
00157 FENNEL_END_NAMESPACE
00158 
00159 #endif
00160 
00161 // End SegPageEntryIter.h

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