BTreeLeafReader.cpp

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00001 /*
00002 // $Id: //open/dev/fennel/btree/BTreeLeafReader.cpp#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 #include "fennel/common/CommonPreamble.h"
00025 #include "fennel/btree/BTreeLeafReader.h"
00026 #include "fennel/btree/BTreeAccessBaseImpl.h"
00027 #include "fennel/btree/BTreeReaderImpl.h"
00028 
00029 FENNEL_BEGIN_CPPFILE("$Id: //open/dev/fennel/btree/BTreeLeafReader.cpp#3 $");
00030 
00031 BTreeLeafReader::BTreeLeafReader(BTreeDescriptor const &descriptor)
00032     : BTreeReader(descriptor)
00033 {
00034     currLeafPageId = NULL_PAGE_ID;
00035 }
00036 
00037 bool BTreeLeafReader::adjustRootLockMode(LockMode &lockMode)
00038 {
00039     assert(lockMode == leafLockMode);
00040     return true;
00041 }
00042 
00043 bool BTreeLeafReader::searchExtreme(bool first)
00044 {
00045     assert(currLeafPageId != NULL_PAGE_ID);
00046     pageLock.lockPage(currLeafPageId, leafLockMode);
00047     BTreeNode const &node = pageLock.getNodeForRead();
00048     if (node.nEntries == 0) {
00049         singular = true;
00050         return false;
00051     }
00052     singular = false;
00053     if (first) {
00054         iTupleOnLowestLevel = 0;
00055     } else {
00056         iTupleOnLowestLevel = node.nEntries - 1;
00057     }
00058     accessLeafTuple();
00059     return true;
00060 }
00061 
00062 bool BTreeLeafReader::searchForKey(
00063     TupleData const &key,
00064     DuplicateSeek dupSeek,
00065     bool leastUpper)
00066 {
00067     assert(currLeafPageId != NULL_PAGE_ID);
00068     return
00069         searchForKeyInternal(
00070             key, dupSeek, leastUpper, currLeafPageId, leafLockMode,
00071             READ_LEAF_ONLY);
00072 }
00073 
00074 bool BTreeLeafReader::searchNext()
00075 {
00076     assert(currLeafPageId != NULL_PAGE_ID);
00077     assert(!singular);
00078     assert(pageLock.isLocked());
00079     assert(!pageLock.getNodeForRead().height);
00080     ++iTupleOnLowestLevel;
00081     BTreeNode const &node = pageLock.getNodeForRead();
00082     if (iTupleOnLowestLevel < node.nEntries) {
00083         accessLeafTuple();
00084         return true;
00085     } else {
00086         // might as well preserve position
00087         --iTupleOnLowestLevel;
00088         singular = true;
00089         return false;
00090     }
00091 }
00092 
00093 void BTreeLeafReader::endSearch()
00094 {
00095     BTreeReader::endSearch();
00096     currLeafPageId = NULL_PAGE_ID;
00097 }
00098 
00099 void BTreeLeafReader::setCurrentPageId(PageId pageId)
00100 {
00101     currLeafPageId = pageId;
00102 }
00103 
00104 FENNEL_END_CPPFILE("$Id: //open/dev/fennel/btree/BTreeLeafReader.cpp#3 $");
00105 
00106 // End BTreeLeafReader.cpp

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