182 lines
4.7 KiB
C++
182 lines
4.7 KiB
C++
/*
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----
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This file is part of SECONDO.
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Copyright (C) 2004, University in Hagen, Department of Computer Science,
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Database Systems for New Applications.
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SECONDO is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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SECONDO is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with SECONDO; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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----
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//paragraph [1] Title: [{\Large \bf \begin{center}] [\end{center}}]
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//paragraph [10] Footnote: [{\footnote{] [}}]
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//[TOC] [\tableofcontents]
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[1] Implementation of the unpin\_nodes Operator
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[TOC]
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0 Overview
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1 Defines and Includes
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*/
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#include "op_unpin_nodes.h"
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#include "ListUtils.h"
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#include "QueryProcessor.h"
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#include "BTree2.h"
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#include "Symbols.h"
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extern NestedList* nl;
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extern QueryProcessor *qp;
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namespace BTree2Algebra {
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namespace Operators {
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/*
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2 Operator ~unpin\_nodes~
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Signature is
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----
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unpin\_nodes: stream(int) x (btree2) --> stream(tuple( (Node int)
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(Ok bool)))
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----
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2.1 TypeMapping
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*/
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ListExpr unpin_nodes::TypeMapping( ListExpr args){
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if(nl->ListLength(args) != 2){
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return listutils::typeError("Operator expects two arguments");
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};
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NList first (nl->First(args));
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ListExpr second = nl->Second(args);
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if(!(first.hasLength(2) && first.first().isSymbol() &&
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first.first().str() == Symbol::STREAM() &&
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first.second().isSymbol()
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&& first.second().str() == CcInt::BasicType())){
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return listutils::typeError("Operator expects a stream "
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"of ints as first argument:");
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}
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if(!listutils::isBTree2Description(second)){
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return listutils::typeError("Operator expects a btree2"
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" object as second argument.");
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}
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ListExpr attr = nl->TwoElemList(nl->TwoElemList(nl->SymbolAtom("Node"),
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nl->SymbolAtom(CcInt::BasicType())),
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nl->TwoElemList(nl->SymbolAtom("Ok"),
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nl->SymbolAtom(CcBool::BasicType())));
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ListExpr res = (nl->TwoElemList(nl->SymbolAtom(Symbol::STREAM()),
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nl->TwoElemList(nl->SymbolAtom(Tuple::BasicType()),
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attr)));
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return res;
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}
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/*
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2.2 Valuemapping
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*/
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struct ValueMapInfo{
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BTree2* btree;
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TupleType* tType;
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};
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int
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unpin_nodes::ValueMapping(Word* args, Word& result, int message,
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Word& local, Supplier s)
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{
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CcInt* currentInt;
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Word current;
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Tuple* tuple;
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ValueMapInfo* vmi;
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switch( message )
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{
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case OPEN: { // initialize the local storage
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vmi = new ValueMapInfo;
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vmi->btree = (BTree2*)args[1].addr;
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ListExpr resultType = GetTupleResultType( s );
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vmi->tType = new TupleType(nl->Second(resultType));
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qp->Open(args[0].addr);
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local.addr = vmi;
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return 0;
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}
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case REQUEST: { // return the next stream element
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vmi = (ValueMapInfo*)local.addr;
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qp->Request(args[0].addr, current);
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if (qp->Received(args[0].addr))
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{
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currentInt = (CcInt*)current.addr;
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bool res = vmi->btree->removeCachePinnedNode(currentInt->GetIntval());
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tuple = new Tuple(vmi->tType);
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tuple->PutAttribute(0, currentInt);
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tuple->PutAttribute(1, new CcBool(true, res));
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result.setAddr(tuple);
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return YIELD;
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}
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else
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{
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result.addr = 0;
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return CANCEL;
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}
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}
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case CLOSE: { // free the local storage
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if (local.addr)
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{
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vmi = (ValueMapInfo*)local.addr;
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vmi->tType->DeleteIfAllowed();
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delete vmi;
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local.addr = 0;
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}
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qp->Close(args[0].addr);
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return 0;
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}
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default: {
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return -1;
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}
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}
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}
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/*
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2.3 Operator specification
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*/
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struct unpinNodesInfo : OperatorInfo {
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unpinNodesInfo() : OperatorInfo()
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{
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name = "unpin_nodes";
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signature = "(stream(int)) x (btree2 Tk Td u) -> stream("
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"tuple( (Node int) (Ok bool)))" ;
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syntax = "_ unpin_nodes [ _ ]";
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meaning = "Unpins the nodes with given NodeId in the btree2's cache.";
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example = "query intstream (0, 4) unpin_nodes [staedte_btree2] consume";
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}
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};
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Operator unpin_nodes::def( unpinNodesInfo(), unpin_nodes::ValueMapping,
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unpin_nodes::TypeMapping);
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}
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}
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