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secondo/Algebras/SharedStream/SharedStreamAlgebra.cpp
2026-01-23 17:03:45 +08:00

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C++

/*
----
This file is part of SECONDO.
Copyright (C) 2004, University in Hagen, Department of Computer Science,
Database Systems for New Applications.
SECONDO 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.
SECONDO 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 SECONDO; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
----
//paragraph [1] Title: [{\Large \bf \begin{center}] [\end{center}}]
//paragraph [10] Footnote: [{\footnote{] [}}]
//[->] [$\rightarrow$]
//[TOC] [\tableofcontents]
//[_] [\_]
*/
#include "Attribute.h" // implementation of attribute types
#include "Algebra.h" // definition of the algebra
#include "NestedList.h" // required at many places
#include "QueryProcessor.h" // needed for implementing value mappings
#include "AlgebraManager.h" // e.g., check for a certain kind
#include "Operator.h" // for operator creation
#include "StandardTypes.h" // priovides int, real, string, bool type
#include "Algebras/FText/FTextAlgebra.h"
#include "Symbols.h" // predefined strings
#include "ListUtils.h" // useful functions for nested lists
#include "Stream.h" // wrapper for secondo streams
//#include "GenericTC.h" // use of generic type constructors
#include "LogMsg.h" // send error messages
#include "Tools/Flob/DbArray.h" // use of DbArrays
#include "Algebras/Relation-C++/RelationAlgebra.h" // use of tuples
#include "Algebras/Distributed2/ErrorWriter.h"
#include "Algebras/Distributed2/DArray.h"
#include <math.h> // required for some operators
#include <stack>
#include <limits>
#include "SocketIO.h"
#include <iostream>
#include <boost/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/lock_guard.hpp>
#include <boost/lexical_cast.hpp>
/*
0.5 Global Variables
Secondo uses some variables designed as singleton pattern. For accessing these
global variables, these variables have to be declared to be extern:
*/
extern NestedList *nl;
extern QueryProcessor *qp;
extern AlgebraManager *am;
using namespace std;
/*
0.6 Namespace
Each algebra file defines a lot of functions. Thus, name conflicts may arise
with function names defined in other algebra modules during compiling/linking
the system. To avoid these conflicts, the algebra implementation should be
embedded into a namespace.
*/
namespace sharedstream {
ListExpr provideTupleTypeTM(ListExpr args) {
// check number of arguments
if (!nl->HasLength(args, 2)) {
return listutils::typeError("wrong number of arguments");
}
//first argument must be of type stream
if (!Stream<Tuple>::checkType(nl->First(args))) {
return listutils::typeError("stream x int expected");
}
// second argument must be of type integer
if (!CcInt::checkType(nl->Second(args))) {
return listutils::typeError("stream x int expected");
}
// create the result type (stream)
return nl->First(args);
}
class provideTupleTypeLI {
//constructor: initializes the class with port and tupleType
public:
provideTupleTypeLI(int _port, std::string _tupleType) {
port = _port;
tupleType = _tupleType;
listener = Socket::CreateGlobal("localhost",
boost::lexical_cast<string>
(port));
if (listener->IsOk()) {
running = true;
t1 = new boost::thread(&provideTupleTypeLI::runInThread, this);
} else {
running = false;
t1 = 0;
delete listener;
listener = 0;
}
}
// destructor
~provideTupleTypeLI() {
if (running) {
running = false;
listener->CancelAccept();
t1->join();
delete t1;
delete listener;
}
}
void runInThread() {
while (running) {
Socket *srv = listener->Accept();
if (srv) {
if (srv->IsOk()) {
std::iostream &io = srv->GetSocketStream();
io << "TupelType: " << tupleType << endl;
srv->Close();
}
delete srv;
}
}
}
private:
Socket *listener;
bool running;
string tupleType;
int port;
boost::thread *t1;
}; //end provideTupleTypeLI class
int provideTupleTypeVM(Word *args, Word &result, int message,
Word &local, Supplier s) {
provideTupleTypeLI *li = (provideTupleTypeLI *) local.addr;
switch (message) {
case OPEN : {
qp->Open(args[0].addr);
if (li) {
delete li;
local.addr = 0;
}
CcInt *port = (CcInt *) args[1].addr;
if (!port->IsDefined()) {
return 0;
}
string tupleType = nl->ToString(nl->Second(qp->GetType(s)));
local.addr = new provideTupleTypeLI(port->GetValue(),
tupleType);
return 0;
}
case REQUEST: {
qp->Request(args[0].addr, result);
return qp->Received(args[0].addr) ? YIELD : CANCEL;
}
case CLOSE: {
if (li) {
delete li;
local.addr = 0;
}
qp->Close(args[0].addr);
return 0;
}
}
return 0;
}
OperatorSpec provideTupleTypeSpec(
" stream x int -> stream",
" _ provideTupleType[_] ",
"The incoming stream is pass-through. As an side effect "
"a server is started on the specified port providing the"
"tuple type of the stream.",
" query plz feed provideTupleType[4211] count"
);
Operator provideTupleTypeOp(
"provideTupleType",
provideTupleTypeSpec.getStr(),
provideTupleTypeVM,
Operator::SimpleSelect,
provideTupleTypeTM
);
class SharedStreamAlgebra : public Algebra {
public:
SharedStreamAlgebra() : Algebra() {
AddOperator(&provideTupleTypeOp);
}
};
}//end namespace
/*
9 Initialization of the Algebra
This piece of code returns a new instance of the algebra.
*/
extern "C"
Algebra *
InitializeSharedStreamAlgebra(NestedList *nlRef,
QueryProcessor *qpRef) {
return new sharedstream::SharedStreamAlgebra;
}