mapnik/plugins/input/postgis/connection.hpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2011 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#ifndef POSTGIS_CONNECTION_HPP
#define POSTGIS_CONNECTION_HPP

// mapnik
#include <mapnik/debug.hpp>
#include <mapnik/datasource.hpp>
#include <mapnik/timer.hpp>

// boost
#include <boost/make_shared.hpp>

// std
#include <sstream>
#include <iostream>

extern "C" {
#include "libpq-fe.h"
}

#include "resultset.hpp"

class Connection
{
public:
    Connection(std::string const& connection_str)
        : cursorId(0),
          closed_(false)
    {
        conn_ = PQconnectdb(connection_str.c_str());
        if (PQstatus(conn_) != CONNECTION_OK)
        {
            std::ostringstream s;
            s << "Postgis Plugin: ";
            if (conn_ )
            {
                std::string msg = PQerrorMessage(conn_);
                if (! msg.empty())
                {
                    s << msg.substr(0, msg.size() - 1);
                }
                else
                {
                    s << "unable to connect to postgres server";
                }
            }
            else
            {
                s << "unable to connect to postgres server";
            }
            s << "\n" << connection_str;

            throw mapnik::datasource_exception(s.str());
        }
    }

    ~Connection()
    {
        if (! closed_)
        {
            PQfinish(conn_);

            MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: postgresql connection closed - " << conn_;

            closed_ = true;
        }
    }

    bool execute(const std::string& sql) const
    {
#ifdef MAPNIK_STATS
        mapnik::progress_timer __stats__(std::clog, std::string("postgis_connection::execute ") + sql);
#endif

        PGresult *result = PQexec(conn_, sql.c_str());
        bool ok = (result && (PQresultStatus(result) == PGRES_COMMAND_OK));
        PQclear(result);
        return ok;
    }

    boost::shared_ptr<ResultSet> executeQuery(const std::string& sql, int type = 0) const
    {
#ifdef MAPNIK_STATS
        mapnik::progress_timer __stats__(std::clog, std::string("postgis_connection::execute_query ") + sql);
#endif

        PGresult* result = 0;
        if (type == 1)
        {
            result = PQexecParams(conn_,sql.c_str(), 0, 0, 0, 0, 0, 1);
        }
        else
        {
            result = PQexec(conn_, sql.c_str());
        }

        if (! result || (PQresultStatus(result) != PGRES_TUPLES_OK))
        {
            std::ostringstream s;
            s << "Postgis Plugin: PSQL error";
            if (conn_)
            {
                std::string msg = PQerrorMessage(conn_);
                if (! msg.empty())
                {
                    s << ":\n" <<  msg.substr(0, msg.size() - 1);
                }

                s << "\nFull sql was: '" <<  sql << "'\n";
            }
            else
            {
                s << "unable to connect to database";
            }

            if (result)
            {
                PQclear(result);
            }

            throw mapnik::datasource_exception(s.str());
        }

        return boost::make_shared<ResultSet>(result);
    }

    std::string client_encoding() const
    {
        return PQparameterStatus(conn_, "client_encoding");
    }

    bool isOK() const
    {
        return (PQstatus(conn_) != CONNECTION_BAD);
    }

    void close()
    {
        if (! closed_)
        {
            PQfinish(conn_);

            MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: datasource closed, also closing connection - " << conn_;

            closed_ = true;
        }
    }

    std::string new_cursor_name()
    {
        std::ostringstream s;
        s << "mapnik_" << (cursorId++);
        return s.str();
    }

private:
    PGconn *conn_;
    int cursorId;
    bool closed_;
};

#endif //CONNECTION_HPP