mapnik/plugins/input/postgis/connection.hpp
2024-07-22 10:20:47 +01:00

280 lines
8.2 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2024 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>
// std
#include <memory>
#include <sstream>
#include <iostream>
extern "C" {
#include "libpq-fe.h"
}
#include "resultset.hpp"
class Connection
{
public:
Connection(std::string const& connection_str, std::optional<std::string> const& password)
: cursorId(0)
, closed_(false)
, pending_(false)
{
std::string connect_with_pass = connection_str;
if (password && !password->empty())
{
connect_with_pass += " password=" + *password;
}
conn_ = PQconnectdb(connect_with_pass.c_str());
MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: postgresql connection create - " << this;
if (PQstatus(conn_) != CONNECTION_OK)
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "Connection string: '";
err_msg += connection_str;
err_msg += "'\n";
MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: creation failed, closing connection - " << this;
close();
throw mapnik::datasource_exception(err_msg);
}
PGresult* result =
PQexec(conn_, "SET DEFAULT_TRANSACTION_READ_ONLY = TRUE; SET CLIENT_MIN_MESSAGES = WARNING;");
bool ok = (result && (PQresultStatus(result) == PGRES_COMMAND_OK));
if (result)
PQclear(result);
if (!ok)
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "Connection string: '";
err_msg += connection_str;
err_msg += "'\n";
close();
throw mapnik::datasource_exception(err_msg);
}
}
~Connection()
{
if (!closed_)
{
PQfinish(conn_);
MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: postgresql connection closed - " << this;
closed_ = true;
}
}
bool execute(std::string const& sql)
{
#ifdef MAPNIK_STATS
mapnik::progress_timer __stats__(std::clog, std::string("postgis_connection::execute ") + sql);
#endif
if (!executeAsyncQuery(sql))
return false;
PGresult* result = 0;
// fetch multiple times until NULL is returned,
// to handle multi-statement queries
while (PGresult* tmp = getResult())
{
if (result)
PQclear(result);
result = tmp;
}
bool ok = (result && (PQresultStatus(result) == PGRES_COMMAND_OK));
if (result)
PQclear(result);
return ok;
}
std::shared_ptr<ResultSet> executeQuery(std::string const& sql, int type = 0)
{
#ifdef MAPNIK_STATS
mapnik::progress_timer __stats__(std::clog, std::string("postgis_connection::execute_query ") + sql);
#endif
PGresult* result = 0;
if (executeAsyncQuery(sql, type))
{
// fetch multiple times until NULL is returned,
// to handle multi-statement queries
while (PGresult* tmp = getResult())
{
if (result)
PQclear(result);
result = tmp;
}
}
if (!result || (PQresultStatus(result) != PGRES_TUPLES_OK))
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "in executeQuery Full sql was: '";
err_msg += sql;
err_msg += "'\n";
if (result)
PQclear(result);
throw mapnik::datasource_exception(err_msg);
}
return std::make_shared<ResultSet>(result);
}
std::string status() const
{
std::string status;
if (conn_)
{
char* err_msg = PQerrorMessage(conn_);
if (err_msg == nullptr)
{
status = "Bad connection\n";
}
else
{
status = std::string(err_msg);
}
}
else
{
status = "Uninitialized connection\n";
}
return status;
}
bool executeAsyncQuery(std::string const& sql, int type = 0)
{
int result = 0;
if (type == 1)
{
result = PQsendQueryParams(conn_, sql.c_str(), 0, 0, 0, 0, 0, 1);
}
else
{
result = PQsendQuery(conn_, sql.c_str());
}
if (result != 1)
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "in executeAsyncQuery Full sql was: '";
err_msg += sql;
err_msg += "'\n";
clearAsyncResult(PQgetResult(conn_));
close();
throw mapnik::datasource_exception(err_msg);
}
pending_ = true;
return result;
}
PGresult* getResult()
{
PGresult* result = PQgetResult(conn_);
return result;
}
std::shared_ptr<ResultSet> getNextAsyncResult()
{
PGresult* result = getResult();
if (result && (PQresultStatus(result) != PGRES_TUPLES_OK))
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "in getNextAsyncResult";
clearAsyncResult(result);
// We need to guarde against losing the connection
// (i.e db restart) so here we invalidate the full connection
close();
throw mapnik::datasource_exception(err_msg);
}
return std::make_shared<ResultSet>(result);
}
std::shared_ptr<ResultSet> getAsyncResult()
{
PGresult* result = getResult();
if (!result || (PQresultStatus(result) != PGRES_TUPLES_OK))
{
std::string err_msg = "Postgis Plugin: ";
err_msg += status();
err_msg += "in getAsyncResult";
clearAsyncResult(result);
// We need to be guarded against losing the connection
// (i.e db restart), we invalidate the full connection
close();
throw mapnik::datasource_exception(err_msg);
}
return std::make_shared<ResultSet>(result);
}
std::string client_encoding() const { return PQparameterStatus(conn_, "client_encoding"); }
bool isOK() const { return (!closed_) && (PQstatus(conn_) != CONNECTION_BAD); }
bool isPending() const { return pending_; }
void close()
{
if (!closed_)
{
PQfinish(conn_);
MAPNIK_LOG_DEBUG(postgis) << "postgis_connection: closing connection (close)- " << this;
closed_ = true;
}
}
std::string new_cursor_name()
{
std::ostringstream s;
s << "mapnik_" << (cursorId++);
return s.str();
}
private:
PGconn* conn_;
int cursorId;
bool closed_;
bool pending_;
void clearAsyncResult(PGresult* result)
{
// Clear all pending results
while (result)
{
PQclear(result);
result = PQgetResult(conn_);
}
pending_ = false;
}
};
#endif // CONNECTION_HPP