pgsqlconnection.cpp

C++连接一写常用数据库的接口

/*
 * PostgresqlConnection object defines the needed connection functions for the dbConnect PostgrSQL driver
 * Copyright (C) 2003 Johnathan Ingram, [e-mail]
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  US
 *
 */


#include "pgsqlConnection.h"


#include "pgsqlQuery.h"


// -----------------------------------------------------------------------------
// PRIVATE:
// -----------------------------------------------------------------------------


// -----------------------------------------------------------------------------
// PostgresqlConnection::_pgsqlConnect
// -----------------------------------------------------------------------------
void 
PostgresqlConnection::_pgsqlConnect(
         int index)
{  
   // Make sure the handle is valid and we are not already connected.
   if (index > _numHandles || index < 0)
      throw Error("_pgsqlConnect(): Invalid index to database handle.");

   if (_handles[index]->status != BaseHandle::DISCONNECTED)
      throw AlreadyConnected("_pgsqlConnect(): "
         "The database connection is already connected to the database.");

   // Connect to the PostgreSQL database.   
   _handles[index]->__conn = PQsetdbLogin(host.c_str(), _pgsqlOptions.port.c_str(), NULL, NULL, databaseName.c_str(), username.c_str(), password.c_str());
      
   // Check if an error occured while connecting to the database.
   if (PQstatus(_handles[index]->__conn) == CONNECTION_BAD)
   {
      string err = "_pgsqlConnect(): ";
      err += PQerrorMessage(_handles[index]->__conn);

      PQfinish(_handles[index]->__conn);
      _handles[index]->__conn = NULL;
     
      throw ErrorConnecting(err);
   }

   // Set the date time format to ISO standard format using a query.
   PGresult *r = PQexec(_handles[index]->__conn, "SET DATESTYLE TO 'ISO'");
   if (!r || PQresultStatus(r) != PGRES_COMMAND_OK)
   {
      string err = "_pgsqlConnect(): Unable to set the iso date format on the connection using \"SET DATESTYLE TO 'ISO'\". ";
      if (r)
      {
         err += PQresultErrorMessage(r);
         PQclear(r);
      }
      
      PQfinish(_handles[index]->__conn);
      _handles[index]->__conn = NULL;
     
      throw ErrorConnecting(err);
   }
   
   PQclear(r);

   
   _handles[index]->status = BaseHandle::CONNECTED;
   _handles[index]->lastUsed = time(NULL);
} // PostgresqlConnection::_pgsqlConnect


// -----------------------------------------------------------------------------
// PostgresqlConnection::_pgsqlDisconnect
// -----------------------------------------------------------------------------
void 
PostgresqlConnection::_pgsqlDisconnect(
         int index)
{
   // Make sure the handle is valid and we are not already connected.
   if (index > _numHandles || index < 0)
      throw Error("_pgsqlDisconnect(): Invalid index to database handle.");   

   if (_handles[index]->status == BaseHandle::DISCONNECTED || 
       _handles[index]->status == BaseHandle::UNKNOWN)
      throw NotConnected("_pgsqlDisconnect(): "
         "The database handle does not have a valid connection to the database.");

   // Disconnect from the server.
   PQfinish(_handles[index]->__conn);
   _handles[index]->__conn = NULL;
   _handles[index]->status = BaseHandle::DISCONNECTED;
   _handles[index]->lastUsed = time(NULL);
} // PostgresqlConnection::_pgsqlDisconnect


// -----------------------------------------------------------------------------
// PostgresqlConnection::_pgsqlPing
// -----------------------------------------------------------------------------
void 
PostgresqlConnection::_pgsqlPing(
      int index)
{
   // Make sure the handle is valid.
   if (index > _numHandles || index < 0)
      throw Error("_pgsqlPing(): Invalid index to database handle.");

   // Only ping the connection if the ping interval has expired since the
   //   connection was last used.
	time_t currentTime = time(NULL);
	if (currentTime - _handles[index]->lastUsed >= pingInterval)
	{      
      // Do a dummy query to simulate a ping      
      PGresult *r = PQexec(_handles[index]->__conn, "SELECT CURRENT_TIMESTAMP");
      if (!r || PQresultStatus(r) != PGRES_COMMAND_OK)
      {
         // An error occured while pinging, so reconnect.         
         if (r)
            PQclear(r);
         
         // Try and reconnect the lost connection using PQreset function.
         PQreset(_handles[index]->__conn);
         if (PQstatus(_handles[index]->__conn) == CONNECTION_BAD)
         {            
            string err = "_pgsqlPing(): Unable to ping connection, ";
            err += PQerrorMessage(_handles[index]->__conn);
      
            PQfinish(_handles[index]->__conn);
            _handles[index]->__conn = NULL;
           
            throw ErrorPingingConnection(err);
         }
      }
      else
      {
         // Ping was OK
         PQclear(r);
      }
   }   
} // PostgresqlConnection::_pgsqlPing


// -----------------------------------------------------------------------------
// PostgresqlConnection::_pgsqlQuery
// -----------------------------------------------------------------------------
PGresult*
PostgresqlConnection::_pgsqlQuery(
      int           index,
      const string& sqlStatement)
{
   // Make sure the handle is in the connected used state.
   if (_handles[index]->status != BaseHandle::CONNECTED_USED)
      throw ErrorQuerying("_pgsqlQuery(): The database connection is not valid. May have been terminated by the connection object?");

   //Execute the query
   PGresult *r = PQexec(_handles[index]->__conn, sqlStatement.c_str());      
   if (!r || PQresultStatus(r) == PGRES_BAD_RESPONSE || PQresultStatus(r) == PGRES_FATAL_ERROR)
   {         
      string err = "_pgsqlQuery(): ";
      err += "SQL statement: ";
      err += sqlStatement;
      
      if (r)
      {
         err += ", ";
         err += PQresultErrorMessage(r);
         PQclear(r);
      }
      throw ErrorQuerying(err);
   }
   
   // Set the last used
   _handles[index]->lastUsed = time(NULL);
   
   return r;
} // PostgresqlConnection::_pgsqlQuery


//------------------------------------------------------------------------------
// PostgresqlConnection::_freeCollection
//------------------------------------------------------------------------------
void PostgresqlConnection::_freeCollection(
      CollectionType type)
{
   int i;
   switch (type)
   {
      case CONNECTION_HANDLES:
         if (_handles)
         {
            for (i=0; i<_numHandles; i++)
            {
               if (_handles[i])
               {
                  delete _handles[i];
                  _handles[i] = NULL;         
               }
            }
            free(_handles);
            _handles = NULL;
            _numHandles = 0;
         }
      
         break;      
    }
} // PostgresqlConnection::_freeCollection


// -----------------------------------------------------------------------------
// PUBLIC:
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// PostgresqlConnection::PostgresqlConnection
// -----------------------------------------------------------------------------
PostgresqlConnection::PostgresqlConnection(
      int argc,