winix/winixd/db/dbconn.cpp

/*
 * This file is a part of Winix
 * and is distributed under the 2-Clause BSD licence.
 * Author: Tomasz Sowa <t.sowa@ttmath.org>
 */

/* 
 * Copyright (c) 2010-2022, Tomasz Sowa
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#include <unistd.h>
#include "dbconn.h"
#include "core/log.h"
#include "core/error.h"


namespace Winix
{




DbConn::DbConn()
{
	pg_conn      = 0;
}



DbConn::~DbConn()
{
	Close();
}



PGconn * DbConn::GetPgConn()
{
	return pg_conn;
}


void DbConn::SetConnParam(const std::wstring & conn_string)
{
	db_conn_string = conn_string;
	db_host.clear();
	db_hostaddr.clear();
	db_port.clear();
	db_database.clear();
	db_user.clear();
	db_pass.clear();
}


void DbConn::SetConnParam(const std::wstring & host, const std::wstring & hostaddr, const std::wstring & port,
						  const std::wstring & database, const std::wstring & user, const std::wstring & pass)
{
	db_conn_string.clear();
	db_host     = host;
	db_hostaddr = hostaddr;
	db_port     = port;
	db_database = database;
	db_user     = user;
	db_pass     = pass;
}



void DbConn::Connect()
{
	Close();
	
	conn_info.Clear();
	conn_info.SetExtented(false);

	if( !db_conn_string.empty() )
	{
		conn_info << R(db_conn_string);
	}
	else
	{
		conn_info << R("dbname=")    << db_database
				  << R(" user=")     << db_user
				  << R(" password=") << db_pass;

		if( !db_host.empty() )
		{
			conn_info << R(L" host=") << db_host;
		}

		if( !db_hostaddr.empty() )
		{
			conn_info << R(L" hostaddr=") << db_hostaddr;
		}

		if( !db_port.empty() )
		{
			conn_info << R(L" port=") << db_port;
		}
	}

	pg_conn = PQconnectdb(conn_info.CStr());
	
	// warning! pg_conn can be not null but there cannnot be a connection established
	// use PQstatus(pg_conn) to check whether the connection works fine
}


void DbConn::LogNoConnection(size_t attempts)
{
	log << log2 << "Db: connection to the database cannot be established";
	log << ", (" << attempts << " attempt(s))" << logend;
	log << logsave;
}


void DbConn::LogConnectionSocket()
{
	log << log2 << "Db: connection to the database works fine" << logend;
	log << log3 << "Db: connection socket: " << PQsocket(pg_conn) << logend;
	log << logsave;
}



bool DbConn::WaitForConnection(size_t attempts_max, size_t attempt_delay)
{
	size_t attempts = 0;
	bool attempts_exceeded = false;

	if( attempt_delay == 0 )
		attempt_delay = 1;

	if( attempt_delay > 120 )
		attempt_delay = 120;

	if( !pg_conn || PQstatus(pg_conn) != CONNECTION_OK )
	{
		log << log3 << "Db: waiting for the db to be ready...." << logend << logsave;

		while( !attempts_exceeded && !AssertConnection(false, false) )
		{
			if( attempts_max != 0 )
			{
				attempts += 1;
				attempts_exceeded = (attempts >= attempts_max);
			}

			if( !attempts_exceeded )
			{
				sleep(attempt_delay);
			}
		}
	}

	if( attempts_exceeded )
	{
		LogNoConnection(attempts);
	}
	else
	{
		LogConnectionSocket();
	}

	return !attempts_exceeded;
}



void DbConn::Close()
{
	if( pg_conn )
	{
		PQfinish(pg_conn);
		pg_conn = 0;
	}
}



bool DbConn::AssertConnection(bool put_log, bool throw_if_no_connection)
{
bool was_connection = true;


	if( !pg_conn )
	{
		was_connection = false;
		Connect();
	}
	else
	if( PQstatus(pg_conn) != CONNECTION_OK )
	{
		if( put_log )
			log << log2 << "Db: connection to the database is lost, trying to recover" << logend;

		was_connection = false;
		PQreset(pg_conn);
	}
	
	
	if( pg_conn && PQstatus(pg_conn) == CONNECTION_OK )
	{
		if( !was_connection )
		{
			if( put_log )
				LogConnectionSocket();

			SetDbParameters();
		}

		return true;
	}
	else
	{
		if( put_log )
			log << log1 << "Db: connection to db server cannot be established" << logend;

		if( throw_if_no_connection )
			throw Error(WINIX_ERR_DB_FATAL_ERROR_DURING_CONNECTING);

		return false;
	}
}



void DbConn::SetDbParameters()
{
	if( PQsetClientEncoding(pg_conn, "UTF8") == -1 )
		log << log1 << "Db: Can't set the proper client encoding" << logend;
}



} // namespace Winix