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one/include/PostgreSqlDB.h
2020-04-30 15:00:02 +02:00

197 lines
5.6 KiB
C++

/* -------------------------------------------------------------------------- */
/* Copyright 2002-2020, OpenNebula Project, OpenNebula Systems */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); you may */
/* not use this file except in compliance with the License. You may obtain */
/* a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. */
/* See the License for the specific language governing permissions and */
/* limitations under the License. */
/* -------------------------------------------------------------------------- */
#ifndef POSTGRESQL_DB_H_
#define POSTGRESQL_DB_H_
#include <string>
#include <stdexcept>
#include <queue>
#include "NebulaLog.h"
#include "SqlDB.h"
#include "ObjectSQL.h"
#ifdef POSTGRESQL_DB
#include <libpq-fe.h>
/**
* PostgreSqlDB class. Provides a wrapper to the PostgreSQL database interface.
*/
class PostgreSqlDB : public SqlDB
{
public:
PostgreSqlDB(
const string& _server,
int _port,
const string& _user,
const string& _password,
const string& _database,
int _connections);
~PostgreSqlDB();
/**
* This function returns a legal SQL string that can be used in an SQL
* statement.
* @param str the string to be escaped
* @return a valid SQL string or NULL in case of failure
*/
char * escape_str(const string& str) override;
/**
* Frees a previously scaped string
* @param str pointer to the str
*/
void free_str(char * str) override;
/**
* @param sid the offset
* @param eid the rowcount
* @return string with compatible LIMIT clause syntax
* LIMIT row_count OFFSET offset
*
* +---+---+---+---+---+---+---+---+--
* | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |...
* +---+---+---+---+---+---+---+---+--
* | |
* /-------------------/
* LIMIT 5 OFFSET 3
*/
std::string limit_string(int sid, int eid) override
{
std::ostringstream oss;
oss << "LIMIT " << eid << " OFFSET " << sid;
return oss.str();
}
std::string limit_string(int sid) override
{
std::ostringstream oss;
oss << "LIMIT " << sid << " OFFSET 0";
return oss.str();
}
protected:
int exec_ext(std::ostringstream& cmd, Callbackable *obj, bool quiet) override;
private:
/**
* Number of concurrent DB connections.
*/
int max_connections;
/**
* Connection pool
*/
queue<PGconn *> db_connect;
/**
* DB connection to escape strings
*/
PGconn * db_escape_connect;
/**
* Connection parameters
*/
string server;
int port;
string user;
string password;
string database;
/**
* Fine-grain mutex for DB access (pool of DB connections)
*/
pthread_mutex_t mutex;
/**
* Conditional variable to wake-up waiting threads.
*/
pthread_cond_t cond;
/**
* Gets a free DB connection from the pool.
*/
PGconn * get_db_connection();
/**
* Returns the connection to the pool.
*/
void free_db_connection(PGconn * db);
/**
* Preprocesses the query to be compatible with PostgreSQL syntax
*
* Any change to this method should be reflected in BackEndPostgreSQL class
* in src/onedb/onedb_backend.rb
*
* This method alters to queries:
* - CREATE TABLE to adjust type names
* . MEDIUMTEXT -> TEXT
* . LONGTEXT -> TEXT
* . BIGINT UNSIGNED -> NUMERIC
*
* - REPLACE INTO into PostgreSQL INSERT INTO query with ON CONFLICT
* clause. For example:
* REPLACE INTO pool_control (tablename, last_oid) VALUES ('acl',0)
* changes to:
* INSERT INTO pool_control (tablename, last_oid) VALUES ('acl',0)
* ON CONFLICT (tablename) DO UPDATE SET last_oid = EXCLUDED.last_oid
***************************************************************************
* Any change to this method should be reflected in BackEndPostgreSQL class
* in src/onedb/onedb_backend.rb
***************************************************************************
*/
static std::string preprocess_query(std::ostringstream& cmd);
};
#else
// Class stub
class PostgreSqlDB : public SqlDB
{
public:
PostgreSqlDB(
const string& _server,
int _port,
const string& _user,
const string& _password,
const string& _database,
int _connections)
{
throw runtime_error("Aborting oned, PostgreSQL support not compiled!");
}
~PostgreSqlDB(){}
char * escape_str(const string& str) override {return 0;};
void free_str(char * str) override {};
std::string limit_string(int sid, int eid) override {return "";}
protected:
int exec_ext(std::ostringstream& c, Callbackable *o, bool q) override {
return -1;
};
};
#endif
#endif /*POSTGRESQL_DB_H*/