/* -------------------------------------------------------------------------- */
/* Copyright 2002-2011, OpenNebula Project Leads (OpenNebula.org) */
/* */
/* 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 POOL_SQL_H_
#define POOL_SQL_H_
#include <map>
#include <string>
#include <queue>
#include "SqlDB.h"
#include "PoolObjectSQL.h"
#include "Log.h"
#include "Hook.h"
using namespace std;
/**
* PoolSQL class. Provides a base class to implement persistent generic pools.
* The PoolSQL provides a synchronization mechanism (mutex) to operate in
* multithreaded applications. Any modification or access function to the pool
* SHOULD block the mutex.
*/
class PoolSQL: public Callbackable, public Hookable
{
public:
/**
* Initializes the oid counter. This function sets lastOID to
* the last used Object identifier by querying the corresponding database
* table. This function SHOULD be called before any pool related function.
* @param _db a pointer to the database
* @param table the name of the table supporting the pool (to set the oid
* counter). If null the OID counter is not updated.
* @param with_uid the Pool objects have an owner id (uid)
*/
PoolSQL(SqlDB * _db, const char * _table);
virtual ~PoolSQL();
/**
* Allocates a new object, writting it in the pool database. No memory is
* allocated for the object.
* @param objsql an initialized ObjectSQL
* @return the oid assigned to the object or -1 in case of failure
*/
virtual int allocate(
PoolObjectSQL *objsql,
string& error_str);
/**
* Gets an object from the pool (if needed the object is loaded from the
* database).
* @param oid the object unique identifier
* @param lock locks the object if true
*
* @return a pointer to the object, 0 in case of failure
*/
PoolObjectSQL * get(int oid, bool lock);
/**
* Gets an object from the pool (if needed the object is loaded from the
* database).
* @param name of the object
* @param uid id of owner
* @param lock locks the object if true
*
* @return a pointer to the object, 0 in case of failure
*/
PoolObjectSQL * get(const string& name, int uid, bool lock);
/**
* Finds a set objects that satisfies a given condition
* @param oids a vector with the oids of the objects.
* @param the name of the DB table.
* @param where condition in SQL format.
*
* @return 0 on success
*/
virtual int search(
vector<int>& oids,
const char * table,
const string& where);
/**
* Updates the object's data in the data base. The object mutex SHOULD be
* locked.
* @param objsql a pointer to the object
*
* @return 0 on success.
*/
virtual int update(
PoolObjectSQL * objsql)
{
int rc;
rc = objsql->update(db);
if ( rc == 0 )
{
do_hooks(objsql, Hook::UPDATE);
}
return rc;
};
/**
* Drops the object's data in the data base. The object mutex SHOULD be
* locked.
* @param objsql a pointer to the object
* @param error_msg Error reason, if any
* @return 0 on success, -1 DB error
*/
virtual int drop(PoolObjectSQL * objsql, string& error_msg)
{
int rc = objsql->drop(db);
if ( rc != 0 )
{
error_msg = "SQL DB error";
return -1;
}
return 0;
};
/**
* Removes all the elements from the pool
*/
void clean();
/**
* Dumps the pool in XML format. A filter can be also added to the
* query
* @param oss the output stream to dump the pool contents
* @param where filter for the objects, defaults to all
*
* @return 0 on success
*/
virtual int dump(ostringstream& oss, const string& where) = 0;
protected:
/**
* Pointer to the database.
*/
SqlDB * db;
/**
* Dumps the pool in XML format. A filter can be also added to the
* query
* @param oss the output stream to dump the pool contents
* @param elem_name Name of the root xml pool name
* @param table Pool table name
* @param where filter for the objects, defaults to all
*
* @return 0 on success
*/
int dump(ostringstream& oss, const string& elem_name,
const char * table, const string& where);
/* ---------------------------------------------------------------------- */
/* Interface to access the lastOID assigned by the pool */
/* ---------------------------------------------------------------------- */
/**
* Gets the value of the last identifier assigned by the pool
* @return the lastOID of the pool
*/
int get_lastOID()
{
return lastOID;
};
/**
* Sets the lastOID of the pool and updates the control database
* @param _lastOID for the pool
*/
void set_update_lastOID(int _lastOID)
{
lastOID = _lastOID;
update_lastOID();
};
private:
pthread_mutex_t mutex;
/**
* Max size for the pool, to control the memory footprint of the pool. This
* number MUST be greater than the max. number of objects that are
* accessed simultaneously.
*/
static const unsigned int MAX_POOL_SIZE;
/**
* Last object ID assigned to an object. It must be initialized by the
* target pool.
*/
int lastOID;
/**
* Tablename for this pool
*/
string table;
/**
* The pool is implemented with a Map of SQL object pointers, using the
* OID as key.
*/
map<int,PoolObjectSQL *> pool;
/**
* This is a name index for the pool map. The key is the name of the object
* , that may be combained with the owner id.
*/
map<string,PoolObjectSQL *> name_pool;
/**
* Factory method, must return an ObjectSQL pointer to an allocated pool
* specific object.
*/
virtual PoolObjectSQL * create() = 0;
/**
* OID queue to implement a FIFO-like replacement policy for the pool
* cache.
*/
queue<int> oid_queue;
/**
* Function to lock the pool
*/
void lock()
{
pthread_mutex_lock(&mutex);
};
/**
* Function to unlock the pool
*/
void unlock()
{
pthread_mutex_unlock(&mutex);
};
/**
* FIFO-like replacement policy function. Before removing an object (pop)
* from the cache its lock is checked. The object is removed only if
* the associated mutex IS NOT blocked. Otherwise the oid is sent to the
* back of the queue.
*/
void replace();
/**
* Generate an index key for the object
* @param name of the object
* @param uid owner of the object, only used if needed
*
* @return the key, a string
*/
string key(const string& name, int uid)
{
ostringstream key;
key << name << ':' << uid;
return key.str();
};
/**
* Inserts the last oid into the pool_control table
*/
void update_lastOID();
/* ---------------------------------------------------------------------- */
/* ---------------------------------------------------------------------- */
/**
* Callback to set the lastOID (PoolSQL::PoolSQL)
*/
int init_cb(void *nil, int num, char **values, char **names);
/**
* Callback to store the IDs of pool objects (PoolSQL::search)
*/
int search_cb(void *_oids, int num, char **values, char **names);
/**
* Callback function to get output in XML format
* @param num the number of columns read from the DB
* @param names the column names
* @param vaues the column values
* @return 0 on success
*/
int dump_cb(void * _oss, int num, char **values, char **names);
};
#endif /*POOL_SQL_H_*/