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mirror of https://github.com/OpenNebula/one.git synced 2024-12-22 13:33:52 +03:00
one/include/PoolSQLCache.h
Tino Vázquez 05d147c524
M #-: Bump version 6.10.0
Also bump copyright year to 2024
2024-07-29 14:27:11 +02:00

113 lines
3.0 KiB
C++

/* -------------------------------------------------------------------------- */
/* Copyright 2002-2024, 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 POOL_SQL_CACHE_H_
#define POOL_SQL_CACHE_H_
#include <map>
#include <mutex>
#include "PoolObjectSQL.h"
/**
* This class stores the active reference to pool objects. It can also
* cache to not reload object state from the DB.
*
* Access to the cache needs to happen in a critical section.
*/
class PoolSQLCache
{
public:
PoolSQLCache();
~PoolSQLCache() = default;
/**
* Allocates a new cache line to hold an active pool object. If the line
* does not exist it is created. Any active reference is deallocated to
* load a fresh copy of the object.
*
* The cache line is locked to sync access to the given object.
*
* @param oid of the object
*/
std::mutex * lock_line(int oid);
private:
/**
* This class represents a cache line. It stores a reference to the pool
* object and a mutex to control concurrent access to the object
*/
struct CacheLine
{
CacheLine():active(0)
{
}
~CacheLine() = default;
void lock()
{
_mutex.lock();
}
void unlock()
{
_mutex.unlock();
}
bool trylock()
{
return _mutex.try_lock();
}
/**
* Concurrent access to object
*/
std::mutex _mutex;
/**
* Number of threads waiting on the line mutex
*/
int active;
};
/**
* Max number of references in the cache.
*/
static unsigned int MAX_ELEMENTS;
/**
* Cache of pool objects indexed by their oid
*/
std::map<int, CacheLine *> cache;
/**
* Deletes all cache lines if they are not in use.
*/
void flush_cache_lines();
/**
* Controls concurrent access to the cache map.
*/
std::mutex _mutex;
};
#endif /*POOL_SQL_CACHE_H_*/