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/**
*
* ***** BEGIN GPL LICENSE BLOCK *****
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Contributor(s): Peter Schlaile <peter@schlaile.de> 2005
*
* ***** END GPL LICENSE BLOCK *****
*/
#ifndef __MEM_cache_limiter_h_included__
#define __MEM_cache_limiter_h_included__ 1
/**
* @section MEM_CacheLimiter
* This class defines a generic memory cache management system
* to limit memory usage to a fixed global maximum.
*
* Please use the C-API in MEM_CacheLimiterC-Api.h for code written in C.
*
* Usage example:
*
* class BigFatImage {
* public:
* ~BigFatImage() { tell_everyone_we_are_gone(this); }
* };
*
* void doit() {
* MEM_Cache<BigFatImage> BigFatImages;
*
* MEM_Cache_Handle<BigFatImage>* h = BigFatImages.insert(new BigFatImage);
*
* BigFatImages.enforce_limits();
* h->ref();
*
* work with image...
*
* h->unref();
*
* leave image in cache.
*/
#include <list>
#include "MEM_Allocator.h"
template<class T>
class MEM_CacheLimiter;
#ifndef __MEM_cache_limiter_c_api_h_included__
extern "C" {
extern void MEM_CacheLimiter_set_maximum(intptr_t m);
extern intptr_t MEM_CacheLimiter_get_maximum();
};
#endif
template<class T>
class MEM_CacheLimiterHandle {
public:
explicit MEM_CacheLimiterHandle(T * data_,
MEM_CacheLimiter<T> * parent_)
: data(data_), refcount(0), parent(parent_) { }
void ref() {
refcount++;
}
void unref() {
refcount--;
}
T * get() {
return data;
}
const T * get() const {
return data;
}
int get_refcount() const {
return refcount;
}
bool can_destroy() const {
return !data || !refcount;
}
bool destroy_if_possible() {
if (can_destroy()) {
delete data;
data = 0;
unmanage();
return true;
}
return false;
}
void unmanage() {
parent->unmanage(this);
}
void touch() {
parent->touch(this);
}
private:
friend class MEM_CacheLimiter<T>;
T * data;
int refcount;
typename std::list<MEM_CacheLimiterHandle<T> *,
MEM_Allocator<MEM_CacheLimiterHandle<T> *> >::iterator me;
MEM_CacheLimiter<T> * parent;
};
template<class T>
class MEM_CacheLimiter {
public:
typedef typename std::list<MEM_CacheLimiterHandle<T> *,
MEM_Allocator<MEM_CacheLimiterHandle<T> *> >::iterator iterator;
~MEM_CacheLimiter() {
for (iterator it = queue.begin(); it != queue.end(); it++) {
delete *it;
}
}
MEM_CacheLimiterHandle<T> * insert(T * elem) {
queue.push_back(new MEM_CacheLimiterHandle<T>(elem, this));
iterator it = queue.end();
--it;
queue.back()->me = it;
return queue.back();
}
void unmanage(MEM_CacheLimiterHandle<T> * handle) {
queue.erase(handle->me);
delete handle;
}
void enforce_limits() {
intptr_t max = MEM_CacheLimiter_get_maximum();
intptr_t mem_in_use= MEM_get_memory_in_use();
intptr_t mmap_in_use= MEM_get_mapped_memory_in_use();
if (max == 0) {
return;
}
for (iterator it = queue.begin();
it != queue.end() && mem_in_use + mmap_in_use > max;) {
iterator jt = it;
++it;
(*jt)->destroy_if_possible();
}
}
void touch(MEM_CacheLimiterHandle<T> * handle) {
queue.push_back(handle);
queue.erase(handle->me);
iterator it = queue.end();
--it;
handle->me = it;
}
private:
std::list<MEM_CacheLimiterHandle<T>*,
MEM_Allocator<MEM_CacheLimiterHandle<T> *> > queue;
};
#endif
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